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Background Patients undergoing bronchoscopy in spontaneous breathing are prone to hypoxaemia and hypercapnia. Sedation, airway obstruction, and lung diseases impair respiration and gas exchange. The restitution of normal respiration takes place in the recovery room. Nonetheless, there is no evidence on the necessary observation time. We systematically reviewed current guidelines on bronchoscopy regarding sedation, monitoring and recovery. Methods This review was registered at the PROSPERO database (CRD42020197476). MEDLINE and awmf.org were double-searched for official guidelines, recommendation or consensus statements on bronchoscopy from 2010 to 2020. The PICO-process focussed on adults (Patients), bronchoscopy with maintained spontaneous breathing (Interventions), and recommendations regarding the intra- and postprocedural monitoring and sedation (O). The guideline quality was graded. A catalogue of 54 questions was answered. Strength of recommendation and evidence levels were recorded for each recommendation. Results Six guidelines on general bronchoscopy and three expert statements on special bronchoscopic procedures were identified. Four guidelines were evidence-based. Most guidelines recommend sedation to improve the patient’s tolerance. Midazolam combined with an opioid is preferred. The standard monitoring consists of non-invasive blood pressure, and pulse oximetry, furthermore electrocardiogram in cardiac patients. Only one guideline discusses hypercapnia and capnometry, but without consensus. Two guidelines discuss a recovery time of two hours, but a recommendation was not given because of lack of evidence. Conclusion Evidence for most issues is low to moderate. Lung-diseased patients are not represented by current guidelines. Capnometry and recovery time lack evidence. More primary research in these fields is needed so that future guidelines may address these issues, too.

Volatile organic compounds (VOCs) released through skin (transcutaneous gas) has been increasing in importance for the continuous and real-time assessment of diseases or metabolisms. For stable monitoring of transcutaneous gas, finding a body part with little interference on the measurement is essential. In this study, we have investigated the possibility of external ears for stable and real-time measurement of ethanol vapour by developing a monitoring system that consisted with an over-ear gas collection cell and a biochemical gas sensor (bio-sniffer). The high sensitivity with the broad dynamic range (26 ppb–554 ppm), the high selectivity to ethanol, and the capability of the continuous measurement of the monitoring system uncovered three important characteristics of external ear-derived ethanol with alcohol intake for the first time: there is little interference from sweat glands to a sensor signal at the external ear; similar temporal change in ethanol concentration to that of breath with delayed peak time (avg. 13 min); relatively high concentration of ethanol relative to other parts of a body (external ear-derived ethanol:breath ethanol = 1:590). These features indicated the suitability of external ears for non-invasive monitoring of blood VOCs.

The impact of abnormalities in the vascular bed of the external genitalia and vagina on female sexuality is not well defined because of some methodological difficulties in correctly assessing vascular changes of genitalia in women. Transmucosal oxygen tension (TmPO2) represents a precise measure of oxygen partial pressure at the clitoris surface and is expression of clitoral tissue perfusion. Aim of the study was to correlate TmPO2 with female sexual dysfunction (FSD) in healthy women in order to evaluate the impact of clitoral vascularization on female sexual health. Twenty-seven healthy, heterosexual, and sexually active women of reproductive age (mean age: 31.18 ± 4.71) were enrolled in the study. TmPO2 was assessed in every woman. In addition, all the women filled out the Female sexual function index (FSFI). After adjustment for some covariates (age, BMI, and smoking), TmPO2 significantly correlated with FSFI total score (r = 0.4261; p = 0.0379) and with arousal (r = 0.3239; p = 0.0390), lubrication (r = 0.4345; p = 0.0339), orgasm (r = 0.4092; p = 0.0471), and satisfaction (r = 0.4456; p = 0.0291) scores. In addition, TmPO2 was significantly lower in the FSD than in the NO FSD group (28.4 ± 14.5 versus 48.1 ± 25.1 mmHg; p = 0.0416). This study first shows that in healthy women of reproductive age clitoral tissue perfusion, as assessed by TmPO2, correlates very well with FSD and in particular with arousal, lubrication, orgasm, and satisfaction. Further studies should confirm our data and test TmPO2 as potential predictor for cardiovascular disease and metabolic conditions in women.

BackgroundNoninvasive ventilation (NIV) represents an effective treatment for chronic respiratory failure. However, empirically determined NIV settings may not achieve optimal ventilatory support. Therefore, the efficacy of NIV should be systematically monitored. The minimal recommended monitoring strategy includes clinical assessment, arterial blood gases (ABG) and nocturnal transcutaneous pulsed oxygen saturation (SpO2). Polysomnography is a theoretical gold standard but is not routinely available in many centers. Simple tools such as transcutaneous capnography (TcPCO2) or ventilator built-in software provide reliable informations but their role in NIV monitoring has yet to be defined. The aim of our work was to compare the accuracy of different combinations of tests to assess NIV efficacy.MethodsThis retrospective comparative study evaluated the efficacy of NIV in consecutive patients through four strategies (A, B, C and D) using four different tools in various combinations. These tools included morning ABG, nocturnal SpO2, TcPCO2and data provided by built-in software via a dedicated module. Strategy A (ABG + nocturnal SpO2), B (nocturnal SpO2 + TcPCO2) and C (TcPCO2 + builtin software) were compared to strategy D, which combined all four tools (NIV was appropriate if all four tools were normal).ResultsNIV was appropriate in only 29 of the 100 included patients. Strategy A considered 53 patients as appropriately ventilated. Strategy B considered 48 patients as appropriately ventilated. Strategy C misclassified only 6 patients with daytime hypercapnia.ConclusionMonitoring ABG and nocturnal SpO2is not enough to assess NIV efficacy. Combining data from ventilator built-in software and TcPCO2seems to represent the best strategy to detect poor NIV efficacy.TrialregistrationInstitutional Review Board of the Société de Pneumologie de Langue Française (CEPRO 2016 Georges)

Background: Several studies suggested that abnormalities in tissue perfusion of external genitalia and vagina can lead to female sexual dysfunctions (FSDs) and can be associated to metabolic and cardiovascular risk factors. However, there are some technical difficulties in assessing these abnormalities. The measurement of oxygen partial pressure is a noninvasive method to measure oxygen partial pressure (pO 2 ) at the skin surface to assess tissue perfusion. The aim of this study was to evaluate whether transmucosal oxygen tension (TmPO 2 ) can be measured at the mucosal surface of clitoris and whether the measurements are reliable. Methods: TmPO 2 was measured in six young healthy women by using a device to measure transcutaneous pO 2 on the skin and by choosing a small sensor, usually used for newborns. The identical procedure for the detection of pO 2 at the skin surface was used. Results: The mean value of TmPO 2 was 42.3 mmHg (range: 24.1–53.4 mmHg). All the trend curves of the TmPO 2 showed the same behavior: after a stabilization time, there was a stable pO 2 (plateau phase) that corresponds to the TmPO 2 of the clitoris. These curves had a similar trend to those recorded at the skin surface. Conclusions: TmPO 2 can be easily measured at the mucosal surface of clitoris. Large epidemiological studies in healthy and unhealthy women and in women with FSD are needed to establish both the normal range of TmPO 2 and the meaning that different values of TmPO 2 can have on sexual and general health of the women.

Panic disorder (PD) is associated with hyperventilation. The efficacy of a brief respiratory feedback program for PD has been established. The aim of the present study was to expand these results by testing a similar program with more clinically representative patients and settings. Sixty-nine adults with PD received 4 weeks of Capnometry Guided Respiratory Intervention (CGRI) using Freespira, which provides feedback of end-tidal CO2 (PETCO2) and respiration rate (RR), in four non-academic clinical settings. This intervention is delivered via home use following initial training by a clinician and provides remote monitoring of client adherence and progress by the clinician. Outcomes were assessed post-treatment and at 2- and 12-month follow-up. CGRI was associated with an intent-to-treat response rate of 83% and a remission rate of 54%, and large decreases in panic severity. Similar decreases were found in functional impairment and in global illness severity. Gains were largely sustained at follow-up. PETCO2 moved from the slightly hypocapnic range to the normocapnic range. Benchmarking analyses against a previously-published controlled trial showed very similar outcomes, despite substantial differences in sample composition and treatment settings. The present study confirms prior clinical results and lends further support to the viability of CGRI in the treatment of PD.

Background Delirium is an acute mental disorder and common postoperative complication. Monitoring regional cerebral oxygen saturation (rSO2) in endovascular therapeutic surgery may allow real-time monitoring of cerebral desaturation, avoiding profound cerebral dysfunction, and reducing the incidence of delirium. We sought to examine the incidence of delirium in patients undergoing endovascular surgery. Methods This was a clinical cohort trial (registered with http://www.clinicaltrials.gov [NCT02356133]). We monitored the rSO2 of 43 patients undergoing general anesthesia and cerebral endovascular surgery. The occurrence of delirium after surgery was recorded with the Confusion Assessment Method (CAM). Multivariate logistic regression was performed to identify the main predictor of delirium. Results rSO2 was significantly different between the delirium and no-delirium groups. The occurrence of delirium was 35% in our cohort, and higher rSO2 desaturation scores were significantly associated with profound delirium (higher CAM score; odds ratio = 1.002; P = 0.021). The maximum declines of systolic blood pressure were 24.86 (21.78–27.93) and 32.98 (28.78–37.19) in the no-delirium and delirium groups, respectively, which were significantly different (P = 0.002) but not closely associated with delirium in multivariate analysis (P = 0.512). Anesthesia, mechanical ventilation duration, and having two vascular risk factors differed significantly between groups but were poorly associated with delirium outcome. Conclusions Elevated rSO2 desaturation score was predictive of the occurrence of postoperative delirium following endovascular surgery. Monitoring rSO2 is invaluable for managing controlled hypotension during endovascular surgery and reducing postoperative delirium. Trial registration ClinicalTrials.gov, NCT02356133. Registered 1 February 2015. All statistical analysis results submitted August 4, 2018. Electronic supplementary material The online version of this article (10.1186/s13063-019-3586-y) contains supplementary material, which is available to authorized users.

Background Although the mononuclear cell (MNC) transplantation could theoretically induce therapeutic angiogenesis in the patients with no-option critical limb ischemia (NO-CLI), the clinical responses to this approach are inconsistent among different clinical trials. The purpose of this study was to identify the prognostic factors of responders and develop a predictive nomogram to guide patient selection. Methods We retrospectively reviewed a consecutive NO-CLI cohort who received peripheral blood-derived transplantation in our center. The patients who survived and achieved complete remission of CLI at 6 months post-transplantation were defined as responders. Logistic regression models were used to screen and identify the prognostic factors based on which predictive nomogram was developed. A receiver operating characteristic (ROC) curve and a calibration curve were drawn to determine the discrimination level and predictive accuracy. Results The study ultimately enrolled 103 patients, including 58 responders and 45 non-responders. Based on the multivariate regression analysis, age ≥ 50 years (odds ratio [OR] 0.201, P = 0.004), blood fibrinogen > 4 g/L (OR 0.176, P = 0.003), arterial occlusion above the knee/elbow (OR 0.232, P = 0.010), the transcutaneous pressure of oxygen (TcPO2) (OR 1.062, P = 0.006), and the Log total transplanted CD34+ cell count (OR 3.506, P = 0.046) were identified as independent prognostic factors of the responders in the nomogram. An area under the ROC curve of 0.851 indicated good discrimination, and the calibration curve of the predicted probability showed optimal agreement with that of the observed probability. Conclusions Age, blood fibrinogen, arterial occlusion level, TcPO2, and the total transplanted CD34+ cell count were independent prognostic factors of the responders. A nomogram with high discrimination and accuracy was developed to provide individualized predictions. Trail registration ChiCTR, ChiCTR1800019401. Registered 9 November 2018—Retrospectively registered Electronic supplementary material The online version of this article (10.1186/s13287-018-1117-5) contains supplementary material, which is available to authorized users.

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, identified by daytime hypercapnia or nocturnal desaturation. Recently, transcutaneous measure of CO2 (TcCO2) has been increasingly used to detect hypoventilation, using different cut-offs. We aimed to compare the prevalence of hypoventilation in an unselected adult NMD population according to different definitions issued from the literature. All consecutive nocturnal capno-oximetries performed between 2010 and 2014 in unventilated adult NMD patients were analysed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Hypoventilation was defined according to eight criteria, based on daytime PaCO2, daytime base excess, nocturnal SpO2 or TcCO2. Data from 232 patients were analysed (mean age 43.1 ± 15.4 years; 50.0 % women; vital capacity 59.2 ± 24.2 % of predicted). The hypoventilation prevalence was 10.3 to 61.2 %, depending on the used definition. The different definitions showed 49.1 to 94.8 % concordance (Cohen’s kappa for agreement 0.115 to 0.763). Overall agreement between the eight definitions was poor (Light’s kappa 0.267), and agreement between definitions based on nocturnal SpO2 and those based on TcCO2 was even lower (Light’s kappa 0.204). We found large differences in hypoventilation prevalence according to the used definition. This has practical consequences, as HMV indication relies upon hypoventilation detection. We believe that capno-oximetry should be included in the diagnostic tools used to detect hypoventilation but this requires an update of consensus guidelines to agree upon the best definition.

The aim of this study was to determine if transcutaneous CO(2) monitoring (TCO(2)) is feasible to avoid hypercapnia during complex catheter ablation. Cumulative analgesic and anxiolytic effects during complex catheter ablation can rarely provoke hypoventilation and respiratory complications. End tidal CO(2) monitors have limitations in non-ventilated patients, and frequent arterial blood gas sampling is impractical.Consecutive patients undergoing catheter ablation for atrial fibrillation (AF) or ventricular tachycardia (VT) received continuous TCO(2) monitoring. Procedural evaluation of TCO(2) was performed concomitantly with point-of-care arterial blood gas testing. Endpoints included PCO(2) protocol feasibility, TCO(2)/PCO(2) agreement, and avoidance of hypercapnia-related procedural complications.Fifty patients [AF n = 36 (72 %), VT n = 14 (28 %)] underwent catheter ablation (mean 221.7 ± 57.0 min duration, median 41.4 ± 21.1 min fluoroscopy) in which 6.0 ± 2.6 mg midazolam and 449 ± 225.5 mcg of fentanyl were administered. Monitoring protocol implementation was feasible in 50/50 (100 %) cases. Protocol-driven anesthesia consultation avoided an unplanned intubation in 1 case (2 %) and there was only 1 unplanned intubation (2 %) for oxygen desaturation due to heart failure without hypercapnia during a VT ablation (TCO(2)/PCO(2) agreement5 mmHg). There were no respiratory or pulseless electrical arrests (0 %) in the study. TCO(2) and PCO(2) correlated well (baseline: r = 0.75, p 0.001; 1 h:r= 0.72, p 0.001; 2 h: r = 0.55, p = 0.003; 3 h: r = 0.79, p = 0.02). However, desired agreement was lower than expected [baseline: 33/50 (66 %) 5 mmHg, 48/50 (96 %) 10 mmHg; 1 h: 29/45 (64 %) 5 mmHg, 39/45 (87 %) 10 mmHg; 2 h: 14/26 (54 %) 5 mmHg, 22/26 (85 %) 10 mmHg; 3 h: 7/11 (64 %) 5 mmHg, 10/11 (91 %) 10 mmHg;3 h: 1/3 (33 %) 5 mmHg, 2/3 (66 %) 10 mmHg].Transcutaneous CO2 monitoring is feasible during complex catheter ablation and correlates with invasively obtained data. However, further development is needed to achieve the desired level of agreement.

Physicians often need to measure arterial PCO2 in clinical practice. Arterial blood gas sampling is typically available only in hospitals and may be unpleasant for patients. Minimally invasive techniques for measuring PCO2 offer the potential for overcoming these limitations. The MicroStat monitor non-invasively measures PCO2 in the sublingual tissues, which should track arterial PCO2 in hemodynamically stable patients. This was a prospective observational study. Patients undergoing routine cardiac catheterization were recruited. Following arterial cannulation, two sequential sublingual PCO2 measurements were taken and a contemporaneous arterial sample was sent for blood gas analysis. For each subject we calculated the mean sublingual-arterial CO2 gradient and the test-retest sublingual PCO2 difference. Twenty-five patients were studied. Mean sublingual-arterial PCO2 gradient was +6.8 mmHg (95 % limits of agreement -3.0 to 16.6 mmHg). Test-retest difference was 3.4 mmHg (95 % limits of agreement -1.1 to 7.9 mmHg), p = 0.11 (Wilcoxon test), repeatability was 11 mmHg. The MicroStat sublingual PCO2 monitor over-estimates arterial PCO2 with wide limits of agreement. Test-retest repeatability was poor. Use of sublingual PCO2 monitoring with the MicroStat monitor cannot currently replace blood gas sampling.

Fluid therapy after initial resuscitation in critically ill, septic patients may lead to harmful overloading and should therefore be guided by indicators of an increase in stroke volume (SV), i.e. fluid responsiveness. Our objective was to investigate whether tissue perfusion and oxygenation are able to monitor fluid responsiveness, even after initial resuscitation. Thirty-five critically ill, septic patients underwent infusion of 250 mL of colloids, after initial fluid resuscitation. Prior to and after fluid infusion, SV, cardiac output sublingual microcirculatory perfusion (SDF: sidestream dark field imaging) and skin perfusion and oxygenation (laser Doppler flowmetry and reflectance spectroscopy) were measured. Fluid responsiveness was defined by a a parts per thousand yen5 or 10 % increase in SV upon fluids. In responders to fluids, SDF-derived microcirculatory and skin perfusion and oxygenation increased, but only the increase in cardiac output, mean arterial and pulse pressure, microvascular flow index and relative Hb concentration and oxygen saturation were able to monitor a SV increase. Our proof of principle study demonstrates that non-invasively assessed tissue perfusion and oxygenation is not inferior to invasive hemodynamic measurements in monitoring fluid responsiveness. However skin reflectance spectroscopy may be more helpful than sublingual SDF.

Our objective was to assess within a feasibility study the correlation and agreement of transcutaneous carbon dioxide (PtcCO2) monitoring with venous carbon dioxide (PvCO2) in infants with bronchiolitis in the emergency room (ER) and pediatric department. Sixty infants (aged 3.6 ± 3.3 months) admitted to our ER with bronchiolitis were included. PtcCO2 measurements (SenTec Digital Monitoring System) collected prospectively were compared with simultaneous PvCO2 drawn for patient care. Analysis included 100 measurements. The correlation of PtcCO2 and PvCO2 (r = 0.71, p

Carbon dioxide (CO(2)) insufflation reduces abdominal pain and discomfort after endoscopic procedures; however, there is no previous study focusing the safety of CO(2) insufflation for patients with obstructive ventilatory disturbance. Here, we investigated the safety of CO(2) insufflation during colorectal endoscopic submucosal dissection (ESD) for patients with obstructive disturbance.Between January 2010 and January 2013, colorectal ESD was performed using CO(2) insufflation for 385 consecutive patients. End-tidal CO(2) (EtCO(2)) and transcutaneous oxygen saturation (SpO(2)) were consecutively measured from the time before insertion of the colonoscope to the end of ESD. Patients were monitored by two nurses during the procedure and controlled for clinical symptoms of hypercapnia such as apnea or a depressed level of consciousness. According to their respiratory function, patients were stratified into a normal group and an obstructive disturbance group. We retrospectively compared EtCO(2) and SpO(2) during the procedures and the incidence of symptoms related to CO(2) retention between the two groups.The obstructive disturbance group consisted of 77 patients. There were similar changes of EtCO(2) in the obstructive disturbance group and normal group and no significant rise in EtCO(2). The maximum EtCO(2) level in any patient was60 mmHg. In the obstructive disturbance group, there were no symptoms associated with CO(2) retention. There were no significant differences in the median SpO(2) between both groups and no prolonged drop of SpO(2).CO(2) insufflation during colorectal ESD is safe for patients with obstructive ventilatory disturbance.

Obese patients are at increased risk for hypoventilation, leading to hypercapnea and acidosis. The primary objective of this study was to compare the incidence of perioperative hypercapnea in non-obese and morbidly obese patients using the SenTec transcutaneous PCO2 (tcPCO2) monitor. 10 morbidly obese subjects (BMI 40 kg/m(2)) undergoing laparoscopic bariatric surgery, and 10 non-obese subjects (BMI 30 kg/m(2)) undergoing laparoscopic abdominal procedures were studied, using a standardized anesthesia regimen. TcPCO2 and SpO2 were monitored continuously intraoperatively, and during the first 24 h postoperatively. Opiate consumption, respiratory rate (RR), and pain scores were collected from postanesthesia care unit (PACU) and ward nursing notes. RR, SpO2, and tcPCO2 did not differ significantly between groups during PACU or ward time periods. End-tidal CO2 (EtCO2) values were similar between groups during the intraoperative period, but tcPCO2 was significantly higher in the obese group at specific time points, and trended towards being higher throughout the case. Our study did not show significant tcPCO2 differences between non-obese and obese post-surgical patients, however, it did allow for continuous, trendable, nonobtrusive monitoring throughout the perioperative period. As V/Q mismatch increases with the PaCO2/EtCO2 gradient, and this effect is most pronounced in morbidly obese patients, tcPCO2 monitoring may prove to be a useful additional monitor in these patients during the intraoperative period.

This study was designed to determine whether a decrease in renal oxygenation occurs during CO2 pneumoperitoneum in children with normal renal function undergoing laparoscopy. Near infrared spectroscopy (NIRS) probes were applied to both the lateral flank (T10-L2) and lateral cerebral area of all patients with normal renal function undergoing a laparoscopic procedure. Information was recorded in 5-s intervals for 15-min before, during, and for 15-min after pneumoperitoneum insufflation and desufflation. Simultaneously, additional hemodynamic parameters (arterial saturation, mean arterial pressure, end tidal CO2, and urine output) were recorded every 5-min. Pneumoperitoneum pressures used were: 0–1 month old

The ability of practitioners to assess the adequacy of global oxygen delivery is dependent on an accurate measurement of central venous saturation. Traditional techniques require the placement of invasive central venous access devices. This study aimed to compare two non-invasive technologies for the estimation of regional venous saturation (reflectance plethysmography and near infrared spectroscopy [NIRS]), using venous blood gas analysis as gold standard. Forty patients undergoing cardiac surgery were recruited in two groups. In the first group a reflectance pulse oximeter probe was placed on the skin overlying the internal jugular vein. In the second group, a Somanetics INVOS oximeter patch was placed on the skin overlying the internal jugular vein and overlying the ipsilateral cerebral hemisphere. Central venous catheters were placed in all patients. Oxygen saturation estimates from both groups were compared with measured saturation from venous blood. Twenty patients participated in each group.Data were analyzed by the limits of agreement technique suggested by Bland and Altman and by linear regression analysis. In the reflectance plethysmography group, the mean bias was 4.27% and the limits of agreement were 58.3 to -49.8% (r(2) = 0.00, p = 0.98). In the NIRS group the mean biases were 10.8% and 2.0% for the sensors attached over the cerebral hemisphere and over the internal jugular vein, respectively, and the limits of agreement were 33.1 to -11.4 and 19.5 to -15.5% (r(2) = 0.22, 0.28;p = 0.04, 0.03) for the cerebral hemisphere and internal jugular sites, respectively. While transcutaneous regional oximetry and NIRS have both been used to estimate venous and tissue oxygen saturation non-invasively, the correlation between estimates of ScvO(2) and SxvO(2) were statistically significant for near infrared spectroscopy, but not for transcutaneous regional oximetry. Placement of cerebral oximetry patches directly over the internal jugular vein (as opposed to on the forehead) appeared to approximate internal jugular venous saturation better (lower mean bias and tighter limits of agreement), which suggests this modality may with refinement offer the practitioner additional clinically useful information regarding global cerebral oxygen supply and demand matching.

For transcutaneous carbon dioxide pressure (tcPCO(2)) measurement, the probe on the trunk or extremities has been used for many years. Our previous study showed that chest was better than arm for tcPCO(2) monitoring. Recently, the ear probe has been developed. The accuracy of tcPCO(2) as a surrogate measurement of arterial carbon dioxide pressure (PaCO(2)) has not been compared between the measurement with probe on the chest and measurement with probe on the earlobe. This study compared the accuracy of tcPCO(2) measured on the chest and tcPCO(2) measured on earlobe during general anesthesia in adults using linear regression analysis and Bland-Altman plot.Ten patients aged 30-70 years scheduled for abdominal surgery under general anesthesia were enrolled. TcPCO(2) by TCM4™ (Radiometer, Copenhagen, Denmark, TtcPCO(2)) with its probe on the chest, tcPCO(2) by Sentec™ (Sentec AG, Therwil, Switzerland, StcPCO(2)) with ear probe, end-tidal carbon dioxide pressure (EtCO(2)), and PaCO(2) were simultaneously measured at four different sets of EtCO(2) levels in each patient. In total, 40 measurements were performed. The Scatter plot and Bland-Altman plot were obtained. Correlation coefficient (R(2)) ≥0.70 and limits of agreement ≤4 mmHg were judged as significant.TtcPCO(2) showed significant positive correlation with PaCO(2) (R(2) = 0.80) but StcPCO(2) did not (R(2) = 0.55). TtcPCO(2) and PaCO(2), and StcPCO(2) and PaCO(2) had large limits of agreement (-6.56 mmHg, 4.21 mmHg and -11.05 mmHg, 7.64 mmHg, respectively). TtcPCO(2) and StcPCO(2) had no significant correlation (R(2) = 0.63) and large limits of agreement (-8.98 mmHg to 7.91 mmHg).During general anesthesia in adults, both TtcPCO(2) and StcPCO(2) were not interchangeable with PaCO(2), but only TtcPCO(2) had good positive correlation with PaCO(2).

Cyanosis was used for a century after dentists began pulling teeth under 100% N(2)O in 1844 because brief (2 min) severe hypoxia is harmless. Deaths came with curare and potent anesthetic respiratory arrest. Leland Clark's invention of a polarographic blood oxygen tension electrode (1954) was introduced for transcutaneous PO2 monitoring to adjust PEEP and CPAP PO2 to prevent premature infant blindness from excess O2 (1972). Oximetry for warning military aviators was tried after WW II but not used for routine monitoring until Takuo Aoyagi (1973) discovered an equation to measure SaO2 by the ratio of ratios of red and IR light transmitted through tissue as it changed with arterial pulses. Pulse oximetry (1982) depended on simultaneous technology improvements of light emitting red and IR diodes, tiny cheap solid state sensors and micro-chip computers. Continuous monitoring of airway anesthetic concentration and oxygen also became very common after 1980. Death from anesthesia fell 10 fold between 1985 and 2000 as pulse oximetry became universally used, but no proof of a causative relationship to pulse oximetry exists. It is now assumed that all anesthesiologist became much more aware of the dangers of prolonged hypoxia, perhaps by using the pulse oximeters.

To assess postprocedural angiograms, the ankle–brachial index (ABI), and transcutaneous oxygen tension (TcPO2) to predict outcome after infrageniculate angioplasty (PTA) in diabetic patients with critical limb ischemia (CLI) scheduled for amputation. PTA was performed in 28 diabetic patients with CLI confined to infrapopliteal vessels. We recorded patency of crural vessels, including the vascular supply of the foot as well as the ABI and TcPO2 of the foot. Technical success rate was 92.9% (n = 26), and limb-salvage rate at 12 months was 60.7% (n = 17). The number of patent straight vessels above and below the level of the malleoli increased significantly in patients avoiding amputation. Amputation was unnecessary in 88.2% (n = 15) patients when patency of at least one tibial artery was achieved. In 72.7% (n = 8) of patients, patency of the peroneal artery alone was not sufficient for limb salvage. ABI was of no predictive value for limb salvage. TcPO2 values increased significantly only in patients not requiring amputation (P = 0.015). In patients with only one tibial artery supplying the foot or only a patent peroneal artery in postprocedural angiograms, TcPO2 was capable of reliably predicting the outcome. Below-the-knee PTA as an isolated part of therapy was effective to prevent major amputation in more than a half of diabetic patients with CLI. TcPO2 was a valid predictor for limb salvage, even when angiographic outcome criteria failed.

Proof of the relationship between gastroesophageal reflux disease (GERD) and respiratory symptoms remains a challenge. Our aim was to determine the association between reflux events and O(2) desaturation in GERD patients with primary respiratory symptoms (RS) compared to those with primary esophageal symptoms (ES) using ambulatory monitoring systems.One thousand eight hundred fifty-one reflux episodes were detected by multichannel intraluminal impedance (MII)-pH testing in 30 patients with symptoms of GERD (20 RS, ten ES.) All patients underwent simultaneous 24-h MII-pH and continuous O(2) saturation monitoring via pulse oximetry. Reflux-associated desaturation events were determined by correlating synchronized 24-h esophageal pH and/or impedance and O(2) desaturation.One thousand one hundred seventeen reflux events occurred in patients with RS and 734 in those with ES. Nearly 60% of these 1,851 reflux events were associated with O(2) desaturation. Markedly more events were associated with O(2) desaturation in patients with RS (74.5%, 832/1,117) than in patients with ES (30.4%, 223/734, p0.0001). The difference in reflux desaturation association was more profound with proximal reflux--80.3% with RS vs. 29.4% with ES (p0.0001).A remarkably high prevalence of O(2) desaturation associated with gastroesophageal reflux was noted in patients with RS. Given further study, simultaneous combined esophageal reflux and O(2) saturation monitoring may prove a useful diagnostic tool in this difficult group of patients.

Objective: To determine the reliability of estimating arterial CO2 pressure (PaCO2) using a recently introduced transcutaneous CO2 pressure (PtcCO2) monitor in severe obese patients. Design: Observational and interventional study. Setting: District hospital with respiratory ward and bariatric surgery unit. Patients and methods: PtcCO2 was measured in 35 obese patients with varied pathology, including chronic obstructive pulmonary disease, obstructive sleep apnea syndrome and hypoventilation syndrome. Ten minutes after the probe had been attached to an earlobe, PtcCO2 was recorded immediately before arterial blood sampling. The PtcCO2 and PaCO2 values obtained with two methods were compared by Bland–Altman analysis. In a subgroup of 18 obese patients with chronic obstructive pulmonary disease and/or obstructive sleep apnea syndrome with moderate to severe hypercapnia both PtcCO2 and PaCO2 were re-evaluated during continuous positive airways pressure (CPAP) or bi-level positive airway pressure (Bi-PAP) treatment. Results: The mean difference between PaCO2 and PtcCO2 was –1.4 mmHg, and the standard deviation of the difference was 1.3 mmHg. Bland–Altman analysis showed generally good agreement between the two methods with a 95% limit of agreement of –4 to 1.1. The agreement between methods did not significantly change before and during cPAP or Bi-PAP treatment in hypercapnic patients. Conclusions: The accuracy of estimation of PaCO2 by transcutaneous monitoring was generally good in comparison with standard arterial blood gases examination. The device appears to be promising for use in obese patients to evaluate abnormalities in their alveolar ventilation.

This study assessed the effect of hydromorphone treatment on ventilation and the intensity of dyspnea in palliative care patients. The assessments measured changes in peripheral oxygen saturation (SaO(2)), transcutaneous arterial pressure of carbon dioxide (tcpaCO(2)), respiratory rate (f), and pulse frequency (PF) during the titration phase with hydromorphone for symptomatic therapy of dyspnea. The aims of the study were to verify the efficacy of hydromorphone for the management of dyspnea and assess its effect on ventilation.Fourteen patients admitted to our palliative care unit were included in this prospective, nonrandomized trial. At admission, all patients suffered from dyspnea. TcpaCO(2), SaO(2), and PF were measured transcutaneously by means of a SenTec Digital Monitor (SenTec AG, Switzerland).As early as 30 min after the first hydromorphone application, mean respiratory rate decreased from 38.8 +/- 4.9 breaths/min (range 30.0-45.0 breaths/min) to 34.6 +/- 4.2 breaths/min (29.0-41.0 breaths/min); after 120 min to 29.0 +/- 3.1 breaths/min (range 24.0-33.0 breaths/min) (p = 0.001). The other monitored respiratory parameter, however, showed no significant changes. A significant improvement was shown in the intensity of dyspnea [numeric rating scale 0-10: 5.2 +/- 1.5 (4-8)/6.4 +/- 2.1 (4-10) vs 1.1 +/- 0.9 (0-3)/2.3 +/- 1.3 (1-5); p = 0.001].Neither was there a significant decrease in SaO(2) nor a significant increase in tcpaCO(2) after the initial hydromorphone application, i.e., there was no hydromorphone-induced respiratory depression. The first hydromorphone application, however, resulted in a significant decrease in the intensity of dyspnea and respiratory rate.

Acute Heart Failure is a major cause of hospitalisation, with a rate of death and complications. New guidelines have been developed in order to diagnose and treat this disease. Despite these efforts pathophysiology and treatments options are still limited. There is agreement among the experts that increasing the cardiac output and the stroke volume without fluid overloading the patient should be the goal of every treatment. Despite this, there is no agreement on how to monitor the cardiac function and how to follow it after a therapeutic intervention. In other fields of critical care cardiovascular monitoring and application of early goal directed protocols showed benefits. This review explores the available possibilities of how to monitor the cardiac function in Acute Heart Failure. Standard and more advanced techniques are presented. Cardiac output monitors from the pulmonary artery catheter to the pulse pressure analysis and Doppler techniques are discussed, with focus on this specific clinical setting. Undoubtedly monitoring is valuable tool, but without a protocol of how to manipulate the haemodynamics, no monitor will prove alone to be beneficial. Haemodynamic driven early goal directed therapy are largely awaited in this field of medicine.

To investigate the effects of acupressure on lower limb blood flow for the treatment of peripheral arterial occlusive diseases (PAOD).From February 2004 to February 2005, 30 patients with stage II PAOD underwent measurements of the lower limb blood flow. Six patients (group A) were assigned as controls without any acupoint stimulation, while 24 (group B) underwent stimulation at acupoints by acupressure. The acupoints Yanglingquan (GB34), Zusanli (ST36), Yinlingquan (SP9), and Sanyinjiao (SP6) of the symptomatic lower limbs were stimulated for 3 min. Transcutaneous oximetry (tcPO2) was used to determine the blood flow of the chest wall, bilateral distal crura, and bilateral dorsa of the foot before and during the stimulations at the acupoints.Group A showed no significant change in the lower limb blood flow. In group B, the tcPO2 values of chest wall, bilateral distal crura, and the dorsum of foot of the stimulated lower limb increased significantly during acupressure (P0.01), whereas no significant change was shown in the dorsum of the foot of the non-stimulated lower limb. Moreover, the blood flow of the lower limbs that had undergone an ipsilateral sympathectomy increased significantly (P0.01).Acupressure was found to cause significant increases in the lower limb blood flow of stage II PAOD patients. This treatment modality may therefore be effective for improving the symptoms of such patients.

The transcutaneous measurement of oxygen (tcP(O2)) and carbon dioxide (tcP(CO2)) tensions may serve as a surrogate of arterial oxygen (Pa(O2)) and carbon dioxide (Pa(CO2)) tensions, respectively. We investigated the effects of the electrode temperature of a new device, TCM4, on the measurement of tcP(O2) and tcP(CO2). Twenty-five patients scheduled for major lower abdominal surgery were enrolled. The electrode of the TCM4 was attached to the chest, with its temperature set to 37 degrees C, 40 degrees C, 42 degrees C, 43 degrees C, or 44 degrees C. tcP(O2), tcP(CO2), end-tidal carbon dioxide tension (Et(CO2)), Pa(O2), and Pa(CO2) were simultaneously measured at various Et(CO2) levels and inhaled oxygen concentrations. The times required for stabilization of the tcP(O2) and tcP(CO2) values were measured. A Bland-Altman plot was used to compare the two measurements. The time required for stabilization was shorter with a higher electrode temperature, but the shortest time was still more than 150 s. TcP(O2) correlated well with Pa(O2) at 43 degrees C and 44 degrees C. TcP(CO2) correlated well with Pa(CO2) and Et(CO2) at 43 degrees C. The bias and limits of agreement were larger with lower electrode temperature for TcP(O2)--Pa(O2), tcP(CO2)--Pa(CO2), and tcP(CO2)-Et(CO2). We concluded that the electrode of the TCM4 should be heated to at least 43 degrees C to measure tcP(O2) and tcP(CO2). However, the absolute values of tcP(O2) and tcP(CO2) could not be used as surrogate measurements of Pa(O2) and Pa(CO2), respectively.

To investigate the cause of acidosis following release of an aortic cross-clamp, we measured tissue PCO2 using a transcutaneous (TC) CO2 monitor placed below the level of the cross-clamp in 10 patients undergoing aortic arch surgery. Following placement of the aortic cross-clamp, the TC CO2 value from the lower extremity increased from 41 +/- 4 to 92 +/- 41, whereas there was no change in the TC CO2 value from the upper extremity. With release of the cross-clamp, end-tidal CO2 increased by 6.2 +/- 1.9 mmHg, the upper TC CO2 increased by 8.4 +/- 4.8 mmHg, and the lower extremity TC CO2 value returned to baseline. During cross-clamping, there was an increase in the base deficit of 4.3 +/- 2.9 when comparing the baseline arterial blood gas value with the one obtained after cross-clamp release (p = 0.0004). These data demonstrate that the acidosis occurring during aortic cross-clamping is a mixed metabolic and hypercarbic acidosis. Appropriate treatment includes the provision of adequate minute ventilation to ensure CO2 removal and the use of sodium bicarbonate based on the degree of metabolic acidosis demonstrated by arterial blood gas analysis.

Cerebral hemodynamics play a pivotal role in stroke pathogenesis. Transcranial Doppler (TCD) studies demonstrated the importance of cerebral vasomotor reactivity (VMR) on the outcome of carotid artery occlusion (CAO). So far, positron emission tomography represents the best technique for detecting both hemodynamic and metabolic aspects of cerebral perfusion adaptive processes in cerebrovascular patients. Near-infrared spectroscopy (NIRS) is a new method allowing for a non-invasive assessment of cerebral blood flow and hemoglobin (Hb) oxygenation parameters. A recent TCD and NIRS study demonstrated that patients with symptomatic CAO had lower VMR values measured by TCD and lower oxygen saturation (oxygen%) increases detected by NIRS than asymptomatic ones. The parameters were obtained simultaneously after CO2 inhalation. The present study aims to investigate if Hb oxygen % could represent also at rest a marker of hemodynamic status in carotid disease. Thirty-five symptomatic and 17 asymptomatic patients with CAO underwent a simultaneous examination by means of TCD and NIRS at rest condition and during CO2 reactivity test. Symptomatic patients presented with oxygen% values at rest higher (p = 0.001) and VMR values lower (p

To test the hypothesis that microcirculatory blood flow is the main determinant of sublingual carbon dioxide pressure in patients with septic shock. Prospective, open-label study A 31-bed medico-surgical department of intensive care. Eighteen consecutive mechanically ventilated patients with septic shock. A 5 μg/kg · min dobutamine infusion was used to increase blood flow. Sublingual carbon dioxide pressure was monitored using a microelectrode sensor, and sublingual microcirculation was assessed using orthogonal polarization spectral imaging. The sublingual carbon dioxide pressure gap was calculated as the difference between sublingual and arterial carbon dioxide pressures. In each patient, a nasogastric tonometry catheter was inserted for gastric mucosal carbon dioxide pressure measurement. The gastric carbon dioxide pressure gap was calculated as the difference between gastric mucosal and arterial carbon dioxide pressures. Dobutamine infusion was associated with increases cardiac index and mixed venous blood oxygen saturation. Dobutamine infusion resulted in decreases in sublingual carbon dioxide pressure gap from 40 ± 15 to 17 ± 8 mmHg (p

Background and Objectives. Early noninvasive hemodynamic monitoring with an outcome predictor and a therapeutic decision support system may be useful to identify and correct hemodynamic deficiencies in emergency patients. The first aim was to apply a stochastic (probability) search and display model to predict outcome as early as possible. The second aim was to explore the usefulness of a therapeutic decision support system to evaluate the relative effectiveness of various therapies. Methods. A stochastic control and display program based on noninvasive hemodynamic monitoring was applied in 100 consecutive critically ill patients admitted to the emergency department of an inner city public hospital. The program continuously displayed the noninvasive hemodynamic data and the patient's predicted survival probability (SP) that was based on the patient's diagnosis, covariates, and hemodynamic data. The accuracy of the SP at the initial resuscitation on admission to the emergency department (ED) was evaluated by the actual outcome at hospital discharge. The therapeutic decision support program evaluated the relative effectiveness of various therapies on based on their hemodynamic and SP responses and outcome of patients with similar clinical-hemodynamic states. Results. The cardiac index, mean arterial pressure, arterial saturation, transcutaneous oxygen and carbon dioxide tensions were appreciably higher in survivors than in nonsurvivors in the initial resuscitation. Heart rate was higher in the nonsurvivors. The calculated Survival Probability (SP) of survivors averaged 81 ± 1.4% in the first 24-hour observation period. It was 58 ± 2.2% for nonsurvivors during this period. Misclassifications were 10/100 or 10%.

To investigate the effect of the red vine leaf extract AS 195 on cutaneous microvascular blood flow, transcutaneous oxygen pressure (tcpO2), and leg oedema in patients with chronic venous insufficiency (CVI).The study was a randomised, double-blind, placebo-controlled, crossover trial for which 129 men and women, agedor =18 years, with CVI stage I or II were screened. Seventy-one fulfilled the inclusion criteria and were randomised.A total of 71 patients were divided into two groups. The first group (n = 36) received AS 195 360mg once daily during a first 6-week treatment period, followed by a 4-week placebo washout period and then placebo during the second 6-week treatment period. The second group (n = 35) started with placebo and received AS 195 360mg after the placebo washout. The cutaneous microvascular blood flow in the malleolar region was measured using a newly developed laser Doppler device. TcpO2 was measured using a solid-state electrode.After 6 weeks, patients in the AS 195 group had increased microvascular blood flow values (+241.8 +/- 18.7 arbitrary units [AU] versus a decrease of -41.0 +/- 18.7AU in the placebo group; p0.0001). Oxygen increased to 1.35 +/- 0.97mm Hg (placebo: decrease of -7.27 +/- 0.97mm Hg; p0.0001). After 6 weeks of treatment the leg circumference was decreased (ankle level: by -0.39 +/- 0.09cm versus +0.29 +/- 0.09cm; p0.0001; calf level: by -0.54 +/- 0.05cm versus +0.14 +/- 0.05cm; p0.0001).The administration of AS 195 improved objective symptoms of CVI and may prevent CVI deterioration.

The main purpose of our study was to determine the parameters of the postocclusive reactive hyperemia test that could help and provide the clinician with information about the tissue oxygenation, the severity of the disease, and the results of the applied therapies. Near infrared spectroscopy (NIRS) proved to be a valid noninvasive trend monitor useful for investigating the physiology of oxygen transport to tissue. Important advantages of NIRS over transcutaneous oximetry (TcpO2) are: (a) a more dynamic nature of the NIRS signals which reflects more closely the actual response of the peripheral vasculature to the occlusive provocation; (b) larger sampling volume; and (c) the ability of assessing tissue oxygenation at deeper tissue levels. We demonstrated that the time parameters of reactive hyperemia, the rate of reactive hyperemia, and the maximal change during reactive hyperemia, all calculated from the oxyhemoglobin (HbO2) signal of the NIRS, clearly distinguish between healthy volunteers and patients with vascular disorder. The time parameters of reactive hyperemia were significantly longer (p < 0.01), and the rate of reactive hyperemia (p = 0.01) as well as the maximal change during reactive hyperemia (p = 0.02) were significantly lower in patient group compared to healthy volunteers. These parameters were also in good correlation with the values of ankle brachial index (ABI) and the resting values of oxygen partial pressure (TcpO2). Values of the chosen parameters obtained from the HbO2 signal were further compared between groups of diabetic and nondiabetic patients with peripheral vascular disease. Although longer time parameters of reactive hyperemia and lower rates of hyperemic response were detected, the difference between both groups was not statistically significant. © 2001 Biomedical Engineering Society.

Objective: The aim of the study was to test the applicability of Ventrak 1550/Capnogard 1265 (V-C) for respiratory dead space (Vd) measurement and to determine anatomic (VDana), physiologic (VDphys), and alveolar dead spaces (VDalv) in ventilated neonates. Design: Prospective study. Setting: Neonatal intensive care unit. Patients: 33 investigations in 22 ventilated neonates; median gestational age 34.5 weeks (range 27–41), median birthweight 2658 g (range 790–3940). Method: The single-breath CO2 test (SBT-CO2) and transcutaneous partial pressure of carbon dioxide (PCO2) were recorded simultaneously and Vd was determined (1) automatically (V-C software), (2) by interactive analysis of the PCO2 volume plot, and (3) manually by Bohr/Enghoff equations using data obtained by V-C. Results: Vd measurements were possible in all cases by method 3 but not possible by methods 1 and 2 in 22 of 33 investigations (67 %), especially in preterm neonates, because of disturbed signals. VDana/kg (1.6 ± 0.6 ml/kg, mean ± SD), VDana/tidal volume (Vt) (0.36 ± 0.09) were lower compared to published data in spontaneously breathing infants, whereas VDphys/kg (2.3 ± 0.9 ml/kg) and VDphys/Vt (0.50 ± 0.12) are comparable to data obtained from the literature. Five minutes after insertion of the sensor (dead space 2.6 ml) into the ventilatory circuit, the transcutaneous PCO2 rose above baseline for 3.2 % (patients > 2500 g) and 5.7 % (patients < 2500 g). The time necessary for one analysis was 50–60 min. Conclusion: In ventilated newborns, dead space measurements were possible only in one-third by SBT-CO2, but in all cases by Bohr/Enghoff equations. Improved software could further reduce the time needed for one analysis.

Whereas during the last few years handling of the transcutaneous PO2 (tcPO2) and PCO2 (tcPCO2) sensor has been simplified, the high electrode temperature and the short application time remain major drawbacks. In order to determine whether the application of a topical metabolic inhibitor allows reliable measurement at a sensor temperature of 42 degrees C for a period of up to 12 h, we performed a prospective, open, nonrandomized study in a sequential sample of 20 critically ill neonates. A total of 120 comparisons (six repeated measurements per patient) between arterial and transcutaneous values were obtained. Transcutaneous values were measured with a control sensor at 44 degrees C (conventional contact medium, average application time 3 h) and a test sensor at 42 degrees C (Eugenol solution, average application time 8 h). Comparison of tcPO2 and PaO2 at 42 degrees C (Eugenol solution) showed a mean difference of +0.16 kPa (range +1.60 to -2.00 kPa), limits of agreement +1.88 and -1.56 kPa. Comparison of tcPO2 and PaO2 at 44 degrees C (control sensor) revealed a mean difference of +0.02 kPa (range +2.60 to -1.90 kPa), limits of agreement +2.12 and -2.08 kPa. Comparison of tcPCO2 and PaCO2 at 42 degrees C (Eugenol solution) showed a mean difference of +0.91 (range +2.30 to +0.10 kPa), limits of agreement +2.24 and -0.42 kPa. Comparison of tcPCO2 and PaCO2 at 44 degrees C (control sensor) revealed a mean difference of +0.63 kPa (range 1.50 to -0.30 kPa), limits of agreement +1.73 and -0.47 kPa.Our results show that the use of an Eugenol solution allows reliable measurement of tcPO2 at a heating temperature of 42 degrees C; the application time can be prolongued up to a maximum of 12 h without aggravating the skin lesions. The performance of the tcPCO2 monitor was slightly worse at 42 degrees C than at 44 degrees C suggesting that for the Eugenol solution the metabolic offset should be corrected.

Conflicting patterns of change in cytochrome c oxidase (Cyt a,a3) redox status have been obtained between different near-infrared spectrophotometers when making measurements during tissue ischaemia. This study identifies possible sources of error that could be the cause of the discrepancy. A single set of optical density data was repeatedly analysed using each of the absorption spectra from 13 publications. In addition, changes in Cyt a,a3 redox status were calculated from the data set using three numerical methods, five computer software routines, eight displacements in wavelength, and ten incremental changes in the value of absorption or concentration coefficients. All Cyt a,a3 absorption spectra resulted in algorithms yielding similar patterns of change, regardless of the numerical method or computer process employed (0.9996 average r2, coefficient of correlation). However, a significantly different pattern of change in Cyt a,a3 redox status, resembling that reported by Piantadosi [Piantadosi CA (1993) Methods Toxicol. 2:107-126], was obtained when either the wavelengths, and/or the absorption values were altered to simulate erroneous values. This implies that all of the present algorithms are valid (including those of Piantadosi), but that microchip encoding errors may exist in the instrument used by Piantadosi.

The growing number of patients admitted for outpatient surgery or for same-day admission makes it difficult to obtain thorough pulmonary evaluation. We wanted to evaluate the applicability of pre-operative pulse oximetry and capnography as possible pulmonary screening tools. In this preliminary study, 200 unselected, unmedicated adult patients who were being admitted for surgery were connected to a dual parameter patient monitor (Capnomac Ultima TM , Datex). A standard adult clip-on finger probe was used for pulse oximetric oxygen saturation. Sidestream capnometry documented the end-tidal carbon dioxide and the capnogram which was recorded for further analysis. In these unmedicated patients, the oxygen saturation ranged from 91 to 99% and was found to be 94% or less in five percent (N=10) of the cases. The end-tidal carbon dioxide ranged from 21 to 48 mmHg. In five percent of the cases (N=10) it was found to be 45 mmHg or higher, reflecting elevated arterial CO2. When the shape of the capnogram was rated, it was found normal in 54% of the cases. Slow rising capnogram, indicating mild (N=84) or moderate (N=8) airway obstruction was detected in 42% or 4% of the cases respectively. Since pulse oximeter and end-tidal carbon dioxide values are often not measured until after sedation or after induction of anesthesia, patients with pre-operative abnormalities might escape pre-operative detection. In unmedicated patients, routine pre-operative or pre-admission determination of oxygen saturation, end-tidal carbon dioxide and the capnogram may be a valuable screening tool.

On reaching the respiratory compensation point (RCP) during rapidly increasing incremental exercise, the ratio of minute ventilation (VE) to CO2 output (VCO2) rises, which coincides with changes of arterial partial pressure of carbon dioxide (PaCO2). Since PaCO2 changes can be monitored by transcutaneous partial pressure of carbon dioxide (PCO2,tc) RCP may be estimated by PCO2,tc measurement. Few available studies, however, have dealt with comparisons between PCO2,tc threshold (TAT) and lactic, ventilatory or gas exchange threshold (VAT), and the results have been conflicting. This study was designed to examine whether this threshold represents RCP rather than VAT. A group of 11 male athletes performed incremental exercise (25 W.min-1) on a cycle ergometer. The PCO2,tc at (44 degrees C) was continuously measured. Gas exchange was computed breath-by-breath and hyperaemized capillary blood for lactate concentration ([la-]b) and PaCO2 measurements was sampled each 2 min. The TAT was determined at the deflection point of PCO2,tc curve where PCO2,tc began to decrease continuously. The VAT and RCP were evaluated with VCO2 compared with oxygen uptake (VO2) and VE compared with the VCO2 method, respectively. The PCO2,tc correlated with PaCO2 and end-tidal PCO2. At TAT, power output [P, 294 (SD 40) W], VO2 [4.18 (SD 0.57) l.min.1] and [la(-)] [4.40 (SD 0.64) mmol.l-1] were significantly higher than those at VAT[P 242 (SD 26) W, VO2 3.56 (SD 0.53) l.min-1 and [la(-)]b 3.52 (SD 0.75), mmol.l-1 respectively], but close to those at RCP [P 289 (SD 37) W; VO2 3.97 (SD 0.43) l.min-1 and [la(-)]b 4.19 (SD 0.62) mmol.l-1, respectively]. Accordingly, linear correlation and regression analyses showed that P, VO2 and [la(-)]b at TAT were closer to those at RCP than at VAT. In conclusion, the TAT reflected the RCP rather than VAT during rapidly increasing incremental exercise.

Objective. Venous oximetry catheters provide useful realtime information about mixed venous hemoglobin saturation (Svo2). Currently available systems utilize either two or three wavelengths of light to obtain these measurements. Previous animal and clinical studies have attempted to compare the accuracy of these two devices under similar circumstances. However, the relative accuracy of the two-wavelength versus three-wavelength systems has never been assessed under identical conditions. For this purpose, we designed an animal model for simultaneous measurement ofSvo2 over a wide range of physiologic and pathologic states.Methods. Seven anesthetized swine underwent simultaneous placement of two- and three-wavelength catheters. Paired data points consisted of values obtained from a reference oximeter and from each of the catheters. Observations were obtained every 15 min during the following manipulations: (1) eucarbic hypoxia induced by reducing Fio2 to 0.18, 0.15, and 0.12 for 15 min each; (2) simulated surgical manipulation; and (3) hypovolemic shock produced by hemorrhage to a mean arterial pressure of 50 torr for 1 hr. Data were analyzed by calculation of mean error (bias) and precision for each system in comparison with the oximeter.Results. The overall error of the two-wavelength system was +0.15%, with a precision of ±2.54%. The three-wavelength system had an overall error of +3.71%, with a precision of ±2.30%. Overall correlation between catheterSvo2 and oximeter values was the same for both devices (r=0.99).Conclusions. Both currently available in vivo spectrophotometric systems are capable of producing satisfactory results over wide ranges ofSvo2. In contradistinction to older reports, we found that the two-wavelengthSvo2 system produced results equivalent to those obtained from the three-wavelength device. In this regard, there is no detectable advantage in accuracy to measuring in vivoSvo2 with three rather than with two wavelengths.

In term infants sucrose given by mouth has been reported to reduce duration of crying after a heel prick. This study was designed primarily to investigate the effect of sucrose administered orally immediately before heel lancing on the nociceptive reaction in preterm infants as assessed by change in heart rate and duration of crying. A secondary objective was to document changes in cerebral blood volume during acute pain. We used a randomized, masked, placebo-controlled, crossover trial in a neonatal intermediate care unit in a level 3 perinatal center. The patients studied were 16 preterm infants; birth weight, 900-1900 g; gestational wk, 27-34; corrected postmenstrual age at time of investigation, 33-36 wk. Each infant was assessed twice receiving 2 mL of sucrose 50% or 2 mL of distilled water in random order immediately before heel lance. Heart rate, thoracic movements, and transcutaneous blood gases were monitored continuously. Crying during the procedure was documented by a video-camera. A change in cerebral blood volume was assessed by near-infrared spectroscopy. We found the heart increased by a mean of 35 beats/min (bpm) after sucrose and 51 bpm after placebo (median difference 16 bpm, interquartile range 1-30 bpm, p = 0.005). Infants cried 67% of time after sucrose and 88% after placebo (median difference 10%, interquartile range 3-33%, p = 0.002). Cerebral blood volume decreased in 5 of 14 infants after sucrose and in 6 of 14 infants after placebo (difference not significant).

Top of pageAbstract The patient with spinal cord injury is at high risk of tissue breakdown at all times due to a number of adverse factors, such as reduced mobility and anaesthesia. It is therefore essential that each patient is prescribed appropriate support media during initial rehabilitation. In this study, the effectiveness of prescribed wheelchair cushions has been assessed in terms of tissue response at the ischial tuberosities. A total of 42 subjects who had sustained traumatic spinal cord injury within 1 year were monitored on at least two occasions during initial rehabilitation. Changes in transcutaneous gas response (TCPO2 and TCPCO2) were monitored concurrently with regional interface pressures. A series of six transcutaneous gas variables were established, as markers of tissue viability. Non-parametric statistical analyses revealed some significant correlations between these variables. The results of this study also indicate that (1) spinal cord injury subjects with lesions below T6 show a progressive decrease in ability to maintain blood flow in sitting on prescribed support cushions and (2) SCI subjects with lesions above T6 show a progressive improvement in tissue viability status at the seating support interface. Therefore results imply that paraplegics are at a potentially higher risk of tissue breakdown than tetraplegics and thus require effective support cushions with strict adherence to a pressure relief regime. Keywords: pressure sores; paraplegia; tissue viability; cushion; transcutaneous gas tension

Objective To compare the effects of intravenously injected with inhaled salbutamol in ventilator dependent infants with chronic lung disease (CLD). Design Prospective randomized study in which each patient served as his/her own control. Setting Multidisciplinary neonatal and pediatric ICU. Patients 8 ventilator dependent premature infants with CLD. Interventions Salbutamol, 10 μg/kg was given intravenously, and 10–19 h later, twice 100 μg as pressurized aerosol, or vice versa, sequence randomized. The pressurized aerosol was delivered by a metered dose inhaler into a newly developed aerosol holding chamber, integrated into the inspiratory limb of the patient circuit. Respiratory system mechanics were assessed by the single breath occlusion method before and 10 and 60 min after drug administration. Measurements and results Compliance improved significantly after intravenous injection (0.48±0.18 to 0.67±0.16, p

In this study, the relationship between the fluctuation in blood oxygen and carbon dioxide tension and the progression of acute retinopathy of prematurity (ROP) was evaluated. Eighteen extremely premature infants were selected on the basis of the following criteria: gestational age less than 26 weeks, oxygen supply or mechanical ventilation for more than 50 days, transcutaneous oxygen pressure (TcPO2) recorded almost once per hour, and arterial oxygen pressure (PaO2) and arterial carbon dioxide pressure (PaCO2) measured intermittently, for over 8 weeks after birth. All of these infants developed ROP, which ceased progressing in 7 infants (group I, stage 1 or 2 ROP, international classification), but advanced in 11 (group II, stage 3 or 3+). The fluctuations in TcPO2, PaO2, and PaCO2 are represented as coefficients of both variation (CV) and mean difference (D) in these two groups. The results demonstrate that both the CV and D values of TcPO2 are significantly elevated in group II infants compared with group I infants, in the first and second 3-weeks periods, and over the entire 9-week period after birth. The incidences of extreme hyperoxemia (TcPO2 > or = 100 mm Hg) and hypoxemia (TcPO2 < 30 mm Hg) in recorded TcPO2 time series show no significant differences between these two groups. We conclude that extremely premature infants with widely fluctuating arterial oxygen tension may have a greater chance of developing progressive ROP.

In 40 intensive care patients, tissue oxygen partial pressure distribution within skeletal muscle was measured in order to estimate peripheral oxygen availability. In septic patients with multiple organ failure (n = 20) mean skeletal muscle pO2 was abnormally high (48.8 +/- 8.5 mmHg, p less than 0.001) in contrast to patients with limited infection without sepsis (28.3 +/- 5.9 mmHg, n = 10). Mean muscle pO2 also discriminated between septic and cardiogenic shock (22.6 +/- 6.9 mmHg, p less than 0.001). The characteristic pattern of oxygen availability in septic patients--but not in patients with limited infection--was high skeletal muscle pO2 high whole body oxygen delivery and low whole body oxygen extraction, which was not influenced by the type of pathogenic agent of sepsis. In our patients in severe stage of sepsis, we did not observe local skeletal muscle hypoxia due to microcirculatory disorder. High mean skeletal muscle pO2 suggested reduced oxygen consumption within tissue rather than reduced oxygen transport to tissue in sepsis.

We compared the 95% response time (95% RT) of two tissue oxygen tonometers under two sets of circumstances. We first evaluated the devices during normoxia, hyperoxia, and anoxia in vitro, using a transcutaneous PO2 electrode (PtcO2) as the reference. The responses to normoxia and to different grades of hyperoxia were examined in vivo in 8 healthy volunteers to assess the relationship between changes in subcutancous PO2 and PtcO2, an estimate of arterial PO2 (PaO2). One subcutaneous method (ScA) used a technique based on a polarographic needle electrode in situ connected to an ammeter; the second method (ScB) was based on a blood gas analyzer system first described by Hunt (Lancet 164;2:1370). ScA and PtcO2 both responded to stepwise changes in ambient oxygen concentration (21–100%) in vitro within 10 seconds; the 95% RT of ScA was 1.39±0.5 to 2.39±0.8 minutes and that of PtcO2 was 0.32±0.1 to 0.49±0.1 minutes. ScB had a lag of 3 minutes, and the 95% RT was 6.75±0.5 to 8.2±0.8 minutes. In contrast to the results in vitro, the response of ScA to changes in FiO2 in vivo was delayed compared with the rapid response of PtcO2, reflecting the physiologic delay of tissue PO2 in response to increased PaO2. The time lag and the long 95% RT of ScB were even more evident in vivo. ScA reacted three to four times faster than ScB, both in vitro and in vivo, to changes in the oxygen environment. The in vitro 95% RT of ScA to changes in ambient oxygen varied from 2 to 3.5 minutes. In contrast, the 95% RT of ScB was 8 to 9 minutes. PtcO2 had the fastest 95% RT, from 0.4 to 0.5 minutes. The results suggest that the subcutaneous needle electrode method (ScA) provides close to real-time assessment of tissue PO2.

Transcutaneous oxygen pressure (TcPO2) and skin blood flow (as evaluated by laser doppler) (LD) were investigated in 24 systemic sclerosis (SSc) patients in sclerotic skin (dorsal aspect of the hand) and non-sclerotic skin (interscapular region) and in 24 controls matched for sex and age for the same sites. The two parameters were evaluated at 44 degrees C (temperature of the two sensors) in 13 patients and 13 controls, and at 36-37 degrees C in the remaining 11. At 44 degrees C, TcPO2 was lower in SSc patients than in controls for both sclerotic and non-sclerotic skin. At 37 degrees C there was no significant difference. At 44 degrees C, LD values were decreased in patients with respect to controls for both sclerotic and and non-sclerotic skin. In contrast, at 37 degrees C the values were increased in patients only for the sclerotic skin. It can be hypothesized that the increased LD values at physiological temperature are at least in part balancing a decreased tissue oxygen tension, then a normal TcPO2 is ensured. On the other hand, the decreased LD values at 44 degrees C, when TcPO2 is also decreased, indicates that there is an inability of SSc vessels to significantly increase their flow under the stimulus of a maximal hyperaemia-inducing temperature.

Transcutaneous PO2 (PtcO2) is suggested to reflect tissue oxygenation in intensive care patients, whereas transcutaneous PCO2 (PtcCO2) is advocated as a noninvasive method for assessing PaCO2. In 24 critically ill adult patients (mean Apache II score 14.2, SD 4.7) we investigated the impact of variables that are commonly thought to determine PtcO2 and PtcCO2 measurements. A linear correlation was found between PtcO2 and PaO2 (r = 0.6; p less than or equal to 0.0001) and between PtcO2 and mean arterial blood pressure (MAP; r = 0.42; p less than or equal to 0.003). Cardiac index (CI) correlated with tc-index (PtcO2/PaO2; r = 0.31; p less than or equal to 0.03). There was no relationship between PtcO2 and hemoglobin concentration (Hb) and the position of the oxygen dissociation curve (ODC). Stepwise multiple regression analysis demonstrated a significant influence of PaO2 and MAP on PtcO2. The contribution of CI, Hb and the ODC was not significant. Only 40% of the variability of a single PtcO2 measurement could be explained by PaO2 and MAP. A significant linear correlation was demonstrated between PtcCO2 and PaCO2 (r = 0.76; p less than or equal to 0.0001) but not between PtcCO2 and CI, MAP and arterial base excess (BEa). Stepwise multiple regression analysis revealed an influence of PaCO2 and of CI on PtcCO2; 66% of the variability of a single PtcCO2-value could be explained by PaCO2 and CI. Our data demonstrate that transcutaneous derived gas tensions result from complex interaction between hemodynamic, respiratory and local factors, which can hardly be defined in ICU-patients.

In vitro and in vivo animal studies have shown accurate measurements of arterial blood pH (pHa), carbon dioxide tension (PaCO2), and oxygen tension (PaO2) with small intravascular fluorescent probes. Initial human clinical studies showed unexplained intermittent large drops in sensor oxygen tension (PiO2). Normal volunteers were studied to elucidate this problem. In the first part of this study, the probe and cannula were manipulated and the probe configuration and its position within the cannula were varied. The decreases in PiO2 were judged to be primarily due to the sensor touching the arterial wall. Retraction of the sensor tip within the cannula eliminated the problem. In the second part of this study, the accuracy of the retracted probe was evaluated in 4 subjects who breathed varying fractions of inspired oxygen and carbon dioxide. The arterial ranges achieved were 7.20 to 7.59 for pH, 22 to 70 mm Hg for PaCO2, and 46 to 633 mm Hg for PaO2. Linear regression of 48 paired sensor (i) versus arterial values showed pHi = 0.896 pHa + 0.773 (r = 0.98, SEE = 0.017); PiCO2 = 1.05 PaCO2 - 1.33 (r = 0.98, SEE = 2.4 mm Hg); and PiO2 = 1.09 PaO2 - 20.6 (r = 0.99, SEE = 21.2 mm Hg). Bias (defined as the mean differences between sensor and arterial values) and precision (SD of differences) were, respectively, -0.003 and 0.02 for pHi, 0.77 and 2.44 mm Hg for PiCO2, and -2.9 and 25.4 mm Hg for PiO2. The mean in vivo 90% response times for step changes in inspired gas were 2.64, 3.88, and 2.60 minutes, respectively, for pHi, PiCO2, and PiO2.

PtcO2 monitoring is a reliable technique of predicting change in PaO2 However there are many factors that should be taken into account to minimize sources of error. Such factors include skin properties, site of application, skin perfusion, blood pressure, anesthetic agents and electrode temperature. Despite these limitations PtcO2 continues to be a useful, non-invasive monitoring device in the intensive care unit.

After irradiated by 8 Gy 60Co gamma-ray, mice were intraperitoneally injected immediately with 0.2 ml 100% compound blood-activating soup twice a day for 10 days. The in situ ulnar bone marrow partial pressure of oxygen (PbO2) was determined in vivo before, during and after irradiation respectively. The bone marrow sections in the same part were observed. Our results showed that the normal murine ulnar PbO2 was 12.72 +/- 1.05 kPa. During irradiation, the level of PbO2 decreased to 10.78 +/- 1.17 kPa (P0.001). And 3 days after irradiation, PbO2 decreased to 9.75 +/- 0.52 kPa, suggesting that the commonly used "blood-activating and stasis-eliminating" Chinese drugs could promote the rehabilitation and proliferation of bone marrow microvessels in the acute radiation injured mice, expand their areas, increase the oxygen supply of bone marrow microenvironment, thereby leading to PbO2 much higher increase than that of control group. It is also helpful in the proliferation and rehabilitation of hematopoietic cells.

Background PCO2 and PO2 are important monitoring parameters in neonatal intensive care units (NICU). Compared to conventional blood gas measurements that cause significant blood loss in preterms, transcutaneous (tc) measurements allow continuous, non-invasive monitoring of blood gas levels. The aim of the study was to survey the usage and opinions among German speaking NICUs concerning tc blood gas monitoring. Methods A questionnaire was developed and sent to 56 head nurses of different NICUs in Germany, Switzerland and Austria. Results A completely answered questionnaire was obtained from 41 NICUs. In two of these units tc measurements are not performed. In most NICUs (77%), both PtcO2 and PtcCO2 are measured simultaneously. Most units change the sensors every 3 hours; however, the recommended temperature of 44°C is used in only 15% of units. In only 8% of units are arterial blood gases obtained to validate tc values. Large variations were found concerning the targeted level of oxygen saturation [median upper limit: 95% (range 80–100%); median lower limit: 86% (range 75–93%)] and PO2 [median upper limit: 70 mmHg (range 45–90 mmHg); median lower limit: 44 mmHg (range 30–60 mmHg)]. Conclusion Our survey shows that the use of tc monitors remains widespread among German speaking NICUs, despite earlier data suggesting that their use had been abandoned in many NICUs worldwide. In addition, we suggest that the current method of monitoring oxygenation may not prevent hyperoxemia in preterm infants.