When controlling for known CPR quality variables, increases in CC depth, CC rate and CCRV were each associated with a statistically significant but clinically modest increase in EtCO2. Given the small effect sizes, the clinical utility of using EtCO2 to guide CPR performance is unclear. Further research is needed to determine the practicality and impact of using real-time EtCO2 to guide CPR delivery in the prehospital environment.

No abstract

Introduction: AHA guidelines emphasize the importance of limiting pauses during CPR to less than 10 seconds due to the association of interruptions in chest compressions (CC) with adverse outcomes. Previous literature has associated shorter peri-shock pause times with greater odds of survival and longest pause in CC with lower odds of survival, though these analyses were restricted to patients with initial shockable rhythm. The aim of this analysis is to investigate the association between CC pause duration and patient outcomes in all-rhythm OHCA. Methods: OHCA cases from three EMS Agencies in Arizona between Jan 2016-Dec 2016 (n=229) were analyzed. De-identified prehospital patient data were linked to outcome data as part of the state quality program. Pauses calculated from CPR pad accelerometer data were defined by a minimum duration of 1000 ms. Mean pause duration was calculated by case as the average of all pauses, while longest pause duration was defined as the single longest pause in CC. Descriptive statistics and multivariate logistic regression was performed in STATA 15.1. Primary outcome measures defined were ROSC, survival-to-discharge, and favorable neurological outcome (Cerebral Performance Category 1 or 2). Covariates included in the statistical model include time in CPR, age, witnessed arrest, initial shockable rhythm, bystander CPR, and CPR quality. Results: A total of 37.1% of patients (n=85) achieved prehospital ROSC, 12.7% (n=29) survived, and 10.5% (n=24) had favorable neurological outcome. Average mean and longest pause duration was 8.13 + 0.76 s and 24.93 + 2.84 in survivors with favorable neurological outcome compared to 9.21 + 0.47 s and 35.56 + 3.55 s in non-survivors. Mean pause duration was associated with survival (adjusted OR 0.89, 95% CI 0.80-0.99) and favorable neurological outcome (adjusted OR 0.83, 95% CI 0.72-0.97). Longest pause duration was associated with favorable neurological outcome (adjusted OR 0.97, 95% CI 0.94-1.00). Conclusions: Prolonged pauses in CC during prehospital resuscitation was associated with worse survival and neurological function in OHCA patients with all cardiac rhythms. Pause duration should be kept as brief as possible due to the impact upon outcomes regardless of presenting cardiac rhythm.

No abstract

Background: Little is known about the ventilatory aspects of overdose-related OHCA (OD-OHCA). We compared maximum ETCO2 (mETCO2; each patient’s highest CO2 level) and mean for each recorded minute of CPR in OD-OHCA to that of respiratory (R-OHCA) and cardiac (C-OHCA) arrests. Methods: Continuous CO2 data (Zoll E/X series monitors) were obtained from 3 Arizona EMS agencies. Cases had at least 3 min of recorded CO2 during CPR. Arrests were classified as OD-OHCA by EMS and/or hospital documentation. Any drug OD was included (e.g., opioids, mixed). C-OHCA and R-OHCA cases were randomly chosen for comparison. The groups were compared using Fisher’s exact test or Chi-squared for categorical and Kruskal-Wallis for continuous variables. Results: Included were 263 subjects (37 OD-OHCA, 157 C-OHCA and 69 R-OHCA; median age 61, 64% male, 1/10-12/18) with 10,271 min of data [median resuscitation interval 37 min (IQR 29, 47)]. Mean ETCO2 (SD): OD-OHCA [41 mmHg (24)]; R-OHCA [40 (23)], C-OHCA [30 (13); p<0.01]. Median mETCO2: OD-OHCA [57 mmHg (95CI: 50, 77)]; R-OHCA [61 (50, 73)], C-OHCA [48 (44, 50); p<0.001; Fig 1]. While mean ETCO2 and mETCO2 were similar for OD-OHCA and R-OHCA, they were both significantly higher than C-OHCA (p<0.01 for all comparisons). ETCO2 waveforms in OD-OHCA resembled the very high, full waveforms typical of R-OHCA while those in C-OHCA tended to be low and blunted. Conclusions: We believe this is the first report of continuous capnography during resuscitation of OD-OHCA. The mean ETCO2 and median of mETCO2 of OD-OHCA and R-OHCA imply similar physiology (hypoventilation and hypercapnia leading to arrest). Both etiologies had much higher ETCO2 values compared to C-OHCA, where low blood flow delivers minimal CO2 to the lungs and yields low, and morphologically different, waveforms. Future studies assessing OD arrest physiology and various approaches to resuscitation and pharmacological reversal are needed.