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It was hypothesised that there is a linear relationship between the severity of exercise induced calf ischaemia and the prevalence of calf claudication on a treadmill until a plateau is reached. It was expected that no pain would be present in the absence of ischaemia and all severely ischaemic calves would be symptomatic.This was a retrospective analysis of a cross sectional acquired database recording. Transcutaneous oxygen pressure (TcPOA linear relationship was found between the degree of ischaemia and the proportion of symptomatic calves for DROPm values ranging from 0 mmHg to -28 mmHg (proportion = -0.014 × DROPm + 0.32, r = 0.961, p.001). For DROPm values lower than -28 mmHg (severe ischaemia), on average one of three limbs remained asymptomatic. The biphasic relationship between DROPm and prevalence of symptoms persists after exclusion of patients with diabetes mellitus, exercise induced hypoxaemia, and no evidence of lower extremity arterial disease (LEAD).The relationship between exercise induced pain and ischaemia is biphasic with a linear increase in the proportion of symptomatic limbs with ischaemia severity, until a plateau is reached for the more severely ischaemic limbs. The presence of exercise related calf symptoms should not automatically be reported as indicating the presence of LEAD; and the absence of exercise induced symptoms is not proof that ischaemia does not occur during exercise.

There is a general underappreciation of the spectrum of obesity-related breathing disorders and their consequences. We therefore compared characteristics of obese patients with eucapnic obstructive sleep apnea (OSA), OSA with obesity-related sleep hypoventilation (ORSH) or obesity hypoventilation syndrome (OHS) to identify the major determinants of hypoventilation.In this prospective, diagnostic study (NCT04570540), obese patients with OSA, ORSH or OHS were characterized applying polysomnography with transcutaneous capnometry, blood gas analyses, bodyplethysmography and measurement of hypercapnic ventilatory response (HCVR). Pathophysiological variables known to contribute to hypoventilation and differing significantly between the groups were specified as potential independent variables in a multivariable logistic regression to identify major determinants of hypoventilation.Twenty, 43 and 19 patients were in the OSA, ORSH and OHS group, respectively. BMI was significantly lower in OSA as compared to OHS. The extent of SRBD was significantly higher in OHS as compared to OSA or ORSH. Patients with ORSH or OHS showed a significantly decreased forced expiratory volume in 1 s and forced vital capacity compared to OSA. HCVR was significantly lower in OHS and identified as the major determinant of hypoventilation in a multivariable logistic regression (Nagelkerke RAlthough there were differences in BMI, respiratory mechanics and severity of upper airway obstruction between groups, our data support HCVR as the major determinant of obesity-associated hypoventilation.

Objective To compare the potential healing prognosis of the different routine noninvasive techniques implemented in the International Working Group Diabetic Foot Guidelines with the novel use of hyperspectral imaging (HSI) in patients with diabetic foot ulcers (DFUs). Methods Twenty-one patients with active DFUs participated in this 1-year prospective study in a specialized diabetic foot unit between December 2018 and January 2020. HSI was performed at baseline to quantify tissue oxygenation and should be presented on an anatomical map by analyzing the following parameters: (1) oxygen saturation of the hemoglobin, (2) tissue hemoglobin index, (3) the near-infrared perfusion index, and (4) tissue water index. In addition, transcutaneous oxygen pressure (TcpO2), systolic toe and ankle pressures, ankle-brachial index, and toe-brachial index values were calculated for the ulcerated limb. The primary outcome measure was wound healing, defined as complete epithelization without any drainage confirmed for at least 10 days after closure was first documented at 24 weeks. Results During the follow-up period 14 patients (66.66 %) healed and 7 patients did not heal (33.3%) by 24 weeks. The TcpO2 optimal cut-off point as determined by a balance of sensitivity and specificity of 28.5 mm Hg that yielded a sensitivity of 91% and a specificity of 100%, and area under the curve of 0.989 (P = .005; 95% confidence interval [CI], 0.945-1.000). Followed by the oxygen saturation of the hemoglobin optimal cut-off point as determined by a balance of sensitivity and specificity of 48.5 mm Hg that yielded a sensitivity of 93% and a specificity of 0.71%, and area under the curve of 0.932 (P = .013; 95% CI, 0.787-1.000). The logistic regression analyses showed that TcpO2 was the only variable associated with wound healing at 24 weeks (P Conclusions The HSI was shown to be effective in the prognosis of DFU healing compared with other noninvasive test; only TcpO2 values resulted in better diagnosis potential in wound healing.

Purpose Photo-optical TCpO2 (pTCpO2) has been proposed as a new method to determine the partial oxygen pressure of the lower extremity in patients with peripheral arterial disease. It is aimed to determine the level of agreement between pTCpO2 and the traditional electro-chemical transcutaneous oxygen tension measurement (eTCpO2). Methods Eighteen patients with intermittent claudication underwent simultaneous ankle-brachial index measurement, toe-pressure, pTCpO2 and eTCpO2 tests. Oxygen tension levels were measured on anterior chest and calf prior in rest (T0), during induced ischemia (T1) and after blood flow restoration (T2). TCpO2 agreement was assessed according to the principles of Bland and Altman. Results Absolute average TCpO2 values differed between eTCpO2 and pTCpO2 for calf in T2 (38,1 mmHg (σ 14,4) vs. 49,8 (σ 22.3) with P = 0.35). The Bland-Altman plots demonstrated eTCpO2 and pTCpO2 bias of 3,7 mmHg (σ 18,8), 11,6 mmHg (σ 17,6) and 6,7 mmHg (σ 23,5) for T0, T1 and T2 for the calf. Conclusion pTCpO2 is in agreement with eTCpO2 in measuring pO2 levels of the lower extremity in rest and during induced ischemia in patients with vascular claudication. The large variability between eTCpO2 and pTCpO2 should be accounted for, while pTCpO2 values have a tendency to demonstrate higher values in comparison to eTCpO2.

Objective The aim of this study was to evaluate changes in transcutaneous oxygen pressure (tcpO2) and systolic toe pressure (TP) during endovascular intervention. Methods This was a single centre prospective, non-randomised, observational feasibility study. Patients with chronic limb threatening ischaemia (CLTI) due to infrainguinal disease scheduled for endovascular treatment were included between March 2018 and December 2019. TcpO2 was measured continuously bilaterally at foot level throughout the procedure and at follow up. Specific time points during the intervention were chosen for comparison to baseline (before arterial puncture): average tcpO2 level five minutes prior to percutaneous transluminal angioplasty (PTA); 10 minutes after PTA; and at completion. Bilateral TP was recorded using laser Doppler flowmetry before arterial puncture, at completion, and at clinical follow up. Angiograms were analysed for successful revascularisation and vascular lesions classified according to the Global Limb Anatomical Scoring System (GLASS). Rutherford and WIfI (Wound, Ischaemia, and foot Infection) classifications were registered, as well as clinical outcome. Results Twenty-one patients completed the study. Completion angiograms showed inline flow to the foot in all but two patients. Median time to follow up was 10 weeks (range 8 – 13 weeks) and all patients except one improved clinically. TcpO2 decreased during the initial stage of the intervention, from before arterial puncture to five minute average before PTA (p Conclusion TcpO2 and TP measurements are safe and feasible non-invasive techniques for haemodynamic monitoring during endovascular revascularisation. TP increased significantly immediately after completion of the successful intervention, whereas tcpO2 did not. Both TP and tcpO2 demonstrated a significant increase at the 10 week follow up.

Testing for collateral circulation of the hand before any radial artery procedure has been a subject of many controversies. Neither the Allen's test (AT) nor the plethysmography based Barbeau test, adequately and reliably test for collateral circulation. With growing interest in radial approaches for vascular procedures, its common use for arterial monitoring and blood gas sampling, there has been a growing interest in the relevance of assessing collateral hand circulation. Multiple studies now refute the utility of collateral testing, yet it continues to be propagated as an essential triaging assessment tool by educators. Allen's, or modified Allen tests (MAT) are operator dependent and often subjected to observational bias. Barbeau test is more objective, however, it fails to show added benefit in assessing pre-procedural patency. Despite studies questioning the validity of collateral circulation assessment, these tests continue to preclude radial approach. There is no standardization for being considered an abnormal test across literature and the significance of an abnormal test translating into a clinical outcome has not been investigated in prior studies. This may be attributed to the robust vascular supply of the hand, connections at the digital circulation level and vessel recruitment in an event of occlusion. We reviewed this topic extensively and make an argument that non-invasive collateral testing should be abandoned as a triage tool for radial artery procedures such as arterial punctures, arterial monitoring, and transradial vascular procedures.

Background: Improving tissue perfusion can improve clinical outcomes in surgical patients, where monitoring may aid clinicians in detecting adverse conditions and guide interventions. Transcutaneous monitoring (TCM) of oxygen (tcpO2) and carbon dioxide (tcpCO2) is a well-proven technology and could potentially serve as a measure of local circulation, perfusion and metabolism, but the clinical use is not thoroughly explored. The purpose of this proof-of-concept study was to investigate whether TCM of blood gasses could detect changes in perfusion during major vascular surgery. Methods: Ten patients with peripheral arterial disease scheduled for lower limb major arterial revascularization under general anaesthesia were consecutively included. TcpO2 and tcpCO2 were continuously recorded from anaesthesia induction until skin closure with a TCM monitor placed on both legs and the thorax. Peripheral oxygen saturation was kept ≥94% and mean arterial blood pressure ≥65 mmHg. The primary outcomes were changes in tcpO2 and tcpCO2 related to arterial clamping and declamping during the procedure and analyzed by paired statistics. Results: Femoral artery clamping resulted in a significant decrease in tcpO2 (−2.1 kPa, IQR-4.2; −0.8), p=.017)), followed by a significant increase in response to arterial declamping (5.5 kPa, IQR 0–7.3), p=.017)). Arterial clamping resulted in a statistically significant increase in tcpCO2 (0.9 kPa, IQR 0.3–5.4), p=.008)) and a significant decrease following declamping (−0.7 kPa, IQR −2.6; −0.2), p=.011)). Conclusion: Transcutaneous monitoring of oxygen and carbon dioxide is a feasible method for detection of extreme changes in tissue perfusion during arterial clamping and declamping, and its use for improving patient outcomes should be explored. Clinical Trials identifier: NCT04040478. Registered on July 31, 2019.

Transcutaneous oxygen pressure (TcpO2) measurement has been used for years at rest in patients with lower extremity artery disease. It was proposed for exercise testing (Ex-TcpO2) in the 80ies to evaluate regional blood flow impairment (RBFI) at the proximal and distal levels simultaneously and on both sides, in case of claudication. It was suggested that the use of a chest electrode was mandatory to show that decreases in TcpO2 at the limb level result from limb RBFI and not from a systemic pO2 decrease of cardiopulmonary origin (exercise-induced hypoxemia). Unfortunately, a major pitfall of Ex-TcpO2 was the low absolute reliability of the regional perfusion index (RPI: ratio of limb to chest values) and the technique was almost abandoned until 2003, when the DROP index (Decrease from rest of oxygen pressure: limb changes minus chest changes from rest) was proposed. The DROP mathematical formula makes Tcpo2 results independent from the absolute pO2 starting values, improving reliability of Ex-TcpO2 as compared to the RPI. Since then, Ex-TcpO2 has been of renewed interest. The present paper addresses the physiology of Ex-TcpO2, interpretation of its results, and common misunderstandings about its use.

Background: Carbon dioxide tension (PCO2) monitoring during sleep, is crucial to identify respiratory failure in patients with neuromuscular disorders (NMD). Transcutaneous PCO2 monitoring is an available technique to measure PCO2. Objectives: To assess the quality level of transcutaneous blood gas measurements via SenTec monitor. Methods: A 12-month analysis of SenTec measurements was conducted in a Belgian Centre for Home Mechanical Ventilation (HMV). Over two consecutive nights; SpO2 and PCO2 measurements, the presence of PCO2 drift and drift correction with SenTec, were reviewed and scores (0, 1, 2 for poor, medium and high level) were assigned to estimate the quality of measurements. Results: Sixty-nine NMD patients met the inclusion criteria, of which 48/69 used HMV. PCO2 drift and drift correction were present in 15% and 68% of the 138 recordings, respectively. The quality level of measurements throughout night 1, scored 1.55 (0–2). The relevance of our clinical findings from SenTec scoring 1.94 (1–2); was considered highly satisfactory. HMV was ineffective in 24/48 patients. Among 12 patients with hypercapnia, 8 patients improved PCO2 between night 1 and 2. Among 12 patients with hypocapnia, PCO2 improved in 4/12 patients, who reached the range of normal PCO2 (35–47 mmHg). Conclusions: The quality of SenTec measurements was acceptable in the majority of recordings and clinical findings were deemed satisfactory in all cases. A single SenTec measurement was sufficient to determine the need for NIV. However, two SenTec registrations were insufficient to both improve NIV effectiveness in 50% of cases, and, to ensure follow-up of our interventions.

Objective: To assess the quality of SpO2 and PCO2 recordings via transcutaneous monitoring in children with neurological conditions. Methods: Overnight transcutaneous SpO2 and PCO2 were analyzed. T...

International audience; Background and aims: Transcutaneous oxygen pressure (TcpO2) is used in patients with suspected critical limb ischemia (CLI). Sinusoidal changes (SC~) in TcpO2 are found in patients with Cheyne-Stokes respiration (CSR). We aimed to determine the characteristics of TcpO2 changes at rest in patients with suspected CLI, define the objective criteria for SC ~ TcpO2 patterns (SC+), and estimate the prevalence of SC+ in our population and its impact on the outcome.Methods: We retrospectively analyzed 300 chest TcpO2 recordings performed in a 16-month period. We determined the presence/absence of SC ~ TcpO2 by visual analysis. We determined the acceptable error in the regularity of peaks of the cross-correlation with ROC curve analysis, among patients with typical SC ~ TcpO2 and non-sinusoidal patterns. Then, we defined SC + as a minimum of five peaks, a standard deviation of TcpO2 >1.25 mmHg, an error in regularity of peaks of the cross-correlation < 10%, and a cycle length between 30 and 100 s. In patients included until October 2019, we compared the outcome as a function of SC + or SC- with Cox models.Results: Mathematical detection of SC + found that 43 patients (14.3%) fulfilled all four defined criteria at the chest level, but only 23 did so at the limb level. In the follow-up of 207 patients, the presence of Sc ~ TcpO2 at the chest significantly increased the risk of mortality: hazard ratio: 2.69 [95%CI: 1.37-5.30]; p < 0.005.Conclusions: SC ~ TcpO2 is frequent, and is associated with a poor outcome in patients with suspected CLI.

Background: Flexible bronchoscopy (FB) in analgosedation causes alveolar hypoventilation and hypercapnia, the more so if patients suffer from COPD. Nonetheless, neither is capnometry part of standard monitoring nor is there evidence on how long patients should be monitored after sedation. Objectives: We investigated the impact of COPD on hypercapnia during FB with endobronchial ultrasound (EBUS) in sedation and how the periprocedural monitoring should be adapted. Methods: Two cohorts of consecutive patients – with advanced and without COPD – with the indication for FB with EBUS-guided transbronchial needle aspiration in analgosedation received continuous transcutaneous capnometry (ptcCO2) before, during, and for 60 min after the sedation with midazolam and alfentanil. Main Results: Forty-six patients with advanced COPD and 44 without COPD were included. The mean examination time was 26 ± 9 min. Patients with advanced COPD had a higher peak ptcCO2 (53.7 ± 7.1 vs. 46.8 ± 4.8 mm Hg, p < 0.001) and mean ptcCO2 (49.5 ± 6.8 vs. 44.0 ± 4.4 mm Hg, p < 0.001). Thirty-six percent of all patients reached the maximum hypercapnia after FB in the recovery room (8 ± 11 min). Patients with COPD needed more time to recover to normocapnia (22 ± 24 vs. 7 ± 11 min, p < 0.001). They needed a nasopharyngeal tube more often (28 vs. 11%, p < 0.001). All patients recovered from hypercapnia within 60 min after FB. No intermittent ventilation manoeuvres were needed. Conclusion: A relevant proportion of patients reached their peak-pCO2 after the end of intervention. We recommend using capnometry at least for patients with known COPD. Flexible EBUS in analgosedation can be safely performed in patients with advanced COPD. For patients with advanced COPD, a postprocedural observation time of 60 min was sufficient.

Background Chronic lung disease remains a burden for extremely preterm infants. The changes in ventilation over time and optimal ventilatory management remains unknown. Newer, non-invasive technologies provide insight into these patterns. Methods This single-center prospective cohort study enrolled infants ≤32 0/7 weeks. We obtained epochs of transcutaneous carbon dioxide (TcCO2) measurements twice each week to describe the pattern of hypercarbia throughout their hospitalization. Results Patterns of hypercarbia varied based on birth gestational age and post-menstrual age (PMA) (p = 0.03), regardless of respiratory support. Infants receiving the most respiratory support had values 16–21 mmHg higher than those on room air (p

The aim of this study was to investigate the effects of different oxygen delivery methods during noninvasive positive-pressure ventilation (NPPV) on transcutaneous oxygen pressure (PtcO2), transcutaneous carbon dioxide pressure (PtcCO2) and fraction of inspired oxygen (FiO2) in order to find more effective oxygen delivery methods.A total of 20 healthy volunteers participated in this study, all of whom received NPPV. All volunteers received oxygen through a nasal cannula (NC) located in a mask or through a mask alone (OSTM) (oxygen flow rate was 3L/min and 5L/min), PtcO2 and PtcCO2 were measured, and the effects of the 2 methods of oxygen concentration on PtcO2 and PtcCO2 levels were evaluated during noninvasive ventilation. Then, the additional oxygen concentration was stopped, oxygen was delivered through the ventilator, and the oxygen concentration was adjusted so that the PtcO2 reached the same oxygen concentration level as noted through the NC or OSTM. This concentration of oxygen indirectly reflects FiO2 in different oxygen delivery methods.When NPPV was used under the same pressure, FiO2 increased from 44.4% to 65.3% when oxygen was delivered through an NC compared with oxygen supplied by OSTM alone. PtcO2 was also significantly increased from 18.9% to 24.9%; the difference was significant (P.05), while there was no significant change in PtcCO2 (P.05).When NPPV is used, an NC can obviously improve FiO2 and PtcO2 without increasing PtcCO2. It can save oxygen and is more suitable for NPPV during an emergency and for home use.

Background Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) is the virus responsible for the coronavirus disease 2019(COVID-19) pandemic. Despite the extensive studies aiming to understand the pathology of COVID-19, the clinicopathological characteristics and risk factors associated with COVID-19 remain mostly unclear. In this study, we assessed the clinical course and features of COVID-19 patients. Findings There were 59 patients (54.1%) that had no fever. One-hundred(91.7%) patients required oxygen therapy, which improved percutaneous oxygen saturation (SpO2). Seventy-two (66.1%) patients aged over 60; these patients were more likely to develop respiratory symptoms. Only 13(11.9%) patients were positive for anti-SARS-CoV-2 antibodies, SARS-CoV-2 nucleic acid, and computed tomography (CT) findings. We found significant differences in age, respiratory symptoms, and heart rates between patients with and without underlying conditions. Conclusions Our findings suggest that oxygen plays an important role in the treatment of COVID-19 patients and that age and underlying diseases are significant risk factors for COVID-19. Most COVID-19 patients have no fever, and CT provides higher detection rates than antibody- and nucleic acid-based detection methods. Methods We analyzed data from 109 confirmed COVID-19 cases. We compared the clinicopathological characteristic of patients stratified according to age and underlying diseases, as well as assessed the detection rates of different diagnostic methods.

Control of breathing is automatic and its regulation is keen to autonomic functions. Therefore, involuntary and voluntary nervous regulation of breathing affects ventilatory variations, which has profound potential to address expanding challenges in contemporary pulmonology. Nonetheless, the fundamental attributes of the aforementioned phenomena are rarely understood and/or investigated. Implementation of unconventional approach like breathomics may leads to a better comprehension of those complexities in respiratory medicine. We applied breath-resolved spirometry and capnometry, non-invasive hemodynamic monitoring along with continuous trace analysis of exhaled VOCs (volatile organic compounds) by means of real-time mass-spectrometry in 25 young and healthy adult humans to investigate any possible mirroring of instant ventilatory variations by exhaled breath composition, under varying respiratory rhythms. Hemodynamics remained unaffected. Immediate changes in measured breath compositions and corresponding variations occurred when respiratory rhythms were switched between spontaneous (involuntary/unsynchronised) and/or paced (voluntary/synchronised) breathing. Such changes in most abundant, endogenous and bloodborne VOCs were closely related to the minute ventilation and end-tidal CO2 exhalation. Unprecedentedly, while preceded by a paced rhythm, spontaneous rhythms in both independent setups became reproducible with significantly (P-value ≤ 0.005) low intra- and inter-individual variation in measured parameters. We modelled breath-resolved ventilatory variations via alveolar isoprene exhalation, which were independently validated with unequivocal precision. Reproducibility i.e. attained via our method would be reliable for human breath sampling, concerning biomarker research. Thus, we may realize the actual metabolic and pathophysiological expressions beyond the everlasting in vivo physiological noise. Consequently, less pronounced changes are often misinterpreted as disease biomarker in cross-sectional studies. We have also provided novel information beyond conventional spirometry and capnometry. Upon clinical translations, our findings will have immense impact on pulmonology and breathomics as they have revealed a reproducible pattern of ventilatory variations and respiratory homeostasis in endogenous VOC exhalations.

BACKGROUND Non-invasive tests are still required to improve the holistic diagnostic approach of thoracic outlet syndrome (TOS). OBJECTIVES We aimed to analyze the diagnostic accuracy of the decrease from rest oxygen pressure (DROP) index of transcutaneous oximetry (TcpO2) in TOS. METHODS Seventy-six patients and 40 asymptomatic volunteers (Controls) were enrolled. In TOS-suspected patients, the arteriograms were investigated for the presence of≥75% stenosis. The area under receiver operating characteristics curve (AUC) analysis tested the ability of forearm TcpO2 during provocative maneuvers to discriminate patients from controls and, to predict a positive arteriographic findings in the 44 TOS-suspected patients that had an arteriography. RESULTS The media [25/75° centile] DROP values of controls and patients were -14 [-8/-22] mmHg and -22 [-12/-42] mmHg, respectively (p for Mann-Whitney

We evaluated the outcome of multimodal supervised exercise training (SET) on walking performances and different hemodynamic parameters (ankle/toe-brachial index [ABI/TBI], and transcutaneous oxygen pressure [TcPO2]) in patients with symptomatic lower extremity peripheral artery disease (PAD). Whether hemodynamic parameters predict walking performances at baseline and following SET was also investigated. Fontaine stage II PAD’s patients following a 3-month SET were retrospectively included. Hemodynamic parameters and walking performances (pain-free [PFWD], maximal [MWD], and 6-minute [6MWD] walking distance) were measured in each patient. Eighty-five symptomatic PAD patients were included. Following SET, PFWD, MWD, and 6MWD significantly increased (+142%, +94%, +14%; respectively; P ≤ .001). Toe-brachial index significantly increased (MD: 0.04 ± 0.01; P = .02), whereas ABI and TcPO2 did not change significantly. At baseline, patients with higher TBI and TcPO2 performed significantly better (PFWD: β = 0.25, P = .01 for TBI; PFWD: β = 0.30, P = .005, and MWD: β = 0.22, P = .04, for TcPO2). No significant relationship was observed at baseline between ABI and walking performances. Baseline values of hemodynamic parameters did not significantly correlate with changes in walking performances. Multimodal SET significantly improves walking performances. Following SET, no significant changes in ABI and TcPO2 were observed. Toe-brachial index values significantly improved after SET. However, this increase was very modest and its clinical relevance remains questionable. Although baseline TBI and supine TcPO2 values predict baseline walking performances, no association was found between baseline hemodynamic parameters and changes in walking performances following SET.

The vascular causes of lower-extremity ulcers cannot be neglected because they can directly affect treatment methods. No detailed epidemiological statistics have described vascular etiological diagnosis in China. This study aimed to explore the prevalence of clinical vascular etiological examination of lower-extremity ulcers and improve the diagnosis and treatment effectiveness of lower-extremity ulcers. Data were collected from the WoundCareLog database, which includes 2413 cases of lower-extremity ulcers from 478 hospitals nationwide. Data analysis revealed that 1698 (70.4%) lower-extremity blood flow examinations (including physical examination [PE] and assistant examinations [AE]) were performed, of which 61.7% were PE, 10.4% were AE only, and 27.9% were the combined PE and AE[PAE]. The proportion of nonexaminations was higher in the nondiabetic group than in the diabetic group (χ2 = 34.5; P < .01). The positive rates of vascular etiological examination in the diabetic and nondiabetic groups were 69.7% and 70.7%, respectively. Among the four economic regions of China, there were statistically significant differences in the use of the different examination methods. The examination of vascular diseases in lower-extremity ulcers in China has not been fully popularized and requires improvement; there was no statistically significant difference between examination rates by doctors and nurses, which is mainly based on PE. However, PE has certain rates of misdiagnosis and missed diagnosis. The false-positive and false-negative rates were 25.7% and 57.6%, respectively. The use of an AE can compensate for this deficiency by making diagnosis more precise, while the quantitative diagnostic criteria allow disease diagnosis to transcend geographical and operator differences and maximize uniformity. The vascular B-ultrasound examination is more suitable for the medical environment in China because of its mature technology, high hospital penetration rate, and low cost.

Patients with critical limb ischemia have nonhealing wounds and/or ischemic rest pain and are at high risk for amputation and mortality. Accurate evaluation of foot perfusion should help avoid unnecessary amputation, guide revascularization strategies, and offer efficient surveillance for patency. Our aim is to review current modalities of assessing foot perfusion in the context of the practical clinical management of patients with critical limb ischemia.

International audience; In patients with exertional limb symptoms and normal ankle-brachial index (ABI) at rest, exercise testing can be used to diagnose lower extremity arterial disease (LEAD). Post-exercise ABI decrease or Exercise transcutaneous oxygen pressure measurement (Exercise-TcPO2) can be used to diagnose LEAD. Objectives were (i) to assess the agreement between both methods (ii) to define the variables associated with the discordance, and (iii) to present results of healthy subjects. In this prospective cross-sectional study, patients with exertional limb symptoms and normal rest ABI were consecutively included. ABI was measured at rest and after standardized exercise protocol as well as Exercise-TcPO2. A kappa coefficient with a 95% confidence interval was used to assess the agreement between the two methods. Logistic regression analysis was performed to outline variables potentially responsible for discordance. Ninety-six patients were included. The agreement between the tests was weak with a k value of 0.23 [0.04-0.41]. Logistic regression analysis found that a medical history of lower extremity arterial stenting (odds ratio 5.85[1.68-20.44]) and age (odds ratio 1.06[1.01-1.11]) were the main cause of discordance. This study suggests that post-exercise ABI and Exercise-TcPO2 cannot be used interchangeably for the diagnosis of LEAD in patients with exertional symptoms and normal rest ABI.

BACKGROUND Adequate tissue perfusion is an important prognostic and diagnostic factor during the management of lower limb peripheral arterial disease. Convenient and real-time tissue perfusion monitoring remains an elusive challenge. METHODS Tissue perfusion on the dorsal and plantar surfaces of both feet of 20 participants was measured during and after cuff-induced ischemia using a novel 4-channel, laser-based perfusion monitoring device based on diffuse speckle contrast analysis technology (Pedra sensors). Participants were free of significant peripheral arterial disease. Transcutaneous partial pressure of oxygen (TcPO2) measurements were recorded concurrently for comparison. RESULTS Pedra sensors detected perfusion changes significantly more quickly than TcPO2 sensors. One minute after induced ischemia, the mean percent changes from baseline values (before ischemia) were -22.7±32.0% and -3.1±8.8% (P

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 (EtCOParticipants 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 tcPCOPACU RNs (N = 108) reported they 'never' or 'rarely' used EtCOCapnography monitoring should be considered a standard of care for PACU patients. Education of registered nurses working in the PACU is critical before implementing EtCO

A skin-gas cam that allows continuous imaging of transcutaneous blood volatile organic compounds (VOCs) emanated from human skin was developed. The skin-gas cam is able to reveal the relationship between the local skin conditions and transcutaneous blood VOCs in the field of volatile metabolomics (volatolomics). A ring-type ultraviolet (UV) light-emitting diode was mounted around a camera lens as an excitation light source, which enabled the simultaneous excitation and imaging of fluorescence. A nicotinamide adenine dinucleotide (NAD)-dependent alcohol dehydrogenase (ADH) was used to detect ethanol as a model sample. When gaseous ethanol was applied to an ADH-immobilized mesh that was wetted with an oxidized NAD solution placed in front of the camera, a reduced form of NAD (NADH) was produced through an ADH-mediated reaction. NADH emits fluorescence by UV excitation, and thus, the concentration distribution of ethanol was visualized by measuring the distribution of the fluorescence light intensity from NADH on the ADH-immobilized mesh surface. In this study, a new gas application method that mimicked the release mechanism of transcutaneous gas for quantification of the transcutaneous gas concentration was evaluated. Also, spatiotemporal changes of transcutaneous ethanol for various body parts were measured. As a result, we revealed a relationship between local skin conditions and VOCs that could not be observed previously. In particular, we demonstrated the facile measurement of transdermal gases from around the ear where capillaries are densely distributed below a thin stratum corneum.

BACKGROUND Transcutaneous carbon dioxide measurement (TcCO2) is frequently used as a surrogate for arterial blood gas sampling in adults and children with critical illness. Data from noninvasive TcCO2 monitoring assists with clinical decisions regarding mechanical ventilation settings, estimation of metabolic consumption and determination of adequate end-organ tissue perfusion. OBJECTIVES To report TcCO2 values obtained from various fruits, vegetables and elite critical care medicine specialists. DESIGN Prospective, observational, nonblinded cohort study. SETTINGS Single-centre, tertiary paediatric referral centre and organic farmers' market. PARTICIPANTS Vegetables and fruits included 10 samples of each of the following: red delicious apple (Malus domestica), manzano banana (Musa sapientum), key lime (Citrus aurantiifolia), miniature sweet bell pepper (Capsicum annuum), sweet potato (Ipomoea batatas) and avocado (Persea americana). Ten human controls were studied including a paediatric intensivist, a paediatric inpatient hospital physician, four paediatric resident physicians and four paediatric critical care nurses. INTERVENTIONS None. MAIN OUTCOME MEASURES TcCO2 values for each species and device response times. RESULTS TcCO2 readings were measurable in all study species except the sweet potato. Mean ± SD values of TcCO2 for human controls [4.34 ± 0.37 kPa (32.6 ± 2.8 mmHg)] were greater than apples [3.09 ± 0.19 kPa (23.2 ± 1.4 mmHg), P

In heart failure with reduced ejection fraction (HFrEF), nitric oxide-soluble guanylyl cyclase (sGC) pathway dysfunction impairs skeletal muscle arteriolar vasodilation and thus capillary hemodynamics, contributing to impaired oxygen uptake [Formula: see text] kinetics. Targeting this pathway with sGC activators offers a new treatment approach to HFrEF. We tested the hypotheses that sGC activator administration would increase the O(2) delivery [Formula: see text] ratio in the skeletal muscle interstitial space (PO(2)is) of HFrEF rats during twitch contractions due, in part, to increases in red blood cell (RBC) flux (f(RBC)), velocity (V(RBC)), and capillary hematocrit (Hct(cap)). HFrEF was induced in male Sprague-Dawley rats via myocardial infarction. After 3 weeks, rats were treated with 0.3 mg/kg of the sGC activator BAY 60–2770 (HFrEF + BAY; n = 11) or solvent (HFrEF; n = 9) via gavage b.i.d for 5 days prior to phosphorescence quenching (PO(2)is, in contracting muscle) and intravital microscopy (resting) measurements in the spinotrapezius muscle. Intravital microscopy revealed higher f(RBC) (70 ± 9 vs 25 ± 8 RBC/s), V(RBC) (490 ± 43 vs 226 ± 35 μm/s), Hct(cap) (16 ± 1 vs 10 ± 1%) and a greater number of capillaries supporting flow (91 ± 3 vs 82 ± 3%) in HFrEF + BAY vs HFrEF (all P < 0.05). Additionally, PO(2)is was especially higher during 12–34s of contractions in HFrEF + BAY vs HFrEF (P < 0.05). Our findings suggest that sGC activators improved resting [Formula: see text] via increased f(RBC), V(RBC), and Hct(cap) allowing for better [Formula: see text] matching during the rest-contraction transient, supporting sGC activators as a potential therapeutic to target skeletal muscle vasomotor dysfunction in HFrEF.

BackgroundAll diagnostic procedures of peripheral arterial disease (PAD) in diabetic foot (DF) are complicated due to diabetes mellitus and its late complications.The aim of our study is to enhance diagnosis of PAD using a novel transcutaneous oximetry (TcPO2) stimulation test.MethodsThe study comprised patients with mild-to-moderate PAD(WIfI–I 1 or 2) and baseline TcPO2 values of 30-50 mmHg.TcPO2 was measured across 107 different angiosomes. Stimulation examination involved a modification of the Ratschow test. All patients underwent PAD assessment (systolic blood pressures (SBP), toe pressures (TP), the ankle-brachial indexes (ABI) and toe-brachial indexes (TBI), duplex ultrasound of circulation). Angiosomes were divided into two groups based on ultrasound findings: group M(n=60) with monophasic flow; group T(n=47) with triphasic flow. Large vessel parameters and TcPO2 at rest and after exercise (minimal TcPO2, changes in TcPO2 from baseline (Δ,%), TcPO2 recovery time) measured during the stimulation test were compared between study groups.ResultsDuring the TcPO2 stimulation exercise test, group M exhibited significantly lower minimal TcPO2 (26.2 ± 11.1 vs. 31.4 ± 9.4 mmHg; pConclusionCompared to resting TcPO2, TcPO2 measured during stimulation improves detection of latent forms of PAD and restenosis/obliterations of previously treated arteries in diabetic foot patients.Clinical Trial RegistrationClinicalTrials.gov [https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0009V7W&selectaction=Edit&uid=U0005381&ts=2&cx=3j24u2], identifier NCT04404699

Carbon dioxide (CO2) monitoring in human subjects is of crucial importance in medical practice. Transcutaneous monitors based on the Stow-Severinghaus electrode make a good alternative to the painful and risky arterial “blood gases” sampling. Yet, such monitors are not only expensive, but also bulky and continuously drifting, requiring frequent recalibrations by trained medical staff. Aiming at finding alternatives, the full panel of CO2 measurement techniques is thoroughly reviewed. The physicochemical working principle of each sensing technique is given, as well as some typical merit criteria, advantages, and drawbacks. An overview of the main CO2 monitoring methods and sites routinely used in clinical practice is also provided, revealing their constraints and specificities. The reviewed CO2 sensing techniques are then evaluated in view of the latter clinical constraints and transcutaneous sensing coupled to a dye-based fluorescence CO2 sensing seems to offer the best potential for the development of a future non-invasive clinical CO2 monitor.

Arterial blood gas analysis is the gold standard for monitoring of PWe conducted a study in children undergoing general anesthesia to validate the use and to determine the accuracy of continuous transcutaneous measurements of the partial pressures of PCOA prospective observational study in a tertiary care pediatric hospital in The Netherlands, from April to October 2018, in children aged 0-18 years undergoing general anesthesia. Patients were included when endotracheally intubated and provided with an arterial catheter for regular blood sampling. Patients with a gestational age31 weeks, burn victims, and patients with skin disease were excluded. TcPCOWe included 53 patients (median age 4.1 years, IQR 0.7-14.4 years) and retrieved 175 samples. TcPCOThis study showed good agreement between P

New types of miniaturized biomedical devices transform contemporary diagnostic and therapeutic techniques in medicine. This evolution has demonstrated exceptional promise in providing infrastructures for enabling precision health by creating diverse sensing modalities. To this end, this paper presents a prototype for transcutaneous carbon dioxide monitoring to diversify the measurable critical parameters for human health. Transcutaneous carbon dioxide monitoring is a noninvasive, surrogate method of assessing the partial pressure of carbon dioxide in the blood. The partial pressure of carbon dioxide is a vital index that can help understand momentarily changing ventilation trends. Therefore, it needs to be reported continuously to monitor the ventilatory status of critically ill patients. The proposed prototype employs an infrared LED as the excitation source. The infrared emission, which decreases in response to an increasing carbon dioxide concentration, is applied to a thermopile sensor that can detect the infrared intensity variations precisely. We have measured the changes in the partial pressure of carbon dioxide in the range of 0-120 mmHg, which covers humans' typical values, 35-45 mmHg. The prototype occupies an area of 25 cm

Capnometry, the measurement of respiratory carbon dioxide, is regarded as a highly recommended safety technology in intubated and nonintubated sedated and/or anesthetized patients. Its utility includes confirmation of initial and ongoing placement of an airway device as well as in detecting gas exchange, bronchospasm, airway obstruction, reduced cardiac output, and metabolic changes. The utility applies prehospital and throughout all phases of inhospital care. Unfortunately, capnometry devices are not readily available in many countries, especially those that are resource-limited. Constraining factors include cost, durability of devices, availability of consumables, lack of dependable power supply, difficulty with cleaning, and maintenance. There is, thus, an urgent need for all stakeholders to come together to develop, market, and distribute appropriate devices that address costs and other requirements. To foster this process, the World Federation of Societies of Anaesthesiologists (WFSA) has developed the "WFSA-Minimum Capnometer Specifications 2021." The intent of the specifications is to set the minimum that would be acceptable from industry in their attempts to reduce costs while meeting other needs in resource-constrained regions. The document also includes very desirable and preferred options. The intent is to stimulate interest and engagement among industry, clinical providers, professional associations, and ministries of health to address this important patient safety need. The WFSA-Minimum Capnometer Specifications 2021 is based on the International Organization for Standardization (ISO) capnometer specifications. While industry is familiar with such specifications and their presentation format, most clinicians are not; therefore, this article serves to more clearly explain the requirements. In addition, the specifications as described can be used as a purchasing guide by clinicians.

OBJECTIVE: To evaluate the accuracy and safety of measurements of transcutaneous carbon dioxide partial pressure (TcPCO(2)) and transcutaneous oxygen partial pressure (TcPO(2)) at electrode temperatures lower than the value used in clinical practice in very low birth weight infants. METHODS: A total of 45 very low birth weight infants were enrolled. TcPCO(2) and TcPO(2) measurements were performed in these infants. Two transcutaneous monitors were placed simultaneously for each subject. One electrode was set and maintained at 42℃ used in clinical practice for neonates (control group), and the other was successively set at 38℃, 39℃, 40°C, and 41℃ (experimental group). The paired t-test was used to compare the measurement results between the groups. A Pearson correlation analysis was used to analyze the correlation between the measurement results of the experimental group and control group, and between the measurement results of experimental group and arterial blood gas parameters. RESULTS: There was no significant difference in TcPCO(2) between each experimental subgroup (38-41℃) and the control group. TcPCO(2) in each experimental subgroup (38-41℃) was strongly positively correlated with TcPCO(2) in the control group (r>0.9, P0.8, P

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

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.