ETCO2 Values Research Articles

Effect of classical laryngeal mask or I-gel use on otolaryngeal system in ambulatory inhalation general anesthesia: A prospective study

Objective: To investigate the effects of supraglottic airway tools such as classical laryngeal mask (cLMA) and I-gel, which can be used without the need for muscle relaxation in the airway management of general anesthesia patients, on the otolaryngeal system. Methods: This prospective randomised study was conducted at Karadeniz Technical University Hospital, Faculty of Medicine, Trabzon, Turkey, during November 2020 to December 2021. Eighty-nine patients in the American Society of Anesthesiologists (ASA) grade I-II group, who would undergo elective surgery under general anesthesia, were randomized into two groups, namely Group cLMA and Group I-gel. cLMA and I-gel were used for airway management of the patients. After anesthesia induction, tympanometric measurements were taken at regular intervals for middle ear pressures of both ears. Results: While air way pressures, SpO2 and EtCO2 values were within normal limits, there were no differences in terms of complications. In tympanometric measurements, middle ear pressure increase was statistically higher in the cLMA group than in the I-gel group (p <0.001). Conclusions: We think that I-gel may be a more advantageous supra glottic airway device in terms of otolaryngeal effecs and middle ear pressure in theair way management during short surgical procedures. doi: https://doi.org/10.12669/pjms.40.10.8416 How to cite this: Saylan S, Cobanoglu HBY. Effect of classical laryngeal mask or I-gel use on otolaryngeal system in ambulatory inhalation general anesthesia: A prospective study. Pak J Med Sci. 2024;40(10):2299-2304. doi: https://doi.org/10.12669/pjms.40.10.8416 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Comparison of end tidal CO2 levels between automated head up and conventional cardiopulmonary resuscitation: A pre-post intervention trial

BackgroundThe combination of controlled automated head/thorax elevation, active compression-decompression (ACD) cardiopulmonary resuscitation (CPR), and an impedance threshold device (ITD-16), termed AHUP-CPR, lowers intracranial pressure and increases circulation and neurologically-sound survival in pigs versus conventional (C) CPR. This study examined whether AHUP-CPR increased end tidal (ET) CO2, a non-invasive marker of cardiac output and organ perfusion, compared with C-CPR in witnessed out-of-hospital cardiac arrest patients. MethodWe conducted a prospective, single-arm, pre-post intervention trial in France between October 2019 and October 2022.Firefighters treated patients enrolled during the pre-intervention period with manual C-CPR and with AHUP-CPR during the post-intervention period. Advanced life support was provided by a physician-staffed 2nd-tier response vehicle for the two study periods. The primary outcome was the peak ETCO2 value measured during CPR. Results122 patients with a mean age of 67 years (standard deviation [SD], 17) were enrolled (59 in the pre-intervention period and 63 in the post-intervention period). Based on an intention-to-treat analysis, mean baseline ETCO2 values were comparable between pre- (20.1 mmHg, SD,16.3) and post-(19.2 mmHg, SD, 16.3) intervention periods. Mean peak ETCO2 values during CPR were 30.3 mmHg (SD, 13.1) versus 40.7 mmHg (SD, 17.8) for the pre- and post-intervention study periods (mean difference, 10.6, 95% confidence interval, 4.6 to 16.1, P < 0.001). Mean differences in peak ETCO2 between study periods did not vary according to the first recorded cardiac rhythm (P for interaction = 0.99). The proportion of return of spontaneous circulation [19 (32.2%) vs. 21 (33.3%)], survival on hospital admission [17 (28.8%) vs. 19 (30.2%)], and 30-day survival with favorable neurological outcome [8 (13.6%) vs. 7 (11.1%)] did not differ between study periods. ConclusionETCO2 values during AHUP-CPR reached the range of non-arrest normal physiological levels and were significantly higher than with C-CPR, regardless of the presenting cardiac rhythm.

The complexity of cerebral blood flow regulation: the interaction of posture and vasomotor reactivity.

Arterial carbon dioxide ([Formula: see text]) and posture influence the middle (MCAv) and posterior (PCAv) cerebral artery blood velocities, but there is paucity of data about their interaction and need for an integrated model of their effects, including dynamic cerebral autoregulation (dCA). In 22 participants (11 males, age 30.2 ± 14.3 yr), blood pressure (BP, Finometer), dominant MCAv and nondominant PCAv (transcranial Doppler ultrasound), end-tidal CO2 (EtCO2, capnography), and heart rate (HR, ECG) were recorded continuously. Two recordings (R) were taken when the participant was supine (R1, R2), two taken when the participant was sitting (R3, R4), and two taken when the participant was standing (R5, R6). R1, R3, and R5 consisted of 3 min of 5% CO2 through a mask and R2, R4, and R6 consisted of 3 min of paced hyperventilation. The effects of [Formula: see text] were expressed with a logistic curve model (LCM) for each parameter. dCA was expressed by the autoregulation index (ARI), derived by transfer function analysis. Standing shifted LCM to the left for MCAv (P < 0.001), PCAv (P < 0.001), BP (P = 0.03), and ARI (P = 0.001); downward for MCAv and PCAv (both P < 0.001), and upward for HR (P < 0.001). For BP, LCM was shifted downward by sitting and standing (P = 0.024). For ARI, the hypercapnic range of LCM was shifted upward during standing (P < 0.001). A more complete mapping of the combined effects of posture and arterial CO2 on the cerebral circulation and peripheral variables can be obtained with the LCM over a broad physiological range of EtCO2 values.NEW & NOTEWORTHY Data from supine, sitting, and standing postures were measured. Modeling the data with logistic curves to express the effects of CO2 reactivity on middle cerebral artery blood velocity (MCAv), posterior cerebral artery blood velocity (PCAv), heart rate, blood pressure (BP), and the autoregulation index (ARI), provided a more comprehensive approach to study the interaction of arterial CO2 with posture than in previous studies. Above all, shifts of the logistic curve model with changes in posture have shown interactions with [Formula: see text] that have not been previously demonstrated.

Evaluation of the effect of trendelenburg position duration on intracranial pressure in laparoscopic hysterectomies using ultrasonographic optic nerve sheath diameter measurements

BackgroundDuring laparoscopic surgery, pneumoperitoneum and Trendelenburg positioning applied to provide better surgical vision can cause many physiological changes as well as an increase in intracranial pressure. However, it has been reported that cerebral autoregulation prevents cerebral edema by regulating this pressure increase. This study aimed to investigate whether the duration of the Trendelenburg position had an effect on the increase in intracranial pressure using ultrasonographic optic nerve sheath diameter (ONSD) measurements.MethodsThe near infrared spectrometry monitoring of patients undergoing laparoscopic hysterectomy was performed while awake (T0); at the fifth minute after intubation (T1); at the 30th minute (T2), 60th minute (T3), 75th minute (T4), and 90th minute (T5) after placement in the Trendelenburg position; and at the fifth minute after placement in the neutral position (T6). Results: The study included 25 patients. The measured ONSD values were as follows: T0 right/left, 4.18±0.32/4.18±0.33; T1, 4.75±0.26/4.75±0.25; T2, 5.08±0.19/5.08±0.19; T3, 5.26±0.15/5.26±0.15; T4, 5.36±0.11/5.37±0.12; T5, 5.45±0.09/5.48±0.11; and T6, 4.9±0.24/4.89±0.22 ( p < 0.05 compared with T0). ). No statistical difference was detected in all measurements in terms of MAP, HR and ETCO2 values compared to the T0 value (p > 0.05).ConclusionsIt was determined that as the Trendelenburg position duration increased, the ONSD values ​​increased. This suggests that as the duration of Trendelenburg positioning and pneumoperitoneum increases, the sustainability of the mechanisms that balance the increase in intracranial pressure becomes insufficient.Trial registrationThis study was registered at Clinical Trials.gov on 21/09/2023 (registration number NCT06048900).

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.

Investigation of the Relationship Between the Measured Alpha Angle in Capnography and Readmission Within Thirty Days in Chronic Obstructive Pulmonary Disease Patients Who Presented to the Emergency Department

BackgroundIndividuals with chronic obstructive pulmonary disease (COPD) constitute a significant portion of patients who present to the emergency department with dyspnea. However, there is no ideal method for predicting mortality or making hospitalization decisions in the emergency department (ED). In this regard, objective findings are needed for these patients. Since there are no objective findings regarding the hospitalization decision, there may be an increase in the re-admission rate of patients who needed hospitalization but were decided to be discharged. Side-stream end-tidal carbon dioxide (EtCO2) measurements offer a non-invasive, easy-to-interpret, quickly accessible, and reproducible method that can be applied at the bedside. ObjectivesThe aim of this study was to evaluate the relationship between the alpha angle values obtained by capnography and readmission rates within 30 days for patients experiencing COPD exacerbations who presented to the ED with dyspnea and were discharged after treatment. MethodsIn this study, we studied with 130 participants presented to the emergency department of a tertiary care university hospital with dyspnea, who are >18 y. Forty patients were excluded after evaluation for eligibility for the study. Thus, the data of 90 patients included were analyzed. We obtained alpha angle and EtCO2 values for all patients at the time of admission and also after treatment. The primary outcome measure of the study was the relationship between the patients’ readmission situations within 30 days of the alpha angle measurements. The secondary outcome measure was the association between patients’ EtCO2 values ​​and readmission within 30 days. ResultsIt was observed that both the pretreatment alpha angle values and the posttreatment alpha angle variables were statistically significant in predicting the readmission of the patients within 30 days (p = 0.001, p = 0.003) ConclusionThe results of this study show that alpha angle values measured for patients with COPD who present to the ED with the complaint of dyspnea may be used to predict readmission.

Retrospective Evaluation of the Effects of Local Anesthesia Before Tooth Extraction Procedures under General Anesthesia on Physiologic Parameters and Postoperative Bleeding in Children

Background: Studies have been conducted to evaluate changes in hemodynamics, postoperative bleeding, and pain in pediatric dental patients receiving general anesthesia (GA). However, a limited number of studies have evaluated the effects of local anesthetics (LA) on tooth extraction procedures during GA. There is no consensus in the literature regarding LA application in the perioperative period for dental treatments performed within the scope of GA. Aim: This study aimed to determine the retrospective physiologic effects of fluctuations in vital signs and postoperative bleeding in children who did or did not receive LA for tooth extraction under GA. Methods: A retrospective evaluation of 77 patients aged 5.16 ± 1.85 years who had the extraction of primary posterior teeth with or without LA under GA were reviewed in the post-anaesthesia care unit (PACU) for postoperative bleeding and the effects of intraoperative LA on fluctuations in postoperative parameters such as mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2), respiratory rate (RR), and the end-tidal carbon dioxide (EtCO2). These were compiled from the patient records of the procedures. Results: Significant differences between the baseline and peak MAP (P &lt; 0.001), HR (P = 0.011), and EtCO2 (P = 0.002) were noted in children without LA compared to those who had LA. In addition, substantial variations were observed between the baseline and peak values for MAP (P &lt; 0.001) and HR (P = 0.037) in children who had tooth extraction in the mandibular region. Statistically significant differences were noted between the baseline and peak values for patients who did not receive LA before the extraction of the first primary molar in terms of MAP (P &lt; 0.02) and EtCO2 (P = 0.032). Similarly, significant differences in MAP (P &lt; 0.02) and EtCO2 (P = 0.034) were noted in the extraction of the second primary molar. In addition, there was a significant difference in bleeding based on the number of tooth extractions in those who did not receive LA (P = 0.020). Conclusion: This study showed that in children who underwent tooth extraction under GA, additional LA application minimized changes in HR, MAP, and EtCO2, whereas a lack of LA application produced significant fluctuations from baseline to peak values of HR, MAP, and EtCO2. In addition, LA application reduced postoperative bleeding.

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.

Comparative Case Series on LMA-Assisted Flexible Fiberoptic Bronchoscopy

ABSTRACT Fiberoptic bronchoscopy in children requires sedation, while routinely employed techniques for oxygenation under sedation don’t provide airway protection.LMA during FOB can provide safer ventilation with good operative views.Although the use of laryngeal mask airway for FOB was described in 1982, its application has not been established in pediatric patients. The aim of our study was to compare the safety and efficacy of LMA-assisted bronchoscopy compared to nasal airway with oxygenation-assisted bronchoscopy. The study was conducted on 12 patients, 6 in each group. Data collected includes monitoring of oxygen saturation, hemodynamics, ETCO2, and complications. LMA group children had lower episodes of desaturation as compared to nasal airway group. ETCO2 values were maintained and rate of complications were less in LMA group. Hemodynamic stability in both groups were comparable. Hence the use of LMA allows better airway conduit, with stable O2 saturation and ETCO2 values than nasal airway-assisted bronchoscopy.

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.

HIGH-FLOW NASAL OXYGEN THERAPY: AN ALTERNATIVE TO PRE-OXYGENATION IN THE OPERATING ROOM

High-flow nasal oxygen therapy (HFO) is a device that supplies warmed and humidified inspiratory gas through a nasal cannula at higher flow rates than conventional oxygen therapy, with an inspired oxygen fraction that can fluctuate from 21% to 100%. The primary aim of our study is to compare the efficacy of ONHD versus face mask. This trial was an experimental cohort study carried out at the Central Block of the Ibn Rochd University Hospital in Casablanca, over a period of three months, and involved 40 patients distributed into two groups: the face mask PO group (n=20) and the ONHD PO group (n=20). We evaluated apnea time without desaturation (SPO2˃95%), mean SPO2 during pre-oxygenation and apnea time, ETCO2 value after intubation and the frequency of complications during pre-oxygenation, The results show that ONHD compared with the face mask prolongs the duration of apnea without desaturation (SPO2˃95%), especially in high-risk patients, especially obese individuals.

TO ASSESS EFFECTS OF PNEUMOPERITONEUM ON VENTILATORY MECHANICS AND HEMODYNAMICS DURING LAPAROSCOPIC CHOLECYSTECTOMY IN OBESE AND NON-OBESE PATIENTS

Aim: The aim of the study was to assess effects of pneumoperitoneum on ventilatory mechanics and hemodynamic during laparoscopic cholecystectomy in obese and non-obese patients Method: A total of 100 patients were divided into two groups of 50 each. Obese (O) group consisted of 50 patients with BMI&gt;30 kg/m2 and non-obese (NO) group consisted of 50 patients with BMI&lt;30 kg/m2. Anaesthesia protocol was kept uniform in both the groups. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), peripheral oxygen saturation (SpO2), end-tidal carbon dioxide (EtCO2), perfusion index (PI), peak (PPEAK), plateau (PPLAT) and driving (PDRIVING) pressures, static (CST) and dynamic (CDYN) lung compliances were measured at baseline and at sequential time intervals following induction of anaesthesia, insufflation, desufflation and before extubation. Results: On induction of anaesthesia, a decrease in HR was observed in non-obese patients whereas an increase was observed in obese patients though statistically non-significant (p&gt;0.05). A higher SBP, DBP and MAP was observed following insufflation, after desufflation and before extubation in the obese patients but was non-significant . The PI value was high in obese patients though non-significant. Also, EtCO2 values remained minimally elevated in obese patients but were statistically insignificant. PPEAK, PPLAT as well as PDRIVING remained high in obese individuals following insufflation, after desufflation, and before extubation and were significant (p&lt;0.05). CST and CDYN remained low in obese patients following insufflation, after desufflation, and before extubation and were statistically significant (p&lt;0.05). Conclusion: Obese patients undergoing LC have slightly higher hemodynamic variations than non-obese patients, but non-significant (p&gt;0.05). The respiratory parameters PPEAK, PPLAT and PDRIVING remained elevated whereas CST and CDYN remained low following insufflation, after desufflation, and before extubation in obese patients as compared to non-obese patients and were statistically significant (p&lt;0.05).

The Use of End-Tidal CO2 and Integrated Pulmonary Index to Predict Postspinal Hypotension in Cesarean Section.

Early diagnosis and treatment of postspinal hypotension (PSH) in obstetric anaesthesia reduces the risk of maternofetal complications. In this study, the effect of EtCO2 and the integrated pulmonary index (IPI) in predicting PSH was investigated. Patients scheduled for cesarean section under spinal anaesthesia were included. The Capnostream 35 respiratory monitor (Medtronic, Inc., Dublin, Ireland) was used for EtCO2 and IPI. PSH developed in 52 (63.4%) of the 82 patients. EtCO2 and IPI values decreased significantly compared with baseline values in patients who developed PSH. There were statistically significant differences in EtCO2 (p = 0.001) and the IPI change (p = 0.045) in patients who developed PSH compared with those who did not. It was found that the EtCO2 difference had an independent effect on predicting PSH (p < 0.05), whereas the IPI difference did not (p > 0.05). One unit decrease in EtCO2 from the baseline increased the risk of PSH by 3.3 times. ROC curve analysis showed that the magnitude of change in EtCO2 was diagnostic for predicting PSH (AUC: 0.90 (0.83-0.97; p < 0.001)). IPI showed no predictive value for postspinal hypotension in cesarean section. However, EtCO2 monitoring, which is non-invasive and real-time monitoring, can be used to predict postspinal hypotension.

Comparative Analysis of Perfusion Index and End-Tidal Carbon Dioxide in Cardiac Arrest Patients: Implications for Hemodynamic Monitoring and Resuscitation Outcomes.

During cardiopulmonary resuscitation (CPR), some parameters (e.g., intraarterial pressure measurement and end-tidal carbon dioxide (EtCO2)) indicate the quality andoutcome of resuscitation. These parameters are generally based on monitoring the hemodynamic status. Perfusion index (PI) is a calculation from the photoplethysmography (PPG) signal and displays the proportion of pulsatile to non-pulsatile light absorption or reflection in the PPG signal. It helps to evaluate cardiac output and tissue perfusion in the care of a critical patient. Its most important advantages are that it can be easily measured with a pulse oximeter probe attached to the finger (non-invasive), can be objectively repeated, can be applied quickly, and is inexpensive. Normal PI values range from 0.2% to 20%. Despite being recognized as a valuable indicator of hemodynamics, there is limited information regarding its relevance in patients experiencing cardiac arrest. Although the PI is known to be a valuable parameter to indicate hemodynamics, information about its value in cardiac arrest patients is limited. This study aims to evaluate the performance of PI and EtCO2 in predicting the return of spontaneous circulation (ROSC) among cardiac arrest patients. This was a single-center, prospective, observational clinical study including both out-of-hospital and in-hospital adult cardiac arrest patients. The study was conducted from November 1, 2018 to April 30, 2019 at the Emergency Department (ED) of the Hacettepe University Hospital, Ankara, Turkey. The EtCO2 values of the patients were recorded at the time they were intubated (t0) and every five minutes (t5, t10, t15...) during CPR. Along with these measurements, PI values were measured with the Masimo Signal Extraction Technology device (Masimo, California, United States). The study's primary outcome was PI's performance in predicting the ROSC among cardiac arrest patients. The secondary outcomes of the study were the performance of EtCO2 in predicting the ROSC among cardiac arrest patients and the association between PI and EtCO2 values. We included a total of 100 cases. The mean age of patients was 70.4 ± 13.4 years, and 65% were male. The ROSC was achieved in 29patients. There was no statistical difference in PI values between the ROSC (+) and ROSC (-) groups at any minute. However, in the ROSC (+) group, EtCO2 values were observed to be high starting from the fifth minute (t5, p=0.010; t10, p<0.001; t15, p=0.014; t20, p=0.033; t25, p=0.003, respectively). There was no correlation between the PI and EtCO2 values at 0, 5, 10, 15, 20, and 25 minutes (t0, p=0.436; t5, p=0.154; t10, p=0.557; t15, p=0.740; t20 p=0.241; t25 p=0.201, respectively). Measuring PI values during resuscitation in intubated cardiac arrest patients does not help clinicians predict the outcome. In addition, no correlation was found with EtCO2 values. However, EtCO2 values remained high in patients with the ROSC from the fifth minute onward. Further larger-scale studies are needed regarding the optimal use of PI in cardiac arrest patients.

Utility of end-tidal carbon dioxide to guide resuscitation termination in prolonged out-of-hospital cardiac arrest

Study objectiveTo evaluate if the change in end-tidal carbon dioxide (ETCO2) over time has improved discriminatory value for determining resuscitation futility compared to a single ETCO2 value in prolonged, refractory non-shockable out-of-hospital cardiac arrest (OHCA). MethodsThis is a retrospective analysis of adult refractory non-shockable, non-traumatic OHCA patients in the Portland Cardiac Arrest Epidemiologic Registry (PDX Epistry) from 2018 to 2021. We defined refractory non-shockable OHCA cases as patients with lack of a shockable rhythm at any time or return of spontaneous circulation at any time prior to 30-min of on-scene resuscitation. We abstracted ETCO2 values first recorded after advanced airway placement and nearest to the 30-min mark of on-scene resuscitation (30 min-ETCO2) from EMS charts. The primary outcome was survival to hospital discharge. We compared 30 min-ETCO2 cutoffs of 10 mmHg and 20 mmHg to the trend (increasing or not) from initial to 30 min-ETCO2 (delta-ETCO2) using sensitivity, specificity, and area under the receiver operating curves (AUROC). ResultsOf 3837 adult OHCA, 2850 were initially non-shockable, and there were 617 (16.1%) cases of refractory non-shockable OHCA at 30-min. We excluded 320 cases without at least two ETCO2 recordings in the EMS chart, leaving 297 cases that met inclusion criteria. Of these, 176 (59.3%) were transported and 2 (0.7%) survived to discharge. Using absolute 30 min-ETCO2 cutoffs, both survivors were in the >10 mmHg group (sensitivity 100.0%, specificity 12.5%), whereas only one survivor was identified in the >20 mmHg group (sensitivity 50.0%, specificity 32.5%). Using delta-ETCO2, both survivors were in the increasing ETCO2 group (sensitivity 100.0%, specificity 60.7%). In comparing the two tests that did not misclassify survivors, the AUROC [95% CI] was higher when using delta-ETCO2 (0.803 [0.775–0.831]) compared to an absolute cutoff of 10 mmHg (0.563 [0.544–0.582]). ConclusionsNearly one-sixth of EMS-treated adult OHCA patients had refractory non-shockable arrests after at least 30 min of ongoing resuscitation. In this group, the ETCO2 trend following advanced airway placement may be more accurate in guiding termination of resuscitation than an absolute ETCO2 cutoff of 10 or 20 mmHg.

Abstract 185: Regional Oxygen Saturation and Capnography Monitoring During Resuscitation After Cardiac Arrest in a Swine Pediatric ARDS Model

Introduction: Survival and outcomes after cardiac arrest (CA) depend largely on the effectiveness of cardiopulmonary resuscitation (CPR). Traditional invasive methods of monitoring CPR can be challenging out-of-hospital and are lacking in more than 50% of in-hospital pediatric CA. Regional oxygen saturation (rSO 2 ) monitoring with Near Infrared Spectroscopy (NIRS) and volumetric capnography offers a noninvasive approach that could potentially overcome these challenges. Aim: To determine the feasibility and effectiveness of NIRS and volumetric capnography monitoring in a swine model of pediatric hypoxia induced CA. Approach: Juvenile pigs were sedated and mechanically ventilated. Mild to moderate Acute Respiratory Distress Syndrome (ARDS) was induced by continuous oleic acid infusion. Respiratory and hemodynamic variables were monitored using invasive and noninvasive (NIRS and capnography) monitoring to assess efficacy of CPR. Animals were randomized into one of the two groups: High-quality CPR (hqCPR) to achieve coronary perfusion pressure of 25-30 mmHg and low-quality CPR (lqCPR) to achieve coronary perfusion pressure of 10-15 mmHg. Trajectories over time were analyzed using regression analyses. The discriminatory ability to distinguish between groups based on trajectories were analyzed using receiver operating characteristics curve (ROC) analysis. Results: 39 animals (23±3 kg) were included in our study. In the hqCPR group, there are generally higher values for cerebral and renal rSO 2 , ETCO 2 , volume of CO 2 elimination (VCO 2 ), and carotid blood flow, compared to the lqCPR group (p&lt;0.0001). Cerebral and renal rSO 2 values increase over time, while ETCO 2 , VCO 2 , and carotid flow values decrease in the hqCPR group. Cerebral rSO2 had a ROC AUC of 0.76 (95% CI: 0.58-0.94), whereas renal rSO2 had a ROC AUC of 0.54 (95% CI: 0.22-0.87) representing nearly no discrimination ability. ETCO 2 had a ROC AUC of 0.66 (95% CI: 0.49-0.84), whereas VCO 2 had a ROC AUC of 0.62 (95% CI: 0.38-0.85). Conclusions: Higher mean cerebral rSO2 values during CPR might be used to assess quality of CPR effectiveness and provide real-time adjustments as needed. This could guide healthcare providers in optimizing CPR quality and improving outcomes for cardiac arrest patients.

Abstract 136: Does End-Tidal Carbon Dioxide Measured at the Facial Mask Predict Return of Spontaneous Circulation in Out-of-Hospital Cardiac Arrest?

Introduction: High value of end-tidal carbon dioxide (EtCO2), measured at the end of a tracheal tube, is closely associated with return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA) resuscitation. The aim of this study was to evaluate whether EtCO2 measured at the face mask (FM) before an intubation procedure, may also predict ROSC in OHCA. Material and Methods: This was a prospective non-interventional study. Between May 1 st 2022 and January 30 th 2023, all patients ≥ 18 years with an OHCA on EMS arrival and for whom a laryngoscopy for tracheal intubation was considered, were included. An EtCO2 sensor was directly placed between the valve of the bag-valve-mask and the FM while cardiopulmonary resuscitation was continued. Age, gender, initial rhythm, ROSC on scene and last EtCO2 at the FM (FM-EtCO2) value before laryngoscopy were collected. Patients were assigned to 3 groups: FM-EtCO2 &lt; 10 mmHg ; 10 mmHg &lt; FM-EtCO2 &lt; 30 mmHg and FM-EtCO2 &gt; 30 mmHg. Results: Twenty-three patients were included. Mean age was 64.9 ± 12.2 years and sex ratio was 3.6. Initial rhythm was asystole for 16 (69.6 %) patients, ventricular fibrillation for 5 (21.7 %) and pulseless rhythm for 2 (8.7%). Eight (34.8 %) patients had a ROSC on scene. Five (21,8 %) patients had a FM-EtCO2 &lt; 10 mmHg ; 7 (30,4%) a 10 mmHg &lt; FM-EtCO2 &lt; 30 mmHg and 11 (47,8 %) a FM-EtCO2 &gt; 30 mmHg. Among those with a ROSC, 2 had a FM-EtCO2 &lt; 10 mmHg and 6 a FM-EtCO2 &gt; 30 mmHg (p=0,038). Conclusion: A high value of EtCO2 measured at the face mask (above 30mmHg) was significantly associated with ROSC. This survey proposes a method that would facilitate the knowledge of an EtCO2 value, well known to predict ROSC in OHCA, earlier than with the reference method. Further studies are needed to validate these results.

Association of small adult ventilation bags with return of spontaneous circulation in out of hospital cardiac arrest

IntroductionLittle is known about the impact of tidal volumes delivered by emergency medical services (EMS) to adult patients with out-of-hospital cardiac arrest (OHCA). A large urban EMS system changed from standard adult ventilation bags to small adult bags. We hypothesized that the incidence of return of spontaneous circulation (ROSC) at the end of EMS care would increase after this change. MethodsWe performed a retrospective analysis evaluating adults treated with advanced airway placement for nontraumatic OHCA between January 1, 2015 and December 31, 2021. We compared rates of ROSC, ventilation rate, and mean end tidal carbon dioxide (ETCO2) by minute before and after the smaller ventilation bag implementation using linear and logistic regression. ResultsOf the 1,994 patients included, 1,331 (67%) were treated with a small adult bag. ROSC at the end of EMS care was lower in the small bag cohort than the large bag cohort, 33% vs 40% (p = 0.003). After adjustment, small bag use was associated with lower odds of ROSC at the end of EMS care [OR 0.74, 95% CI 0.61 – 0.91]. Ventilation rates did not differ between cohorts. ETCO2 values were lower in the large bag cohort (33.2 ± 17.2 mmHg vs. 36.9 ± 19.2 mmHg, p < 0.01). ConclusionUse of a small adult bag during OHCA was associated with lower odds of ROSC at the end of EMS care. The effects on acid base status, hemodynamics, and delivered minute ventilation remain unclear and warrant additional study.

Relationship of Intraoperative SpO2 and ETCO2 Values with Postoperative Hypoxemia in Elderly Patients after Non-Cardiac Surgery.

Elderly patients are at higher risk of postoperative hypoxemia due to their decreased respiratory function. The aim of this study was to investigate the relationship of intraoperative oxygen saturation (SpO2) and end-expiratory carbon dioxide (ETCO2) values with postoperative hypoxemia in elderly patients. The inclusion criteria were: 1) patients aged≥75 years; 2) underwent general anesthesia in non-cardiac surgery; 3) operative time longer than two hours; and 4) admission to the intensive care unit (ICU) following surgery performed between January and December 2019. Intraoperative SpO2 and ETCO2 values were collected every minute for the first two hours during surgery. The 253 patients were divided into two groups: SpO2≥92% and SpO2<92%. The time-weighted averages of intraoperative SpO2 and ETCO2 were used to compare differences between the two groups. The incidence of postoperative hypoxemia was 22.5%. For similar ventilator settings, patients with postoperative hypoxemia had lower intraoperative SpO2 and higher ETCO2 values. Sex, ASA classification, and intraoperative SpO2 were independent risk factors for postoperative hypoxemia. In conclusion, postoperative SpO2<92% was a frequent occurrence (> 20%) in elderly patients who underwent major non-cardiac surgery. Postoperative hypoxemia was associated with low intraoperative SpO2 and relatively higher ETCO2.

A neonatal in-vitro study on the effect of the inflation pressure on end-tidal carbon dioxide levels.

Describing the association of the peak inflation pressure (PIP) with end-tidal carbon dioxide (ETCO2) is a prerequisite for the development of closed loop ventilation in neonatal intensive care. We aimed to develop an in-vitro system to study this relationship. A ventilator was connected to a test lung, supplied with a stable CO2 concentration from a cylinder. The PIP was altered and the change in ETCO2 per unit of PIP was calculated in three models mimicking respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD) and viral bronchiolitis. The median (IQR) change in ETCO2 per unit of PIP was 0.23(0.13-0.38) kPa/cmH2O, using 138 paired measurements of PIP and ETCO2. The median (IQR) change in ETCO2 per unit of PIP, was higher when starting at an ETCO2>6kPa [0.43(0.33-0.58) kPa/cmH2O] compared to starting at an ETCO2<6kPa [0.14(0.08-0.20) kPa/cmH2O, p<0.001]. The median (IQR) change in ETCO2 per unit of PIP, was larger in the model of RDS [0.33(0.13-0.51) kPa/cmH2O] compared to the BPD [0.23(0.13-0.33) kPa/cmH2O, p=0.043] and the bronchiolitis models [0.15(0.10-0.31) kPa/cmH2O, p=0.017]. The change in ETCO2 in response to increasing PIP was larger for higher ETCO2 values and in a model simulating neonatal RDS, compared to BPD and bronchiolitis.