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

STUDY OBJECTIVE: To 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). METHODS: This 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). RESULTS: Of 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]). CONCLUSIONS: Nearly 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.

Capnography access and use in Kenya and Ethiopia.

PURPOSE: Lack of access to safe and affordable anesthesia and monitoring equipment may contribute to higher rates of morbidity and mortality in low- and middle-income countries (LMICs). While capnography is standard in high-income countries, use in LMICs is not well studied. We evaluated the association of capnography use with patient and procedure-related characteristics, as well as the association of capnography use and mortality in a cohort of patients from Kenya and Ethiopia. METHODS: For this retrospective observational study, we used historical cohort data from Kenya and Ethiopia from 2014 to 2020. Logistic regression was used to study the association of capnography use (primary outcome) with patient/procedure factors, and the adjusted association of intraoperative, 24-hr, and seven-day mortality (secondary outcomes) with capnography use. RESULTS: A total of 61,792 anesthetic cases were included in this study. Tertiary or secondary hospital type (compared with primary) was strongly associated with use of capnography (odds ratio [OR], 6.27; 95% confidence interval [CI], 5.67 to 6.93 and OR, 6.88; 95% CI, 6.40 to 7.40, respectively), as was general (vs regional) anesthesia (OR, 4.83; 95% CI, 4.41 to 5.28). Capnography use was significantly associated with lower odds of intraoperative mortality in patients who underwent general anesthesia (OR, 0.31; 95% CI, 0.17 to 0.48). Nevertheless, fully-adjusted models for 24-hr and seven-day mortality showed no evidence of association with capnography. CONCLUSION: Capnography use in LMICs is substantially lower compared with other standard anesthesia monitors. Capnography was used at higher rates in tertiary centres and with patients undergoing general anesthesia. While this study revealed decreased odds of intraoperative mortality with capnography use, further studies need to confirm these findings.

RéSUMé: OBJECTIF: Le manque d'accès à des équipements d'anesthésie et de monitorage sécuritaires et abordables peut contribuer à des taux plus élevés de morbidité et de mortalité dans les pays à revenu faible et intermédiaire (PRFI). Alors que la capnographie est une modalité standard dans les pays à revenu élevé, son utilisation dans les PRFI n'est pas bien étudiée. Nous avons évalué l'association de l'utilisation de la capnographie avec les caractéristiques des patient·es et des interventions, ainsi que l'association de l'utilisation de la capnographie et de la mortalité dans une cohorte de patient·es du Kenya et d'Éthiopie. MéTHODE: Pour cette étude observationnelle rétrospective, nous avons utilisé des données de cohortes historiques du Kenya et de l'Éthiopie de 2014 à 2020. Une régression logistique a été utilisée pour étudier l'association entre l'utilisation de la capnographie (critère d'évaluation principal) et les facteurs patient·es/interventions, ainsi que pour étudier l'association ajustée entre la mortalité peropératoire, à 24 h et à sept jours (critères d'évaluation secondaires) et l'utilisation de la capnographie. RéSULTATS: Au total, 61 792 cas d'anesthésie ont été inclus dans cette étude. Le type d'hôpital tertiaire ou secondaire (par rapport à un établissement primaire) était fortement associé à l'utilisation de la capnographie (rapport de cotes [RC], 6,27; intervalle de confiance [IC] à 95 %, 5,67 à 6,93 et RC, 6,88; IC 95 %, 6,40 à 7,40, respectivement), tout comme l'était l'anesthésie générale (vs régionale) (RC, 4,83; IC 95 %, 4,41 à 5,28). L'utilisation de la capnographie était significativement associée à une probabilité plus faible de mortalité peropératoire chez les patient·es ayant reçu une anesthésie générale (RC, 0,31; IC 95 %, 0,17 à 0,48). Néanmoins, les modèles entièrement ajustés pour la mortalité à 24 heures et à sept jours n'ont montré aucune donnée probante d'association avec la capnographie. CONCLUSION: L'utilisation de la capnographie dans les PRFI est considérablement moins répandue que celle d'autres moniteurs d'anesthésie standard. La capnographie a été utilisée à des taux plus élevés dans les centres tertiaires et chez des patient·es sous anesthésie générale. Bien que cette étude ait révélé une diminution de la probabilité de mortalité peropératoire avec l'utilisation de la capnographie, d'autres études doivent confirmer ces résultats.

Trace of delirium after robotic lower abdominal tumor resection at different end-tidal carbon dioxide: a RCT trial.

BACKGROUND: Postoperative delirium (POD) often occurs in oncology patients, further increasing the medical and financial burden. Robotic technology in lower abdominal tumors resection reduces surgical trauma but increases risks such as carbon dioxide (CO2) absorption. This study aimed to investigate the differences in their occurrence of POD at different end-tidal CO2 levels. METHOD: This study was approved by the Ethics Committee of Affiliated Hospital of He Bei University (HDFY-LL-2022-169). The study was registered with the Chinese Clinical Trials Registry on URL: http://www.chictr.org.cn , Registry Number: ChiCTR2200056019 (Registry Date: 27/08/2022). In patients scheduled robotic lower abdominal tumor resection from September 1, 2022 to December 31, 2022, a comprehensive delirium assessment was performed three days postoperatively using the CAM scale with clinical review records. Intraoperative administration of different etCO2 was performed depending on the randomized grouping after intubation. Group L received lower level etCO2 management (31-40mmHg), and Group H maintained the higher level(41-50mmHg) during pneumoperitoneum. Data were analyzed using Pearson Chi-Square or Wilcoxon Rank Sum tests and multiple logistic regression. Preoperative mental status score, alcohol impairment score, nicotine dependence score, history of hypertension and diabetes, duration of surgery and worst pain score were included in the regression model along with basic patient information for covariate correction analysis. RESULTS: Among the 103 enrolled patients, 19 (18.4%) developed postoperative delirium. The incidence of delirium in different etCO2 groups was 21.6% in Group L and 15.4% in Group H, respectively, with no statistical differences. In adjusted multivariate analysis, age and during of surgery were statistically significant predictors of postoperative delirium. The breath-hold test was significantly lower postoperatively, but no statistical differences were found between two groups. CONCLUSION: With robotic assistant, the incidence of postoperative delirium in patients undergoing lower abdominal tumor resection was not modified by different end-tidal carbon dioxide management, however, age and duration of surgery were positively associated risk factors.

The safety and utility of the semi-sitting position for clipping of posterior circulation aneurysms.

BACKGROUND: The semi-sitting position offers advantages for surgeries in the posterior cranial fossa. However, data on its safety and effectiveness for clipping aneurysms in the posterior cerebral circulation are limited. This retrospective cohort study evaluates the safety and effectiveness of using the semi-sitting position for these surgeries. METHODS: We conducted a retrospective study of 17 patients with posterior cerebral circulation aneurysms who underwent surgical clipping in the semi-sitting position in the Department of Neurosurgery at Hannover Medical School over a 10-year period. RESULTS: The mean age at surgery was 62 years (range, 31 to 75). Fourteen patients were admitted with subarachnoid hemorrhage and 3 patients had incidental aneurysmas. Fifteen patients had PICA aneurysms, and two had aneurysms of the vertebral artery and the superior cerebellar artery, respectively. The median diameter of the aneurysms was 5 mm (range 3-17 mm). Intraoperative venous air embolism (VAE) occurred in 4 patients, without affecting the surgical or clinical course. VAE was associated with a mild decrease of EtCO2 levels in 3 patients and in 2 patients a decrease of blood pressure occurred which was managed effectively. Surgical procedures proceeded as planned in all instances. There were no complications secondary to VAE. Two patients died secondary to respiratory problems (not related to VAE), and one patient was lost to follow-up. Eleven of fourteen patients were partially or completely independent (Barthel index between 60 and 100) at a median follow-up duration of 13.5 months (range, 3-103 months). CONCLUSION: The semi-sitting position is a safe and effective technique for the surgical clipping of aneurysms in the posterior cerebral circulation. The incidence of VAE is comparable to that seen in tumor surgery. However, it is crucial for the surgical and anesthesiological team to be familiar with potential complications and to react immediately in case of an occurrence of VAE.

Implementation of Continuous Capnography Protocol in a Postanesthesia Care Unit for Adult Patients at High-risk of Postoperative Respiratory Depression.

PURPOSE: This project aimed to implement a continuous capnography protocol in the postanesthesia care unit (PACU) for postoperative adult patients who are at high risk for respiratory failure. DESIGN: A preintervention and postintervention quality improvement design with retrospective chart reviews evaluated patient demographics (age, weight, body mass index [BMI], perioperative fluid intake and output, use of intraoperative positive-end expiratory pressure), length of surgery, average length of PACU stay, incidence of respiratory events, and adherence to a PACU capnography protocol. METHODS: Preimplementation data were collected from retrospective chart reviews over a 3-month period. A continuous capnography protocol was implemented for same-day surgery patients with a BMI of 35 kg/m2 or greater and who received general anesthesia. Postimplementation data were collected over 3 months in addition to adherence to the capnography protocol. This was presented using descriptive statistics. FINDINGS: Age, length of surgery, weight, BMI, perioperative fluid intake and output, and use of positive-end expiratory pressure did not impact PACU length of stay. The average PACU length of stay decreased from 76.76 to 71.82 minutes postimplementation but was not statistically significant (P = .470). The incidence of respiratory events was 6% (n = 3). After the implementation of the continuous capnography protocol, adherence to the continuous capnography monitoring was 86% (n = 43). CONCLUSIONS: Patients who are at high risk for postoperative respiratory failure may benefit from continuous capnography monitoring in the PACU. Capnography monitoring may decrease PACU length of stay and provide earlier detection of pending respiratory depression or failure than pulse oximetry alone.

[Research Progress on End-Tidal Carbon Dioxide Detection Technology Based on Non-Dispersive Infrared Method].

The concentration of end-tidal carbon dioxide is one of the important indicators for evaluating whether the human respiratory system is normal. Accurately detecting of end-tidal carbon dioxide is of great significance in clinical practice. With the continuous promotion of the localization of end-tidal carbon dioxide monitoring technology, its application in clinical practice in China has become increasingly widespread in recent years. The study is based on the non-dispersive infrared method and comprehensively elaborates on the detection principle, gas sampling methods, key technologies, and technological progress of end-tidal carbon dioxide detection technology. It comprehensively introduces the current development status of this technology and provides reference for application promotion and further improvement.

Arterial to end-tidal carbon dioxide gap and its characterization in mechanically ventilated adults in the emergency department.

PURPOSE: To evaluate early measurement of the arterial to end-tidal carbon dioxide (PaCO2-PetCO2) gap, a surrogate for physiologic dead space, and its association with clinical outcomes in intubated adults in the emergency department (ED). MATERIALS AND METHODS: Observational cohort study of invasively mechanically ventilated adults in an academic medical center (years 2009 to 2016). The association of the PaCO2-PetCO2 gap was evaluated with respect to clinical outcomes; the primary outcome was in-hospital mortality. RESULTS: 519 patients were included. 325 (63%) patients had an elevated (>5 mmHg) PaCO2-PetCO2. Patients with an elevated PaCO2-PetCO2 were significantly older, had higher APACHE II scores, more frequently had chronic obstructive pulmonary disease (COPD), had lower arterial oxygen to fraction of inspired oxygen (P:F) ratios, and were more likely to be intubated for exacerbation of COPD or sepsis. There was no difference in mortality for patients with an elevated PaCO2-PetCO2 (25% vs 26%) in unadjusted analysis (p = 0.829) or adjusted analysis (aOR = 0.81 [95% CI: 0.53-1.26]), as compared to a non-elevated PaCO2-PetCO2. CONCLUSIONS: An elevated PaCO2-PetCO2 gap is common in the post-intubation period in the ED, but not significantly associated with clinical outcomes.

Diagnostic value of end-tidal carbon dioxide in the differential diagnosis of unstable angina and non-cardiac chest pain.

OBJECTIVE: This study aims to investigate the diagnostic value of End-tidal carbon dioxide (ETCO2) measured non-invasively at the bedside in order to distinguish between unstable angina pectoris (UAP) and non-cardiac chest pain among patients who present to the emergency department with chest pain without a history of cardiac pathology. MATERIAL AND METHODS: This clinical study is a prospective case-control study among patients presenting to the emergency department of a tertiary hospital with chest pain. After evaluating the inclusion and exclusion criteria, the patients were divided into two groups: 62 patients with UAP and 62 patients with non-cardiac chest pain. Receiver Operating Characteristic (ROC) analysis was used to determine the cut-off in diagnostic value measurements. For UAP prediction, the odds ratio of ETCO2 (including 95% confidence intervals) was calculated using univariate with binary logistic regression analysis. RESULTS: ETCO2 had an excellent diagnostic power in detecting UAP, with 35 cut-offs determined (AUC: 0.84, 95% Cl: 0.76-0.90, p < 0.001). When ETCO2, which affects both non-cardiac chest pain and UAP, is evaluated, an ETCO2 of <35 is statistically significant and 9.74 times more common among UAP patients than patients with non-cardiac chest pain. CONCLUSION: ETCO2, a non-invasive parameter that can be measured immediately at the bedside, may be proposed as a potential biomarker for differentiating patients with UAP from those with non-cardiac chest pain.

Noninvasive carbon dioxide monitoring in pediatric patients undergoing laparoscopic surgery: transcutaneous vs. end-tidal techniques.

PURPOSE: The present study aimed to investigate the correlation between transcutaneous carbon dioxide partial pressure (PtcCO2) and arterial carbon dioxide pressure (PaCO2) and the accuracy of PtcCO2 in predicting PaCO2 during laparoscopic surgery in pediatric patients. METHODS: Children aged 2-8 years with American Society of Anesthesiologists (ASA) class I or II who underwent laparoscopic surgery under general anesthesia were selected. After anesthesia induction and tracheal intubation, PtcCO2 was monitored, and radial arterial catheterization was performed for continuous pressure measurement. PaCO2, PtcCO2, and end-tidal carbon dioxide partial pressure (PetCO2) were measured before pneumoperitoneum, and 30, 60, and 90 min after pneumoperitoneum, respectively. The correlation and agreement between PtcCO2 and PaCO2, PetCO2, and PaCO2 were evaluated. RESULTS: A total of 32 patients were eventually enrolled in this study, resulting in 128 datasets. The linear regression equations were: PtcCO2 = 7.89 + 0.82 × PaCO2 (r2 = 0.70, P < 0.01); PetCO2 = 9.87 + 0.64 × PaCO2 (r2 = 0.69, P < 0.01). The 95% limits of agreement (LOA) of PtcCO2 - PaCO2 average was 0.66 ± 4.92 mmHg, and the 95% LOA of PetCO2 - PaCO2 average was -4.4 ± 4.86 mmHg. A difference of ≤ 5 mmHg was noted between PtcCO2 and PaCO2 in 122/128 samples and between PetCO2 and PaCO2 in 81/128 samples (P < 0.01). CONCLUSION: In pediatric laparoscopic surgery, a close correlation was established between PtcCO2 and PaCO2. Compared to PetCO2, PtcCO2 can estimate PaCO2 accurately and could be used as an auxiliary monitoring indicator to optimize anesthesia management for laparoscopic surgery in children; however, it is not a substitute for PetCO2. REGISTRATION NUMBER OF CHINESE CLINICAL TRIAL REGISTRY: ChiCTR2100043636.

Quantitative end-tidal carbon dioxide at initiation of resuscitation may help guide the ventilation of infants born at less than 30 weeks gestation.

AIM: Estimation of end-tidal carbon dioxide (EtCO2 ) with capnography can guide mask ventilation in infants born at less than 30 weeks of gestation. Chemical-sensitive colorimetric devices to detect CO2 are widely used at resuscitation. We aimed to quantify EtCO2 in the first breaths following initiation of mask ventilation at birth and correlated need for endotracheal intubation. METHODS: Infants <30 weeks gestation receiving mask ventilation were randomised into two groups of mask-hold technique (one-person vs. two-person). Data on EtCO2 in the first 30 breaths, time to achieve 5 mmHg, 10 mmHg and 15 mmHg CO2 using a respiratory function monitor was determined. RESULTS: Twenty-five infants with a mean gestation of 27.3 (±3 weeks) and mean birth weight 920.4 (±188.3 g) were analysed. The median EtCO2 was 5.6 mmHg in the first 10 breaths, whereas it was 12.6 mmHg for 11-20 breaths and 18 mmHg for 21-30 breaths. There was no significant difference in maximum median EtCO2 for the first 20 breaths, although EtCO2 was significantly lower in infants who were intubated (32.0 vs. 15.0, p = 0.018). CONCLUSION: EtCO2 monitoring in infants <30 weeks gestation at birth is feasible and reflective of alveolar ventilation. EtCO2 may help guide ventilation of preterm infants at birth.

Supraglottic airway device versus tracheal tube for pediatric laparoscopic surgery-A systematic review and meta-analysis.

BACKGROUND: Conventionally, tracheal tubes have been used for general anesthesia in pediatric laparoscopic surgeries. Recently, supraglottic devices are being used for the same. The performance of supraglottic devices versus tracheal tubes in children undergoing laparoscopic surgery is uncertain. METHODS: A systematic review and meta-analysis of randomized controlled trials that compared supraglottic devices versus tracheal tubes in patients ≤18 years undergoing laparoscopic surgery under general anesthesia was conducted. The outcomes were peak airway pressures (cm H2 O), end-tidal carbon dioxide during pneumoperitoneum (mm Hg), recovery time (min), postoperative sore throat and adverse events. Mean difference and odds ratio, with 95% confidence intervals were reported using a random effect model. RESULTS: Eight trials (n = 591) were included in the final meta-analysis. There was no statistically significant difference in the peak airway pressures (MD 0.58, 95% CI: -0.65 to 1.8; p = .36) and end-tidal carbon dioxide (MD -0.60, 95% CI: -2.00 to 0.80; p = .40) during pneumoperitoneum in the supraglottic device and the tracheal tube group. The tracheal tube group had higher odds of sore throat (OR 3.30, 95% CI: 1.69-6.45; p = .0005) and the supraglottic airway group had faster recovery time (MD 4.21, 95% CI: 3.12-5.31; p < .0001), which were statistically significant. The certainty of evidence is graded low. CONCLUSION: There is low quality evidence to suggest that for pediatric laparoscopic surgeries of short duration, supraglottic devices could provide comparable intraoperative ventilation in terms of peak airway pressures and end tidal carbon dioxide, with lower odds of postoperative sore throat and faster recovery time when compared to tracheal tubes.

Respiratory function monitoring during early resuscitation and prediction of outcomes in prematurely born infants.

OBJECTIVES: Over the last decade, there has been increased use of end-tidal carbon dioxide (ETCO2) and oxygen saturation (SpO2) monitoring during resuscitation of prematurely born infants in the delivery suite. Our objectives were to test the hypotheses that low end-tidal carbon dioxide (ETCO2) levels, low oxygen saturations (SpO2) and high expiratory tidal volumes (VTE) during the early stages of resuscitation would be associated with adverse outcomes in preterm infants. METHODS: Respiratory recordings made in the first 10 min of resuscitation in the delivery suite of 60 infants, median GA 27 (interquartile range 25-29) weeks were analysed. The results were compared of infants who did or did not die or did or did not develop intracerebral haemorrhage (ICH) or bronchopulmonary dysplasia (BPD). RESULTS: Twenty-five infants (42%) developed an ICH and 23 (47%) BPD; 11 (18%) died. ETCO2 at approximately 5 min after birth was lower in infants who developed an ICH, this remained significant after adjusting for gestational age, coagulopathy and chorioamnionitis (p=0.03). ETCO2 levels were lower in infants who developed ICH or died compared to those that survived without ICH, which remained significant after adjustment for gestational age, Apgar score at 10 min, chorioamnionitis and coagulopathy (p=0.004). SpO2 at approximately 5 min was lower in the infants who died compared to those who survived which remained significant after adjusting for the 5-min Apgar score and chorioamnionitis (p=0.021). CONCLUSIONS: ETCO2 and SpO2 levels during early resuscitation in the delivery suite were associated with adverse outcomes.

Comparison of mainstream end tidal carbon dioxide on Y-piece side versus patient side of heat and moisture exchanger filters in critically ill adult patients: a prospective observational study.

The purpose of the study was to investigate the accuracy of mainstream EtCO2 measurements on the Y-piece (filtered) side of the heat and moisture exchanger filter (HMEF) in adult critically ill patients, compared to that on the patient (unfiltered) side of HMEF. We conducted a prospective observational method comparison study between July 2019 and December 2019. Critically ill adult patients receiving mechanical ventilation with HMEF were included. We performed a noninferiority comparison of the accuracy of EtCO2 measurements on the two sides of HMEF. The accuracy was measured by the absolute difference between PaCO2 and EtCO2. We set the non-inferiority margin at + 1 mmHg in accuracy difference between the two sides of HMEF. We also assessed the agreement between PaCO2 and EtCO2 using Bland-Altman analysis. Among thirty-seven patients, the accuracy difference was - 0.14 mmHg (two-sided 90% CI - 0.58 to 0.29), and the upper limit of the CI did not exceed the predefined margin of + 1 mmHg, establishing non-inferiority of EtCO2 on the Y-piece side of HMEF (P for non-inferiority < 0.001). In the Bland-Altman analyses, 95% limits of agreement between PaCO2 and EtCO2 were similar on both sides of HMEF (Y-piece side, - 8.67 to + 10.65 mmHg; patient side, - 8.93 to + 10.67 mmHg). The accuracy of mainstream EtCO2 measurements on the Y-piece side of HMEF was noninferior to that on the patient side in critically ill adults. Mechanically ventilated adult patients could be accurately monitored with mainstream EtCO2 on the Y-piece side of the HMEF unless their tidal volume was extremely low.

Comparison between mainstream (Capnostat 5) and a low-flow sidestream capnometer (Capnostream) in mechanically ventilated, sevoflurane-anesthetized rabbits using a Bain coaxial delivery system.

OBJECTIVE: To evaluate agreement between end-tidal carbon dioxide (Pe'CO2) and PaCO2 with sidestream and mainstream capnometers in mechanically ventilated anesthetized rabbits, with two ventilatory strategies. STUDY DESIGN: Prospective experimental study. ANIMALS: A total of 10 New Zealand White rabbits weighing 3.6 ± 0.3 kg (mean ± standard deviation). METHODS: Rabbits anesthetized with sevoflurane were intubated with an uncuffed endotracheal tube (3.0 mm internal diameter) and adequate seal. For Pe'CO2, the sidestream capnometer sampling adapter or the mainstream capnometer was placed between the endotracheal tube and Bain breathing system (1.5 L minute-1 oxygen). PaCO2 was obtained from arterial blood collected every 5 minutes. A time-cycled ventilator delivered an inspiratory time of 1 second and 12 or 20 breaths minute-1. Peak inspiratory pressure was initially set to achieve Pe'CO2 normocapnia of 35-45 mmHg (4.6-6.0 kPa). A total of five paired Pe'CO2 and PaCO2 measurements were obtained with each ventilation mode for each capnometer. Anesthetic episodes were separated by 7 days. Agreement was assessed using Bland-Altman analysis and linear mixed models; p < 0.05. RESULTS: There were 90 and 83 pairs for the mainstream and sidestream capnometers, respectively. The mainstream capnometer underestimated PaCO2 by 12.6 ± 2.9 mmHg (proportional bias 0.44 ± 0.06 mmHg per 1 mmHg PaCO2 increase). With the sidestream capnometer, ventilation mode had a significant effect on Pe'CO2. At 12 breaths minute-1, Pe'CO2 underestimated PaCO2 by 23.9 ± 8.2 mmHg (proportional bias: 0.81 ± 0.18 mmHg per 1 mmHg PaCO2 increase). At 20 breaths minute-1, Pe'CO2 underestimated PaCO2 by 38.8 ± 5.0 mmHg (proportional bias 1.13 ± 0.10 mmHg per 1 mmHg PaCO2 increase). CONCLUSIONS AND CLINICAL RELEVANCE: Both capnometers underestimated PaCO2. The sidestream capnometer underestimated PaCO2 more than the mainstream capnometer, and was affected by ventilation mode.

Airways management in SARS-COV-2 acute respiratory failure: A prospective observational multi-center study.

Objective: Few studies have reported the implications and adverse events of performing endotracheal intubation for critically ill COVID-19 patients admitted to intensive care units. The aim of the present study was to determine the adverse events related to tracheal intubation in COVID-19 patients, defined as the onset of hemodynamic instability, severe hypoxemia, and cardiac arrest. Setting: Tertiary care medical hospitals, dual-centre study performed in Northern Italy from November 2020 to May 2021. Patients: Adult patients with positive SARS-CoV-2 PCR test, admitted for respiratory failure and need of advanced invasive airways management. Interventions: Endotracheal Intubation Adverse Events. Main variables of interests: The primary endpoint was to determine the occurrence of at least 1 of the following events within 30 minutes from the start of the intubation procedure and to describe the types of major adverse peri-intubation events: severe hypoxemia defined as an oxygen saturation as measured by pulse-oximetry <80%; hemodynamic instability defined as a SBP 65 mmHg recoded at least once or SBP < 90 mmHg for 30 minutes, a new requirement or increase of vasopressors, fluid bolus >15 mL/kg to maintain the target blood pressure; cardiac arrest. Results: Among 142 patients, 73.94% experienced at least one major adverse peri-intubation event. The predominant event was cardiovascular instability, observed in 65.49% of all patients undergoing emergency intubation, followed by severe hypoxemia (43.54%). 2.82% of the patients had a cardiac arrest. Conclusion: In this study of intubation practices in critically ill patients with COVID-19, major adverse peri-intubation events were frequent. Clinical Trial registration: www.clinicaltrials.gov identifier: NCT04909476.

Objetivo: Pocos estudios han informado las implicaciones y los eventos adversos de realizar una intubación endotraqueal para pacientes críticos con COVID-19 ingresados ​​en unidades de cuidados intensivos. El objetivo del presente estudio fue determinar los eventos adversos relacionados con la intubación traqueal en pacientes con COVID-19, definidos como la aparición de inestabilidad hemodinámica, hipoxemia severa y paro cardíaco. Ámbito: Hospitales médicos de atención terciaria, estudio de doble centro realizado en el norte de Italia desde noviembre de 2020 hasta mayo de 2021. Pacientes: Pacientes adultos con prueba PCR SARS-CoV-2 positiva, ingresados por insuficiencia respiratoria y necesidad de manejo avanzado de vías aéreas invasivas. Intervenciones: Eventos adversos de la intubación endotraqueal. Principales variables de interés: El punto final primario fue determinar la ocurrencia de al menos 1 de los siguientes eventos dentro de los 30 minutos posteriores al inicio del procedimiento de intubación y describir los tipos de eventos adversos periintubación mayores. : hipoxemia severa definida como una saturación de oxígeno medida por pulsioximetría <80%; inestabilidad hemodinámica definida como PAS 65 mmHg registrada al menos una vez o PAS < 90 mmHg durante 30 minutos, nuevo requerimiento o aumento de vasopresores, bolo de líquidos > 15 mL/kg para mantener la presión arterial objetivo; paro cardiaco. Resultados: Entre 142 pacientes, el 73,94% experimentó al menos un evento periintubación adverso importante. El evento predominante fue la inestabilidad cardiovascular, observada en el 65,49% de todos los pacientes sometidos a intubación de urgencia, seguido de la hipoxemia severa (43,54%). El 2,82% de los pacientes tuvo un paro cardíaco. Conclusión: En este estudio de prácticas de intubación en pacientes críticos con COVID-19, los eventos adversos periintubación mayores fueron frecuentes. Registro de ensayos clínicos: www.clinicaltrials.gov identificador: NCT04909476.

Value of variation of end-tidal carbon dioxide for predicting fluid responsiveness during the passive leg raising test in patients with mechanical ventilation: a systematic review and meta-analysis.

BACKGROUND: The ability of end-tidal carbon dioxide (ΔEtCO2) for predicting fluid responsiveness has been extensively studied with conflicting results. This meta-analysis aimed to explore the value of ΔEtCO2 for predicting fluid responsiveness during the passive leg raising (PLR) test in patients with mechanical ventilation. METHODS: PubMed, Embase, and Cochrane Central Register of Controlled Trials were searched up to November 2021. The diagnostic odds ratio (DOR), sensitivity, and specificity were calculated. The summary receiver operating characteristic curve was estimated, and the area under the curve (AUROC) was calculated. Q test and I2 statistics were used for study heterogeneity and publication bias was assessed by Deeks' funnel plot asymmetry test. We performed meta-regression analysis for heterogeneity exploration and sensitivity analysis for the publication bias. RESULTS: Overall, six studies including 298 patients were included in this review, of whom 149 (50%) were fluid responsive. The cutoff values of ΔEtCO2 in four studies was 5%, one was 5.8% and the other one was an absolute increase 2 mmHg. Heterogeneity between studies was assessed with an overall Q = 4.098, I2 = 51%, and P = 0.064. The pooled sensitivity and specificity for the overall population were 0.79 (95% CI 0.72-0.85) and 0.90 (95% CI 0.77-0.96), respectively. The DOR was 35 (95% CI 12-107). The pooled AUROC was 0.81 (95% CI 0.77-0.84). On meta-regression analysis, the number of patients was sources of heterogeneity. The sensitivity analysis showed that the pooled DOR ranged from 21 to 140 and the pooled AUC ranged from 0.92 to 0.96 when one study was omitted. CONCLUSIONS: Though the limited number of studies included and study heterogeneity, our meta-analysis confirmed that the ΔEtCO2 performed moderately in predicting fluid responsiveness during the PLR test in patients with mechanical ventilation.

Cardiopulmonary exercise testing in patients with moderate-severe obesity: a clinical evaluation tool for OSA?

PURPOSE: Obstructive sleep apnea (OSA) is a widespread comorbidity of obesity. Nasal continuous positive airway pressure (CPAP) has been demonstrated very effective in treating patients with OSA. The aims of this study were to investigate whether or not cardiopulmonary exercise testing (CPET) can characterize patients with OSA and to evaluate the effect of nasal CPAP therapy. METHODS: An observational study was conducted on patients with moderate to severe obesity and suspected OSA. All patients underwent cardiorespiratory sleep study, spirometry, and functional evaluation with ECG-monitored, incremental, maximal CPET. RESULTS: Of the 147 patients, 94 presented with an apnea-hypopnea index (AHI) ≥ 15 events/h and were thus considered to have OSA (52 receiving nasal CPAP treatment; 42 untreated) while 53 formed a control group (AHI < 15 events/h). Patients with untreated OSA showed significantly lower oxygen uptake (VO2), heart rate, minute ventilation (VE), and end tidal carbon dioxide (PETCO2) at peak exercise compared to controls. Patients receiving nasal CPAP showed higher VE and VO2 at peak exercise compared to untreated patients. A difference in PETCO2 between the maximum value reached during test and peak exercise (ΔPETCO2 max-peak) of 1.71 mmHg was identified as a predictor of OSA. CONCLUSION: Patients with moderate to severe obesity and untreated OSA presented a distinctive CPET-pattern characterized by lower aerobic and exercise capacity, higher PETCO2 at peak exercise associated with a lower ventilatory response. Nasal CPAP treatment was shown to positively affect these cardiorespiratory adaptations during exercise. ΔPETCO2 max-peak may be used to suggest OSA in patients with obesity.

Low initial in-hospital end-tidal carbon dioxide predicts poor patient outcomes and is a useful trauma bay adjunct.

INTRODUCTION: Appropriate triage of the trauma patient is critical. Low end-tidal carbon dioxide (ETCO2) is associated with mortality and hemorrhagic shock in trauma, but the relationship between low ETCO2 and important clinical variables is not known. This study investigates the association of initial in-hospital ETCO2 and patient outcomes, as well as the utility of ETCO2 as a predictive aid for blood transfusion. METHODS: Adult patients who presented to a Level One trauma center from 2019 to 2020 were eligible. Trauma bay ETCO2 measured by side-stream capnography was prospectively obtained for all trauma activations at time of initial evaluation. Using the Liu method of cut point estimation, patients were stratified as having low (≤29.5 mmHg) or normal ETCO2 (>29.5 mmHg). Multivariable regression was used to estimate the association of low ETCO2 with patient outcomes. RESULTS: A total of 955 patients underwent initial in-hospital ETCO2 measurement. Median time from arrival to ETCO2 measurement was 4 min. Among admitted patients (N = 493), 48.9% had low ETCO2. Compared to patients with normal ETCO2, those with low ETCO2 were older (median age 53 vs 46, p = 0.01) and more likely to have the highest trauma activation (27.4% vs 19.8%, p = 0.048). There was no difference in head injury. After adjustment, patients with low ETCO2 had greater odds of blood transfusion (OR 4.65, 95%CI 2.0-10.7), mortality (OR 5.10, 95%CI 1.1-24.9), inferior disposition (OR 1.64, 95%CI 1.1-2.6), and complications (OR 3.35, 95%CI 1.5-7.4). ETCO2 was more predictive of early blood transfusion than Shock Index (area under ROC = 67.6% vs 58.2%). CONCLUSIONS: Low trauma bay ETCO2 remains significantly associated with inferior clinical outcomes after adjustment. In comparison to other triage tools, low ETCO2 values may be more predictive of the need for blood transfusion. Further studies are needed to evaluate the role of ETCO2 as a decision making tool for early trauma management.

Comparison of blood flow between two mechanical compression devices using ultrasound: Animal trial.

BACKGROUND: During manual chest compression, maintaining accurate compression depth and consistency is a challenge. Therefore, mechanical chest compression devices(mCCDs) have been increasingly incorporated in clinical practice. Evaluation and comparison of the efficacy of these devices is critical for extensive clinical application. Hence, this study compared the cardiopulmonary resuscitation(CPR) efficiency of two chest compression devices, LUCAS™ 3(Physio-Control, Redmond, USA) and Easy Pulse (Schiller Medizintechnik GMBH, Feldkirchen, Germany), in terms of blood flow using ultrasonography(USG) in a swine model. METHODS: A swine model was used to compare two mCCDs, LUCAS™ 3 and Easy Pulse. Cardiac arrest was induced by injecting potassium chloride(KCl) solution in eight male mongrel pigs and the animals were randomly divided into two groups. Mechanical CPR was provided to two groups using LUCAS™ 3(LUCAS™ 3 group) and Easy Pulse(Easy Pulse group). USG was used to measure hemodynamic parameters including femoral peak systolic velocity(PSV) and femoral artery diameters(diameter during systole and diastole). Blood flow rate was calculated by multiplying the PSV and cross-sectional area of the femoral artery during systole. The end-tidal carbon dioxide(EtCo2), chest compression depth was measured. Systolic blood pressure, mean blood pressure, and diastolic blood pressure were also measured using an arterial catheter. RESULTS: The chest compression depth was much deeper in LUCAS™ 3 group than Easy Pulse group(LUCAS™ 3: 6.80 cm; Easy Pulse: 3.279 cm, p < 0.001). However, EtCo2 was lower in the LUCAS™ 3 group(LUCAS™ 3: 19.8 mmHg; Easy Pulse: 33.4 mmHg, p < 0.001). The PSV was higher in the LUCAS™ 3 group(LUCAS™ 3: 67.6 cm s-1; Easy Pulse: 55.0 cm s-1, p < 0.001), while the systolic(LUCAS™ 3: 1.5 cm; Easy Pulse: 2.0 cm, p < 0.001) and diastolic diameters were larger in the Easy Pulse group(LUCAS™ 3: 0.4; Easy Pulse: 0.8 cm, p < 0.001). The femoral flood flow rate was also lower in the LUCAS™ 3 group(LUCAS™ 3: 32.55 cm3/s; Easy Pulse: 61.35 cm3/s, p < 0.001). CONCLUSION: The Easy Pulse had a shallower compression depth and slower PSV but had a wider systolic diameter in the femoral artery as compared to that in LUCAS™ 3. Blood flow and EtCo2 were higher in the easy pulse group probably because of the wider diameter. Therefore, an easy pulse may create and maintain more effective intrathoracic pressure.

Difference between arterial and end-tidal carbon dioxide and adverse events after non-cardiac surgery: a historical cohort study.

PURPOSE: The difference between arterial and end-tidal partial pressure of carbon dioxide (ΔCO2) is a measure of alveolar dead space, commonly evaluated intraoperatively. Given its relationship to ventilation and perfusion, ΔCO2 may provide prognostic information and guide clinical decisions. We hypothesized that higher ΔCO2 values are associated with occurrence of a composite outcome of re-intubation, postoperative mechanical ventilation, or 30-day mortality in patients undergoing non-cardiac surgery. METHODS: We conducted a historical cohort study of adult patients undergoing non-cardiac surgery with an arterial line at a single tertiary care medical centre. The composite outcome, identified from electronic health records, was re-intubation, postoperative mechanical ventilation, or 30-day mortality. Student's t test and Chi-squared test were used for univariable analysis. Logistic regression was used for multivariable analysis of the relationship of ΔCO2 with the composite outcome. RESULTS: A total of 19,425 patients were included in the final study population. Univariable analysis showed an association between higher mean (standard deviation [SD]) intraoperative ΔCO2 values and the composite outcome (6.1 [5.3] vs 5.7 [4.5] mm Hg; P = 0.002). After adjusting for baseline subject characteristics, every 5-mm Hg increase in the ΔCO2 was associated with a nearly 20% increased odds of the composite outcome (odds ratio, 1.20; 95% confidence interval, 1.12 to 1.28; P < 0.001). CONCLUSIONS: In this patient population, increased intraoperative ΔCO2 was associated with an increased odds of the composite outcome of postoperative mechanical ventilation, re-intubation, or 30-day mortality that was independent of its relationship with pre-existing pulmonary disease. Future studies are needed to determine if ΔCO2 can be used to guide patient management and improve patient outcomes.

RéSUMé: OBJECTIF: La différence entre la pression partielle artérielle et télé-expiratoire en dioxyde de carbone (ΔCO2) est une mesure de l'espace mort alvéolaire couramment évaluée en période peropératoire. Compte tenu de sa relation avec la ventilation et la perfusion, la ΔCO2 pourrait fournir des informations pronostiques et guider les décisions cliniques. Nous avons émis l'hypothèse que des valeurs de ΔCO2 plus élevées seraient associées à l'apparition d'un résultat composite de réintubation, de ventilation mécanique postopératoire ou de mortalité à 30 jours chez les patients bénéficiant d'une chirurgie non cardiaque. MéTHODE: Nous avons mené une étude de cohorte historique de patients adultes bénéficiant d'une chirurgie non cardiaque dans un seul centre médical de soins tertiaires et chez lesquels une canule artérielle était installée. Le résultat composite, identifié à partir des dossiers de santé électroniques, était la réintubation, la ventilation mécanique postopératoire ou la mortalité à 30 jours. Le test t de Student et le test du chi carré ont été utilisés pour l'analyse univariée. La régression logistique a été utilisée pour l'analyse multivariée de la relation entre la ΔCO2 et le résultat composite. RéSULTATS: Au total, 19 425 patients ont été inclus dans la population finale à l'étude. L'analyse univariée a montré une association entre des valeurs peropératoires moyennes plus élevées (écart type [ET]) de ΔCO2 et le résultat composite (6,1 [5,3] vs 5,7 [4,5] mmHg; P = 0,002). Après ajustement pour tenir compte des caractéristiques de base des sujets, chaque augmentation de 5 mmHg de la ΔCO2 a été associée à une augmentation de près de 20 % de la probabilité du résultat composite (rapport de cotes, 1,20; intervalle de confiance à 95 %, 1,12 à 1,28; P < 0,001). CONCLUSION: Dans cette population de patients, une augmentation peropératoire de la ΔCO2 était associée à une probabilité accrue du résultat composite de ventilation mécanique postopératoire, de réintubation ou de mortalité à 30 jours, indépendamment de sa relation avec une maladie pulmonaire préexistante. D'autres études sont nécessaires à l'avenir pour déterminer si la ΔCO2 peut être utilisée pour guider la prise en charge des patients et améliorer les devenirs des patients.