Exhaled Carbon Dioxide Research Articles

Machine learning-based identification of efficient and restrictive physiological subphenotypes in acute respiratory distress syndrome

IntroductionAcute respiratory distress syndrome (ARDS) is a severe condition with high morbidity and mortality, characterized by significant clinical heterogeneity. This heterogeneity complicates treatment selection and patient inclusion in clinical trials. Therefore, the objective of this study is to identify physiological subphenotypes of ARDS using machine learning, and to determine ventilatory variables that can effectively discriminate between these subphenotypes in a bedside setting with high performance, highlighting potential utility for future clinical stratification approaches.MethodologyA retrospective cohort study was conducted using data from our ICU, covering admissions from 2017 to 2021. The study included 224 patients over 18 years of age diagnosed with ARDS according to the Berlin criteria and undergoing invasive mechanical ventilation (IMV). Data on physiological and ventilatory variables were collected during the first 24 h IMV. We applied machine learning techniques to categorize subphenotypes in ARDS patients. Initially, we employed the unsupervised Gaussian Mixture Classification Model approach to group patients into subphenotypes. Subsequently, we applied supervised models such as XGBoost to perform root cause analysis, evaluate the classification of patients into these subgroups, and measure their performance.ResultsOur models identified two ARDS subphenotypes with significant clinical differences and significant outcomes. Subphenotype Efficient (n = 172) was characterized by lower mortality, lower clinical severity and presented a less restrictive pattern with better gas exchange compared to Subphenotype Restrictive (n = 52), which showed the opposite. The models demonstrated high performance with an area under the ROC curve of 0.94, sensitivity of 94.2% and specificity of 87.5%, in addition to an F1 score of 0.85. The most influential variables in the discrimination of subphenotypes were distension pressure, respiratory frequency and exhaled carbon dioxide volume.ConclusionThis study presents an approach to improve subphenotype categorization in ARDS. The generation of clustering and prediction models by machine learning involving clinical, ventilatory mechanics, and gas exchange variables allowed for more accurate stratification of patients. These findings have the potential to optimize individualized treatment selection and improve clinical outcomes in patients with ARDS.Graphical

Capnometry-Guided Respiratory Intervention in Veteran PTSD: Impact on Symptom Clusters.

Background/Objectives: Post-traumatic stress disorder (PTSD) is a challenging psychiatric condition to treat, with suboptimal recovery and difficulty tolerating exposure-based psychotherapies often noted in outcomes research. The aim of this study was to examine patterns of symptom reduction in veterans with PTSD treated with a Capnometry-Guided Respiratory Intervention (CGRI), a 28-day treatment teaching about the normalization of respiratory rate and exhaled carbon dioxide levels via biofeedback. We hypothesized reductions in total PCL-5 scores and all symptom clusters immediately post-treatment but with relative resistance to changes in hyperarousal symptoms, as reported in the outcomes of research using other evidence-based psychotherapies. Methods: In this report of real-world outcomes, we included 164 veterans treated with CGRI. Pre- and post-treatment PTSD Checklists for DSM-5 (PCL-5) scales were recorded and analyzed based on the total, cluster, and item scores. Subjects were additionally classified into Recovered, Improved, or Suboptimal subgroups based on their response to treatment. Data were compiled during routine clinical care and are available for retrospective analysis. Results: Treatment response was reported in 53% of participants, with a mean total PCL-5 score reduction of 12 points post-treatment (effect size, Glass's Δ = 0.99, large) and individual PCL-5 clusters showing medium to large effect sizes (effect size = 0.71 to 0.98). Contrary to our hypothesis, a large effect size was found in the hyperarousal cluster, with post-treatment scores being significantly improved compared to pre-treatment scores (effect size = 0.98). In the Recovered group, all 20 PCL-5 items showed significant declines, while significant reductions were reported in some items in the Improved group and no item improvements were noted in the Suboptimal group. Conclusions: Consistently with prior published trials reporting overall improvements in PTSD symptoms, in this report, the CGRI produced clinically meaningful reductions in PCL-5 cluster scores in addition to total scores. Unlike reports from several trials of cognitive therapies, this study found hyperarousal symptoms to be responsive to treatment. The CGRI shows evidence of improvement across the range of PTSD symptoms in the immediate post-treatment interval. The absence of an extended post-treatment follow up introduces uncertainty concerning the durability of benefits experienced, although previous CGRI research on both panic disorder and PTSD has shown the maintenance of symptom reduction in six- to twelve-month intervals.

Effect of neuromuscular electrical stimulation combined with respiratory rehabilitation training on pulmonary rehabilitation in patients with chronic obstructive pulmonary disease

Objectivethe study aimed to analyze the therapeutic effects of neuromuscular electrical stimulation (NMES) combined with respiratory muscle training (RMT) on patients with moderate-to-severe chronic obstructive pulmonary disease (COPD).Methods135 patients with moderate/severe chronic obstructive pulmonary disease were selected as the research object and randomly selected. 72 cases were divided into rehabilitation group and 63 cases in control group. 63 healthy individuals who underwent physical examination in the same period were also included in the internal control group (blank group). Data on pulmonary function parameters (FEV1, FEV1%pred, FEV1/FVC ratio), blood gas analysis parameters (arterial oxygen partial pressure (PaO2), carbon dioxide partial pressure (PaCO2), and arterial oxygen saturation (SaO2)), and anxiety and depression scores were collected before and after the intervention for the RG, CG, and BG. Additionally, the COPD assessment test (CAT) scores were recorded for both the RG and CG. Results: following intervention, PaO2 was clearly reduced, and PaCO2 and SaO2 were visibly higher in subjects; PaO2 was clearly reduced, and PaCO2 and SaO2 were visibly higher in the RG as against the CG; Forced expiratory volume in one second (FEV1), percentage of predicted FEV1 (FEV1%pred), and FEV1/forced vital capacity (FVC) in subjects were visibly higher, and FEV1%pred and FEV1/FVC were visibly higher in the RG as against the CG; The CAT scores and anxiety and depression scores in subjects were clearly reduced, and those were clearly reduced in the RG as against the CG (P < 0.05).ConclusionNMES and pulmonary rehabilitation (PR) exercise training can visibly improve the lung function, oxygenation capacity, carbon dioxide exhalation, and quality of life (QoL) in COPD patients, effectively alleviating anxiety and depression.

Influence of Ambient Temperature on Resting Energy Expenditure in Metabolically Healthy Males and Females.

Influence of Ambient Temperature on Resting Energy Expenditure in Metabolically Healthy Males and Females.

Capnodynamic determination of end-expiratory lung volume in a porcine model of hypoxic pulmonary vasoconstriction

PurposeThe capnodynamic method, End Expiratory Lung Volume CO2 (EELV-CO2), utilizes exhaled carbon dioxide analysis to estimate End-Expiratory Lung Volume (EELV) and has been validated in both normal lungs and lung injury models. Its performance under systemic hypoxia and variations in CO2 elimination is not examined. This study aims to validate EELV-CO2 against inert gas wash in/wash out (EELV- SF6, sulfur hexafluoride) in a porcine model of stable hemodynamic conditions followed by hypoxic pulmonary vasoconstriction and inhaled nitric oxide (iNO).MethodsTen mechanically ventilated piglets were exposed to a hypoxic gas mixture and selective pulmonary vasoconstriction. Inhalation of nitric oxide was used to reverse the pulmonary vasoconstriction. Paired recordings of EELV-CO2 and EELV-SF6, were conducted to assess their agreement of absolute values.ResultsEELV-CO2 showed a bias of + 5 ml kg− 1 compared to EELV-SF6, upper limit of agreement of 11 ml kg− 1 (95%CI: 9–13 ml kg− 1), lower limit of agreement − 1 ml kg− 1 (95%CI: -3- 0 ml kg− 1), mean percentage error 34%. Agreement between EELV-CO2 and EELV-SF6 was largely constant but was affected by progressing hypoxia and reached maximum limit of agreement after iNO exposure. Re-introduction of normoxemia then stabilized bias and limits of agreement to baseline levels.ConclusionEELV-CO2 generates absolute values in parallel with EELV -SF6. Stressing EELV-CO2 with hypoxic pulmonary vasoconstriction and iNO, transiently impairs the agreement which stabilizes once normoxemia is reestablished.

Tracheostomy Tube Monitoring Accessory to Detect Accidental Decannulation and Obstruction Emergencies in Ventilator-Independent Pediatric Patients

Introduction: Some of the leading causes of tracheostomy-related complications in pediatric populations are accidental decannulation and obstruction events that result in permanent neurological damage or death if not mitigated quickly enough. Despite the severity of tracheostomy tube emergency events, there is currently no effective medical technology available that can specifically detect accidental decannulation or obstruction in a tracheostomized patient that is not ventilator dependent. Therefore, a pediatric tracheal breathing model system was developed to assist with testing new tracheostomy tube technologies for identifying emergency events. Methods: A custom carbon dioxide monitoring tracheostomy tube attachment was engineered to collect breathing waveform data during emergency events (e.g., improper insertion, accidental decannulation, and mucus obstruction). Anatomically accurate pediatric tracheal models for various age groups (0-3 months, 2-4 years, and 10-12 years old) were developed with modelling software and a 3D printer. A breathing simulator was integrated with the tracheal models to generate age-dependent respiration patterns during simulated tracheostomy tube emergencies. Results: Carbon dioxide readings from the custom tracheostomy tube attachment indicated distinct waveform recordings during simulated tracheostomy tube emergency events for all age groups tested. During incorrect insertion, accidental decannulation, and complete blockage of a tracheostomy tube, exhaled carbon dioxide readings remained static at ambient levels. Partial mucus obstruction of a tracheostomy tube decreased exhaled carbon dioxide waveform amplitude relative to unobstructed conditions. Conclusions: The tracheostomy tube attachment successfully recorded respiration patterns during simulated tracheostomy tube emergencies in pediatric patients of varying age. Breathing waveform data collected from the model system will aid in the development of emergency airway event detection software integrated in the tracheostomy tube sensing accessory.

Review of Tracheotomy Auxiliary Device Patents

Background: Tracheotomy is a surgical technique in which the trachea in the front of the neck is cut to construct an artificial airway. Bypassing blockage or lesions in the upper airway, this opening permits oxygen provision and carbon dioxide exhalation straight through the trachea. A more profound comprehension of the pathophysiologic role of the airway has made tracheotomy a crucial component of treatment for several illnesses. Medical devices used both during and after a tracheotomy are known as auxiliary devices for tracheotomies. These devices, which include dilators, cannulas, plugging devices for cannulas, and immobilization devices, ensure the procedure is completed safely and the patient recovers quickly. Objective: This paper aims to identify the key issues, summarize the many tracheotomy auxiliary device constructions in recent years, and serve as a resource for researchers working on related topics. Methods: Assess and evaluate the benefits and drawbacks of the tracheotomy auxiliary devices covered by the patents filed in the last several years and identify areas for development. Results: This patent research examines the shortcomings of current tracheotomy auxiliary devices and speculates about future directions for their advancement. Conclusion: Although they are challenging to use, the tracheotomy auxiliary devices now in use provide good stability and dependability. Enhancing the mechanical structure of tracheotomy auxiliary devices and strengthening clinical trials for various patient populations and intricate surgical settings are essential improvements. Furthermore, pertinent patents for auxiliary equipment used in tracheotomies have not yet been created.

A two-person verbal check to confirm tracheal intubation: evaluation of practice changes to prevent unrecognised oesophageal intubation

A two-person verbal check to confirm tracheal intubation: evaluation of practice changes to prevent unrecognised oesophageal intubation

No effect of circulating leptin on energy metabolism in normal weight or overweight/obese lactating mothers: The case-control Breastmilk and the Link to Overweight/Obesity and Maternal diet (BLOOM) study

Pregnancy and lactation are associated with metabolic changes, including alterations in energy metabolism, which are closely linked to body mass and composition due to hormonal status. Therefore, the objective of this study was to investigate the energy metabolism in exclusively or predominantly breastfeeding mothers with normal weight (NW) and overweight/obesity (OW/OB) and evaluate its associations with fasting serum leptin. This cross-sectional BLOOM study was conducted among 39 mothers (n=19 NW, n=20 OW/OB) in 15.5±1.2 weeks of lactation. The leptin was analyzed in a blood sample using an enzyme-linked immunosorbent assay, body composition was analyzed by dual-energy X-ray absorptiometry, and resting metabolic rate (RMR) was measured by indirect calorimetry method. The average RMR for all groups was 1747.5±281.9kcal/d, with a statistically significant difference between groups (1932.7±222.6 vs. 1550.5±190.6, p<0.001, respectively in the OW/OB and NW group). The OW/OB mothers had higher oxygen uptake (VO2) and exhaled carbon dioxide (VCO2), but not respiratory quotient (RQ), carbohydrate (CHO%) and lipid oxidation (FAT%). When analyzing correlations stratified by BMI category, we found that serum leptin was correlated with CHO% negatively, and with FAT% positively in the NW but not in OW/OB mothers. Additionally, serum leptin was a significant predictor of RMR, VCO2, VO2, CHO%, and RMR/kg of total body weight. However, after adjusting for confounders, the observed associations were no longer statistically significant (RMR: β=0.113, 95% CI-0.354-0.319; VO2: β=0.141, 95% CI-0.462-0.744; VCO2: β=0.238, 95% CI-0.411-0.888; CHO%: β=-0.146, 95% CI-0.151-0.444; RMR/kg of total body weight: β=-0.294, 95% CI-0.831-0.244). Our results did not support the hypothesis that leptin plays a role in regulating energy homeostasis during lactation.

Relationship between Exhaled Aerosol and Carbon Dioxide Emission Across Respiratory Activities.

Respiratory particles produced during vocalized and nonvocalized activities such as breathing, speaking, and singing serve as a major route for respiratory pathogen transmission. This work reports concomitant measurements of exhaled carbon dioxide volume (VCO2) and minute ventilation (VE), along with exhaled respiratory particles during breathing, exercising, speaking, and singing. Exhaled CO2 and VE measured across healthy adult participants follow a similar trend to particle number concentration during the nonvocalized exercise activities (breathing at rest, vigorous exercise, and very vigorous exercise). Exhaled CO2 is strongly correlated with mean particle number (r = 0.81) and mass (r = 0.84) emission rates for the nonvocalized exercise activities. However, exhaled CO2 is poorly correlated with mean particle number (r = 0.34) and mass (r = 0.12) emission rates during activities requiring vocalization. These results demonstrate that in most real-world environments vocalization loudness is the main factor controlling respiratory particle emission and exhaled CO2 is a poor surrogate measure for estimating particle emission during vocalization. Although measurements of indoor CO2 concentrations provide valuable information about room ventilation, such measurements are poor indicators of respiratory particle concentrations and may significantly underestimate respiratory particle concentrations and disease transmission risk.

FFP2 induced breathing resistance does not affect metabolism and well-being during brisk walking and stair climbing - a randomized controlled trial

ObjectivesN95 or Type II filtering face pieces (FFP2) are often worn during work hours or on public transportation to prevent airborne infection. The aim of this randomized controlled crossover study is to assess the impact of FFP2 induced breathing resistance on pulmonary function, blood gas values and discomfort during walking and stair climbing.MethodsN = 16 healthy adults (24.8 ± 2.2 years; 10 females, ) participated. Interventions included (1) six minutes of walking in a 16-meter-long hallway (612 m) and (2) eight minutes of stair climbing in a two-story staircase (420 stairs), both with and without a FFP2 (> 48 h wash-out). Spiroergometric data (Ventilation, breathing frequency, tidal volume, oxygen uptake and carbon dioxide exhalation (primary outcome), end tidal carbon dioxide- and oxygen pressure) and self-reported response (Perceived exertion, dyspnoea and pain) were assessed during activities. Blood gas analysis (capillary carbon dioxide- (pCO2) (primary outcome) and oxygen partial pressure (pO2), pH, lactate and base excess) was measured immediately after cessation of activities. Manipulation effects (FFP2 versus no mask) were tested using repeated measures analyses of variance.ResultsAnalysis showed no effect of FFP2 on pCO2 or other blood-gas parameters but on carbon dioxide exhalation during walking: (mean 1067, SD 209 ml/min) (mean 1908, SD 426 ml/min) (F(15) = 19.5; p < 0.001; ηp2 = 0.566) compared to no mask wearing (mean 1237, SD 173 ml/min; mean 1908, SD 426 ml/min). Ventilation was decreased and dyspnoea was increased by FFP2 during activities. FFP2 led to lower oxygen uptake and lower end tidal oxygen but higher end tidal carbon dioxide during stair climbing.ConclusionsFFP2 decreased ventilation based on slower breathing patterns and led to limitations in pulmonary gas exchange and increased subjective dyspnoea. However, invasive diagnostics revealed no signs of clinically relevant metabolic effects immediately after everyday physical activities.

P-486 EFFECTS OF INTERNAL FACEPIECE PRESSURE SETTINGS TRIGGERING THE FAN OPERATION OF POWERED AIR PURIFYING RESPIRATORS (PART 1)—EFFECTS ON THE INTRA-FACEPIECE CARBON DIOXIDE CONCENTRATION

Abstract Introduction Our previous study found that commercial powered air-purifying respirators (PAPRs) effectively protected against particles but retained high levels of exhaled carbon dioxide (CO2) gas within the facepieces. This study investigates the effects of internal facepiece pressure settings, which trigger the fan operation of PAPRs, on the intra-facepiece CO2 concentration. Methods Twelve healthy, non-smoking men participated in the study. Three types of breath-responsive PAPR were used: PAPR-A, having a higher pressure setting than a commercial model; PAPR-B, a commercial model; and PAPR-C, having non-fan operation. To mitigate order effects and exercise-induced fatigue, participants were randomly assigned to six groups. Participants wore each PAPR and exercised for 10 minutes at 40% of their maximal oxygen uptake while the intra-facepiece gas concentration was measured. This study was approved by the Ethics Committee of the University of Occupational and Environmental Health, Japan. Results During inhalation, the intra-facepiece CO2 concentration decreased in the order of PAPR-C, PAPR-B, and PAPR-A, with the mean values for each individual ranging 2.1%–5.0%, 1.6%–4.0%, and 1.6%–3.1%, respectively. Discussion Increasing the internal facepiece pressure setting improved the intra-facepiece air quality. This improvement is attributed to the longer fan operation, which increased the air supply and enhanced ventilation within the facepiece. However, a disadvantage of a higher pressure setting was a shorter operating time of the battery powering the fan. Conclusion A higher internal facepiece pressure setting was found to be effective in maintaining an appropriate intra-facepiece CO2 concentration compared with a commercial model. The development of smaller longer-lasting batteries is expected.

Temporal Trends in End-Tidal Capnography and Outcomes in Out-of-Hospital Cardiac Arrest

While widely measured, the time-varying association between exhaled end-tidal carbon dioxide (EtCO2) and out-of-hospital cardiac arrest (OHCA) outcomes is unclear. To evaluate temporal associations between EtCO2 and return of spontaneous circulation (ROSC) in the Pragmatic Airway Resuscitation Trial (PART). This study was a secondary analysis of a cluster randomized trial performed at multicenter emergency medical services agencies from the Resuscitation Outcomes Consortium. PART enrolled 3004 adults (aged ≥18 years) with nontraumatic OHCA from December 1, 2015, to November 4, 2017. EtCO2 was available in 1172 cases for this analysis performed in June 2023. PART evaluated the effect of laryngeal tube vs endotracheal intubation on 72-hour survival. Emergency medical services agencies collected continuous EtCO2 recordings using standard monitors, and this secondary analysis identified maximal EtCO2 values per ventilation and determined mean EtCO2 in 1-minute epochs using previously validated automated signal processing. All advanced airway cases with greater than 50% interpretable EtCO2 signal were included, and the slope of EtCO2 change over resuscitation was calculated. The primary outcome was ROSC determined by prehospital or emergency department palpable pulses. EtCO2 values were compared at discrete time points using Mann-Whitney test, and temporal trends in EtCO2 were compared using Cochran-Armitage test of trend. Multivariable logistic regression was performed, adjusting for Utstein criteria and EtCO2 slope. Among 1113 patients included in the study, 694 (62.4%) were male; 285 (25.6%) were Black or African American, 592 (53.2%) were White, and 236 (21.2%) were another race; and the median (IQR) age was 64 (52-75) years. Cardiac arrest was most commonly unwitnessed (n = 579 [52.0%]), nonshockable (n = 941 [84.6%]), and nonpublic (n = 999 [89.8%]). There were 198 patients (17.8%) with ROSC and 915 (82.2%) without ROSC. Median EtCO2 values between ROSC and non-ROSC cases were significantly different at 10 minutes (39.8 [IQR, 27.1-56.4] mm Hg vs 26.1 [IQR, 14.9-39.0] mm Hg; P < .001) and 5 minutes (43.0 [IQR, 28.1-55.8] mm Hg vs 25.0 [IQR, 13.3-37.4] mm Hg; P < .001) prior to end of resuscitation. In ROSC cases, median EtCO2 increased from 30.5 (IQR, 22.4-54.2) mm HG to 43.0 (IQR, 28.1-55.8) mm Hg (P for trend < .001). In non-ROSC cases, EtCO2 declined from 30.8 (IQR, 18.2-43.8) mm Hg to 22.5 (IQR, 12.8-35.4) mm Hg (P for trend < .001). Using adjusted multivariable logistic regression with slope of EtCO2, the temporal change in EtCO2 was associated with ROSC (odds ratio, 1.45 [95% CI, 1.31-1.61]). In this secondary analysis of the PART trial, temporal increases in EtCO2 were associated with increased odds of ROSC. These results suggest value in leveraging continuous waveform capnography during OHCA resuscitation. ClinicalTrials.gov Identifier: NCT02419573.

Changes in Exhaled Carbon Dioxide during the Menstrual Cycle and Menopause

Introduction: The menstrual cycle (MC) reflects multifaceted hormonal changes influencing women’s metabolism, making it a key aspect of women’s health. Changes in hormonal levels throughout the MC have been demonstrated to influence various physiological parameters, including exhaled carbon dioxide (CO2). Lumen is a small handheld device that measures metabolic fuel usage via exhaled CO2. This study leverages exhaled CO2 patterns measured by the Lumen device to elucidate metabolic variations during the MC, which may hold significance for fertility management. Additionally, CO2 changes are explored in menopausal women with and without hormonal replacement therapy (HRT). Methods: This retrospective cohort study analyzed exhaled CO2 data from 3,981 Lumen users, including eumenorrheal women and menopausal women with and without HRT. Linear mixed models assessed both CO2 changes of eumenorrheal women during the MC phases and compared between menopausal women with or without HRT. Results: Eumenorrheic women displayed cyclical CO2 patterns during the MC, characterized by elevated levels during the menstrual, estrogenic and ovulation phases and decreased levels during post-ovulation and pre-menstrual phases. Notably, despite variations in cycle length affecting the timing of maximum and minimum CO2 levels within a cycle, the overall pattern remained consistent. Furthermore, CO2 levels in menopausal women without HRT differed significantly from those with HRT, which showed lower levels. Conclusion: This study reveals distinct CO2 patterns across MC phases, providing insights into hormonal influences on metabolic activity. Menopausal women exhibit altered CO2 profiles in relation to the use or absence of HRT. CO2 monitoring emerges as a potential tool for tracking the MC and understanding metabolic changes during menopause.

Video versus Direct Laryngoscopy for Urgent Intubation of Newborn Infants

BackgroundRepeated attempts at endotracheal intubation are associated with increased adverse events in neonates. When clinicians view the airway directly with a laryngoscope, fewer than half of first attempts are successful. The use of a video laryngoscope, which has a camera at the tip of the blade that displays a view of the airway on a screen, has been associated with a greater percentage of successful intubations on the first attempt than the use of direct laryngoscopy in adults and children. The effect of video laryngoscopy among neonates is uncertain.MethodsIn this single-center trial, we randomly assigned neonates of any gestational age who were undergoing intubation in the delivery room or neonatal intensive care unit (NICU) to the video-laryngoscopy group or the direct-laryngoscopy group. Randomization was stratified according to gestational age (<32 weeks or ≥32 weeks). The primary outcome was successful intubation on the first attempt, as determined by exhaled carbon dioxide detection.ResultsData were analyzed for 214 of the 226 neonates who were enrolled in the trial, 63 (29%) of whom were intubated in the delivery room and 151 (71%) in the NICU. Successful intubation on the first attempt occurred in 79 of the 107 patients (74%; 95% confidence interval [CI], 66 to 82) in the video-laryngoscopy group and in 48 of the 107 patients (45%; 95% CI, 35 to 54) in the direct-laryngoscopy group (P<0.001). The median number of attempts to achieve successful intubation was 1 (95% CI, 1 to 1) in the video-laryngoscopy group and 2 (95% CI, 1 to 2) in the direct-laryngoscopy group. The median lowest oxygen saturation during intubation was 74% (95% CI, 65 to 78) in the video-laryngoscopy group and 68% (95% CI, 62 to 74) in the direct-laryngoscopy group; the lowest heart rate was 153 beats per minute (95% CI, 148 to 158) and 148 (95% CI, 140 to 156), respectively.ConclusionsAmong neonates undergoing urgent endotracheal intubation, video laryngoscopy resulted in a greater number of successful intubations on the first attempt than direct laryngoscopy. (Funded by the National Maternity Hospital Foundation; VODE ClinicalTrials.gov number, NCT04994652.)

The Association of Macronutrient Consumption and BMI to Exhaled Carbon Dioxide in Lumen Users: Retrospective Real-World Study.

Metabolic flexibility is the ability of the body to rapidly switch between fuel sources based on their accessibility and metabolic requirements. High metabolic flexibility is associated with improved health outcomes and a reduced risk of several metabolic disorders. Metabolic flexibility can be improved through lifestyle changes, such as increasing physical activity and eating a balanced macronutrient diet. Lumen is a small handheld device that measures metabolic fuel usage through exhaled carbon dioxide (CO2), which allows individuals to monitor their metabolic flexibility and make lifestyle changes to enhance it. This retrospective study aims to examine the postprandial CO2 response to meals logged by Lumen users and its relationship with macronutrient intake and BMI. We analyzed deidentified data from2607 Lumen users who logged their meals and measured their exhaled CO2 before and after those meals between May 1, 2023, and October 18, 2023. A linear mixed model was fitted to test the association between macronutrient consumption, BMI, age, and gender to the postprandial CO2 response, followed by a 2-way ANOVA. The model demonstrated significant associations (P<.001) between CO2 response after meals and both BMI and carbohydrate intake (BMI: β=-0.112, 95% CI -0.156 to -0.069; carbohydrates: β=0.046, 95% CI 0.034-0.058). In addition, a 2-way ANOVA revealed that higher carbohydrate intake resulted in a higher CO2 response compared to low carbohydrate intake (F2,2569=24.23; P<.001), and users with high BMI showed modest responses to meals compared with low BMI (F2,2569=5.88; P=.003). In this study, we show that Lumen's CO2 response is influenced both by macronutrient consumption and BMI. The results of this study highlight a distinct pattern of reduced metabolic flexibility in users with obesity, indicating the value of Lumen for assessing postprandial metabolic flexibility.

A comparative study between serum lactate level versus change in end tidal carbon dioxide level regarding assessment of hemodynamic instability in intensive care unit patients after cardiac surgeries

ABSTRACT Background After cardiac surgeries, elevated lactate level is used as a marker of tissue hypoperfusion. Still, there is a search for other helpful markers of hemodynamic instability. Exhaled carbon dioxide has been recently studied as marker of cardiac output and tissue perfusion and may be considered a reliable alternative which is more convenient and real time. Objectives The main aim is to correlate between end tidal carbon dioxide (ETCO2) and serum lactate level as indicators of hemodynamic instability in intensive care unit (ICU) patients after cardiac surgeries. The secondary objective is to correlate the measured parameters to the changes in the vital data and the resuscitation efforts. Methods A prospective cohort study that enrolled 51 adult patients admitted to ICU after cardiac surgeries. The serum lactate and ETCO2 values as well as vital data and vasopressor doses were recorded on admission to ICU, after 2 hours and after 6 hours. Results The study shows insignificant weak positive correlation between Lactate and ETCO2 levels at admission (r = 0.172, p value = 0.229), and insignificant negative weak correlation after 2 hours (r = -0.148, p value = 0.300) and after 6 hours (r = -0.235, p value = 0.096). Moreover, lactate level showed significant direct relation with the doses of vasopressors at admission, after 2 hours and after 6 hours postoperative (p value < 0.001 at all intervals). Whereas there was insignificant relation between ETCO2 and doses of vasopressors at all intervals (p value = 0.23, 0.4 and 0.18 respectively). Conclusion In post-cardiac surgery ICU patients we detected no statistically significant relation between serum lactate and ETCO2 as indicators of hemodynamic instability. The change in ETCO2 over a period of time has failed so far to be of a beneficial value as a non-invasive real-time cardiac output monitoring parameter. In addition, serum lactate had strong correlation with changes in vital signs and resuscitation efforts.

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

BackgroundSeveral 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). MethodsMulticenter, 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. ResultsA 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). ConclusionsThe 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.

PULMONARYFUNCTIONINNEUROMUSCULARDISEASES

Respiratory functional assessment in patients with neuromuscular diseases allows us to quantify lung volumes and capacities, cough flows and the effectiveness of of ventilation. Pulse oximetry and non-invasive monitoring of exhaled carbon dioxide are also essential for the non-invasive assessment of hypoventilation associated with ventilatory muscle and cough insufficiency. In this way, it is possible to detect the objective needs for therapeutic assistance and implement health policies appropriate to the needs of this population.

Development and Validation of a Methodology to Measure Exhaled Carbon Dioxide (CO2) and Control Indoor Air Renewal

The measurement of carbon dioxide (CO2) has emerged as a cost-effective and straightforward technique for indirectly managing indoor air quality, aiding in the reduction of the potentially pathogen-laden aerosol concentrations to which we are exposed. Unfortunately, inadequate practices often limit the interpretation of CO2 levels and neglect methodologies that ensure proper air renewal. This study presents a novel methodology for measuring and controlling indoor CO2 levels in shared spaces, comprising four stages: analysis, diagnosis, correction protocols, and monitoring/control/surveillance (MCS). This methodology underwent validation in practical settings, including a cultural center (representing spaces with uniform activities) and 40 commercial spaces (with diverse activities) in Zaragoza, Spain. The results indicate the feasibility of swiftly implementing measures to enhance shared air renewal, with the immediate opening of doors and windows being the most direct solution. The proposed methodology is practical and has the potential to mitigate the risk of the aerosol transmission of respiratory diseases. Consequently, we anticipate that this work will contribute to establishing methodological foundations for CO2 measurement as a valuable, standardized, and reliable tool.