Mean ETCO2 Research Articles

Sonographic Cardiac Activity Correlates with End-Tidal Carbon Dioxide and Cardiac Rhythm in Out-of-Hospital Cardiac Arrest

The majority of cardiac arrests that occur in the United States are treated by EMS, which has stimulated interest in the use of prehospital ultrasound as a prognostic tool. Though end-tidal carbon dioxide (EtCO2) and cardiac rhythm have demonstrated prognostic value in out-of-hospital cardiac arrest (OHCA), few studies of ultrasound in the prehospital setting have attempted to address the same question. This retrospective study assesses the association between sonographic cardiac activity and contemporaneous measurements of EtCO2 and cardiac rhythm. Sixty-six cases of paramedic-performed cardiac sonography for OHCA were reviewed and clinical data for each case was abstracted directly from the monitor/defibrillator record. The mean timing of the initial ultrasound was 21 minutes (95% CI [18.7,23.3]) into the resuscitation. Organized cardiac activity was associated with higher mean EtCO2 than absence of organized activity (49.7mmHg (95% CI [44.4,55.0]) versus 28.3mmHg (95% CI [24.3,32.3]), p<0.001). Organized sonographic activity was also associated with contemporaneous cardiac rhythm (p=0.018) and was most frequently observed in PEA with a sinus rhythm. Paramedics interpreted intra-arrest cardiac ultrasound with 95.7% agreement with physicians (κ = 0.940). Mean pause in compressions to acquire ultrasound was 14.9 seconds (95% CI [13.3,16.6]).

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.

Low intraoperative end-tidal carbon dioxide levels are associated with improved recurrence-free survival after elective colorectal cancer surgery

Study objectiveHigher levels of carbon dioxide (CO2) increase the invasive abilities of colon cancer cells in vitro. Studies assessing target values for end-tidal CO2 concentrations (EtCO2) to improve surgical outcome after colorectal cancer surgery are lacking. Therefore, we evaluated whether intraoperative EtCO2 was associated with differences in recurrence-free survival after elective colorectal cancer (CRC) surgery. DesignSingle center, retrospective analysis. SettingAnesthesia records, surgical databases and hospital information system of a tertiary university hospital. PatientsWe analyzed 528 patients undergoing elective resection of colorectal cancer at Heidelberg University Hospital between 2009 and 2018. InterventionsNone. MeasurementsIntraoperative mean EtCO2 values were calculated. The study cohort was equally stratified into low-and high-EtCO2 groups. The primary endpoint measure was recurrence-free survival until last known follow-up. Groups were compared using Kaplan-Meier analysis. Cox-regression analysis was used to control for covariates. Sepsis, reoperations, surgical site infections and cardiovascular events during hospital stay, and overall survival were secondary outcomes. Main resultsMean EtCO2 was 33.8 mmHg ±1.2 in the low- EtCO2 group vs. 37.3 mmHg ±1.6 in the high-EtCO2 group. Median follow-up was 3.8 (Q1-Q3, 2.5–5.1) years. Recurrence-free survival was higher in the low-EtCO2 group (log-rank-test: p = .024). After correction for confounding factors, lower EtCO2 was associated with increased recurrence-free survival (HR = 1.138, 95%-CI:1.015–1.276, p = .027); the hazard for the primary outcome decreased by 12.1% per 1 mmHg decrease in mean EtCO2. 1-year and 5-year survival was also higher in the low-EtCO2 group. We did not find differences in the other secondary endpoints. ConclusionsLower intraoperative EtCO2 target values in CRC surgery might benefit oncological outcome and should be evaluated in confirmative studies.

Comparison of volume-controlled ventilation and pressure-limited ventilation in laparoscopic appendicectomy - a randomized controlled clinical trial

Background: Laparoscopic appendicectomy is a widely performed surgery globally, offering notable benefits such as reduced postoperative pain, quicker mobility, and shorter hospital stays. Aims and Objectives: The study aimed to assess the changes in respiratory mechanics and compare the outcomes of volume-controlled and pressure-limited ventilation (PLV) in patients undergoing laparoscopic appendectomy. Materials and Methods: This randomized, prospective, single-blinded control study was conducted at K.A.P.V. Government Medical College, Tiruchirapalli, on 60 ASA I and II patients scheduled to undergo laparoscopic appendicectomy under general anesthesia. The patients were randomly divided into two groups (volume-controlled ventilation [VCV] group and the PLV group) of 30 patients. A patient’s history includes age, sex, history of diabetes, hypertension, or any cardiovascular disease, respiratory tract infection, wheezing or chronic chest infections, seizures, neuromuscular disease or weakness, etc. Results: There was no significant difference in gender, age, or body mass index between groups. There is no significant difference in the mean arterial pressure or ETCO2 between groups at various intervals. There was a significant difference in the mean heart rate between the VCV and the PLV groups at 5 and 20 min after induction. There was a significant difference in the peak airway pressure, dynamic compliance, and airway resistance between the VCV group and the PLV group at 10 min after induction (T1), 5 min after pneumoperitoneum (T2), 10 min after pneumoperitoneum (T3), and immediately after Trendelenburg position (T4). Conclusion: The airway resistance and peak airway pressure do not increase, and the dynamic compliance was improved in the PLV during laparoscopic appendicectomy.

Anesthesia for Craniotomy Tumor Removal Patient with Morbid Obesity

Purpose: Obesity is one of the greatest health challenges in the western world. Obesity is defined as a body mass index (BMI) &gt;30 kg/m2, with BMI &gt;35 and &gt;55 kg/m2 considered ‘morbidly’ obese and ‘super morbidly’ obese, respectively. The aim of this study was to examine anesthetic management for craniotomy tumor removal in patients with morbid obesity. Design/methodology/data analysis: This research uses a qualitative descriptive research method with a case study approach of a 39 year old female patient with a body weight of 110 kg, height 160 cm, and body mass index (BMI) 42.9 kg/m2, Mallampati score 2, thyromental distance &gt; 3 fingers hospitalized for removal of meningioma. Data collection techniques in this research used literature study, observation and laboratory tests. The data that has been collected is then analyzed descriptively. Findings: The results of the study showed that in the operating room, the patient was positioned in a neutral position 300 head up and Ramp. Preoxygenation with 100% O2 was performed via a face mask. Anesthesia was maintained with continuous intravenous propofol 25-50 μg/kg/min, intravenous rocuronium 40 mg/h, and volatile anesthesia using sevoflurane 0.5-1%vol with oxygen: air at a fraction of 50%. Monitoring during surgery includes evaluation of systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, oxygen saturation, ECG waves, EtCO2, and urine output. The operation lasted 4 hours in the supine position. Post-surgery patients are then treated in the Intensive Care Unit (ICU) for one day before being transferred to the ward and finally to a regular room. He received treatment for 5 days before being discharged. Problems faced during anesthesia in obese patients are airway management, ventilation, position, drug dosage, presence of comorbidities and post-operative care for recovery from anesthesia and surgery. Originality/value: While addressing common challenges encountered during anesthesia in obese patients, this research takes a step further by proposing innovative solutions. The study acknowledges the complexities of airway management, ventilation, positioning, drug dosage, comorbidities, and post-operative care. However, it introduces novel considerations or techniques to mitigate these challenges, possibly involving emerging technologies or interdisciplinary collaboration for enhanced patient outcomes. Practical implications: The practical implications of this research advocate for a nuanced and individualized approach to anesthetic management in morbidly obese patients undergoing craniotomy tumor removal, fostering improved patient care and safety.

VIDEOLARYNGOSCOPE VERSUS TRADITIONAL LARYNGOSCOPY FOR COMPARISON OF EASE OF INTUBATION AND HEMODYNAMIC CHANGES – A PROSPECTIVE RANDOMIZED STUDY

Objective: The objective of the study is to compare ease of intubation and hemodynamic changes with video laryngoscope (VL) (C-MAC) versus traditional laryngoscopy and to assess any complication such as arrhythmias, local injuries, bleeding, laryngospasm, regurgitation during intubation, and sore throat post-intubation. Methods: This prospective randomized study was conducted on 200 patients of Mallampati (MP) Grades 1 and 2, ASA-PS I and II, randomly allocated to Group M (Macintosh) and Group V (C-MAC) (n=100 each). Hemodynamic changes (heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure [MAP], SpO2, and EtCO2) were recorded at baseline, during pre-oxygenation, during laryngoscopy, and during intubation, at 1 min, 3 min, 5 min, and then, at 10 min after endotracheal intubation. Ease of intubation and any complications were also recorded. Results: Laryngeal view was significantly better in Group V. The mean heart rate during laryngoscopy and intubation (L&amp;I) and after endotracheal intubation at 3rd min (ETI3); mean systolic blood pressure during L&amp;I and after ETI1, ETI3, and ETI5 min; mean diastolic blood pressure after ETI1 and ETI min; and mean MAP during L&amp;I and after ETI1 min were found to be significantly higher in Group M as compared to Group V (p&lt;0.05). The difference in mean SPO2 and ETCO2 between the two groups was not found to be significant at any time interval. No significant difference was observed with respect to complications. Conclusion: Group V (VL C-MAC) showed better ease of intubation, decreased hemodynamic response, and fewer complications as compared to Group M (Macintosh laryngoscope).

Prevalence of Sleep Disordered Breathing in Adult Sickle Cell Clinic Patients and Cardiovascular Correlates

Sleep disordered breathing (SDB) is strongly correlated with hypertension and cardiovascular disease in the general population, and especially in African Americans. In Sickle Cell Disease (SCD), the adverse effect of nocturnal hypoxemia is anticipated to have additional adverse effects with the sickling of red blood cells and microvascular thrombosis unique to the disease. Prospective data regarding the prevalence and consequences of SDB in this population are lacking. In an ongoing study, 27 adult subjects (age &amp;gt; 18 years), with homozygous HbSS genotype, presenting to the Howard University Sickle Cell Center for routine follow up have been recruited irrespective of the presence of sleep symptoms. Exclusion criteria include previous diagnosis or treatment of a sleep disorder or requirement for supplemental oxygen. Testing occurs when subjects are in a stable phase of disease, with no hospitalizations or medication changes for 4 weeks. In addition to clinical history and questionnaires, participants are assessed with blood work, 6 minute walk testing, pain and sleep diaries during 1 week actigraphy, transthoracic echocardiography and overnight in lab polysomnography with capnography. At the time of this interim analysis, the mean age is 42 (range 29-71, +/- std dev 11) and male:female distribution is 17:10. The mean BMI is 20.4 (+/- 4.5). Mean Hgb is 9.1 g/dl (+/- 1.8) and mean LDH is 325 iu/L (+/- 163). Polysomnography scoring utilized a 3% desaturation criterion for hyponeas as per American Academy of Sleep Medicine Scoring Manual Chapter VIII, 1A. Mean sleep efficiency is 77% ( std dev +/- 4.2%). 48% of subjects demonstrate some degree of sleep disordered breathing as defined by an AHI &amp;gt; 5 events/hour (33% mild, 4% moderate, 11% severe). 70% of subjects demonstrate an RDI &amp;gt; 5 events/hour (40% mild, 19% moderate, 11% severe). Twelve participants (44%) exhibit more than 5 minutes sleep duration at saturations &amp;lt;89% (mean = 187 minutes). Hypercapnia is not suggested as an important component of SDB with the mean ET CO2 = 40.7 mm Hg (range 30-46 mm Hg). Echocardiographic values (LVPWd, Lad, MV E/A, PVV, and RVSP) do not correlate with any indices of sleep disordered breathing other than minutes &amp;lt;89% saturation correlating with RVSP. In summary, this interim analysis of sleep in a population of unselected Sickle Cell Clinic patients demonstrates a striking frequency of sleep disordered breathing. This is despite a generally low BMI for these patients which is typically considered one of the most important risk factor for sleep apnea. Ongoing recruitment is planned to confirm these findings. Correlation with clinical outcomes and potential response to therapeutic interventions will be important future research questions.

Effect of Tourniquet Deflation on Intracranial Pressure Measured by Ultrasound of the Optic Nerve Sheath Diameter in Patients Undergoing Orthopedic Surgery Under Spinal Anesthesia: An Observational Study.

Background Orthopedic surgeries of the lower extremities frequently require exsanguination and the use of pneumatic tourniquets. However, the deflation of the tourniquet is accompanied by predominant metabolic changes such as an increase in PaCO2. Prior studies have reported the existence of a correlation between tourniquet deflation and an increase in intracranial pressure in patients undergoing surgery under general anesthesia. However, there is a dearth of literature demonstrating such relationships among patients undergoing surgery under subarachnoid block in the Indian setting. The present research was conducted to study the variations in intracranial pressure after the deflation of the tourniquet by measuring the optic nerve sheath diameter (ONSD) using ultrasound among patients undergoing orthopedic surgery of the lower limb under spinal anesthesia at a tertiary care hospital in eastern India. Methodology After obtaining clearance from the Institutional Ethics Committee, this prospective observational study was conducted among 45 patients undergoing orthopedic surgeries of the lower limb using a pneumatic tourniquet. Changes in intracranial pressure following tourniquet deflation were recorded by measuring ONSD by ultrasound in these patients. Heart rate (HR), mean arterial pressure (MAP), SpO2, EtCO2, and ONSD were noted 15 minutes before administration of subarachnoid block (T0), just before tourniquet deflation (T1) and at 5, 10, and 15 minutes after tourniquet deflation (T5, T10, and T15, respectively). Results The ONSD varied significantlyat each point of observation (p < 0.05). The ONSDs at 5 and 10 minutes after the deflation of the tourniquet were significantly greater than that at T0 (p = 0.002). EtCO2 showed a significant increase compared to baseline values at every point of observation intraoperatively whereas MAP showed a significant decrease (p < 0.05).For all parameters (ONSD, HR, systolic blood pressure, diastolic blood pressure, MAP, and EtCO2), the most significant change in observation was noted at T10, i.e., 10 minutes after the deflation of the tourniquet. Conclusions The significant findingin thisstudy was that the ONSD measurements recorded by ultrasound were increased after the deflation of the tourniquet and that this change can be attributed to an increase in EtCO2. However, the results obtained cannot be validated outside the present research owing to the observational nature of the study and limited sample size. Thus, it is difficult to arrive at a definitive conclusion. Further large-scale multicentric studiesmaybe needed to substantiate the findings of thisstudy.

A New Vital Sign in Determining the Triage Category in Emergency Department Presentations: End-Tidal Carbon Dioxide

Objective: To investigate whether patients’ end-tidal carbon dioxide (ETCO2) values ​​measured at the time of their presentation to the emergency department can be used together with vital signs in determining their triage categories and predicting hospitalization. Material and method: This prospective, observational, cross-sectional study was conducted between May 1, 2023, and June 1, 2023, at the emergency department of a tertiary hospital. The study included patients aged &gt;18 years who presented to the emergency department and were evaluated to have a triage category of level 2, 3, or 4 according to the five-step triage system. The patients’ vital signs were measured at the time of their presentation to the emergency department and the ETCO2 values ​​measured through a nasal cannula were statistically evaluated in terms of their relationship with triage categories and hospitalization indications. Results: A total of 1,100 patients were included in the study. According to the triage category of the patients, the mean ETCO2 values for triage levels 2, 3, and 4 were 27.1±3.6, 30.6±3.1, and 35.4±3.5, respectively, indicating statistically significant differences (p&lt;0.001). When the relationship of ETCO2 and vital signs with hospitalization indications evaluated at the emergency department was examined, the area under the receiver operating characteristic curve for ​​ ETCO2 was 0.733, which was statistically significant (p&lt;0.001). Conclusion: On completion of the study, it was concluded that the ETCO2 values ​​measured at the time of presentation to the emergency department can be a new vital sign that can be used to determine the triage categories of patients and identify those who require hospitalization.

End-tidal carbon dioxide measured at emergency department triage outperforms standard triage vital signs in predicting in-hospital mortality and intensive care unit admission.

This study assessed the ability of end-tidal carbon dioxide (ETCO2 ) in predicting in-hospital mortality and intensive care unit (ICU) admission compared to standard vital signs at ED triage as well as comparing to measures of metabolic acidosis. This prospective study enrolled adult patients presenting to the ED of a tertiary care Level I trauma center over 30 months. Patients had standard vital signs measured along with exhaled ETCO2 at triage. Outcome measures included in-hospital mortality; ICU admission; and correlations with lactate, sodium bicarbonate (HCO3 ), and anion gap. There were 1136 patients enrolled and 1091 patients with outcome data available. There were 26 (2.4%) patients who did not survive to hospital discharge. Mean ETCO2 levels were 34 (33-34) in survivors and 22 (18-26) nonsurvivors (p< 0.001). The area under the curve (AUC) for predicting in-hospital mortality for ETCO2 was 0.82 (0.72-0.91). In comparison the AUC for temperature was 0.55 (0.42-0.68), respiratory rate (RR) 0.59 (0.46-0.73), systolic blood pressure (SBP) 0.77 (0.67-0.86), diastolic blood pressure (DBP) 0.70 (0.59-0.81), heart rate (HR) 0.76 (0.66-0.85), and oxygen saturation (SpO2 ) 0.53 (0.40-0.67). There were 64 (6%) patients admitted to the ICU, and the ETCO2 AUC for predicting ICU admission was 0.75 (0.67-0.80). In comparison the AUC for temperature was 0.51, RR 0.56, SBP 0.64, DBP 0.63, HR 0.66, and SpO2 0.53. Correlations between expired ETCO2 and serum lactate, anion gap, and HCO3 were rho=-0.25 (p< 0.001), rho=-0.20 (p< 0.001), and rho=0.330 (p< 0.001), respectively. ETCO2 was a better predictor of in-hospital mortality and ICU admission than the standard vital signs at ED triage. ETCO2 correlated significantly with measures of metabolic acidosis.

Association between intraoperative end-tidal carbon dioxide and postoperative organ dysfunction in major abdominal surgery: A cohort study.

Data on the effects of intraoperative end-tidal carbon dioxide (EtCO2) levels on postoperative organ dysfunction are limited. Thus, this study was designed to investigate the relationship between the intraoperative EtCO2 level and postoperative organ dysfunction in patients who underwent major abdominal surgery under general anesthesia. We conducted a cohort study involving patients who underwent major abdominal surgery under general anesthesia at Kyoto University Hospital. We classified those with a mean EtCO2 of less than 35 mmHg as low EtCO2. The time effect was determined as the minutes when the EtCO2 value was below 35 mmHg, whereas the cumulative effect was evaluated by measuring the area below the 35-mmHg threshold. The outcome was postoperative organ dysfunction, defined as a composite of at least one organ dysfunction among acute renal injury, circulatory dysfunction, respiratory dysfunction, coagulation dysfunction, and liver dysfunction within 7 days after surgery. Of the 4,171 patients, 1,195 (28%) had low EtCO2, and 1,428 (34%) had postoperative organ dysfunction. An association was found between low EtCO2 and increased postoperative organ dysfunction (adjusted risk ratio, 1.11; 95% confidence interval [CI], 1.03-1.20; p = 0.006). Additionally, long-term exposure to EtCO2 values of less than 35 mmHg (≥224 min) was associated with postoperative organ dysfunction (adjusted risk ratio, 1.18; 95% CI, 1.06-1.32; p = 0.003) and low EtCO2 severity (area under the threshold) (adjusted risk ratio, 1.13; 95% CI, 1.02-1.26; p = 0.018). Intraoperative low EtCO2 of below 35 mmHg was associated with increased postoperative organ dysfunction.

One-person versus two-person mask ventilation in preterm infants at birth: a pilot randomised controlled trial

BackgroundMask leak and airway obstruction are common with mask ventilation in newborn infants, leading to suboptimal ventilation. We aimed to perform a pilot study measuring respiratory mechanics during one-person and...

Polysomnographic characteristics and treatment modalities in a referred population of children with trisomy 21.

Children with Trisomy 21 (T21) are at an increased risk of sleep-disordered breathing (SDB), which can impact daily functioning and cause other health complications. Accordingly, it is imperative to diagnose and treat SDB in this population. Current guidelines recommend screening polysomnogram by age 4 or sooner if clinically indicated. There are limited published studies describing characteristics of SDB in children with T21, particularly in infants and young children. The objective of this study is to characterize SDB and treatment modalities in infants and young children with T21. This is a retrospective review of a cohort of children (≤60 months of age) with T21 who completed a polysomnogram (PSG) between 2015 and 2020 at a pediatric referral center. Demographic information, relevant medical history, polysomnography parameters, and treatment details of these children were collected from EMR. Descriptive and comparative statistics were calculated for the cohort; additional subgroup analysis was completed by age 0-35 months and 36-60 months. Most of the cohort met criteria for sleep apnea (84.1%), and airway surgery was the most common treatment modality (71.4%). The mean AHI was high (21.4 events/hour) with a trend towards hypoventilation (mean EtCO2 = 55.9 mmHg; mean percentage of TST with EtCO2 > 50 mmHg 20.8%). Mean arousal index was elevated (32 events/hour). There were no significant differences in SDB by age when we compared children 0-35 months and 36-60 months. This cohort of referred children with T21 showed high prevalence of SDB with a trend towards hypoventilation and disrupted sleep quality with no significant differences by age. These data highlight the importance of maintaining a high index of suspicion for SDB in young patients with T21 and obtaining PSG testing to characterize sleep and breathing.

Investigating the Relationship Between End Tidal Carbon Dioxide and Arterial Carbon Dioxide Pressure in Patients With Respiratory Distress Referred to the Emergency Room of Hazrat Rasool Akram Hospital

Background: Measuring end-tidal carbon dioxide (ETCO2) can be a non-invasive, fast, and reliable method to predict partial pressure of carbon dioxide (PaCO2) in patients with respiratory distress. This method, which can be a suitable substitute to measure PaCO2, is being used in many emergency rooms and operating rooms in developed countries, but its exact relationship with PaCO2 has not been confirmed yet. This study aims to investigate the relationship between PaCO2 and ETCO2 in patients with respiratory distress referred to the emergency. Materials and Methods: Arterial blood gases were measured in patients referred to the emergency room of Hazrat Rasool Akram (PBUH) Hospital with the main complaint of respiratory distress, and the ETCO2 of the patient was measured simultaneously with a capnograph. At the same time, the blood pressure and body temperature of the patients were also measured. The obtained information was collected in a sheet and statistically analyzed using SPSS software, version 15. Results: A total of 120 patients were included in the study whose mean age was 48.3. The Mean PaCO2 and ETCO2 were 47.45 and 26.9, respectively. The mean respiratory rate was 37.4 and diastolic (89.9) and systolic (124.9) blood pressure. A total of 48.33% of patients were women. Statistical analysis showed a significant relationship between PaCO2 and ETCO2 (P=0.0001; CC=0.436). Linear regression analysis showed that ETCO2 predicts PaCO2 with R=0.424. Conclusion: A good correlation was found between PaCO2 and ETCO2 and this correlation was higher in diseases such as sepsis and COPD. Variables such as age, sex, and blood pressure did not affect this correlation. Of course, more studies on healthy people are necessary to confirm these findings.

Abstract 169: End Tidal CO2 In Multimodal Vest CPR

Introduction: Circumferential constriction vest CPR is more effective at creating forward blood flow than traditional sternal compression only CPR. Active compression-decompression plus the impedance threshold device CPR (ACD-ITD-CPR) incorporates multiple hemodynamic pump mechanisms and also appears more effective. We have developed a new multimodal CPR that combines vest CPR with additional pump mechanisms, one of which is abdominal counterpulsation. Traditional coronary perfusion pressure (CPP) has not been validated during CPR that incorporates compression modalities applied during the relaxation phase. End tidal carbon dioxide (ET-CO2), however, is an indicator of forward blood flow during CPR that is unaffected by relaxation phase compressions. Hypothesis: Multimodal vest CPR that incorporates multiple pump mechanisms may be more effective than standard alternatives as indicated by ET-CO2. Methods: Utilizing a porcine model of ventricular fibrillation, we measured ET-CO2 in: 1) traditional sternal compression CPR (S-CPR), 2) active compression-decompression plus the impedance threshold device CPR (ACD-ITD-CPR) and 3) a new multimodal CPR comprised of circumferential constriction plus abdominal counterpulsation and active sternal decompression (MM-CPR) . After onset of cardiac arrest, 1 min. epochs of each CPR were randomly performed. Results: Seven experiments were performed with a mean number of epochs per experiment of 7. The mean (M + SD) ET-CO2 for S-CPR was 9 + 3 mmHg, for ACD-ITD-CPR 12 + 6, and for MM-CPR 19+8 (P&lt;.05). Conclusions: Multimodal CPR comprising circumferential constriction plus abdominal counterpulsation and active sternal decompression is a promising new type of non-invasive circulatory support.

The association between arterial-end-tidal carbon dioxide difference and outcomes after out-of-hospital cardiac arrest

AimWe sought to determine if the difference between PaCO2 and ETCO2 is associated with hospital mortality and neurologic outcome following out-of-hospital cardiac arrest (OHCA). MethodsThis was a retrospective cohort study of adult patients who achieved return of spontaneous circulation (ROSC) after OHCA over 3 years. The primary exposure was the PaCO2-ETCO2 difference on hospital arrival. The primary outcome was survival to hospital discharge. The secondary outcome was favorable neurologic status at discharge. We used receiver operating characteristic (ROC) curves to determine discrimination threshold and multivariate logistic regression to examine the association between the PaCO2-ETCO2 difference and outcome. ResultsOf 698 OHCA patients transported to the hospitals, 381 had sustained ROSC and qualifying ETCO2 and PaCO2 values. Of these, 160 (42%) survived to hospital discharge. Mean ETCO2 was 39 mmHg among survivors and 43 mmHg among non-survivors. Mean PaCO2-ETCO2 was 6.8 mmHg and 9.0 mmHg (p < 0.05) for survivors and non-survivors. After adjustment for Utstein characteristics, a higher PaCO2-ETCO2 difference on hospital arrival was not associated with hospital mortality (OR 0.99, 95% CI: 0.97–1.0) or neurological outcome. Area under the ROC curve or PaCO2-ETCO2 difference was 0.56 (95% CI 0.51–0.62) compared with 0.58 (95% CI 0.52–0.64) for ETCO2. ConclusionNeither PaCO2-ETCO2 nor ETCO2 were strong predictors of survival or neurologic status at hospital discharge. While they may be useful to guide ventilation and resuscitation, these measures should not be used for prognostication after OHCA.

A Study of NT-ProBNP and ETCO2 in Patients Presenting with Acute Dyspnoea

Objectives: In patients presenting with acute dyspnoea in the emergency department (ED), the early and correct diagnosis may present a significant clinical challenge. The most common diagnoses of acute shortness of breath and manifesting signs of respiratory distress are decompensated heart failure (HF), pneumonia, chronic obstructive pulmonary disease (COPD), pulmonary embolism (PE), asthma, and acute respiratory distress syndrome (ARDS) and other causes like anaemia. The aim of the study was to measure NT-pro brain natriuretic peptide (BNP) and exhaled end-tidal carbon dioxide (ETCO2) in patients presenting with dyspnoea. Material and Methods: This prospective, cross-sectional and observational study was performed at the Government Medical College and Hospital, Nagpur, between October 2019 and October 2021 in patients admitted to the medicine intensive care unit. Three groups of patients were compared: (1) HF-related acute dyspnoea group (n = 52), (2) pulmonary (COPD/PE)-related acute dyspnoea group (n = 31) and (3) sepsis with ARDS-related dyspnoea group (n = 13). All patients underwent initial clinical examination with a recording of initial vital parameters along with on-admission ETCO2 measurement, NT-proBNP testing, arterial blood gas testing, lung ultrasound examination, 2D echocardiography, chest X-rays, and other basic diagnostic laboratory testing. Results: We included 96 patients during the study period. Median NT-proBNP was found to be maximum for the HF group (11,480 pg/ml) followed by the sepsis group (780 pg/ml) and pulmonary group (231 pg/ml). The mean ETCO2 value was found to be maximum in the pulmonary group (48.610 mmHg) followed by HF (31.51 mmHg) and the sepsis group (19.46 mmHg). All results were found to be statistically significant (P &lt; 0.05). Conclusion: NT-proBNP has high diagnostic accuracy in differentiating acute HF-related dyspnoea from pulmonary (COPD and ARDS)-related acute dyspnoea. The higher levels of ETCO2 help in diagnosing patients with COPD.

Verification for Diagnosis of Sleep-Related Hypoventilation and Carbon Dioxide Partial Pressure During Sleep in Children Using End-Tidal Carbon Dioxide

Background and Objective From the past, several researchers have studied and measured the partial pressure of carbon dioxide during sleep in normal children to establish diagnostic criteria for hypoventilation in children. Here we tried to verify the existing definition of sleep-related hypoventilation in Asian by evaluating and analyzing the carbon dioxide partial pressure in pediatric subjects who underwent polysomnography.Methods We retrospectively analyzed clinical information of 196 children who underwent polysomnography at our hospital from Feb 2011 to Apr 2021. Among Asian pediatric subjects, those with serious chronic or genetic diseases, craniofacial deformities, and hypoventilation confirmed by polysomnography were excluded. We evaluated partial pressure of carbon dioxide in target group by end-tidal carbon dioxide (EtCO2) measured with a stream capnometer through nasal cannula. The target group was classified by apnea-hypopnea index and analyzed.Results The mean value of the time with EtCO&lt;sub&gt;2&lt;/sub&gt; ≥ 45 mm Hg in total sleep time was 47.00% which is higher than previous studies. The mean value of the time with EtCO&lt;sub&gt;2&lt;/sub&gt; ≥ 50 mm Hg in total sleep time was 2.77% which is similar to previous studies. Also, our subjects showed the highest mean EtCO&lt;sub&gt;2&lt;/sub&gt; value in non-rapid eye movement (NREM) stage and lowest mean EtCO&lt;sub&gt;2&lt;/sub&gt; value when wake.Conclusions In this study, the diagnostic criteria for sleep-related hypoventilation at the American Academy of Sleep Medicine (AASM) in 2017 established by measuring the EtCO&lt;sub&gt;2&lt;/sub&gt; in western children seems appropriate to apply to Asian children to define hypoventilation.

0729 Assessing the Diagnostic Benefit of Polysomnography with Routine Carbon Dioxide Measurements in Adolescent and Adult Obese Patients

Abstract Introduction The diagnosis of obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS) has increased with the increasing prevalence of obesity. Adding routine transcutaneous carbon dioxide (TcCO2) or end-tidal carbon dioxide sensors (EtCO2) to a polysomnogram (PSG) may expand the analytic capabilities of the study. Our study looks at the utility of using CO2 monitoring in obese adolescent (age 13-18 years) and obese adults in increasing the diagnostic yield of the polysomnogram. Methods A retrospective chart review was conducted on obese adolescents (13-18 years) and obese adults (body mass index [BMI] &amp;gt; 95 percentile and &amp;gt;30 kg/m2 respectively) undergoing a PSG with EtCO2 monitoring. The CO2 values were documented while supine (awake) and while sleeping. The EtCO2 value was correlated with the BMI but the adults were also compared between Group 1 (BMI 30-40 kg/m2) and Group 2 (BMI &amp;gt;40 kg/m2). Patients with known hypoventilation syndromes or studies that had poor EtCO2 waveforms were excluded. Results 72 patients were identified between December 2019 and November 2020 at the Memorial Hermann Sleep Disorders Center. Amongst the adults, 52% were men, with an average age of 55 years (range 26-77) and an average BMI 40.5 kg/m2 (SD +/- 8.8). The average AHI on the diagnostic study (CMS criteria) was 31 events/hour (SD +/- 34.1) and the average oxygen saturation nadir was 80%. Twenty patients (28%) met the diagnostic criteria for OHS based on the baseline awake EtCO2. The mean EtCO2 was 40.1 mmHg in patients with a BMI between 30 and 40 kg/m2 (Group 1) versus 45.1 mmHg in patients with BMI &amp;gt;40 kg/m2 (Group 2) with a statistically significant p-value of 0.0002. Additionally, we identified 18 patients between the ages of 13-18 years with obesity amongst which, 4 patients also had a baseline EtCO2 of &amp;gt;45 torr (22%) with a potential diagnosis of OHS. Conclusion Patients diagnosed with OHS are reported to have a higher overall greater mortality. Our study suggests a higher diagnostic yield of OHS in adults and adolescents with the use of CO2 monitoring especially in the morbidly obese. This evidence would advocate for the routine use of CO2 monitoring in the obese patient population. Support (If Any)

Association between intraoperative end-tidal carbon dioxide and postoperative nausea and vomiting in gynecologic laparoscopic surgery

Gynecologic laparoscopic surgery has a high incidence of postoperative nausea and vomiting (PONV). Studies suggest that low intraoperative end-tidal carbon dioxide (EtCO2) is associated with an increased incidence of PONV, but the results have not been consistent among studies. This study investigated the association between intraoperative EtCO2 and PONV in patients undergoing gynecologic laparoscopic surgeries under general anesthesia. This retrospective cohort study involved patients who underwent gynecologic laparoscopic surgeries under general anesthesia at Kyoto University Hospital. We defined low EtCO2 as a mean EtCO2 of < 35 mmHg. Multivariable modified Poisson regression analysis examined the association between low EtCO2 and PONV during postoperative two days and the postoperative length of hospital stay (PLOS). Of the 739 patients, 120 (16%) had low EtCO2, and 430 (58%) developed PONV during postoperative two days. There was no substantial association between low EtCO2 and increased incidence of PONV (adjusted risk ratio: 0.96; 95% confidence interval [CI] 0.80–1.14; p = 0.658). Furthermore, there was no substantial association between low EtCO2 and prolonged PLOS (adjusted difference in PLOS: 0.13; 95% CI − 1.00 to 1.28; p = 0.816). Intraoperative low EtCO2, specifically a mean intraoperative EtCO2 below 35 mmHg, was not substantially associated with either increased incidence of PONV or prolonged PLOS.