Utility of non-invasive monitoring of exhaled carbon dioxide and perfusion index in adult patients in the emergency department

BACKGROUND

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).

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.

Relationship between ETCO2 and PaCO2 under Changing Capnogram in Ventilated Infants with NAVA: An Observational Study

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.

Prehospital ETCO2 is predictive of death in intubated and non-intubated patients

BACKGROUND

Prehospital identification of shock in trauma patients lacks accurate markers. Low end tidal carbon dioxide (ETCO2) correlates with mortality in intubated patients. The predictive value of ETCO2 obtained by nasal capnography cannula (NCC) is unknown. We hypothesized that prehospital ETCO2 values obtained by NCC and in-line ventilator circuit (ILVC) would be predictive of mortality.

METHODS

This was a prospective, observational, multicenter study. ETCO2 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 ETCO2 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 ETCO2 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 ETCO2 measured by non-invasive NCC or ILVC may be predictive of mortality in injured patients.

Ventilation Targets for Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke: A Systematic Review

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.

Doppler ultrasound peak systolic velocity versus end tidal carbon dioxide during pulse checks in cardiac arrest

BACKGROUND

An accurate, non-invasive measure of return of spontaneous circulation (ROSC) is needed to improve management of cardiac arrest patients.

OBJECTIVES

During a pulse check in Emergency Department (ED) cardiac arrest patients, we compared the correlation between 1) end tidal carbon dioxide (ETCO₂) 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 ETCO₂ ≥ 20 or ≥ 25 mmHg thresholds to predict ROSC with SBP ≥ 60 mmHg.

METHODS

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 ETCO₂ 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 ETCO₂ thresholds for detecting ROSC with SBP ≥ 60 mmHg were compared using McNemar's tests.

RESULTS

Based on data from 35 patients with 111 pulse checks, we found a higher correlation between PSV and SBP than ETCO₂ 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 ETCO₂ ≥ 20 and ≥ 25 mmHg, respectively.

CONCLUSIONS

During a pulse check, Doppler ultrasound PSV outperformed ETCO₂ for correlation with SBP and accuracy in detecting ROSC with SBP ≥ 60 mmHg.

End-tidal carbon dioxide (ETCO2) at intubation and its increase after 10 minutes resuscitation predicts survival with good neurological outcome in out-of-hospital cardiac arrest patients

AIM

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).

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Distinguishing exercise intolerance in early-stage pulmonary hypertension with invasive exercise hemodynamics: Rest VE /VCO2 and ETCO2 identify pulmonary vascular disease

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.

Out-of-hospital cardiac arrest outcomes, end-tidal carbon dioxide and extracorporeal cardiopulmonary resuscitation eligibility: New South Wales pilot data

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.

The association between end-tidal CO2 and return of spontaneous circulation after out-of-hospital cardiac arrest with pulseless electrical activity

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.

Further Exploration of Treatment Response in Latinos with Comorbid Asthma and Panic Disorder: A Brief Report of HRV and ETCO2 as Potential Mediators of Treatment Response

Heart rate variability (HRV) and end tidal CO2 (ETCO2) in relation to treatment response have not been studied in Latino populations or in comorbid asthma and panic disorder (PD). An extension of previously published research, the current study explored psychophysiological variables as possible mediators of treatment response. Latino treatment completers (N = 32) in the Bronx with asthma-PD received either Cognitive-Behavioral Psychophysiological Therapy (CBPT) or Music Relaxation Therapy (MRT). CBPT included HRV-biofeedback (HRVB); in-the-moment heart rate data to help an individual learn to influence his/her own heart rate. The sample was primarily female (93.8%) and Puerto Rican (81.25%). Treatment groups did not differ on demographics, except for less education in CBPT. The Panic Disorder Severity Scale (PDSS) and Asthma Control Questionnaire (ACQ) assessed changes in symptoms. HRV and ETCO2 were measured at four of eight therapy sessions. Baseline ETCO2 and changes in HRV from first to last of psychophysiology sessions were investigated as mediators of change on ACQ and PDSS. Mixed model analyses indicated in the CPBT group, changes in both asthma control and PD severity were not mediated by changes in HRV. In the CBPT and MRT groups combined, changes in PD severity were not mediated by baseline ETCO2. These findings may be due to the brevity of HRVB in CBPT, multiple treatment components, ETCO2 not directly targeted, and/or unique physiological pathways in Latinos with asthma-PD.

Comparison of ETCO2 Value and Blood Gas PCO2 Value of Patients Receiving Non-invasive Mechanical Ventilation Treatment in Emergency Department

Capnography is the non-invasive measurement and graphic representation of the partial pressure of CO2 in expiration. Although there are many studies in the literature comparing the partial pressure of carbon dioxide (pCO2) and end-tidal CO2 (ETCO2) values in patients who underwent IMV (invasive mechanical ventilation), there are no studies showing their interchangeable applicability in patients who received NIMV (non-IMV). We aimed to evaluate whether the use of ETCO2 in the treatment process can replace pCO2 use in patients scheduled for NIMV treatment in the emergency department. Patients who applied to the emergency department with respiratory distress between March 2019 and January 2020, who were diagnosed with acute cardiogenic edema or acute chronic obstructive pulmonary disease (COPD) exacerbation, and who needed NIMV were included in the study. General characteristics of the patients and the pCO2 and ETCO2 values were measured in the blood gas 1 h after the NIMV application was started. 64.2% (99 patients) of the patients included in the study were male, and 35.8% (55 patients) were female. The mean age of the patients included in the study was 69.1 ± 12.2 years. The mean pCO2 values ​​were measured as 52.6 ± 13.2. The mean of ETCO2 values ​​measured simultaneously was 33.6 ± 10.1. There was a significant difference between the controlled pCO2 values ​​and ETCO2 values ​​at the first hour of NIMV treatment (Z: - 10.640, p < 0.001). The ETCO2 level was found to be different in our patients who received NIMV treatment, which could not be used instead of the pCO2 level.

Nasal End-tidal Carbon Dioxide Monitoring during Procedural Sedation: Is it time for Wider Adoption?

How to cite this article: Ravikumar N, Nallasamy K. Nasal End-tidal Carbon Dioxide Monitoring during Procedural Sedation: Is it time for Wider Adoption? Indian J Crit Care Med 2020;24(8):611-612.

Laryngeal mask versus facemask in the respiratory management during catheter ablation

BACKGROUND

The purpose of this study is to investigate if a laryngeal mask could improve respiratory condition during radiofrequency catheter ablation (RFCA).

METHODS

Twenty-four consecutive patients who underwent RFCA for atrial fibrillation were divided into two groups (Facemask group; n = 10, Laryngeal mask group; n = 14). All patients were completely sedated under intravenous anesthesia and fitted with artificial respirators during the RFCA. The capnography waveforms and their differential coefficients were analyzed to evaluate the changes of end-tidal CO₂ (ETCO₂) values, respiratory intervals, expiratory durations, and inspiratory durations.

RESULTS

During the RFCA, ETCO₂ values of the laryngeal mask group were higher than those of the facemask group (36.0 vs. 29.2 mmHg, p = 0.005). The respiratory interval was significantly longer in the laryngeal mask group than those in the facemask group (4.28 s vs.5.25 s, p < 0.001). In both expiratory and inspiratory phases, the mean of the maximum and minimum values of CO₂ was significantly higher when using a laryngeal mask than when using a facemask. The inspiratory-expiratory ratio of the laryngeal mask group was significantly larger than that of the facemask group (1.59 vs. 1.27, p < 0.001). The total procedure duration, fluoroscopic duration and the ablation energy were significantly lower in the laryngeal mask group than in the facemask group. The ETCO₂ value is the most influential parameter on the fluoroscopic duration during the RFCA procedure (β = - 0.477, p = 0.029).

CONCLUSIONS

The use of a laryngeal mask could stabilize respiration during intravenous anesthesia, which could improve the efficiency of RFCA.

Quantitative end-tidal CO2 can predict increase in heart rate during infant cardiopulmonary resuscitation

Aim

To determine the end-tidal CO₂ (ETCO₂) value that predicts a HR > 60 beats per minute (bpm) with the best sensitivity and specificity during neonatal/infant cardiopulmonary resuscitation (CPR) defined as chest compressions ± epinephrine in neonates/infants admitted to a CVICU/PICU.

Methods

This was a retrospective cohort study from 1/1/08 to 12/31/12 of all infants ≤6 month of age who received CPR and had ETCO₂ documented during serial resuscitations in the pediatric (PICU) or pediatric cardiovascular intensive care units (CVICU) of Children's Medical Center of Dallas. A receiver operator characteristic (ROC) curve was generated to determine the ETCO₂ cut-off with the best sensitivity and specificity for predicting HR > 60 bpm. Each ETCO₂ value was correlated to the infant's HR at that specific time.

Results

CPR was provided for 165 infants of which 49 infants had quantitative ETCO₂ documented so only these infants were included. The majority were in the CVICU (81%) and intubated (84%). Mean gestational age was 36 ± 3 weeks and median age (interquartile range) at time of CPR was 30 (16-96) days. An ETCO₂ between 17 and 18 mmHg correlated with the highest sensitivity and specificity for return of a HR > 60 bpm. Area under the curve for the ROC is 0.835.

Conclusions

This study provides critical clinical information regarding correlation between ETCO₂ values and an adequate rise in heart rate in neonates and young infants during CPR. Quantitative ETCO₂ monitoring allows CPR to progress uninterrupted without need to pause to check heart rate every 60 seconds until the critical ETCO₂ threshold is reached. Quantitative ETCO₂ monitoring as an adjunct to cardiac monitoring during infant CPR might enhance perfusion and improve outcomes.

The effect of a holistic self-management plan on asthma control

The holistic self-management plan includes lifelong actions that enable patients to cope with their disease. The present study was designed to evaluate the effect of a holistic self-management plan on asthma control. A 12-month controlled study was conducted. Adult patients with mild-to-moderate asthma (n = 24) who attended the emergency asthma department were randomized to two groups: One group followed four educational sessions and three personal home sessions (n = 12), while a second group received a short manual with asthma information (n = 12). The main measure was the asthma control test (ACT), while secondary outcomes were self-efficacy (general self-efficacy scale, GSE), end-tidal carbon dioxide (ETCO₂), respiratory rate (RR), breathing hold time (BHT), the Nijmegen Questionnaire (NQ), and spirometry (FEV₁% predicted (forced expiratory volume in 1 second % predicted)) scores. The 2 × 4 ANOVA showed a significant interaction effect between intervention and time in ACT (p = 0.001), GSE (p < 0.001), ETCO₂ (p < 0.001), RR (p < 0.001), BHT (p < 0.001), NQ (p = 0.05), and FEV₁% predicted (p < 0.001). Predictors of asthma control were self-efficacy and ETCO₂. In conclusion, this exploratory study provided support for the effectiveness of holistic self-management in asthma control. Behavioral changes, as indicated by the development of self-efficacy and the reduction of hyperventilation, contributed to the effectiveness of the intervention.

Adolescent girls with emotional disorders have a lower end-tidal CO2 and increased respiratory rate compared with healthy controls

Hyperventilation has been linked to emotional distress in adults. This study investigates end-tidal carbon dioxide (ETCO₂), respiratory rate (RR), and heart rate variability (HRV) in adolescent girls with emotional disorders and healthy controls. ETCO₂, RR, HRV, and ratings of emotional symptom severity were collected in adolescent female psychiatric patients with emotional disorders (n = 63) and healthy controls (n = 62). ETCO₂ and RR differed significantly between patients and controls. ETCO₂, HR, and HRV were significant independent predictors of group status, that is, clinical or healthy, while RR was not. ETCO₂ and RR were significantly related to emotional symptom severity and to HRV in the total group. ETCO₂ and RR were not affected by use of selective serotonin reuptake inhibitors. It is concluded that emotional dysregulation is related to hyperventilation in adolescent girls. Respiratory-based treatments may be relevant to investigate in future research.