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Background: Ventilation as a function of elimination of CO2 during incremental exercise (VE/VCO2 slope) has been shown to be a valuable predictor of complications and death after major non‐cardiac surgery. VE/VCO2 slope and partial pressure of end‐tidal carbon dioxide (PetCO2) are both affected by ventilation/perfusion mismatch, but research on the utility of PetCO2 for risk stratification in major abdominal surgery is limited. Aim: We aimed to determine the correlation between VE/VCO2 slope and PetCO2 measured during preoperative cardiopulmonary exercise testing (CPET) and its association with major cardiopulmonary complications (MCPCs) or death following oesophageal and other major abdominal cancer surgeries. Method: In a retrospective cohort of 116 patients undergoing preoperative CPET 2008–2023, VE/VCO2 slope and PetCO2 (kPa) were recorded. The main outcome was MCPC during hospitalisation or death ≤90 days of surgery. We determined threshold values for each measure, corresponding to 90% specificity, using receiver operating characteristics analysis. Results: A strong negative correlation was found between PetCO2 after a 5‐minute warm‐up and VE/VCO2 slope (Pearson r = −.88). In oesophagus cancer, VE/VCO2 slope >38 and PetCO2 < 4.1 kPa (30.8 mmHg) were both significant thresholds for the main outcome. For other major abdominal surgery patients, threshold analyses were non‐significant. The area under the curve to predict outcome was similar using VE/VCO2 slope (0.70, 95% confidence interval 0.51–0.89) as compared to PetCO2 (0.71, 0.53–0‐90). Conclusion: Both preoperative VE/VCO2 slope and PetCO2 could identify subjects with a very high risk of complications following oesophageal resection, with similar prognostic utility. PetCO2 can be measured with simpler equipment and could therefore be useful when CPET is not available. [ABSTRACT FROM AUTHOR]

Objective Design Setting Animals Interventions Measurements and Main Results Conclusions To evaluate if variation in the end‐tidal CO2 partial pressure (∆Petco2) after a fluid challenge could predict fluid responsiveness with a sensitivity of 75% and a specificity of 70% in healthy anesthetized and mechanically ventilated dogs.Diagnostic accuracy study.University hospital.Twenty‐seven dogs admitted for neutering.To obtain a balanced sample between fluid responder and nonresponder dogs, a 10‐mL/kg lactated Ringer's solution was administered over 15 minutes to half of the population before the baseline measurements. All animals then received a fluid challenge of 10 mL/kg lactated Ringer's solution in 5 minutes.The velocity–time integral of aortic blood flow (VTIAo) was evaluated with Doppler echocardiography before and after a fluid challenge to classify the included dogs as fluid responders or nonresponders. Fluid responsiveness was defined as an increase of ≥15% of the VTIAo after the fluid challenge. Petco2 was evaluated at 1, 5, and 10 (T1, T5, T10) minutes after fluid expansion. Area under the receiver operating characteristic curve (AUROC) analysis was used to assess the ability of ∆Petco2 to predict fluid responsiveness at different time points. A total of 13 dogs were fluid responders, and 14 were nonresponders. The best predictive capacity for ∆Petco2 was observed at T10. The AUROC with its 95% confidence interval (CI) for ∆Petco2 at T10 was 0.75 (0.56–0.93), with a sensitivity of 84.62% (95% CI, 54.60–98.10), a specificity of 64.29% (95% CI, 35.10–87.20), a positive predictive value of 68.80% (95% CI, 41.30–89.00), and a negative predictive value of 81.80% (95% CI, 48.20–97.70). The optimal cutoff was 1 mm Hg.The current study showed that, although minimal, ∆Petco2 predicted fluid responsiveness in the dogs studied. [ABSTRACT FROM AUTHOR]

Background: Enhancing venous return during cardiopulmonary resuscitation (CPR) can lead to better hemodynamics and improved outcome after cardiac arrest (CA). Peripheral Intravenous Analysis (PIVA) provides feedback on venous flow changes and may indicate an increase in venous return and cardiac output during CPR. We hypothesize PIVA can serve as an early indicator of increased venous return, preceding end-tidal CO2 (etCO2) increase, before the return of spontaneous circulation (ROSC) in a rat model of CA and CPR. Results: Eight male Wistar rats were intubated and ventilated, and etCO2 was measured. Vessels were cannulated in the tail vein, femoral vein, femoral artery, and central venous and connected to pressure transducers. Ventilation was discontinued to achieve asphyxial CA. After 8 min, CPR began with ventilation, epinephrine, and automated chest compressions 200 times per minute until mean arterial pressure increased to 120 mmHg. Waveforms were recorded and analyzed. PIVA was calculated using a Fourier transformation of venous waveforms. Data are mean ± SE. Maximum PIVA values occurred in the tail vein 34.7 ± 2.9 s before ROSC, with subsequent PIVA peaks in femoral vein and centrally at 30.9 ± 5.4 and 25.1 ± 5.0 s, respectively. All PIVA peaks preceded etCO2 increase (21.5 ± 3.2 s before ROSC). Conclusion: PIVA consistently detected venous pressure changes prior to changes in etCO2. This suggests that PIVA has the potential to serve as an important indicator of venous return and cardiac output during CPR, and also as a predictor of ROSC. [ABSTRACT FROM AUTHOR]

Laparoscopic surgery involves creating a pneumoperitoneum with insufflation of CO2 into the abdomen to visualise during the surgery. Insufflation with CO2 has advantages such as reduced risk of venous air embolism however few disadvantages like sudden tachycardia and hypertension and hypercarbia. This study aimed at measuring the ETCO2 (End Tidal CO2) after intubation, after insufflation and 10 mins after pneumoperitoneum to analyse the rise of PaCo2 due to pneumoperitoneum with CO2 during laparoscopic surgeries. This study included 113 patients between 18-65 years of age, both sexes with ASA 1 & 2 posted for laparoscopic surgeries. Patients with History of Cardiovascular disorders, neurological disorders and pregnant patients were excluded from the study. After the start of the anaesthesia after intubation, the initial ETCO2 was noted and followed by wich the measurements were noted immediately after pneumoperitoneum and 10 mins after the pneumoperitoneum. Result was found that there was an immediate increase in ETCO2 value after pneumoperitoneum when compared to before and after 10 mins of pneumoperitoneum. This may be attributed to the absorption of co2 as a result of higher CO2 tension gradient between the pneumoperitoneum and the blood perfusing the peritoneum. [ABSTRACT FROM AUTHOR]

Abstract Background Enhancing venous return during cardiopulmonary resuscitation (CPR) can lead to better hemodynamics and improved outcome after cardiac arrest (CA). Peripheral Intravenous Analysis (PIVA) provides feedback on venous flow changes and may indicate an increase in venous return and cardiac output during CPR. We hypothesize PIVA can serve as an early indicator of increased venous return, preceding end-tidal CO2 (etCO2) increase, before the return of spontaneous circulation (ROSC) in a rat model of CA and CPR. Results Eight male Wistar rats were intubated and ventilated, and etCO2 was measured. Vessels were cannulated in the tail vein, femoral vein, femoral artery, and central venous and connected to pressure transducers. Ventilation was discontinued to achieve asphyxial CA. After 8 min, CPR began with ventilation, epinephrine, and automated chest compressions 200 times per minute until mean arterial pressure increased to 120 mmHg. Waveforms were recorded and analyzed. PIVA was calculated using a Fourier transformation of venous waveforms. Data are mean ± SE. Maximum PIVA values occurred in the tail vein 34.7 ± 2.9 s before ROSC, with subsequent PIVA peaks in femoral vein and centrally at 30.9 ± 5.4 and 25.1 ± 5.0 s, respectively. All PIVA peaks preceded etCO2 increase (21.5 ± 3.2 s before ROSC). Conclusion PIVA consistently detected venous pressure changes prior to changes in etCO2. This suggests that PIVA has the potential to serve as an important indicator of venous return and cardiac output during CPR, and also as a predictor of ROSC.

Pada seksio sesarea, keselamatan pasien adalah menjaga keselamatan ibu dan bayi. Anestesi untuk seksio sesarea dapat dilakukan dengan anestesi umum, anestesi neuraxial atau gabungan spinal-epidural. Keuntungan dari anestesi umum termasuk induksi cepat, keandalan, reproduktifitas, pengendalian, menghindari hipotensi. Sedangkan kelemahan anestesi umum meliputi kemungkinan aspirasi ibu, masalah penatalaksanaan jalan napas, narkotisasi neonatus, dan awarenes ibu. Efek anestesi umum pada bayi adalah karena penyebab fisiologis dan farmakologis. Penyebab fisiologis meliputi hipoventilasi ibu, hiperventilasi ibu dan pengaruh perpanjangan waktu induction-delivery dan uterine incission-delivery yang mempengaruhi aliran darah uteroplacental, sedangkan penyebab farmakologis adalah obat induksi anestesi, obat blokade neuromuskuler, konsentrasi oksigen rendah, N2O dan anestesi inhalasi. Masalah manajemen jalan napas adalah masalah terbesar karena mungkin jalan napas yang sulit pada wanita hamil mengingat adanya kenaikan berat badan dan lingkar leher, leher relatif pendek, dan buah dada membesar. Hipoventilasi akan mengurangi ketegangan oksigen pada ibu dan pada gilirannya akan menyebabkan perubahan asam-basa neonatal atau depresi biokimia. Hiperventilasi ibu juga dapat menimbulkan potensi bahaya pada janin selama anestesi umum dengan mengurangi tekanan oksigen janin. Kesimpulannya, pemasangan kapnograf pada ibu hamil yang dilakukan dengan seksio sesarea dengan anestesi umum mutlak diperlukan untuk memeriksa keberhasilan intubasi dan menentukan end-tidal CO2.

Introduction: End-tidal CO2 (ETCO2) detector is currently recommended for confirmation of endotracheal tube placement during neonatal resuscitation. Whether it is feasible to use ETCO2 detectors during mask ventilation to reduce risk of bradycardia and desaturations, which are associated with increased risk of death in preterm babies, is unknown. Methods: This is a pilot randomized controlled trial (NCT04287907) involving newborns 24 + 0/7 to 32 + 0/7 weeks gestation who required mask ventilation at birth. Infants were randomized into groups with or without colorimetric ETCO2 detectors. Combined duration of any bradycardia (<100 bpm) and time below prespecified target oxygen saturation (SpO2) as measured by pulse oximetry were compared. Results: Fifty participants were randomized, 47 with outcomes analysed (2 incomplete data, 1 postnatal diagnosis of trachea-oesophageal fistula). Mean gestational age and birthweight were 28.5 ± 1.9 versus 29.4 ± 1.6 weeks (p = 0.1) and 1,252.7 ± 409.7 g versus 1,334.6 ± 369.1 g (p = 0.5) in the intervention and control arm, respectively. Mean combined duration of bradycardia and desaturation was 276.7 ± 197.7 s (intervention) and 322.7 ± 277.7 s (control) (p = 0.6). Proportion of participants with any bradycardia or desaturation at 5 min were 38.1% (intervention) and 56.5% (control) (p = 0.2). No chest compressions, epinephrine administration, or death occurred in the delivery room. Conclusion: This pilot study demonstrates the feasibility of a trial to evaluate colorimetric ETCO2 detectors during mask ventilation of very preterm infants to reduce bradycardia and low SpO2. Further assessment with a larger population will be required to determine if ETCO2 detector usage at resuscitation reduces risk of adverse outcomes, including death and disability, in very preterm infants. [ABSTRACT FROM AUTHOR]

Abstract Background Capnography is a quantitative and reliable method of determining the ventilatory status of patients. We describe the test characteristics of capnography obtained during Emergency Department triage for screening acidemia. Results We performed an observational, pilot study of adult patients presenting to Emergency Department (ED) triage. The primary outcome was acidemia, as determined by the basic metabolic panel and/or blood gas during the ED visit. Secondary outcomes include comparison of estimated and measured respiratory rates (RR), relationships between end-tidal CO2 (EtCO 2 ) and venous partial pressure of CO 2 , admission disposition, in-hospital mortality during admission, and capnogram waveform analysis. A total of 100 adult ED encounters were included in the study and acidemia ( $$ \left[HC{O}_{3}^{-}\right]\le 22 \text{mEq/L}$$ or $$ pH< 7.35$$ ) was identified in 28 patients. The measured respiratory rate (20.3 ± 6.4 breaths/min) was significantly different from the estimated rate (18.4 ± 1.6 breaths/min), and its area under the receiver operating curve (c-statistic) to predict acidemia was only 0.60 (95% CI 0.51–0.75, p = 0.03). A low end-tidal CO2 (EtCO 2

Prehospital care is a fundamental component of stroke care that predominantly focuses on shortening the time between diagnosis and reaching definitive stroke management. With growing evidence of the physiological parameters affecting long-term patient outcomes, prehospital clinicians need to consider the balance between rapid transfer and increased physiological-parameter monitoring and intervention. This systematic review explores the existing literature on prehospital physiological monitoring and intervention to modify these parameters in stroke patients. The systematic review was registered on PROSPERO (CRD42022308991) and conducted across four databases with citation cascading. Based on the identified inclusion and exclusion criteria, 19 studies were retained for this review. The studies were classified into two themes: physiological-monitoring intervention and pharmacological-therapy intervention. A total of 14 included studies explored prehospital physiological monitoring. Elevated blood pressure was associated with increased hematoma volume in intracerebral hemorrhage and, in some reports, with increased rates of early neurological deterioration and prehospital neurological deterioration. A reduction in prehospital heart rate variability was associated with unfavorable clinical outcomes. Further, five of the included records investigated the delivery of pharmacological therapy in the prehospital environment for patients presenting with acute stroke. BP-lowering interventions were successfully demonstrated through three trials; however, evidence of their benefit to clinical outcomes is limited. Two studies investigating the use of oxygen and magnesium sulfate as neuroprotective agents did not demonstrate an improvement in patient's outcomes. This systematic review highlights the absence of continuous physiological parameter monitoring, investigates fundamental physiological parameters, and provides recommendations for future work, with the aim of improving stroke patient outcomes. [ABSTRACT FROM AUTHOR]

Reduced exercise tolerance is one of the hallmarks of patients with cardiac amyloidosis (CA), but detailed biological responses during exercise were not investigated. The purpose of this study was to compare the cardiopulmonary exercise test (CPX) parameters between CA patients and propensity-matched heart failure patients. This was a single-center, retrospective, observational study of patients diagnosed with CA. The control group was extracted by propensity score matching from patients who underwent CPX for chronic heart failure during the same period. Clinical data including assessment of biological responses during CPX were compared between the patients with CA (CA group, n = 16) and the control group (non-CA group, n = 16). Echocardiography suggested more impaired diastolic function in the CA group than in the non-CA group. There was no significant difference between groups in the fraction of end-tidal carbon dioxide (FETCO2) at rest. However, the difference between the FETCO2 at rest and the FETCO2 at the respiratory compensation point (ΔFETCO2) was significantly smaller in the CA group than in the non-CA group (0.40% ± 0.37% vs. 0.82% ± 0.33%; p = 0.002). Only in the CA group, there was a significant negative correlation between the ΔFETCO2 and the E/e' ratio on echocardiography (r = − 0.521; p = 0.039) and the serum high-sensitivity troponin T concentration (r = − 0.501; p = 0.048). In conclusion, patients with CA may find it difficult to increase cardiac output during exercise due to severe diastolic dysfunction. [ABSTRACT FROM AUTHOR]

Waveform capnography is a noninvasive measurement of ventilation and perfusion commonly employed in the prehospital setting. It is easy to apply, and modern cardiac monitors are equipped with the necessary ports and capability to display results. Despite its ease of use, end-tidal CO2 monitoring has not yet achieved widespread adoption within the hospital setting. It is routinely used in the emergency department and by anesthesiologists, but its application could support ICU management in critically ill patients. Its use is routinely supported by multiple professional societies, and it has been recommended as a requirement in all cardiac arrests. Careful analysis of the waveform and expired carbon dioxide can guide therapy for patients experiencing respiratory emergencies, hemodynamic compromise, metabolic acidosis, and shock due to trauma, hypovolemia, or sepsis. Use of capnography throughout the hospital could improve patient outcomes and prevent unidentified deterioration. [ABSTRACT FROM AUTHOR]

Face masks were recognized as one of the most effective ways to prevent the spread of the COVID-19 virus in adults. These benefits were extended to children and adolescents. However, the fear of negative consequences from wearing a face mask during physical exercise led to cancellations of physical education lessons. This further decreased the amount of physical activity available to children and adolescents during the pandemic. However, there is little published data on the potential adverse effects of wearing the most effective and partially mandatory FFP2/N95 face masks during PE or physical activity (PA) in this age. Even though the pandemic has been declared as passed by the WHO, the rise of a new pandemic and thus the use of face masks for limiting its spread is inevitable, so we need to be better prepared for alternative options to lockdown and limitation of PA in such a scenario. Twenty healthy children aged 8–10 years performed two identical cardiopulmonary exercise tests as an incremental step test on a treadmill within an interval of 2 weeks, one time without wearing a protective mask and one time wearing an FFP2 mask. The cardiopulmonary exercise parameter and especially the end-expiratory gas exchange for oxygen and carbon dioxide (petO2 and petCO2) were documented for each step, at rest and 1 min after reaching physical exhaustion. Twelve boys (mean age 8.5 ± 1.4 years) and 8 girls (mean age 8.8 ± 1.4 years) showed no adverse events until maximal exertion. The mean parameters measured at peak exercise did not differ significantly between both examinations (mean peak VO2 = 42.7 ± 9.5 vs 47.8 ± 12.9 ml/min/kg, p = 0.097, mean O2pulse 7.84 ± 1.9 ml/min vs. 6.89 ± 1.8, p = 0.064, mean VE/VCO2slope 33.4 ± 5.9 vs. 34.0 ± 5.3, p = 0.689). The only significant difference was the respiratory exchange rate (RER, 1.01 ± 0.08 vs 0.95 ± 0.08, p = 0.004). The measured respiratory gases (end-tidal O2 and CO2) decreased and respectively increased significantly in almost every step when wearing an FFP2 mask. However, these levels were well below hypercapnia and above hypoxia. Conclusion: In this study, no significant differences in the cardiorespiratory function at peak exercise could be discerned when wearing an FFP2/N95 face mask. While the end-tidal values for CO2 increased significantly and the end-tidal values for O2 decreased significantly, these values did never reach levels of hypercapnia or hypoxia. Furthermore, the children terminated the exercise at a lower RER and heart rate (HR) suggesting a subconscious awareness of the higher strain. Since the detrimental effects of limiting sports during the pandemic are well documented, stopping PE lessons altogether because of the minor physiological effects of wearing these masks instead of simply stopping pushing children to perform at their best seems premature and should be reconsidered in the future. What is Known: • Wearing a face mask has an influence on psychological, social, and physiological functions in adults. • Because of the observed effects of wearing face masks in adults, physical activity in children was limited during the pandemic. What is New: • Wearing an FFP2/N95 mask during physical activity did not lead to hypercapnia or hypoxia in children in this study. • Even though end-tidal CO2 values were significantly higher and end-tidal O2 values significantly lower when wearing an FFP2/N95 face mask, no pathological values were reached. [ABSTRACT FROM AUTHOR]

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Early diagnosis and treatment of postspinal hypotension (PSH) in obstetric anaesthesia reduces the risk of maternofetal complications. In this study, the effect of EtCO2 and the integrated pulmonary index (IPI) in predicting PSH was investigated. Patients scheduled for cesarean section under spinal anaesthesia were included. The Capnostream 35 respiratory monitor (Medtronic, Inc., Dublin, Ireland) was used for EtCO2 and IPI. PSH developed in 52 (63.4%) of the 82 patients. EtCO2 and IPI values decreased significantly compared with baseline values in patients who developed PSH. There were statistically significant differences in EtCO2 (p = 0.001) and the IPI change (p = 0.045) in patients who developed PSH compared with those who did not. It was found that the EtCO2 difference had an independent effect on predicting PSH (p < 0.05), whereas the IPI difference did not (p > 0.05). One unit decrease in EtCO2 from the baseline increased the risk of PSH by 3.3 times. ROC curve analysis showed that the magnitude of change in EtCO2 was diagnostic for predicting PSH (AUC: 0.90 (0.83–0.97; p < 0.001)). IPI showed no predictive value for postspinal hypotension in cesarean section. However, EtCO2 monitoring, which is non-invasive and real-time monitoring, can be used to predict postspinal hypotension. [ABSTRACT FROM AUTHOR]

Background: Optimization of pulmonary to systemic blood flow (Qp:Qs) is the key to postoperative care of children with a single-ventricular heart. The ratio of end tidal CO2 to partial pressure of CO2 called alveolar functional fraction (AFF) has shown a strong relationship with Qp:Qs in the catheterization lab in this population (with Qp:Qs of 1 correlating with AFF of 0.7). As there are no studies to understand the relationship between AFF and clinical outcomes in the postoperative care of these children, this study was carried out. Methodology and Results: This retrospective cohort study included 29 postoperative periods of children who underwent surgery for a single-ventricular heart. The average AFF was calculated for each early postoperative period. The primary clinical outcome was time in hours to normalize lactate. Other clinical outcomes included duration of mechanical ventilation, duration of milrinone infusion; presence of acute kidney injury (AKI), seizures and necrotizing enterocolitis (NEC); need for tracheostomy, need for extra-corporeal support, and mortality in the first 60 days postoperatively. The study population was divided into Group 1 with AFF ≤0.7 and Group 2 with AFF >0.7, to compare the outcome differences between the groups. Time to normalize the lactate had a modest negative correlation with the AFF, with Pearson's r = -0.49 (P = 0.007) for the entire cohort. The clinical outcomes were not statistically different for groups with AFF ≤0.7 and with AFF >0.7, although the group with AFF ≤0.7 had a higher incidence of NEC and higher mortality, whereas the group with AFF >0.7 had a higher incidence of AKI. Conclusions: In this small study, the AFF showed a modest negative correlation with the time to normalize lactate in postoperative care after surgery for a single ventricle heart. There were the trends with some other important clinical outcomes but not statistically significant. A larger, multi center study is needed to delineate these relationships further. [ABSTRACT FROM AUTHOR]

In a business as usual scenario, atmospheric carbon dioxide concentration (CO2) could reach 950 parts per million (ppm) by 2100. Indoor CO2 concentrations will rise consequently, given its dependence on atmospheric CO2 levels. If buildings are ventilated following current standards in 2100, indoor CO2 concentration could be over 1300 ppm, depending on specific ventilation codes. Such exposure to CO2 could have physiological and psychological effects on building occupants. We conducted a randomized, within-subject study, examining the physiological effects on the respiratory functions of 15 persons. We examined three exposures, each 150 min long, with CO2 of: 900 ppm (reference), 1450 ppm (decreased ventilation), and 1450 ppm (reference condition with added pure CO2). We measured respiratory parameters with capnometry and forced vital capacity (FVC) tests. End-tidal CO2 and respiration rates did not significantly differ across the three exposures. Parameters measured using FVC decreased significantly from the start to the end of exposure only at the reduced ventilation condition (p

Dysregulation of the autonomic nervous system (ANS) may play an important role in the development and maintenance of persistent post-concussive symptoms (PPCS). Post-injury breathing dysfunction, which is influenced by the ANS, has not been well-studied in youth. This study evaluated cardiorespiratory functioning at baseline in youth patients with PPCS and examined the relationship of cardiorespiratory variables with neurobehavioral outcomes. Participants were between the ages of 13-25 in two groups: (1) Patients with PPCS (concussion within the past 2-16 months; n = 13) and (2) non-injured controls (n = 12). Capnometry was used to obtain end-tidal CO2 (EtCO2), oxygen saturation (SaO2), respiration rate (RR), and pulse rate (PR) at seated rest. PPCS participants exhibited a reduced mean value of EtCO2 in exhaled breath (M = 36.3 mmHg, SD = 2.86 mmHg) and an altered inter-correlation between EtCO2 and RR compared to controls. Neurobehavioral outcomes including depression, severity of self-reported concussion symptoms, cognitive catastrophizing, and psychomotor processing speed were correlated with cardiorespiratory variables when the groups were combined. Overall, results from this study suggest that breathing dynamics may be altered in youth with PPCS and that cardiorespiratory outcomes could be related to a dimension of neurobehavioral outcomes associated with poorer recovery from concussion.

Aim: Children with obstructive sleep apnea have an increased postoperative risk of adverse respiratory events. In our study, we calculated Obstructive Sleep Apnea Scores using the modified STOP-Bang questionnaire in children undergoing oropharyngeal surgery. The groups determined according to this score were compared in terms of mask ventilation levels in the intraoperative period, postoperative complications and postoperative ETCO2 levels. Materials and Methods: A total of 90 patients, aged 7-15 years, who will undergo oropharyngeal surgery, classified as ASA I-II, and who have undergone a modified STOPBang questionnaire at the preoperative examination, were included in the study. Obstructive sleep apnea score (OSAs) was determined according to the modified STOP-Bang questionnaire, and the patients were divided into 3 groups as low, medium, and high-risk. Difficult mask ventilation level was noted in the intraoperative period. At the end of the operation, end-tidal carbon dioxide concentration (ETCO2) values at 0, 3, 5, 10, and 15 minutes after the patient was extubated and whether the patient had spasms were recorded. Results: Among the 8 parameters in the modified STOP-Bang questionnaire, it was found that there was a significant difference between the groups for the other 6 parameters except for snoring and learning disability. Diffucult mask ventilation increased significantly from Group I to Group III. There is a significant difference between Group I and II, Group II and III, and Group I and Group III (p= 0.001). Although there were small differences within the groups and between the measurements of ETCO2 at different minutes, these differences were not statistically significant (p=0.05). Conclusion: In conclusion, associations between the results of the modified STOP-Bang questionnaire and the level of intervention required for difficult mask ventilation, this information could serve as a useful indicator for a higher level of care in the perioperative period for future patients. [ABSTRACT FROM AUTHOR]

Cerebral venous oxygenation (Yv) is a valuable biomarker for a variety of brain diseases. T2 relaxation under spin tagging (TRUST) MRI is a widely used method for Yv quantification. In this work, there were two main objectives. The first was to evaluate the reproducibility of TRUST Yv measurements across MRI scanners from different vendors. The second was to examine the correlation between Yv and end‐tidal CO2 (EtCO2) in a multisite, multivendor setting and determine the usefulness of this correlation to account for variations in Yv caused by normal variations and physiological fluctuations. Standardized TRUST pulse sequences were implemented on three scanners from major MRI vendors (GE, Siemens, Philips). These scanners were located at two research institutions. Ten healthy subjects were scanned. On each scanner, the subject underwent two scan sessions, each of which included three TRUST scans, to evaluate the intrasession and intersession reproducibility of Yv. Each scanner was also equipped with a capnograph device to record the EtCO2 of the subject during the MRI scan. We found no significant bias in Yv measurements across the three scanners (P = 0.18). The measured Yv values on the three scanners were also strongly correlated with each other (intraclass correlation coefficients > 0.85, P < 0.001). The intrasession and intersession coefficients of variation of Yv were less than 4% and showed no significant difference among the scanners. In addition, our results revealed that (1) within the same subject, Yv increased with EtCO2 at a rate of 1.24 ± 0.17%/mmHg (P < 0.0001), and (2) across different subjects, individuals with a higher EtCO2 had a higher Yv, at a rate of 0.94 ± 0.36%/mmHg (P = 0.01). These results suggest that (1) the standardized TRUST sequences had similar accuracies and reproducibilities for the quantification of Yv across the scanners, and (2) recording of EtCO2 may be a useful complement to Yv measurement to account for CO2‐related physiological fluctuations in Yv in multisite, multivendor studies. [ABSTRACT FROM AUTHOR]

Prolonged bedrest provokes orthostatic hypotension and intolerance of upright posture. Limited data are available on the cardiovascular responses of older adults to head-up tilt following bedrest, with no studies examining the potential benefits of exercise to mitigate intolerance in this age group. This randomized controlled trial of head-down bedrest (HDBR) in 55- to 65-yr-old men and women investigated if exercise could avert post-HDBR orthostatic intolerance. Twenty-two healthy older adults (11 female) underwent a strict 14-day HDBR and were assigned to either an exercise (EX) or control (CON) group. The exercise intervention included high-intensity, aerobic, and resistance exercises. Head-up tilt-testing to a maximum of 15 minutes was performed at baseline (Pre-Bedrest) and immediately after HDBR (R1), as well as 6 days (R6) and 4 weeks (R4wk) later. At Pre-Bedrest, three participants did not complete the full 15 minutes of tilt. At R1, 18 did not finish, with no difference in tilt end time between CON (422 ± 287 s) and EX (409 ± 346 s). No differences between CON and EX were observed at R6 or R4wk. At R1, just 1 participant self-terminated the test with symptoms, while 12 others reported symptoms only after physiological test termination criteria were reached. Finishers on R1 protected arterial pressure with higher total peripheral resistance relative to Pre-Bedrest. Cerebral blood velocity decreased linearly with reductions in arterial pressure, end-tidal CO2, and cardiac output. High-intensity interval exercise did not benefit post-HDBR orthostatic tolerance in older adults. Multiple factors were associated with the reduction in cerebral blood velocity leading to intolerance. [ABSTRACT FROM AUTHOR]

Background: Optimization of pulmonary to systemic blood flow (Qp:Qs) is the key to postoperative care of children with a single-ventricular heart. The ratio of end-tidal CO2 to partial pressure of CO2 called alveolar functional fraction (AFF) has shown a strong relationship with Qp:Qs in the catheterization lab in this population (with Qp:Qs of 1 correlating with AFF of 0.7). As there are no studies to understand the relationship between AFF and clinical outcomes in the postoperative care of these children, this study was carried out. Methodology and Results: This retrospective cohort study included 29 postoperative periods of children who underwent surgery for a single-ventricular heart. The average AFF was calculated for each early postoperative period. The primary clinical outcome was time in hours to normalize lactate. Other clinical outcomes included duration of mechanical ventilation, duration of milrinone infusion; presence of acute kidney injury (AKI), seizures and necrotizing enterocolitis (NEC); need for tracheostomy, need for extra-corporeal support, and mortality in the first 60 days postoperatively. The study population was divided into Group 1 with AFF ≤0.7 and Group 2 with AFF >0.7, to compare the outcome differences between the groups. Time to normalize the lactate had a modest negative correlation with the AFF, with Pearson’s r = −0.49 (P = 0.007) for the entire cohort. The clinical outcomes were not statistically different for groups with AFF ≤0.7 and with AFF >0.7, although the group with AFF ≤0.7 had a higher incidence of NEC and higher mortality, whereas the group with AFF >0.7 had a higher incidence of AKI. Conclusions: In this small study, the AFF showed a modest negative correlation with the time to normalize lactate in postoperative care after surgery for a single-ventricle heart. There were the trends with some other important clinical outcomes but not statistically significant. A larger, multi-center study is needed to delineate these relationships further.

Background: Poisoning with carbon monoxide occurs occasionally worldwide, and the gold diagnostic standard is to measure carboxyhemoglobin level in the blood. This study investigated the correlation between carboxyhemoglobin and the end-tidal carbon dioxide levels in 50 patients with carbon monoxide poisoning. Methods: We recruited 50 volunteer patients who had been admitted to the Emergency Services of Istanbul Medipol University Hospital between January 2017 and January 2018. They had been diagnosed with carbon monoxide poisoning unrelated to fire accidents. The arterial and venous blood gases, and other blood and clinical parameters were also measured. The patients’ end-tidal carbon dioxide levels were measured from the nose and mouth air, using a Capnostream 20p bedside monitor. Pearson’s correlation analyses were performed and the results were compared with the end-tidal carbon dioxide, carboxyhemoglobin and oxygen saturation in the arterial and venous blood samples. Results: The Mean±SD age was 33.98±10.89 years. The Mean±SD arterial and venous carboxyhemoglobin values were 18.05±7.10 and 12.11±9.67, respectively. There were no statistically significant differences between the oxygen saturation, and the arterial and venous blood levels of carboxyhemoglobin (P=0.870, P=0.950), respectively. Also, no statistically significant correlations were found between the end-tidal carbon dioxide, and the arterial and venous carboxyhemoglobin levels (P=0.529, P=0.601), respectively. Conclusion: The results from the blood analyses demonstrated that there was no statistically significant difference between the end-tidal carbon dioxide and the carboxyhemoglobin levels in these patients who had been earlier diagnosed with carbon monoxide poisoning, unrelated to fire accidents.

Learning Objective: Hemodynamic monitoring during in-hospital transport of intubated patients is vital; however, no prospective randomized trials have evaluated the hemodynamic consequences of hand versus machine ventilation during transport among pediatric patients’ post-cardiac surgery. The authors hypothesized that manual ventilation after pediatric cardiac surgery would alter hemodynamic and arterial blood gas (ABG) parameters during transport compared to mechanical ventilation. Design: A prospective randomized trial. Setting: Tertiary cardiac care hospital. Participants: Pediatric cardiac surgery patients. Materials and Methods: One hundred intubated pediatric patients were randomized to hand or machine ventilation immediately post-cardiac surgery during transport from the operating room to the pediatric post-operative intensive care unit (PICU). Hemodynamic variables, including end-tidal CO2 (ETCO2), oxygen saturation, heart rate, systolic blood pressure (SBP), diastolic blood pressure (DBP), peak airway pressure (Ppeak), and mean airway pressure (Pmean), were measured at origin, during transport, and at the destination. ABG was measured before and upon arrival in the PICU, and adverse events were recorded. The Chi-square test and independent t-test were used for comparison of categorical and continuous parameters, respectively. Results and Discussion: The mean transport time was comparable between hand-ventilated (5.77 ± 1.46 min) and machine-ventilated (5.96 ± 1.19 min) groups (P = 0.47). ETCO2 consistently dropped during transport and after shifting in the hand-ventilated group, with significantly higher ETCO2 excursion than in machine-ventilated patients (P< 0.05). SBP and DBP significantly decreased during transport (at 5 and 6 min intervals) and after shifting in hand-ventilated patients than in the other group (P < 0.05). Additionally, after shifting, a significant increase in Ppeak (P < 0.001), Pmean (P < 0.001), and pH (P < 0.001), and a decrease in pCO2 (P = 0.0072) was observed in hand-ventilated patients than machine-ventilated patients. No adverse event was noted during either mode of ventilation. Conclusion: Hand ventilation leads to more significant variation in ABG and hemodynamic parameters than machine ventilation in pediatric patients during transport post-cardiac surgery. Therefore, using a mechanical ventilator is the preferred method for transporting post-operative pediatric cardiac patients. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the effectiveness of an educational program about measuring ventilation using devices that assess carbon dioxide levels in patients recovering from a surgical procedure. A pre-post survey of knowledge attainment from an educational intervention about measuring ventilation using end-tidal carbon dioxide (EtCO 2) and transcutaneous carbon dioxide (tcPCO 2) devices in the postanesthesia care unit (PACU) was distributed to current members of the American Society of PeriAnesthesia Nurses. Participants received a 12-question pre-intervention (five were related to demographics) and a five-question post-intervention survey. Non-demographic survey questions used a one to five Likert scale to assess comfortability or confidence. The intervention created was a voice-over presentation designed to improve PACU RN's comfort and confidence with using and interpreting tcPCO 2 or EtCO 2 in the PACU. PACU RNs (N = 108) reported they 'never' or 'rarely' used EtCO 2 (n = 57, 52.7%) monitoring or tcPCO 2 (n = 93, 86.1%) monitoring in the PACU. A paired t test revealed statistically significant differences in the PACU RN's pre-survey and posttest comfortability of applying and interpreting EtCO 2 or tcPCO 2 monitors (P <.05). Capnography monitoring should be considered a standard of care for PACU patients. Education of registered nurses working in the PACU is critical before implementing EtCO 2 or tcPCO 2 monitoring. [ABSTRACT FROM AUTHOR]

Background: Poisoning with carbon monoxide occurs occasionally worldwide, and the gold diagnostic standard is to measure carboxyhemoglobin level in the blood. This study investigated the correlation between carboxyhemoglobin and the end-tidal carbon dioxide levels in 50 patients with carbon monoxide poisoning. Methods: We recruited 50 volunteer patients who had been admitted to the Emergency Services of Istanbul Medipol University Hospital between January 2017 and January 2018. They had been diagnosed with carbon monoxide poisoning unrelated to fire accidents. The arterial and venous blood gases, and other blood and clinical parameters were also measured. The patients' end-tidal carbon dioxide levels were measured from the nose and mouth air, using a Capnostream 20p bedside monitor. Pearson's correlation analyses were performed and the results were compared with the end-tidal carbon dioxide, carboxyhemoglobin and oxygen saturation in the arterial and venous blood samples. Results: The Mean±SD age was 33.98±10.89 years. The Mean±SD arterial and venous carboxyhemoglobin values were 18.05±7.10 and 12.11±9.67, respectively. There were no statistically significant differences between the oxygen saturation, and the arterial and venous blood levels of carboxyhemoglobin (P=0.870, P=0.950), respectively. Also, no statistically significant correlations were found between the end-tidal carbon dioxide, and the arterial and venous carboxyhemoglobin levels (P=0.529, P=0.601), respectively. Conclusion: The results from the blood analyses demonstrated that there was no statistically significant difference between the end-tidal carbon dioxide and the carboxyhemoglobin levels in these patients who had been earlier diagnosed with carbon monoxide poisoning, unrelated to fire accidents. [ABSTRACT FROM AUTHOR]

Aim: Characterise how changes in chest compression depth and rate affect variations in end-tidal CO2 (ETCO2) during manual cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA).Methods: Retrospective analysis of adult OHCA monitor-defibrillator recordings having concurrent capnogram, compression depth, transthoracic impedance and ECG, and with atleast 1,000 compressions. Within each patient, during no spontaneous circulation, nearby segments with changes in chest compression depth and rate were identified. Average ETCO2 within each segment was standardised to compensate for ventilation rate variability. Contributions of relative variations in depth and rate to relative variations in standardised ETCO2 were characterised using linear and non-linear models. Normalisation between paired segments removed intra and inter-patient variation and made coefficients of the model independent of the scale of measurement and therefore directly comparable.Results: A total of 394 pairs of segments from 221 patients were analysed (33% female, median (IQR) age 66 (55-74) years). Chest compression depth and rate were 50.4 (43.2-57.0)mm and 111.1 (106.5-116.1)compressions per minute. ETCO2 before and after standardization was 32.1 (23.0-41.4)mmHg and 28.5 (19.4-38.7)mmHg. Linear model coefficient of determination was 0.89. Variation in compression depth mainly explained ETCO2 variation (coefficient 0.95, 95% confidence interval (CI): 0.93-0.98) while changes in compression rate did not (coefficient 0.04, 95% CI: 0.01-0.07). Non-linear trend analysis confirmed the results.Conclusion: This study quantified the relative importance of chest compression characteristics in terms of their impact on CO2 production during CPR. With ventilation rate standardised, variation in chest compression depth explained variations in ETCO2 better than variation in chest compression rate. [ABSTRACT FROM AUTHOR]

Background: The aim of this study is to reveal the relationship between end-tidal CO2 (EtCO2) values with infarct volume and early prognosis in patients diagnosed with acute ischemic stroke in the emergency department. Materials and Methods: This prospective cross-sectional study was conducted in a tertiary hospital. The demographics, characteristics, EtCO2, volume of the stroke area on diffusion-weighted magnetic resonance imaging and the modified Rankin Scale (mRS) of the patients were recorded. The values calculated at admission and at discharge were labeled as "mRS-1" and "mRS-2," respectively, and the mRS-2 measurement was used as a prognostic indicator. The "good" and the "poor" functional outcomes were defined as mRS ≤2 and mRS >2, respectively. Correlations between levels of EtCO2 and infarct volume, mRS were calculated. Results: In total, 44 patients were included in the study. The median age of the patients was 69 years (interquartile range; 16; min-max: 35 to 88 y) and 68.2% of them were male. In the univariate logistic regression models of the mRS-2 [0 to 2 (0) and 3 to 6 (1)], all variables were not statistically significant to predict mRS-2 group. There were statistically significant differences in EtCO2 values between mRS-1 (P =0.03) and mRS-2 (P =0.04). A negative moderate correlation was found between EtCO2 and mRS-2 (r =−0.410; P =0.006). The correlation between EtCO2 and infarct volume was not statistically significant (r =−0.256; P =0.093). Conclusions: This study highlights the importance of capnography follow-up of patients with acute ischemic stroke. In patients with acute ischemic stroke, the EtCO2 value measured at the time of admission is lower in the group with high mRS at both admission and discharge. [ABSTRACT FROM AUTHOR]

Abstract Purpose In acute respiratory distress syndrome (ARDS), dead space fraction has been independently associated with mortality. We hypothesized that early measurement of the difference between arterial and end-tidal CO2 (arterial-ET difference), a surrogate for dead space fraction, would predict mortality in mechanically ventilated patients with ARDS. Methods We performed two separate exploratory analyses. We first used publicly available databases from the ALTA, EDEN, and OMEGA ARDS Network trials (N = 124) as a derivation cohort to test our hypothesis. We then performed a separate retrospective analysis of patients with ARDS using University of Chicago patients (N = 302) as a validation cohort. Results The ARDS Network derivation cohort demonstrated arterial-ET difference, vasopressor requirement, age, and APACHE III to be associated with mortality by univariable analysis. By multivariable analysis, only the arterial-ET difference remained significant (P = 0.047). In a separate analysis, the modified Enghoff equation ((PaCO2–PETCO2)/PaCO2) was used in place of the arterial-ET difference and did not alter the results. The University of Chicago cohort found arterial-ET difference, age, ventilator mode, vasopressor requirement, and APACHE II to be associated with mortality in a univariate analysis. By multivariable analysis, the arterial-ET difference continued to be predictive of mortality (P = 0.031). In the validation cohort, substitution of the arterial-ET difference for the modified Enghoff equation showed similar results. Conclusion Arterial to end-tidal CO2 (ETCO2) difference is an independent predictor of mortality in patients with ARDS.

Evaluation and monitoring perfusion of vital organs is important during resuscitation from cardiac arrest. We developed a non-invasive electroencephalogram (EEG) based brain resuscitation index (EBRI) as a physiologic indicator measuring organ perfusion during cardiopulmonary resuscitation (CPR) and evaluated the correlation of EBRI and end-tidal carbon dioxide (ETCO2). A randomized crossover experimental study using a porcine cardiac arrest model was designed. After 1 minute of untreated ventricular fibrillation, 10 periods of higher-quality CPR (compression depth 5 cm and compression rate 100/min) for 50 seconds and lower-quality CPR (compression depth 3 cm and compression rate 60/min) for 50 seconds were performed in alternation. EBRI was calculated from the single EEG channel with the lowest noise. Mixed-model analysis was conducted to compare the differences of hemodynamic parameters, ETCO2, and EBRI between higher-quality CPR periods and lower-quality CPR periods. Pearson's correlation coefficient was calculated to assess correlation between EBRI and ETCO2. The experiment was performed on 5 female swine (44.6 ± 2.8 kg). Higher-quality CPR showed significantly higher delta EBRI (median [IQR] 0.1 [0.0-0.2]) than did lower-quality CPR (median [IQR] -0.1 [-0.2-0.0],p < 0.01). EBRI had a statistically moderate positive correlation with ETCO2 (r = 0.51). In this porcine cardiac arrest model, EBRI was successfully obtained during resuscitation and had a statistically moderate correlation with ETCO2. [ABSTRACT FROM AUTHOR]

Background End-tidal carbon dioxide (ETCO2) measurement is more applied in clinical practice, as it is a noninvasive tool that helps to evaluate the ventilatory status of the patient. The aim of the present study was to investigate the relationship between ETCO2 and arterial partial pressure of CO2 (PaCO2) measurements and to estimate the role of capnography during weaning off mechanical ventilation. Patients and methods A prospective cross-sectional study was conducted on 60 adult critically ill patients with respiratory failure, comprising 47 males and 13 females. They were put on mechanical ventilation, and after fulfilling criteria of weaning, they were kept on continuous positive airway pressure (CPAP) mode for 1 h. ETCO2, PaCO2, and gradient were measured before and after weaning. Results Mean difference between PaCO2 and ETCO2 before weaning was 8.3 and after one hour on CPAP was 5.1. There was a highly statistically significant positive correlation between ETCO2 and PaCO2 before weaning and after 1 h on CPAP. Bland-Altman comparison between ETCO2 and PaCO2 before weaning and after 1 h on CPAP revealed limits of agreement were 1.941 to 14.826 and −4.134 to 14.367, respectively. Conclusion ETCO2 measurement gives a proper estimation of PaCO2 in patients on mechanical ventilation. ETCO2 decreases the need for repeated invasive arterial blood gas samples.

Carbon dioxide measurement is useful for confirmation of successful tracheal intubation and ensuring adequate ventilation. There are two types of CO2 detectors, i.e., single-use-only colorimetric devices and capnometers. Although portable capnometers are widely used for resuscitation, there have been no reports regarding their clinical utility in neonates. The correspondence between end-tidal CO2 (PetCO2) level determined using a battery-powered portable capnometer and arterial CO2 (PaCO2) was investigated using paired data obtained simultaneously from 26 neonates weighing 1262 ± 589 g at examination on mechanical ventilation. PetCO2 level and PaCO2 showed a strong correlation (r = 0.839, P < 0.001), and the correlation equation was: PetCO2 = 0.8 × PaCO2 + 1.1. Therefore, PetCO2 readings obtained with a battery-powered portable capnometer were likely to be underestimated. This became more pronounced with decreasing infant body weight at examination as the net difference in measurements of PaCO2 and PetCO2 was significantly positively correlated with infant body weight at examination (r = 0.451, P < 0.001). The observations presented here may be helpful in the use of battery-powered portable capnometers in neonates requiring controlled ventilation with tracheal intubation. [ABSTRACT FROM AUTHOR]

Cerebrovascular reactivity (CVR), which measures the ability of cerebral blood vessels to dilate or constrict in response to vasoactive stimuli such as CO2 inhalation, is an important index of the brain's vascular health. Quantification of CVR using BOLD MRI with hypercapnia challenge has shown great promises in research and clinical studies. However, in order for it to be used as a potential imaging biomarker in large-scale and multi-site studies, the reliability of CO2-CVR quantification across different MRI acquisition platforms and researchers/raters must be examined. The goal of this report from the MarkVCID small vessel disease biomarkers consortium is to evaluate the reliability of CO2-CVR quantification in three studies. First, the inter-rater reliability of CO2-CVR data processing was evaluated by having raters from 5 MarkVCID sites process the same 30 CVR datasets using a cloud-based CVR data processing pipeline. Second, the inter-scanner reproducibility of CO2-CVR quantification was assessed in 10 young subjects across two scanners of different vendors. Third, test-retest repeatability was evaluated in 20 elderly subjects from 4 sites with a scan interval of less than 2 weeks. In all studies, the CO2 CVR measurements were performed using the fixed inspiration method, where the subjects wore a nose clip and a mouthpiece and breathed room air and 5% CO2 air contained in a Douglas bag alternatively through their mouth. The results showed that the inter-rater CoV of CVR processing was 0.08 ± 0.08% for whole-brain CVR values and ranged from 0.16% to 0.88% in major brain regions, with ICC of absolute agreement above 0.9959 for all brain regions. Inter-scanner CoV was found to be 6.90 ± 5.08% for whole-brain CVR values, and ranged from 4.69% to 12.71% in major brain regions, which are comparable to intra-session CoVs obtained from the same scanners on the same day. ICC of consistency between the two scanners was 0.8498 for whole-brain CVR and ranged from 0.8052 to 0.9185 across major brain regions. In the test-retest evaluation, test-retest CoV across different days was found to be 18.29 ± 17.12% for whole-brain CVR values, and ranged from 16.58% to 19.52% in major brain regions, with ICC of absolute agreement ranged from 0.6480 to 0.7785. These results demonstrated good inter-rater, inter-scanner, and test-retest reliability in healthy volunteers, and suggested that CO2-CVR has suitable instrumental properties for use as an imaging biomarker of cerebrovascular function in multi-site and longitudinal observational studies and clinical trials.

Purpose: In acute respiratory distress syndrome (ARDS), dead space fraction has been independently associated with mortality. We hypothesized that early measurement of the difference between arterial and end-tidal CO2 (arterial-ET difference), a surrogate for dead space fraction, would predict mortality in mechanically ventilated patients with ARDS.Methods: We performed two separate exploratory analyses. We first used publicly available databases from the ALTA, EDEN, and OMEGA ARDS Network trials (N = 124) as a derivation cohort to test our hypothesis. We then performed a separate retrospective analysis of patients with ARDS using University of Chicago patients (N = 302) as a validation cohort.Results: The ARDS Network derivation cohort demonstrated arterial-ET difference, vasopressor requirement, age, and APACHE III to be associated with mortality by univariable analysis. By multivariable analysis, only the arterial-ET difference remained significant (P = 0.047). In a separate analysis, the modified Enghoff equation ((PaCO2-PETCO2)/PaCO2) was used in place of the arterial-ET difference and did not alter the results. The University of Chicago cohort found arterial-ET difference, age, ventilator mode, vasopressor requirement, and APACHE II to be associated with mortality in a univariate analysis. By multivariable analysis, the arterial-ET difference continued to be predictive of mortality (P = 0.031). In the validation cohort, substitution of the arterial-ET difference for the modified Enghoff equation showed similar results.Conclusion: Arterial to end-tidal CO2 (ETCO2) difference is an independent predictor of mortality in patients with ARDS. [ABSTRACT FROM AUTHOR]

Transcutaneous oxygen and carbon dioxide provide the status of pulmonary gas exchange and are of importance in diagnosis and management of respiratory diseases. Though significant progress has been made in oximetry, not much has been explored in developing wearable technologies for continuous monitoring of transcutaneous carbon dioxide. This research reports the development of a truly wearable sensor for continuous monitoring of transcutaneous carbon dioxide using miniaturized nondispersive infrared sensor augmented by hydrophobic membrane to address the humidity interference. The wearable transcutaneous CO2 monitor shows well-behaved response curve to humid CO2 with linear response to CO2 concentration. The profile of transcutaneous CO2 monitored by the wearable device correlates well with the end-tidal CO2 trend in human test. The feasibility of the wearable device for passive and unobstructed tracking of transcutaneous CO2 in free-living conditions has also been demonstrated in field test. The wearable transcutaneous CO2 monitoring technology developed in this research can be widely used in remote assessment of pulmonary gas exchange efficiency for patients with respiratory diseases, such as COVID-19, sleep apnea, and chronic obstructive pulmonary disease (COPD). [ABSTRACT FROM AUTHOR]

Arvind Chandrakantan,1 Ronald Jasiewicz,2 Ruth A Reinsel,3 Kseniya Khmara,2 Jonathan Mintzer,4 Joseph D DeCristofaro,4 Zvi Jacob,2 Peggy Seidman51Department of Anesthesiology & Pediatrics, Texas Children’s Hospital, Houston, TX, USA; 2Department of Anesthesiology, Stony Brook University Hospital, Stony Brook, NY, USA; 3Department of Neurology, Stony Brook University Hospital, Stony Brook, NY, USA; 4Department of Neonatology & Pediatrics, Stony Brook University Hospital, Stony Brook, NY, USA; 5Department of Anesthesiology & Pediatrics, UH Rainbow Babies and Children’s Hospital, Cleveland, OH, USAAim: End-tidal CO2 (EtCO2) is the standard in operative care along with pulse oximetry for ventilation assessment. It is known to be less accurate in the infant population than in adults. Many neonatal intensive care units (NICU) have converted to utilizing transcutaneous CO2 (tcPCO2) monitoring. This study aimed to compare perioperative EtCO2 to tcPCO2 in the pediatric perioperative population specifically below 10 kg, which encompasses neonates and some infants.Methods: After IRB approval and parental written informed consent, we enrolled neonates and infants weighing less than 10 kg, who were scheduled for elective surgery with endotracheal tube under general anesthesia. PCO2 was monitored with EtCO2 and with tcPCO2. Venous blood gas (PvCO2) samples were drawn at the end of the anesthetic. We calculated a mean difference of EtCO2 minus PvCO2 (Delta EtCO2), and tcPCO2 minus PvCO2 (Delta tcPCO2) from end-of-case measurements. The mean differences in the NICU and non-NICU patients were compared by t-tests and Bland–Altman analysis.Results: Median age was 10.9 weeks, and median weight was 4.4 kg. NICU (n=6) and non-NICU (n=14) patients did not differ in PvCO2. Relative to the PvCO2, the Delta EtCO2 was much greater in the NICU compared to the non-NICU patients (−28.1 versus −9.8, t=3.912, 18 df, P=0.001). Delta tcPCO2 was close to zero in both groups. Although both measures obtained simultaneously in the same patients agreed moderately with each other (r =0.444, 18 df, P=0.05), Bland–Altman plots indicated that the mean difference (bias) in EtCO2 measurements differed significantly from zero (P

Aim: To evaluate the individual use and predictive value of focused echocardiography, end-tidal carbon dioxide (EtCO2), invasive arterial blood pressure (BP) and near-infrared spectroscopy (NIRS) during cardiopulmonary resuscitation (CPR) in children. Methods: This scoping review was undertaken as part of the continuous evidence evaluation process of the International Liaison Committee on Resuscitation (ILCOR) and based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) extension for scoping reviews. PubMed, MEDLINE, CINAHL and EMBASE were searched from the last ILCOR reviews until September 2020. We included all published studies evaluating the effect of echocardiography, EtCO2, BP or NIRS guided CPR on clinical outcomes and quality of CPR. Results: We identified eight observational studies, including 288 children. Two case series reported the use of echocardiography, one in detecting pulmonary emboli, the second in cardiac standstill, where contractility was regained with the use of extracorporeal membrane oxygenation. The two studies describing EtCO2 were ambivalent regarding the association between mean values and any outcomes. Mean diastolic BP was associated with increased survival and favourable neurological outcome, but not with new substantive morbidity in two studies describing an overlapping population. NIRS values reflected changes in EtCO2 and cerebral blood volume index in two studies, with lower values in patients who did not achieve return of circulation. Conclusion: Although there seems some beneficial effect of these intra-arrest variables, higher quality paediatric studies are needed to evaluate whether echocardiography, EtCO2, BP or NIRS guided CPR could improve outcomes.

Objective: Below normal end-tidal carbon dioxide measurement (ETCO2) is associated with worse outcomes in sepsis and trauma patients as compared to patients with normal ETCO2. We sought to determine if ETCO2 can be used in the prehospital setting to predict transfusion requirement, operative hemorrhage control, or mortality in the first 24 h after admission for trauma.Methods: This is a retrospective cohort study at a suburban, academic Level 1 Trauma Center. Patients were sequentially identified as prehospital trauma alerts from a single EMS system which requires, per policy, ETCO2 for all traumas. One year of prehospital data was collected and paired with hospital trauma registry data. Comparisons were made between ETCO2 values for patients who required transfusion, operative blood loss control, or who died, and those who did not.Results: Two hundred thirty-five trauma patients were transported via the study EMS system, of which 105 (44.7%) had documented ETCO2 values. Patient mean age was 60 (SD24) years with 59 (56.2%) male. Three patients were intubated prehospital and seven were intubated in the trauma bay. Mean prehospital ETCO2 for those who needed transfusion, surgery, or died (n = 11) was 25.7 (9.1) compared to 30.6 (7.8) for those who did not (p = 0.049). Optimal cutoff for our population was EtCO2 ≤ 27 with a sensitivity of 72.7% (95% CI 32-93) and specificity of 72.2% (62-81).Conclusion: Below normal ETCO2 values were associated with increase need for transfusion, operative intervention, and death. Further study is warranted to determine if ETCO2 outperforms other predictors of severe trauma. [ABSTRACT FROM AUTHOR]

The large changes in mean arterial blood pressure (MABP) and cerebral blood flow velocity (CBFV) induced by squat-stand maneuvers (SSM) make this approach particularly suited for studying dynamic cerebral autoregulation (CA). However, the role of other systemic determinants of CBFV has not been described and could provide alternative physiological interpretations of SSM results. In 32 healthy subjects (16 female), continuous recordings of MABP (Finometer), bilateral CBFV (transcranial Doppler, MCA), end-tidal CO2 (EtCO2; capnography), and heart rate (HR; electrocardiogram) were performed for 5 min standing at rest, and during 15 SSM at the frequency of 0.05 Hz. A time-domain, multivariate dynamic model estimated the CBFV variance explained by different inputs, corresponding to significant contributions from MABP (P < 0.00001), EtCO2 (P < 0.0001), and HR (P = 0.041). The autoregulation index (ARI; range 0-9) was estimated from the CBFV response to a step change in MABP. At rest, ARI values (typically 5.7) were independent of the number of model inputs, but during SSM, ARI was reduced compared with baseline (P < 0.0001), and the three input model yielded lower values for the right and left MCA (3.4 ± 1.2, 3.1 ± 1.3) when compared with the single-input MABP-CBFV model (4.1 ± 1.1, 3.9 ± 1.0; P < 0.0001). The high coherence of the MABP-CBFV transfer function at 0.05 Hz (typically 0.98) was considerably reduced (around 0.71-0.73; P < 0.0001) when the contribution of CBFV covariates was taken into account. Not taking into consideration other determinants of CBFV, in addition to MABP, could be misleading and introduce biases in physiological and clinical studies. [ABSTRACT FROM AUTHOR]

Objective: To investigate whether partial arterial carbon dioxide pressure (PaCO2) level in arterial blood gas analysis that was used to predict nocturnal hypoventilation (NH) is concordant with nocturnal end-tidal CO2 (PetCO2) measurement obtained by a noninvasive method of oxycapnography in children with neuromuscular disease (NMD). Methods: Twenty-one patients aged 6-18 years with a confirmed diagnosis of NMD were enrolled. Each patient underwent a nocturnal oxycapnography study using an orinasal probe and a pulse oximetry finger probe to record PetCO2, oxygen saturation (SpO2), pulse rate, and respiratory rate. Arterial blood gas analysis was performed to record PaCO2 levels on three occasions at night (23:00 pm, 03:00 am, 07:00 am). Results: The mean overnight PaCO2 level of the three blood gas analyses (mean PaCO2noct) was 41.78±4.69 mmHg. A significant change was observed between mean PaCO2 23:00 and PaCO2 07:00 levels (p=0.032). There was no significant difference between PaCO2, PetCO2, and SpO2 levels in the NMD group. The interclass correlation coefficient between PaCO2 07:00 and PetCO2 levels was 0.791 (95% CI: 0.533-0.923); the interclass correlation coefficient between overnight mean PaCO2 and PetCO2 levels was 0.811 (95% CI:0.533-0.923). Conclusion: Our study indicates that nocturnal PetCO2 and PaCO2 levels were statistically comparable but the use of PaCO2 alone is not adequate to make an early diagnosis of NH in NMD. There is a need for making more restrictive definitions for NH, and conducting studies with larger study populations to reach an agreement on the best definition of hypoventilation, and updating consensus guidelines. [ABSTRACT FROM AUTHOR]

Transcutaneous PCO2 (PTCCO2) and end-tidal PCO2 (PETCO2) measurement methods serve as alternatives to arterial PCO2 (PaCO2), providing continuous non-invasive monitoring. The objective of this study was to evaluate the PTCCO2 and PETCO2 methods with actual PaCO2 levels, and to assess the variability of measurements in relation to subject-related factors, such as skin and subcutaneous adipose tissue thickness and presence of pulmonary diseases. PTCCO2, PETCO2 and PaCO2 were measured at the same time in intubated pediatric subjects. Subjects' demographic characteristics, clinical features, laboratory parameters, skin and subcutaneous adipose tissue thickness were identified. The study was carried out on 102 subjects with a total of 1118 values for each method. In patients with non-pulmonary disease, the mean difference between PTCCO2 and PaCO2 was − 0.29 mmHg (± 6.05), while it was 0.44 mmHg (± 6.83) bias between PETCO2 and PaCO2. In those with pulmonary diseases, the mean difference between PTCCO2 and PaCO2 was − 1.27 mmHg (± 8.32), while it was − 4.65 mmHg (± 9.01) between PETCO2 and PaCO2. Multiple linear regression demonstrated that increased subcutaneous adipose tissue thickness, core body temperature and inotropic index were related with higher PTCCO2 values relative to the actual PCO2 values. Other factors, such as skin tissue thickness, presence of pulmonary disease, measurement location and measurement times were non-significant. The PTCCO2 method has higher reliability than the PETCO2 method, and PTCCO2 measurements are not influenced by most subject-related factors; however, core body temperature, inotropic index and subcutaneous adipose tissue thickness can lead to significant differences in PCO2 measurement. [ABSTRACT FROM AUTHOR]

During the COVID-19 pandemic wearing face masks was mandatory. Nowadays, face masks are still encouraged indoors, especially in hospitals. People climbing stairs with masks describe unpredictable dyspnea. In this study, healthy adults climbed 5 floors with and without a mask. Various cardio-respiratory parameters were measured, including O 2 -saturation (O 2 -Sat) and end-tidal CO 2 (EtCO 2 ), at baseline and on the top floor. Subjective indexes, such as Borg's scale, were evaluated. Thirty-two volunteers (16 males), median age 39 years (IQR 32.5-43), median BMI = 23.6 (IQR 21.5-25.1), with good fitness levels, participated. Comparing baseline to end-activity, median (IQR): O 2 -Sat change was -1.0% (-2-0) without mask, versus -3.0% (-4-0) with mask, p = 0.003; EtCO 2 + 7.0 (+3.3-+9) without mask, versus +8.0 (+6-+12) with mask, p = 0.0001. Hypercarbia was seen in 5 (15.6%) participants without mask, median = 48 mmHg (IQR 47.5-51), and in 11 (34%) participants with mask, median = 50 mmHg (IQR 47-54), p < 0.001. Desaturation (O 2 -Sat < 95%) was seen in 5 (15.6%) participants without mask, median = 94% (IQR 93%-94%), and in 10 (31%) participants with mask, median = 91.5% (IQR 90%-93%), p = 0.06. Regression analysis demonstrated that only male sex was significantly associated with abnormal EtCO 2 (OR = 26.4, 95% CI = 1.9-366.4, p = 0.005). Ascent duration increased from median (IQR) of 94 s (86-100) without mask to 98 s (89-107) with mask, p < 0.001. Borg's scale of perceived exertion (range 0-10) increased from median (IQR) of 3.0 (2.5-3.87) without mask to 4.0 (3.0-4.37) with mask, p < 0.001. To conclude, during routine daily activities, such as stair-climbing, face masks cause dyspnea, and have measurable influences on ventilation, including true desaturation and hypercapnia, especially in males., (© 2024 IOP Publishing Ltd.)

The literature shows that respiratory complications are common with sedation. Given the inherent risk, capnography monitoring is recommended whenever sedation is administered. We aimed to explore sedation practitioners’ behavior patterns and perceptions regarding capnography monitoring during endoscopy sedation and examine how capnography influenced clinical decision making when assessing respiration. We conducted a focused ethnography with triangulated observations and semi-structured interviews, and we purposively sampled and recruited five sedation practitioners as participants at a hospital in Saudi Arabia. Through data analysis, we identified representative themes and found cultural differences between anesthesia practitioners and nurses when using capnography during sedation. Anesthesia practitioners linked safety and the use of capnography to maintain adequate respiration, while nurses believed capnography was a secondary supportive monitor to patient observation and assessment. Findings also captured the unique cultures and values of each professional group to be associated with the varying perceptions. We also identified several factors facilitating and barring adequate utilization of capnography. In conclusion, professional culture, hospital policy, knowledge and previous experience with capnography guided the monitoring practice of endoscopy practitioners when assessing respiration during sedation.

Cerebrovascular reactivity (CVR), an index of brain vessel’s dilatory capacity, is typically measured using hypercapnic gas inhalation or breath-holding as a vasoactive challenge. However, these methods require considerable subject cooperation and could be challenging in clinical studies. More recently, there have been attempts to use resting-state BOLD data to map CVR by utilizing spontaneous changes in breathing pattern. However, in subjects who have small fluctuations in their spontaneous breathing pattern, the CVR results could be noisy and unreliable. In this study, we aim to develop a new method for CVR mapping that does not require gas-inhalation yet provides substantially higher sensitivity than resting-state CVR mapping. This new method is largely based on resting-state scan, but introduces intermittent modulation of breathing pattern in the subject to enhance fluctuations in their end-tidal CO2 (EtCO2) level. Here we examined the comfort level, sensitivity, and accuracy of this method in two studies. First, in 8 healthy young subjects, we developed the intermittent breath-modulation method using two different modulation frequencies, 6 ​s per breath and 12 ​s per breath, respectively, and compared the results to three existing CVR methods, specifically hypercapnic gas inhalation, breath-holding, and resting-state. Our results showed that the comfort level of the 6-s breath-modulation method was significantly higher than breath-holding (p ​= ​0.007) and CO2-inhalation (p ​= ​0.015) methods, while not different from the resting-state, i.e. free breathing method (p ​= ​0.52). When comparing the sensitivity of CVR methods, the breath-modulation methods revealed higher Z-statistics compared to the resting-state scan (p ​

Cerebrovascular reactivity (CVR) mapping using CO2-inhalation can provide important insight into vascular health. At present, blood-oxygenation-level-dependent (BOLD) MRI acquisition is the most commonly used CVR method due to its high sensitivity, high spatial resolution, and relatively straightforward processing. However, large variations in CVR across subjects and across different sessions of the same subject are often observed, which can cloud the ability of this promising measure in detecting diseases or monitoring treatment responses. The present work aims to identify the physiological components underlying the observed variability in CVR data. When studying the association between CVR value and the subject’s CO2 levels in a total of N = 253 healthy participants, we found that CVR was lower in individuals with a higher basal end-tidal CO2, EtCO2 (slope = −0.0036 ± 0.0008%/mmHg2, p

Background: There is a significant variability in survival rates for cardiopulmonary resuscitation (CPR) in out of-hospital cardiac arrest (OHCA), and some data indicate that ultrasound improves CPR.Objectives: We evaluated the feasibility of ultrasound for monitoring chest compressions in OHCA.Methods: We planned a prospective study in patients with an ultrasound-integrated CPR for OHCA. Chest compressions were performed on the intermammillary line (IML), but the position was changed according to the quality of the heart squeezing, evaluated by ultrasound. End-tidal carbon dioxide (ETCO2) was used as the control parameter. Then we compared the area with the highest squeezing with the position of the heart in the chest computed tomography (CT) scans of 20 hospitalized patients.Results: Chest compressions were good, partial, and inadequate on the IML in 58.4%, 48.9%, and 2.8% of cases, respectively. These percentages were 75%, 25%, and 0% after these modifications: none (47.2%), increased depth (8.3%), hands moved on the lower third of the sternum (27.8%), on left parasternal line of the lower part of the sternum (13.9%), and on the center of the sternum (1 case). Accordingly, ETCO2 improved significantly (20.37 vs. 37.10, p < 0.0001). The CT scans showed that the larger biventricular area (BVA) was under the parasternal line of the lower third of the sternum, and the mean distance IML-BVA was 5.7 cm.Conclusions: Our study has demonstrated that CPR in OHCA can be improved using ultrasound and changing the position of the hands. This finding was connected with the ETCO2 and confirmed by chest CT scans. [ABSTRACT FROM AUTHOR]

Background: Real-time measurement of end-tidal carbon dioxide (ETCO2) is used as a non-invasive estimate of cardiac output and perfusion during cardiopulmonary resuscitation (CPR). However, capnograms are often distorted by chest compressions (CCs) and this may affect ETCO2 measurement. The aim of the study was to quantify the effect of CC-artefact on the accuracy of ETCO2 measurements obtained during out-of-hospital manual CPR.Methods: We retrospectively analysed monitor-defibrillator recordings collected by two advanced life support agencies during out-of-hospital cardiac arrest. These two agencies, represented as A and B used different side-stream capnometers and monitor-defibrillators. One-minute capnogram segments were reviewed. Each ventilation within each segment was identified using the transthoracic impedance signal and the capnogram. ETCO2 values per ventilation were manually annotated and compared to the corresponding capnometry values stored in the monitor-defibrillator. Ventilations were classified as distorted or non-distorted by CC-artefact.Results: A total of 407 1-min capnogram segments from 65 patients were analysed. Overall, 4095 ventilations were annotated, 2170 (32.4% distorted) and 1925 (31.8% distorted) for agency A and B, respectively. Median (IQR) unsigned error in ETCO2 measurement increased from 1.5 (0.6-3.1)% for non-distorted to 5.5 (1.8-14.1)% for distorted ventilations; from 0.7 (0.3-1.2)% to 3.7 (1.0-9.9)% in agency A and from 2.3 (1.2-3.9)% to 8.3 (3.9-19.5)% in agency B (p < 0.001). Errors were higher than 10 mmHg in 9% and higher than 15 mmHg in 5% of the distorted ventilations.Conclusion: CC-artefact causes ETCO2 measurement errors in the two studied devices. This suggests that capnometer algorithms may need to be adapted to reliably perform in the presence of CC-artefact during CPR. [ABSTRACT FROM AUTHOR]