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Orthostatic hypotension (OH) is a form of orthostatic intolerance (OI) and a key physiological indicator of autonomic dysfunction that is associated with an increased risk of major cerebrocardiovascular events. Symptoms of cerebral hypoperfusion have been reported in patients with OH, which worsens symptoms and increases the risk of syncope. Since pharmacological interventions increase blood pressure (BP) independent of posture and do not restore normal baroreflex control, nonpharmacological treatments are considered the foundation of OH management. While reductions in cerebral blood flow velocity (CBFv) during orthostatic stress are associated with a decrease in end-tidal CO2 (EtCO2) and hypocapnia in patients with OI, their contribution to the severity of OH is not well understood. These measures have been physiological targets in a wide variety of biofeedback interventions. This study explored the relationship between cardiovascular autonomic control, EtCO2 and cerebral hypoperfusion in patients (N = 72) referred for OI. Patients with systolic OH were more likely to be male, older, demonstrate reduced adrenal and vagal baroreflex sensitivity, and reduced cardiovagal control during head-up tilt (HUT) than patients without systolic OH. Greater reduction in CBFv during HUT was associated with a larger reduction in ETCO2 and systolic BP during HUT. While deficits in cardiovascular autonomic control played a more important role in systolic OH, reduced EtCO2 was a major contributor to orthostatic cerebral hypoperfusion. These findings suggest that biofeedback treatments targeting both the autonomic nervous system and EtCO2 should be part of nonpharmacological interventions complementing the standard of care in OH patients with symptoms of cerebral hypoperfusion. [ABSTRACT FROM AUTHOR]

Background & objective: Most of the COVID-19 patients suffered from moderate to severe respiratory symptoms. Many of them needed oxygen supplementation or even mechanical ventilation. There is little data available about the use of either end-tidal CO2 (EtCO2) or integrated pulmonary index (IPI) in these patients. The aim of this study to investigate the difference in IPI values for subjects requiring mechanical ventilation compared to those managed without ventilation and the correlation between EtCO2 and SpO2. Methods: This prospective observational study involved adult COVID-19 patients admitted to the ICU with moderate to severe respiratory symptoms. All patients were connected to a portable respiratory monitor with the IPI algorithm (Medtronic Capnostream 35) and treated according to a standardized protocol. Oxygen flow was adjusted to maintain oxygen saturation (92–96%). If the respiratory rate did not fall below 30 breaths per minute and/or the SpO2 did not reach the target, non-invasive ventilation (NIV) was initiated. Patients with NIV failure was eligible for invasive mechanical ventilation. Results: SpO2 was significantly lower, while RR was significantly higher in intubated group compared to nonintubated group (P < 0.001 and 0.018, respectively). However, IPI, EtCO2, and HR did not differ among both groups. There was a significant positive correlation between EtCO2 and SpO2 at baseline before oxygen therapy (r = 0.419; P = 0.007). There was a significant negative correlation between CT score and SpO2 (r = -0.408; P = 0.01); however, there was no correlation between CT score and both IPI and end tidal CO2 at baseline (r = 0.017; P = 0.9). Conclusion: The integrated pulmonary index cannot be used as a single parameter for assessing respiratory severity in COVID-19 patients. [ABSTRACT FROM AUTHOR]

Several noninvasive solutions are available for the assessment of patients at risk of deterioration. Capnography, in the form of end-tidal exhaled CO2 (ETCO2) and perfusion index (PI), could provide relevant information about patient prognosis. The aim of the present project was to determine the association of ETCO2 and PI with mortality of patients admitted to the emergency department (ED). Multicenter, prospective, cohort study of adult patients with acute disease who needed continuous monitoring in the ED. The study included two tertiary hospitals in Spain between October 2022 and June 2023. The primary outcome of the study was in-hospital mortality (all-cause). Demographics, vital signs, ETCO2 and PI were collected. A total of 687 patients were included in the study. The in-hospital mortality rate was 6.8%. The median age was 79 years (IQR: 69–86), and 63.3% were males. The median ETCO2 value was 30 mmHg (26–35) in survivors and 23 mmHg (16–30) in nonsurvivors (p = 0.001). For the PI, the medians were 4.7% (2.8–8.1) for survivors and 2.5% (0.98–4-4) for nonsurvivors (p < 0.001). The model that presented the best AUC was age (odds ratio (OR): 1.02 (1.00–1.05)), the respiratory rate (OR: 1.06 (1.02–1.11)), and the PI (OR: 0.83 (0.75–0.91)), with a result of 0.840 (95% CI: 0.795–0.886); the model with the respiratory rate (OR: 1.05 (1.01–1.10)), the PI (OR: 0.84 (0.76–0.93)), and the ETCO2 (no statistically significant OR), with an AUC of 0.838 (95% CI: 0.787–0.889). The present study showed that the PI and respiratory rate are independently associated with in-hospital mortality. Both the PI and ETCO2 are predictive parameters with improved prognostic performance compared with that of standard vital signs. [ABSTRACT FROM AUTHOR]

This observational study evaluated the validity of end-tidal CO2 (ETCO2) as a surrogate for arterial PCO2 (PaCO2) in infants on neurally adjusted ventilatory assist (NAVA), particularly considering the influence of variable spontaneous breathing on capnography waveforms. The study involved 16 infants, analyzing 50 paired ETCO2 and PaCO2 values. Deming regression analysis highlighted a notably stronger correlation for maximum ETCO2 (r2 = 0.6783, p <0.0001) compared to mean ETCO2 (r2 = 0.5686, p <0.0001) and demonstrated a significantly weaker association for minimum ETCO2 (r2 = 0.1838). These findings emphasize the superior predictive value of maximum ETCO2 in estimating PaCO2, advocating its reliable use in clinical monitoring, especially given the dynamic capnography associated with NAVA's variable pressures. The results suggest ETCO2's potential to enhance noninvasive respiratory management, reduce the frequency of blood sampling, and improve overall care for infants requiring mechanical ventilation. [ABSTRACT FROM AUTHOR]

Abstract Background Mediastinoscopic surgery for esophageal cancer facilitates early postoperative recovery. However, it can occasionally cause serious complications. Here, we present the case of a patient with a tracheal injury diagnosed by a sudden increase in end-tidal carbon dioxide (EtCO2) during mediastinoscopic subtotal esophagectomy. Case presentation A 52-year-old man diagnosed with esophageal cancer was scheduled to undergo mediastinoscopic subtotal esophagectomy. During the mediastinoscopic procedure, the EtCO2 level suddenly increased above 200 mmHg, and the blood pressure dropped below 80 mmHg. We immediately asked the operator to stop insufflation and found a tracheal injury on the right side of the trachea near the carina by bronchoscopy. The endotracheal tube was replaced with a double-lumen tube, and the trachea was repaired via right thoracotomy. There were no further intraoperative complications. After surgery, the patient was extubated and admitted to the intensive care unit. Conclusions Monitoring EtCO2 levels and close communication with the operator is important for safely managing sudden tracheal injury during mediastinoscopic esophagectomy.

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

Background: Mediastinoscopic surgery for esophageal cancer facilitates early postoperative recovery. However, it can occasionally cause serious complications. Here, we present the case of a patient with a tracheal injury diagnosed by a sudden increase in end-tidal carbon dioxide (EtCO2) during mediastinoscopic subtotal esophagectomy. Case presentation: A 52-year-old man diagnosed with esophageal cancer was scheduled to undergo mediastinoscopic subtotal esophagectomy. During the mediastinoscopic procedure, the EtCO2 level suddenly increased above 200 mmHg, and the blood pressure dropped below 80 mmHg. We immediately asked the operator to stop insufflation and found a tracheal injury on the right side of the trachea near the carina by bronchoscopy. The endotracheal tube was replaced with a double-lumen tube, and the trachea was repaired via right thoracotomy. There were no further intraoperative complications. After surgery, the patient was extubated and admitted to the intensive care unit. Conclusions: Monitoring EtCO2 levels and close communication with the operator is important for safely managing sudden tracheal injury during mediastinoscopic esophagectomy. [ABSTRACT FROM AUTHOR]

Abstract Introduction COVID-19 Related Acute Respiratory Syndrome (C-ARDS) is characterized by a mismatch between respiratory mechanics and hypoxemia, suggesting increased dead-space fraction (DSF). Prone position is a cornerstone treatment of ARDS under invasive mechanical ventilation reducing mortality. We sought to investigate the impact of prone position on DSF in C-ARDS in a cohort of patients receiving invasive mechanical ventilation. Methods we retrospectively analysed data from 85 invasively mechanically ventilated patients with C-ARDS in supine and in prone positions, hospitalized in Intensive Care Unit (Reims University Hospital), between November, 1st 2020 and November, 1st 2022. DSF was estimated via 3 formulas usable at patients’ bedside, based on partial pressure of carbon dioxide (PaCO2) and end-tidal carbon dioxide (EtCO2). Results there was no difference of DSF between supine and prone position, using the 3 formulas. According to Enghoff, Frankenfield and Gattinoni equations, DSF in supine vs. prone position was in median respectively [IQR]: 0.29 [0.13–0.45] vs. 0.31 [0.19–0.51] (p = 0.37), 0.5 [0.48–0.52] vs. 0.51 [0.49–0.53] (p = 0.43), and 0.71 [0.55–0.87] vs. 0.69 [0.57–0.81], (p = 0.32). Conclusion prone position did not change DSF in C-ARDS.

BackgroundAmong subjects with exercise intolerance and suspected early-stage pulmonary hypertension (PH), early identification of pulmonary vascular disease (PVD) with noninvasive methods is essential for prompt PH management.HypothesisRest gas exchange parameters (minute ventilation to carbon dioxide production ratio: VE /VCO2 and end-tidal carbon dioxide: ETCO2 ) can identify PVD in early-stage PH.MethodsWe conducted a retrospective review of 55 subjects with early-stage PH (per echocardiogram), undergoing invasive exercise hemodynamics with cardiopulmonary exercise test to distinguish exercise intolerance mechanisms. Based on the rest and exercise hemodynamics, three distinct phenotypes were defined: (1) PVD, (2) pulmonary venous hypertension, and (3) noncardiac dyspnea (no rest or exercise PH). For all tests, *p  40 mm Hg and rest ETCO2   40 mm Hg and ETCO2

Introduction: COVID-19 Related Acute Respiratory Syndrome (C-ARDS) is characterized by a mismatch between respiratory mechanics and hypoxemia, suggesting increased dead-space fraction (DSF). Prone position is a cornerstone treatment of ARDS under invasive mechanical ventilation reducing mortality. We sought to investigate the impact of prone position on DSF in C-ARDS in a cohort of patients receiving invasive mechanical ventilation. Methods: we retrospectively analysed data from 85 invasively mechanically ventilated patients with C-ARDS in supine and in prone positions, hospitalized in Intensive Care Unit (Reims University Hospital), between November, 1st 2020 and November, 1st 2022. DSF was estimated via 3 formulas usable at patients' bedside, based on partial pressure of carbon dioxide (PaCO2) and end-tidal carbon dioxide (EtCO2). Results: there was no difference of DSF between supine and prone position, using the 3 formulas. According to Enghoff, Frankenfield and Gattinoni equations, DSF in supine vs. prone position was in median respectively [IQR]: 0.29 [0.13–0.45] vs. 0.31 [0.19–0.51] (p = 0.37), 0.5 [0.48–0.52] vs. 0.51 [0.49–0.53] (p = 0.43), and 0.71 [0.55–0.87] vs. 0.69 [0.57–0.81], (p = 0.32). Conclusion: prone position did not change DSF in C-ARDS. [ABSTRACT FROM AUTHOR]

Introduction: N95 masks are very popular for daily use and can actively filter microparticles such as viruses. However, there are concerns that prolonged wearing of the mask may result in exhaled CO2 accumulation between the face and the mask, which may cause increased end-tidal carbon dioxide (EtCO2) levels and physiological changes. This study aimed to determine EtCO2 levels in students wearing the N95 mask. Methods: This was an experimental study with a case-control design. The subjects were divided into a treatment and a control group and were subjected to five measurements in 120 minutes. The data were analyzed using the independent samples T-test (normally distributed data) and the Mann-Whitney U test (not normally distributed data). Results: Mann-Whitney test at minute 0 showed that p = 0.010, independent sample T-test at minute 30 showed that the control group p = 0.016, while in the treatment group p = 0.019. Independent sample T-test at minute 60 for the control group p = 0.034, while the treatment group p = 0.037. Independent sample T-test at minute 90 for the control group and treatment p = 0.001, and independent sample T-test showed that at minute 120 in the control and treatment groups p = 0.000. Conclusion: The EtCO2 measurements at each of the five time points showed a statistical difference (p < 0.05). However, medical students who wore an N95 mask did not suffer adverse effects because the EtCO2 values in the control group were higher than in the treatment group.

Objective: In this study, we aimed to determine the most cited first 50 publications on end-tidal carbon dioxide (ETCO2 ) and capnography from past to present using various bibliometric citation analysis methods, and to reveal the intellectual structure of the subject through co-citation analysis. Additionally, we aimed to identify the most active authors, institutions, journals, and countries in this field, and to demonstrate global productivity quantitatively. Methods: A total of 2508 publications on ETCO2 published between 1980 and 2022 were downloaded from the Web of Science database and analyzed using citation and co-citation analyses. VOSviewer (Version 1.6.19) software was utilized to perform citation and co-citation analyses, and bibliometric network visualization maps were created. Results: The top 3 countries with the highest publication productivity in ETCO2 research were the USA (1008), England (220), and Canada (118). The top 3 journals were Anesthesia and Analgesia(148), Anaesthesia (127), and Anesthesiology (89). The most active institutions were Research Libraries UK (98), Harvard University (80), and The University of California System (71). The top 3 authors were Petak F. (22), Tusman G. (22), and Weil MH. (19). The citation density of the top 50 articles in terms of total citations ranged from 83 to 448, while the average citation density per year ranged from 5.39 to 16.23. Among the top 50 most cited articles, the first two journals with the most publications were Annals of Emergency Medicine (8 articles) and Anesthesia and Analgesia (4 articles). Conclusion: Globally, an increasing trend in publications on ETCO2 can be observed from the past to the present. Research leadership in the development of ETCO2 literature is predominantly held by economically strong developed or developing countries. Evaluation of citation and co-citation analyses reveals that the most influential studies on ETCO2 /capnography focus on sedation, endotracheal intubation, cardiopulmonary resuscitation (CPR)/cardiac arrest, and dead space topics. [ABSTRACT FROM AUTHOR]

Mechanical thrombectomy (MT) has become a standard treatment for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). Recent evidence suggests that general anesthesia (GA) and mechanical ventilation do not lead to inferior neurologic outcomes if compared to non-GA. However, the guidelines lack specific recommendations for ventilation targets during MT under GA. This systematic review aims to identify ventilation strategies correlating with better neurological outcomes in AIS patients undergoing MT, particularly focusing on oxygenation and carbon dioxide (CO2) targets. A systematic search of multiple databases was conducted to identify human studies reporting the correlation between ventilation strategies and neurological outcomes in MT for AIS. Eligible studies included clinical trials, observational studies, and case–control studies. Out of 157 studies assessed, 11 met the inclusion criteria. Five studies investigated oxygenation targets, while six studies explored CO2 targets. The published studies highlighted the controversial role of supplemental normobaric oxygen therapy and its potential association with worse outcomes. Regarding CO2 targets, the studies identified a potential association between end tidal CO2 levels and functional outcomes, with hypocapnia being unfavorable. This systematic review demonstrates that the current available evidence still lacks strength to suggest specific ventilation targets, but it highlights the potential risks of hyperoxia and hypocapnia in this specific cohort of patients. [ABSTRACT FROM AUTHOR]

Abstract Introduction This study aimed to evaluate the correlation and agreement between end‐tidal CO2 (EtCO2) measured with the novel portable capnometer (CapnoEye®) and partial pressure of arterial carbon dioxide (PaCO2) levels in patients with respiratory diseases and to compare the efficacy of EtCO2 and PvCO2 in predicting PaCO2 levels. Methods We analyzed the correlation and the agreement between EtCO2 and PaCO2 and between PvCO2 and PaCO2 using Pearson's moment correlation coefficient in patients with type 1 and type 2 respiratory failure and both groups overall. Results A total of 100 samples were included that comprised 67 men (67%). The mean age of the subjects was 77 ± 13 years. Chronic obstructive pulmonary disease (COPD) (43%) was the most common disease. There was a high correlation between EtCO2 and PaCO2 (r = 0.88; p < 0.0001). Sixty‐six PvCO2 samples were obtained, and there was a high correlation between PvCO2 and PaCO2 (r = 0.81; p < 0.0001). Regarding type 2 respiratory failure, there was a high correlation between EtCO2 and PaCO2 (r = 0.81). The Bland–Altman analysis between PaCO2 and EtCO2 revealed a bias of 5.7 mmHg, with limits of agreement ranging from −5.1 mmHg to 16.5 mmHg. In contrast, the analysis between PaCO2 and PvCO2 revealed a bias of −6.8 mmHg, and the limits of agreement ranged from −22.13 mmHg to 8.53 mmHg. Conclusion EtCO2 measured by CapnoEye® was significantly correlated to PaCO2 levels in patients with respiratory diseases. Moreover, CapnoEye® may be more useful for predicting hypercapnia conditions in which respiratory diseases are compared with measure PvCO2.

Aim: The aim of this review was to give an overview of available data on end‐tidal CO2 (etCO2) monitoring, also called capnometry, during neonatal transport. Methods: Pubmed/MEDLINE database was searched using research question (capno* OR etCO2 OR detCO2 OR (['end tidal' OR 'end‐tidal'] AND [CO2 OR 'carbon dioxide']) AND (neonat* OR infant* OR newborn*) AND transport*). All articles relevant to the topic were reviewed and summarised. Results: The lack of studies relevant to neonatal transport prompted us to extend the search to capnometry in a neonatal intensive care setting. The published studies are showing conflicting results. The different study populations, technologies used to measure etCO2, types of etCO2 sampling and the diverse sites of blood gas tests make the data unsuitable for systematic comparison. Conclusion: Further research to obtain more data on capnometry during neonatal transport will be necessary to define precisely under what circumstances can end‐tidal monitoring of CO2 be reliably used in neonates during transport and also how to interpret the measured values. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the correlation and agreement between end‐tidal CO2 (EtCO2) measured with the novel portable capnometer (CapnoEye®) and partial pressure of arterial carbon dioxide (PaCO2) levels in patients with respiratory diseases and to compare the efficacy of EtCO2 and PvCO2 in predicting PaCO2 levels. Methods: We analyzed the correlation and the agreement between EtCO2 and PaCO2 and between PvCO2 and PaCO2 using Pearson's moment correlation coefficient in patients with type 1 and type 2 respiratory failure and both groups overall. Results: A total of 100 samples were included that comprised 67 men (67%). The mean age of the subjects was 77 ± 13 years. Chronic obstructive pulmonary disease (COPD) (43%) was the most common disease. There was a high correlation between EtCO2 and PaCO2 (r = 0.88; p < 0.0001). Sixty‐six PvCO2 samples were obtained, and there was a high correlation between PvCO2 and PaCO2 (r = 0.81; p < 0.0001). Regarding type 2 respiratory failure, there was a high correlation between EtCO2 and PaCO2 (r = 0.81). The Bland–Altman analysis between PaCO2 and EtCO2 revealed a bias of 5.7 mmHg, with limits of agreement ranging from −5.1 mmHg to 16.5 mmHg. In contrast, the analysis between PaCO2 and PvCO2 revealed a bias of −6.8 mmHg, and the limits of agreement ranged from −22.13 mmHg to 8.53 mmHg. Conclusion: EtCO2 measured by CapnoEye® was significantly correlated to PaCO2 levels in patients with respiratory diseases. Moreover, CapnoEye® may be more useful for predicting hypercapnia conditions in which respiratory diseases are compared with measure PvCO2. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the efficiency of the capnography monitoring added to routine monitoring of oxygen desaturation, hypoxemia, and other vital parameters. Materials and Methods: 100 adult patients who had elective vitrectomy under sedation were included in this study. Patients were divided into "experiment"(capnography added to routine monitoring) and "control"(capnography not added to routine monitoring) groups. Hypoxemia, desaturation, tachycardia, bradycardia, and additional maneuvers for the airway were compared. Increase and decrease in end-tidal carbon dioxide (EtCO2) levels, hypoxemia, desaturation, Integrated Pulmonary Index (IPI) levels requiring attention (5-7), and intervention (1-4) were determined in the experiment group, and frequencies of them were assessed. Results: Desaturation and bradycardia rates and counts in the experiment group were significantly lower than the control group. No significant difference was seen between groups in terms of hypoxemia, tachycardia, and additional maneuvers. 76%(38/50) of experiment group patients had decrease in EtCO2, 10%(5/50) increase in EtCO2, 38%(19/50) apnea, 52%(26/50) IPI levels requiring attention, 14%(7/50) IPI levels requiring intervention. Conclusion: With the addition of capnography to routine monitoring of sedated vitrectomy patients, oxygen desaturation and bradycardia can be less likely to occur, and with instant follow-up of the EtCO2, apnea, and IPI levels, respiratory depression can be recognized before oxygen desaturation develops. [ABSTRACT FROM AUTHOR]

Objective: We aimed to examine the effect of different intervals of end tidal CO2 (etCO2) values on hemodynamics and surgery in endoscopic endonasal transsphenoidal pituitary surgery. Material and Methods: Two groups were evaluated retrospectively according to the maximum etCO2 values at the time of mass sellar resection. Group 1: 21 patients, etCO2 =25-37 mmHg and Group 2: 21 patients, etCO2=38-50 mmHg. The demographic characteristics, mean arterial pressure (MAP), heart rate (HR), etCO2, arterial CO2 pressure (PaCO2) at the time of anesthesia induction, sellar excision moment and pre-extubation periods, total amount of bleeding, ease of surgery (good-moderate-bad) were obtained from computer records, anesthesia receipts and surgical reports. Results: There was no difference between the two groups in terms of demographic data, complications or bleeding. A significant relationship was found between PaCO2 values of two groups at the time of sellar excision. Surgical satisfaction was evaluated as "good" in 9 patients in Group 1 and 12 patients in Group 2. Conclusion: High etCO2 values (38-50 mmHg) facilitated surgical excision of the mass and did not affect hemodynamics. Surgery satisfaction has increased. Keeping etCO2 slightly higher than normal may be a good choice in these cases. Well-designed prospective studies are needed. [ABSTRACT FROM AUTHOR]

To evaluate whether end-tidal carbon dioxide (ETCO2) value at intubation and its early increase (10 min) after intubation predict both the survival to hospital admission and the survival at hospital discharge, including good neurological outcome (CPC 1–2), in patients with out-of-hospital cardiac arrest (OHCA). All consecutive OHCA patients of any etiology between 2015 and 2018 in Pavia Province (Italy) and Ticino Region (Switzerland) were considered. Patients died before ambulance arrival, with a "do-not-resuscitate" order, without ETCO2 value or with incomplete data were excluded. The study population consisted of 668 patients. An ETCO2 value at intubation > 20 mmHg and its increase 10 min after intubation were independent predictors (after correction for known predictors of OHCA outcome) of survival to hospital admission and survival at hospital discharge. Relative to hospital discharge with good neurological outcome, ETCO2 at intubation and its 10-min change were confirmed predictors both individually and in a bivariable analysis (OR 1.83, 95 %CI 1.02–3.3; p = 0.04 and OR 3.9, 95 %CI 1.97–7.74; p < 0.001, respectively). This was confirmed also when accounting for gender, age, etiology and location. After further adjustment for bystander and CPR status, presenting rhythm and EMS arrival time, the ETCO2 change remained an independent predictor. ETCO2 value > 20 mmHg at intubation and its increase during resuscitation improve the prediction of survival at hospital discharge with good neurological outcome of OHCA patients. ETCO2 increase during resuscitation is a more powerful predictor than ETCO2 at intubation. A larger prospective study to confirm this finding appears warranted. [ABSTRACT FROM AUTHOR]

Introduction: In former studies, the arterio-alveolar carbon dioxide gradient (ΔCO2) predicted in-hospital mortality after initially survived cardiac arrest. As early outcome predictors are urgently needed, we evaluated ΔCO2 as predictor for good neurological outcome in our cohort.Methods: We retrospectively analyzed all patients ≥18 years of age after non-traumatic in- and out of hospital cardiac arrest in the year 2018 from our resuscitation database. Patients without advanced airway management, incomplete datasets or without return of spontaneous circulation were excluded. The first arterial pCO2 after admission and the etCO2 in mmHg at the time of blood sampling were recorded from patient's charts. We then calculated ΔCO2 (pCO2 - etCO2). For baseline analyses, ΔCO2 was dichotomized into a low and high group with separation at the median. Good neurological outcome on day 30, expressed as Cerebral Performance Category 1-2, defined our primary endpoint. Survival to 30 days was used as secondary endpoint.Results: Out of 302 screened patients, 128 remained eligible for analyses. ΔCO2 was lower in 30-day survivors with good neurological outcome (12.2 mmHg vs. 18.8 mmHg, p = 0.009) and in 30-day survivors (12.5 mmHg vs. 20.0 mmHg, p = 0.001). In patients with high ΔCO2, a cardiac etiology of arrest was found less often. They had a higher body mass index, longer duration of resuscitation, higher amounts of epinephrine, lower pO2 levels but both higher pCO2 and blood lactate levels, resulting in lower blood pH and HCO3- levels at admission. In a crude binary logistic regression analysis, ΔCO2 was associated with 30-day neurological outcome (OR = 1.041 per mmHg of ΔCO2, 95% CI 1.008-1.074, p = 0.014). This association persisted after the adjustment for age, sex, witnessed arrest and shockable first rhythm. However, after addition of the duration of resuscitation or the cumulative epinephrine dosage to the model, ΔCO2 lost its association.Conclusion: ΔCO2 at admission after a successfully resuscitated cardiac arrest is associated with 30 days survival with good neurological outcome. However, a higher ΔCO2 may rather be a surrogate for unfavorable resuscitation circumstances than an independent outcome predictor. [ABSTRACT FROM AUTHOR]

Background and Aims: Intubation with cuffed endotracheal tube (ETT) is common in operation rooms, critical care, and emergency rooms. The pressure exerted by the cuff on the tracheal mucosa can lead to a reduction in blood flow to the tracheal wall and result in mucosal ischemia. There are many methods for ETT cuff inflation. Aim of the study was to compare the cuff pressures and volumes between the three methods of ETT cuff inflation. Material and Methods: One hundred and twenty patients were randomized into three groups: Group SG (stethescope guided), group AL (audible leak), and group P (palpation). In group SG, the cuff was inflated by auscultating with the bell of the stethoscope over the thyroid cartilage for leak around cuff. In group AL, the cuff was inflated by listening for an audible leak around the cuff with observer's ear 5 cm away from the mouth of the patient. In group P, the cuff was inflated by palpating for a leak over the cricoid and trachea. The adequacy of the cuff seal was compared between the groups by assessing the volumes of additional air needed to stop the leak around the cuff as confirmed by supraglottic capnometry. Results: The initial volumes needed to inflate the cuff were significantly more in the stethoscope (SG) and hearing (AL) groups than in the palpation (P) group (SG = 5.1 ± 1.4 ml, AL = 4.6 ± 1.6 ml, P = 3.1 ± 0.9 ml; SG and AL vs. P, P < 0.001). Additional cuff volumes required to achieve zero leak around cuff by supraglottic capnometry were 0.85 ± 1 ml in group SG, 1.3 ± 1.1 ml in group AL, and 2.237 ± 0.8 ml in group P (SG vs. P and AL vs. P; P < 0.001). Conclusion: Out of the auscultation-guided, audible leak-guided, and palpation-guided methods of ETT cuff inflation, the auscultation-guided and audible leak-guided methods achieve significantly better tracheal seal than the palpation-guided method.

Background and Aims: Intubation with cuffed endotracheal tube (ETT) is common in operation rooms, critical care, and emergency rooms. The pressure exerted by the cuff on the tracheal mucosa can lead to a reduction in blood flow to the tracheal wall and result in mucosal ischemia. There are many methods for ETT cuff inflation. Aim of the study was to compare the cuff pressures and volumes between the three methods of ETT cuff inflation. Material and Methods: One hundred and twenty patients were randomized into three groups: Group SG (stethescope guided), group AL (audible leak), and group P (palpation). In group SG, the cuff was inflated by auscultating with the bell of the stethoscope over the thyroid cartilage for leak around cuff. In group AL, the cuff was inflated by listening for an audible leak around the cuff with observer's ear 5 cm away from the mouth of the patient. In group P, the cuff was inflated by palpating for a leak over the cricoid and trachea. The adequacy of the cuff seal was compared between the groups by assessing the volumes of additional air needed to stop the leak around the cuff as confirmed by supraglottic capnometry. Results: The initial volumes needed to inflate the cuff were significantly more in the stethoscope (SG) and hearing (AL) groups than in the palpation (P) group (SG = 5.1 ± 1.4 ml, AL = 4.6 ± 1.6 ml, P = 3.1 ± 0.9 ml; SG and AL vs. P, P < 0.001). Additional cuff volumes required to achieve zero leak around cuff by supraglottic capnometry were 0.85 ± 1 ml in group SG, 1.3 ± 1.1 ml in group AL, and 2.237 ± 0.8 ml in group P (SG vs. P and AL vs. P; P < 0.001). Conclusion: Out of the auscultation-guided, audible leak-guided, and palpation-guided methods of ETT cuff inflation, the auscultation-guided and audible leak-guided methods achieve significantly better tracheal seal than the palpation-guided method. [ABSTRACT FROM AUTHOR]

Background: Among subjects with exercise intolerance and suspected early‐stage pulmonary hypertension (PH), early identification of pulmonary vascular disease (PVD) with noninvasive methods is essential for prompt PH management. Hypothesis: Rest gas exchange parameters (minute ventilation to carbon dioxide production ratio: VE/VCO2 and end‐tidal carbon dioxide: ETCO2) can identify PVD in early‐stage PH. Methods: We conducted a retrospective review of 55 subjects with early‐stage PH (per echocardiogram), undergoing invasive exercise hemodynamics with cardiopulmonary exercise test to distinguish exercise intolerance mechanisms. Based on the rest and exercise hemodynamics, three distinct phenotypes were defined: (1) PVD, (2) pulmonary venous hypertension, and (3) noncardiac dyspnea (no rest or exercise PH). For all tests, *p <.05 was considered statistically significant. Results: The mean age was 63.3 ± 13.4 years (53% female). In the overall cohort, higher rest VE/VCO2 and lower rest ETCO2 (mm Hg) correlated with high rest and exercise pulmonary vascular resistance (PVR) (r ~ 0.5–0.6*). On receiver‐operating characteristic analysis to predict PVD (vs. non‐PVD) subjects with noninvasive metrics, area under the curve for pulmonary artery systolic pressure (echocardiogram) = 0.53, rest VE/VCO2 = 0.70* and ETCO2 = 0.73*. Based on this, optimal thresholds of rest VE/VCO2 > 40 mm Hg and rest ETCO2 < 30 mm Hg were applied to the overall cohort. Subjects with both abnormal gas exchange parameters (n = 12, vs. both normal parameters, n = 19) had an exercise PVR 5.2 ± 2.6* (vs. 1.9 ± 1.2), mPAP/CO slope with exercise 10.2 ± 6.0* (vs. 2.9 ± 2.0), and none included subjects from the noncardiac dyspnea group. Conclusions: In a broad cohort of subjects with suspected early‐stage PH, referred for invasive exercise testing to distinguish mechanisms of exercise intolerance, rest gas exchange parameters (VE/VCO2 > 40 mm Hg and ETCO2 < 30 mm Hg) identify PVD. [ABSTRACT FROM AUTHOR]

Objective: To describe on‐scene times for out‐of‐hospital cardiac arrests (OHCA) transferred to hospital, the number of these that were extracorporeal cardiopulmonary resuscitation (ECPR) eligible and potential association between end‐tidal carbon dioxide (ETCO2) and survival so as to inform planned interventional studies. Methods: Prospective cohort study of all OHCA, of suspected medical cause, where resuscitation was commenced and who were transported to participating hospitals from October 2020 to May 2021. Results: One hundred and forty‐nine OHCA were included. Forty‐four (30%) patients survived to hospital discharge. Eighteen (8%) met ECPR inclusion criteria. Median on‐scene time was 33 min (interquartile range [IQR] 24–44). Initial hospital ETCO2 for non‐survivors was 35 mmHg (IQR 19–50), survivors 36 mmHg (IQR 33–45); P = 0.215. No patient with an ETCO2 less than 20 mmHg on hospital arrival to survived to hospital discharge. Conclusions: Average on‐scene time did not differ on survivorship. A small number of transferred patients with OHCA were ECPR eligible. ETCO2 less than 20 mmHg portends adverse prognosis. Our data will be used for future interventional studies. [ABSTRACT FROM AUTHOR]

Chronic orthostatic intolerance (COI) is defined by changes in heart rate (HR), blood pressure (BP), respiration, symptoms of cerebral hypoperfusion and sympathetic overactivation. Postural tachycardia syndrome (POTS) is the most common form of COI in young adults and is defined by an orthostatic increase in heart rate (HR) of ≥ 30 bpm in the absence of orthostatic hypotension. However, some patients referred for evaluation of COI symptoms do not meet the orthostatic HR response criterion of POTS despite debilitating symptoms. Such patients are ill defined, posing diagnostic and therapeutic challenges. This study explored the relationship among cardiovascular autonomic control, the orthostatic HR response, EtCO2 and the severity of orthostatic symptoms and fatigue in patients referred for evaluation of COI. Patients (N = 108) performed standardized testing protocol of the Autonomic Reflex Screen and completed the Composite Autonomic Symptom Score (COMPASS-31) and the Fatigue Severity Scale (FSS). Greater severity of COI was associated with younger age, larger phase IV amplitude in the Valsalva maneuver and lower adrenal baroreflex sensitivity. Greater fatigue severity was associated with a larger reduction in ETCO2 during 10 min of head-up tilt (HUT) and reduced low-frequency (LF) power of heart rate variability. This study suggests that hemodynamic changes associated with the baroreflex response and changes in EtCO2 show a stronger association with the severity of orthostatic symptoms and fatigue than the overall orthostatic HR response in patients with COI. [ABSTRACT FROM AUTHOR]

Aims: The end-tidal carbon dioxide (ETCO2) is frequently measured in cardiac arrest (CA) patients, for management and for predicting survival. Our goal was to study the PaCO2 and ETCO2 in hypothermic cardiac arrest patients.Methods: We included patients with refractory CA assessed for extracorporeal cardiopulmonary resuscitation. Hypothermic patients were identified from previously prospectively collected data from Poland, France and Switzerland. The non-hypothermic CA patients were identified from two French cohort studies. The primary parameters of interest were ETCO2 and PaCO2 at hospital admission. We analysed the data according to both alpha-stat and pH-stat strategies.Results: We included 131 CA patients (39 hypothermic and 92 non-hypothermic). Both ETCO2 (p < 0.001) and pH-stat PaCO2 (p < 0.001) were significantly lower in hypothermic compared to non-hypothermic patients, which was not the case for alpha-stat PaCO2 (p = 0.15). The median PaCO2-ETCO2 gradient was greater for hypothermic compared to non-hypothermic patients when using the alpha-stat method (46 mmHg vs 30 mmHg, p = 0.007), but not when using the pH-stat method (p = 0.10). Temperature was positively correlated with ETCO2 (p < 0.01) and pH-stat PaCO2 (p < 0.01) but not with alpha-stat PaCO2 (p = 0.5). The ETCO2 decreased by 0.5 mmHg and the pH-stat PaCO2 by 1.1 mmHg for every decrease of 1° C of the temperature. The proportion of survivors with an ETCO2 ≤ 10 mmHg at hospital admission was 45% (9/25) for hypothermic and 12% (2/17) for non-hypothermic CA patients.Conclusions: Hypothermic CA is associated with a decrease of the ETCO2 and pH-stat PaCO2 compared with non-hypothermic CA. ETCO2 should not be used in hypothermic CA for predicting outcome. [ABSTRACT FROM AUTHOR]

Interpretation of end-tidal CO 2 (ETCO 2) during manual cardiopulmonary resuscitation (CPR) is affected by variations in ventilation and chest compressions. This study investigates the impact of standardising ETCO 2 to constant ventilation rate (VR) and compression depth (CD) on absolute values and trends. Retrospective study of out-of-hospital cardiac arrest cases with manual CPR, including defibrillator and clinical data. ETCO 2 , VR and CD values were averaged by minute. ETCO 2 was standardised to 10 vpm and 50 mm. We compared standardised (ET s) and measured (ET m) values and trends during resuscitation. Of 1,036 cases, 287 met the inclusion criteria. VR was mostly lower than recommended, 8.8 vpm, and highly variable within and among patients. CD was mostly within guidelines, 49.8 mm, and less varied. ET s was lower than ET m by 7.3 mmHg. ET s emphasized differences by sex (22.4 females vs. 25.6 mmHg males), initial rhythm (29.1 shockable vs. 22.7 mmHg not), intubation type (25.6 supraglottic vs. 22.4 mmHg endotracheal) and return of spontaneous circulation (ROSC) achieved (34.5 mmHg) vs. not (20.1 mmHg). Trends were different between non-ROSC and ROSC patients before ROSC (–0.3 vs. + 0.2 mmHg/min), and between sustained and rearrest after ROSC (–0.7 vs. –2.1 mmHg/min). Peak ET s was higher for sustained than for rearrest (53.0 vs. 42.5 mmHg). Standardising ETCO 2 eliminates effects of VR and CD variations during manual CPR and facilitates comparison of values and trends among and within patients. Its clinical application for guidance of resuscitation warrants further investigation. [ABSTRACT FROM AUTHOR]

The control of PaCO 2 in ventilated patients is known to be of particular importance in the management and prognosis of trauma patients. Although EtCO 2 is often used as a continuous, non-invasive, surrogate marker for PaCO 2 in ventilated trauma patients in the emergency department (ED), previous studies suggest a poor correlation in this cohort. However, previous data has predominantly been collected retrospectively, raising the possibility that the elapsed time between PaCO 2 sampling and EtCO 2 recording may contribute to the poor correlation. As such this study aimed to analyse the correlation of PaCO 2 to EtCO 2 in the ventilated blunt trauma patient presenting to the ED through contemporaneous sampling. This study was conducted as a prospective observational study analysing the near simultaneous recording of EtCO 2 and Arterial Blood Gas sampling of ventilated adult trauma patients in the ED of a Level 1 trauma centre over a 12-month period. Data was analysed using linear regression and subgroup analysis by Injury Severity Score (ISS) and Abbreviated Injury Score (AIS) of the Chest. Linear regression of EtCO 2 vs PaCO 2 demonstrated a moderate correlation with r = 0.54 (p < 0.01, n = 51, 95 % CI 0.31–0.71). Subgroup analysis by ISS, revealed a stronger correlation in those with minor ISS (0–11) (r = 0.76, p < 0.01, n = 13, 95 % CI 0.36–0.92) compared to those more severely injured patients (ISS > 15) (r = 0.44, P < 0.01, n = 38, 95 % CI 0.14–0.67). Analysis by AIS Chest demonstrated similar correlation between patients without chest injuries (AIS 0) (r = 0.55, n = 29, p < 0.01, 95 % CI 0.23–0.76) and those with an AIS >1 (r = 0.51, n = 22, p = 0.02, 95 % CI 0.11–0.77). In patients with traumatic head injuries who had an EtCO 2 between 30 and 39 mmHg, only 57 % had a measured PaCO 2 within 5 mmHg. As patients transition from minor to seriously injured, a decreasing strength of PaCO 2 to EtCO 2 correlation is observed, decreasing the reliability of EtCO 2 as a surrogate marker of PaCO 2 in this patient group. This inconsistency cannot be accounted for by the presence of chest injuries and worryingly is frequently seen in those with traumatic brain injuries. [ABSTRACT FROM AUTHOR]

Background: Chest compression (CC) depth, CC rate and ventilatory rate (VR) are known to have an impact on end-tidal carbon dioxide (ETCO2) values. Chest compression release velocity (CCRV) is increasingly acknowledged as a novel metric in cardiopulmonary resuscitation (CPR). The objective of this study was to analyze whether CCRV would have any effect on ETCO2 values.Methods: In out-of-hospital cardiac arrests (OHCA), effects of CC depth, CC rate, CCRV and VR on ETCO2 were analyzed through linear mixed effect models. A stratification was made on a CCRV of 300, 400 and 500 mm/s. In these categories, mean ETCO2 values were corrected for CC depth and compared through a one-way ANOVA.Results: A 10 mm increase in CC depth was associated with a 1.5 mmHg increase in ETCO2 (p < 0.001), a 100 mm/s increase in CCRV with a 0.8 mmHg increase (p = 0.010) and a 5 breaths per minute increase in VR with a 2.0 mmHg decrease (p < 0.001). CC depth was strongly correlated with CCRV (Pearson's r = 0.709, p < 0.001). After adjusting for CC depth, ETCO2 was on average 6.5 mmHg higher at a CCRV of 500 than at 400 mm/s (p = 0.005) and 5.3 mmHg higher than at 300 mm/s (p = 0.033).Conclusions: In OHCA patients, higher CCRV values resulted in higher ETCO2 values. This effect is independent of CC depth, despite the strong correlation between CCRV and CC depth. [ABSTRACT FROM AUTHOR]

Background/aim: For identifying hemorrhagic shock in trauma patients, some objective data are needed. The use of base excess (BE) and lactate values have been originated. In this study, it was aimed to determine the usability of end tidal carbon dioxide (ETCO2) in patients with multiple trauma for recognizing hemorrhagic shock. Materials and methods: Patients who were admitted to the emergency department between June 2019 and February 2020 with highenergy multiple trauma were included in the study. ETCO2 and BE values were measured. Correlation coefficients were calculated to determine correlations between ETCO2 and BE levels. Results: One hundred and twenty-two patients were included in the study. Eighty-nine (73%) were men and 33 (27%) were women, and the mean age of the study population was 38.70 ± 19.18. The mortality rate was 14.8% in the study population. The correlation between ETCO2 and BE values was significant (r: 0.27) and in the same range in the Bland-Altmann analysis. ETCO2 levels above 35 were specific for stage 1 hemorrhagic shock. ETCO2 levels below 30 were sensitive for stage 2 and 3 hemorrhagic shocks and when the levels were measured below 22 it was found specific for stage 4 shock. The specificity increased to 99% at levels below 18. The sensitivity for ETCO2 values below 22 for predicting mortality was 33.33%, the specificity was 89.42%, the positive predictive value was 35.29% and the negative predictive value was 88.57%. The sensitivity for BE values below -10 for predicting mortality was 50%, the specificity was 93.27%, the positive predictive value was 56.25% and the negative predictive value was 91.51%. Conclusion: ETCO2 measurement can be a useful parameter as a noninvasive and simple technique in predicting and classifying hemorrhagic shock, which is the leading cause of mortality in trauma patients. Mortality rates increased when ETCO2 was measured below 22 and these patients are more likely to be in the critical hemorrhagic shock state. [ABSTRACT FROM AUTHOR]

Background: Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) utilises a suction cup to lift the chest-wall actively during the decompression phase (AD). We hypothesised that mechanical ACD-CPR (Intervention), with AD up to 30 mm above the sternal resting position, would generate better haemodynamic results than standard mechanical CPR (Control).Methods: This out-of-hospital adult non-traumatic cardiac arrest trial was prospective, block-randomised and non-blinded. We included intubated patients with capnography recorded during mechanical CPR. Exclusion criteria were pregnancy, prisoners, and prior chest surgery. The primary endpoint was maximum tidal carbon dioxide partial pressure (pMTCO2) and secondary endpoints were oxygen saturation of cerebral tissue (SctO2), invasive arterial blood pressures and CPR-related injuries. Intervention device lifting force performance was categorised as Complete AD (≥30 Newtons) or Incomplete AD (≤10 Newtons). Haemodynamic data, analysed as one measurement for each parameter per ventilation (Observation Unit, OU) with non-linear regression statistics are reported as mean (standard deviation). A two-sided p-value < 0.05 was considered as statistically significant.Results: Of 221 enrolled patients, 210 were deemed eligible (Control 109, Intervention 101). The Control vs. Intervention results showed no significant differences for pMTCO2: 29(17) vs 29(18) mmHg (p = 0.86), blood pressures during compressions: 111(45) vs. 101(68) mmHg (p = 0.93) and decompressions: 21(20) vs. 18(18) mmHg (p = 0.93) or for SctO2%: 55(36) vs. 57(9) (p = 0.42). The 48 patients who received Complete AD in > 50% of their OUs had higher SctO2 than Control patients: 58(11) vs. 55(36)% (p < 0.001).Conclusions: Mechanical ACD-CPR provided similar haemodynamic results to standard mechanical CPR. The Intervention device did not consistently provide Complete AD.Clinical Trial Registration: ClinicalTrials.gov identifier (NCT number): NCT02479152. The Haemodynamic Effects of Mechanical Standard and Active Chest Compression-decompression During Out-of-hospital CPR. [ABSTRACT FROM AUTHOR]

Introduction: End-tidal carbon dioxide (ETCO2) has been suggested to have prognostic implications during out-of-hospital cardiac arrest (OHCA). Our objective was to determine if the change in ETCO2 (delta ETCO2) during resuscitation was predictive of future return of spontaneous circulation (ROSC) in patients with pulseless electrical activity (PEA) arrests.Methods: We performed a retrospective, observational study of adult (≥18 years of age) non-traumatic PEA OHCAs in two Canadian EMS systems over a two-year time frame beginning on January 1, 2018. Cases were excluded if there was a Do Not Resuscitate order (DNR), had no advanced airway, or had less than two ETCO2 recordings. We performed multivariable logistic regression to examine the association between ETCO2 measures and ROSC. Second, we examined the prognostic performance (sensitivity, specificity, NPV, PPV) for ETCO2 at specific thresholds for predicting ROSC.Results: A total of 208 OHCA met inclusion criteria of which 67 (32%) obtained ROSC. After adjusting for pre-determined confounders, there was an association between delta ETCO2 and ROSC (odds ratio [OR] per 10 mmHg increase in ETCO2 of 1.74 (95% confidence interval [CI] 1.35 to 2.24); P value < 0.001). We also found significant associations between both initial ETCO2 and final ETCO2 with ROSC.Conclusion: Our analysis indicates that there is a positive linear relationship between delta ETCO2 and ROSC with values of delta ETCO2 > 20 mmHg being highly specific for ROSC in PEA patients. As such, patients with up-trending ETCO2 values should have resuscitation continued unless there is overwhelming clinical evidence to the contrary. [ABSTRACT FROM AUTHOR]

The study of carbon dioxide expiration is called capnometry. The graphical representation of capnometry is called capnography. There is a growing interest in the usage of capnography as the usage has expanded toward the study of metabolism, circulation, lung perfusion and diffusion, quality of spontaneous respiration, and patency of airways outside of its typical usage in the anesthetic and emergency medicine field. The parameters of the capnograph could be classified as carbon dioxide (CO2) concentration and time points and coordinates, slopes angle, volumetric studies, and functional transformation of wave data. Up to date, there is no gold standard device for the calculation of the capnographic parameters. Capnography digitization using the image processing technique could serve as an option. From the algorithm we developed, eight identical breath waves were tested by four investigators. The values of the parameters chosen showed no significant difference between investigators. Although there were no significant differences between any of the parameters tested, there were a few related parameters that were not calculable. Further testing after refinement of the algorithm could be done. As more capnographic parameters are being derived and rediscovered by clinicians and researchers alike for both lung and non-lung-related diseases, there is a dire need for data analysis and interpretation. Although the proposed algorithm still needs minor refinements and further large-scale testing, we proposed that the digitization of the capnograph via image processing technique could serve as an intellectual option as it is fast, convenient, easy to use, and efficient.

Little is known about the impact of tidal volumes delivered by emergency medical services (EMS) to adult patients with out-of-hospital cardiac arrest (OHCA). A large urban EMS system changed from standard adult ventilation bags to small adult bags. We hypothesized that the incidence of return of spontaneous circulation (ROSC) at the end of EMS care would increase after this change. We performed a retrospective analysis evaluating adults treated with advanced airway placement for nontraumatic OHCA between January 1, 2015 and December 31, 2021. We compared rates of ROSC, ventilation rate, and mean end tidal carbon dioxide (ETCO 2) by minute before and after the smaller ventilation bag implementation using linear and logistic regression. Of the 1,994 patients included, 1,331 (67%) were treated with a small adult bag. ROSC at the end of EMS care was lower in the small bag cohort than the large bag cohort, 33% vs 40% (p = 0.003). After adjustment, small bag use was associated with lower odds of ROSC at the end of EMS care [OR 0.74, 95% CI 0.61 – 0.91]. Ventilation rates did not differ between cohorts. ETCO 2 values were lower in the large bag cohort (33.2 ± 17.2 mmHg vs. 36.9 ± 19.2 mmHg, p < 0.01). Use of a small adult bag during OHCA was associated with lower odds of ROSC at the end of EMS care. The effects on acid base status, hemodynamics, and delivered minute ventilation remain unclear and warrant additional study. [ABSTRACT FROM AUTHOR]

Background: Prehospital identification of shock in trauma patients lacks accurate markers. Low end tidal carbon dioxide (ETCO 2 ) correlates with mortality in intubated patients. The predictive value of ETCO 2 obtained by nasal capnography cannula (NCC) is unknown. We hypothesized that prehospital ETCO 2 values obtained by NCC and in-line ventilator circuit (ILVC) would be predictive of mortality., Methods: This was a prospective, observational, multicenter study. ETCO 2 values were collected by a NCC or through ILVC. AUROCs were compared with prehospital systolic blood pressure (SBP) and shock index (SI). The Youden index defined optimal cutoffs., Results: Of 550 enrolled patients, 487 (88.5%) had ETCO 2 measured through an NCC. Median age was 37 (27-52) years; 76.5% were male; median ISS was 13 (5-22). Mortality was 10.4%. Minimum prehospital ETCO 2 significantly predicted mortality with an AUROC of 0.76 (CI 0.69-0.84; Youden index ​= ​22 ​mmHg), outperforming SBP with an AUROC of 0.68; (CI 0.62-0.74, p ​= ​0.04) and shock index with an AUROC of 0.67 (CI 0.59-0.74, p ​= ​0.03)., Conclusion: Prehospital ETCO 2 measured by non-invasive NCC or ILVC may be predictive of mortality in injured patients., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper, (Copyright © 2023 Elsevier Inc. All rights reserved.)

An accurate, non-invasive measure of return of spontaneous circulation (ROSC) is needed to improve management of cardiac arrest patients. During a pulse check in Emergency Department (ED) cardiac arrest patients, we compared the correlation between 1) end tidal carbon dioxide (ETCO 2) and systolic blood pressure (SBP), and 2) Doppler ultrasound peak systolic velocity (PSV) and SBP. Additionally, we assessed the accuracy of PSV ≥ 20 cm/sec in comparison to previously suggested ETCO 2 ≥ 20 or ≥ 25 mmHg thresholds to predict ROSC with SBP ≥ 60 mmHg. This was a secondary analysis of a previously published prospective observational study of ED cardiac arrest patients with an advanced airway and femoral arterial line in place. During each pulse check, highest SBP, highest PSV, and ETCO 2 at the end of the pulse check were recorded. Spearman correlation coefficients were calculated and compared using a Fisher Z-transformation. Accuracy of previously determined PSV and ETCO 2 thresholds for detecting ROSC with SBP ≥ 60 mmHg were compared using McNemar's tests. Based on data from 35 patients with 111 pulse checks, we found a higher correlation between PSV and SBP than ETCO 2 and SBP (0.71 vs 0.31; p < 0.001). Diagnostic accuracy of PSV ≥ 20 cm/sec for detecting ROSC with SBP ≥ 60 mmHg was 89% (95% CI: 82%-94%) versus 59% (95% CI: 49%-68%) and 58% (95% CI: 48%-67%) for ETCO 2 ≥ 20 and ≥ 25 mmHg, respectively. During a pulse check, Doppler ultrasound PSV outperformed ETCO 2 for correlation with SBP and accuracy in detecting ROSC with SBP ≥ 60 mmHg. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the correlation and agreement between end-tidal CO 2 (EtCO 2 ) measured with the novel portable capnometer (CapnoEye®) and partial pressure of arterial carbon dioxide (PaCO 2 ) levels in patients with respiratory diseases and to compare the efficacy of EtCO 2 and PvCO 2 in predicting PaCO 2 levels., Methods: We analyzed the correlation and the agreement between EtCO 2 and PaCO 2 and between PvCO 2 and PaCO 2 using Pearson's moment correlation coefficient in patients with type 1 and type 2 respiratory failure and both groups overall., Results: A total of 100 samples were included that comprised 67 men (67%). The mean age of the subjects was 77 ± 13 years. Chronic obstructive pulmonary disease (COPD) (43%) was the most common disease. There was a high correlation between EtCO 2 and PaCO 2 (r = 0.88; p < 0.0001). Sixty-six PvCO 2 samples were obtained, and there was a high correlation between PvCO 2 and PaCO 2 (r = 0.81; p < 0.0001). Regarding type 2 respiratory failure, there was a high correlation between EtCO 2 and PaCO 2 (r = 0.81). The Bland-Altman analysis between PaCO 2 and EtCO 2 revealed a bias of 5.7 mmHg, with limits of agreement ranging from -5.1 mmHg to 16.5 mmHg. In contrast, the analysis between PaCO 2 and PvCO 2 revealed a bias of -6.8 mmHg, and the limits of agreement ranged from -22.13 mmHg to 8.53 mmHg., Conclusion: EtCO 2 measured by CapnoEye® was significantly correlated to PaCO 2 levels in patients with respiratory diseases. Moreover, CapnoEye® may be more useful for predicting hypercapnia conditions in which respiratory diseases are compared with measure PvCO 2 ., (© 2023 The Authors. The Clinical Respiratory Journal published by John Wiley & Sons Ltd.)

Background: Among subjects with exercise intolerance and suspected early-stage pulmonary hypertension (PH), early identification of pulmonary vascular disease (PVD) with noninvasive methods is essential for prompt PH management., Hypothesis: Rest gas exchange parameters (minute ventilation to carbon dioxide production ratio: V E /VCO 2 and end-tidal carbon dioxide: ETCO 2 ) can identify PVD in early-stage PH., Methods: We conducted a retrospective review of 55 subjects with early-stage PH (per echocardiogram), undergoing invasive exercise hemodynamics with cardiopulmonary exercise test to distinguish exercise intolerance mechanisms. Based on the rest and exercise hemodynamics, three distinct phenotypes were defined: (1) PVD, (2) pulmonary venous hypertension, and (3) noncardiac dyspnea (no rest or exercise PH). For all tests, *p < .05 was considered statistically significant., Results: The mean age was 63.3 ± 13.4 years (53% female). In the overall cohort, higher rest V E /VCO 2 and lower rest ETCO 2 (mm Hg) correlated with high rest and exercise pulmonary vascular resistance (PVR) (r ~ 0.5-0.6*). On receiver-operating characteristic analysis to predict PVD (vs. non-PVD) subjects with noninvasive metrics, area under the curve for pulmonary artery systolic pressure (echocardiogram) = 0.53, rest V E /VCO 2  = 0.70* and ETCO 2  = 0.73*. Based on this, optimal thresholds of rest V E /VCO 2  > 40 mm Hg and rest ETCO 2  < 30 mm Hg were applied to the overall cohort. Subjects with both abnormal gas exchange parameters (n = 12, vs. both normal parameters, n = 19) had an exercise PVR 5.2 ± 2.6* (vs. 1.9 ± 1.2), mPAP/CO slope with exercise 10.2 ± 6.0* (vs. 2.9 ± 2.0), and none included subjects from the noncardiac dyspnea group., Conclusions: In a broad cohort of subjects with suspected early-stage PH, referred for invasive exercise testing to distinguish mechanisms of exercise intolerance, rest gas exchange parameters (V E /VCO 2  > 40 mm Hg and ETCO 2  < 30 mm Hg) identify PVD., (© 2022 The Authors. Clinical Cardiology published by Wiley Periodicals, LLC.)

The study of carbon dioxide expiration is called capnometry. The graphical representation of capnometry is called capnography. There is a growing interest in the usage of capnography as the usage has expanded toward the study of metabolism, circulation, lung perfusion and diffusion, quality of spontaneous respiration, and patency of airways outside of its typical usage in the anesthetic and emergency medicine field. The parameters of the capnograph could be classified as carbon dioxide (CO 2 ) concentration and time points and coordinates, slopes angle, volumetric studies, and functional transformation of wave data. Up to date, there is no gold standard device for the calculation of the capnographic parameters. Capnography digitization using the image processing technique could serve as an option. From the algorithm we developed, eight identical breath waves were tested by four investigators. The values of the parameters chosen showed no significant difference between investigators. Although there were no significant differences between any of the parameters tested, there were a few related parameters that were not calculable. Further testing after refinement of the algorithm could be done. As more capnographic parameters are being derived and rediscovered by clinicians and researchers alike for both lung and non-lung-related diseases, there is a dire need for data analysis and interpretation. Although the proposed algorithm still needs minor refinements and further large-scale testing, we proposed that the digitization of the capnograph via image processing technique could serve as an intellectual option as it is fast, convenient, easy to use, and efficient., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Vijayam, Supriyanto and Malarvili.)