Pragmatic Airway Resuscitation Trial Research Articles

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.

Abstract 432: Temporal Trends in End Tidal Capnography and Outcomes in Out of Hospital Cardiac Arrest

Background: While widely measured and used to direct resuscitation, the time-varying relationship between exhaled end-tidal CO2 (ETCO2) and out-of-hospital cardiac arrest (OHCA) outcomes is unclear. We sought to determine the association between temporal trends in ETCO2 and return of spontaneous circulation (ROSC) in the Pragmatic Airway Resuscitation Trial (PART). Methods: We analyzed data from the PART Trial, which tested endotracheal intubation or laryngeal tube strategies in OHCA resuscitation. Emergency medical services collected continuous ETCO2 recordings using defibrillator monitors. We identified maximal ETCO2 values for each ventilation using previously validated automated signal processing. We determined mean ETCO2 in one-minute(min) epochs from advanced airway insertion through ROSC or end of event. We included all cases with interpretable ETCO2 signal in at least one of the epochs. We compared discrete time points between ROSC and non-ROSC using one way Mann-Whitney and determined the association between temporal trends in ETCO2 comparing the slopes of ETCO2 over time. Results: We included 1147 of 3004 patients with available ETCO2 data. There were 225(20%) ROSC and 923(80%) non-ROSC cases. Mean duration of resuscitation was 16 and 27 minutes for ROSC and non-ROSC cases, respectively. In ROSC cases, ETCO2 increased from 26.8 to 48.9 mmHg over 20-min prior to ROSC. In non-ROSC cases, ETCO2 declined from 30.6 to 21.7 mmHg over the 20-min. Mean ETCO 2 between ROSC and non-ROSC cases did not differ at t-10 (30.6 mmHg vs 26.1 mmHg, p=0.07) or t-20 min (26.8 mmHg vs 30.6 mmHg, p=0.71). However, ETCO 2 changes over time differed between ROSC and non-ROSC (p&lt;0.01, figure 1). Conclusions: Upward temporal increases in ETCO 2 are associated with ROSC. Dynamic time-varying changes in ETCO2 may indicate OHCA outcomes.

Methods for calculating ventilation rates during resuscitation from out-of-hospital cardiac arrest

ObjectiveVentilation control is important during resuscitation from out-of-hospital cardiac arrest (OHCA). We compared different methods for calculating ventilation rates (VR) during OHCA. MethodsWe analyzed data from the Pragmatic Airway Resuscitation Trial, identifying ventilations through capnogram recordings. We determined VR by: 1) counting the number of breaths within a time epoch (“counted” VR), and 2) calculating the mean of the inverse of measured time between breaths within a time epoch (“measured” VR). We repeated the VR estimates using different time epochs (10, 20, 30, 60 sec). We defined hypo- and hyperventilation as VR <6 and >12 breaths/min, respectively. We assessed differences in estimated hypo- and hyperventilation with each VR measurement technique. ResultsOf 3,004 patients, data were available for 1,010. With the counted method, total hypoventilation increased with longer time epochs ([10-s epoch: 75 sec hypoventilation] to [60-s epoch: 97 sec hypoventilation]). However, with the measured method, total hypoventilation decreased with longer time epochs ([10-s epoch: 223 sec hypoventilation] to [60-s epoch: 150 sec hypoventilation]). With the counted method, the total duration of hyperventilation decreased with longer time epochs ([10-s epochs: 35 sec hyperventilation] to [60-s epoch: 0 sec hyperventilation]). With the measured method, total hyperventilation decreased with longer time epochs ([10-s epoch: 78 sec hyperventilation] to [60-s epoch: 0 sec hyperventilation]). Differences between the measured and counted estimates were smallest with a 60-s time epoch. ConclusionsQuantifications of hypo- and hyperventilation vary with the applied measurement methods. Measurement methods are important when characterizing ventilation rates in OHCA.

Abstract 198: Finding The Sweet Spot Of Chest Compression Rate And Fraction For Improved OHCA 72-hour Survival

Introduction: Cardiac arrest resuscitation guidelines recommend optimization of both chest compression rate (CCR) and fraction (CCF). Simultaneous management of CCR and CCF is challenging. The interaction between CCR and CCF is unknown. Our objective was to evaluate the influence of CCR, CCF and their interactions upon OHCA 72-hour survival. Methods: Retrospective analysis of adult OHCA in the Pragmatic Airway Resuscitation Trial (PART). We determined CCF and CCR from automated signal analysis of available CPR process files. CCF categories were &lt;80%, 80-89.99%, and ≥90%. CCR categories were &lt;100, 100-129.99, and ≥130 per minute. The primary outcome was 72-hour survival. We evaluated the multiplicative interaction between CCR and CCF using a) heat maps, and b) linear mixed modeling with EMS agency as a random effect, adjusted for Utstein variables. Results: Of 3,004 enrolled patients, we included 1,606 with available CPR process data. Mean CCR and CCF were 114 compressions/min (SD 9.96) and 88% (SD 0.08). On linear mixed modeling, CCR of &lt;100 (OR 1.55, 95% CI 0.98, 2.44) and ≥130 (OR 1.29, 95% CI 0.86-1.95), referent 100-129.99, was not associated with improved 72-hour survival. A CCF of &lt;80% (OR 1.55, 95% CI 0.98, 2.44) and ≥90% (OR 1.29, 95% CI 0.86-1.95), referent 120-129.99, was also not associated with improved 72-hour survival. Further, the interaction of CCR and CCF was not associated with improved 72-hour survival (p=0.22). Heat map analysis indicated 72-hour survival was lowest when both CCF &lt;80% and CCR &lt;100 per minute, and highest when CCF &gt;90% and CCR &lt;130 per minute (Figure). Conclusion: The interaction between CCR and CCF may influence 72-hour survival. Rescuers must seek to optimize both CCR and CCF during resuscitation attempts. Research in cardiac arrest outcomes should consider this relationship and plan to have sufficient power to explore varying CCR and CCF values when examining OHCA survival.

Abstract 164: Efficacy Of Thoracic Impedance For Ventilation Detection During Continuous Chest Compressions

Introduction: Current technologies to identify ventilations during out-of-hospital cardiac arrest (OHCA) are limited. Thoracic impedance (TI) recorded by defibrillator pads can be used to identify ventilations, but these are often obscured by artifacts due to chest compressions (CC) and electrode motion. We tested a novel automatic algorithm to detect ventilations in TI during continuous CC. Methods: We analyzed Philips MRx CPR processed data from Dallas - Fort Worth patients in the Pragmatic Airway Resuscitation Trial. We extracted one-minute TI segments during continuous CC with concurrent capnogram recordings. We applied a novel algorithm to identify ventilation in the TI signal, which combined a) adaptive signal processing to remove CC artifacts, b) a recurrent neural network to discriminate TI fluctuations as ventilations, and c) a quality control stage to anticipate TI segments in which ventilation detection could be defective. We evaluated the performance of the algorithm in detecting ground truth capnogram ventilations in terms of sensitivity (SE), proportion of correctly identified ventilations, and Positive Predictive Value (PPV), proportion of detections corresponding to actual ventilations. Results: We extracted 2,551 one-minute TI segments from 367 OHCA patients; median of 6 (IQR 3-10) minutes per patient. Median patient-wise SE and PPV were 86.5 (IQR 71.6 - 95.1) % and 85.4 (68.3 - 94.7) %, respectively. The quality control was successful at discriminating TI segments by ventilation detection performance (Figure). For the 75% and 50% of data with highest quality estimates, SE improved to 90.6 (76.8 - 96.7) % and 95.5 (87.1 - 100.0) %, respectively, and PPV improved to 89.5 (75.0 - 96.4) % and 94.9 (87.3 - 99.8) %, respectively. Conclusions: We demonstrated the accuracy of an algorithm to detect ventilations using TI during continuous CC. Ventilation detection using TI during continuous CC is feasible.

Assessment of intensive care unit-free and ventilator-free days as alternative outcomes in the pragmatic airway resuscitation trial

ObjectiveWe sought to evaluate the utility and validity of ICU-free days and ventilator-free days as candidate outcomes for OHCA trials. MethodsWe conducted a secondary analysis of the Pragmatic Airway Resuscitation Trial. We determined ICU-free (days alive and out of ICU during the first 30 days) and ventilator-free days (days alive and without mechanical ventilation). We determined ICU-free and ventilator-free day distributions and correlations with Modified Rankin Scale (MRS). We tested associations with trial interventions (laryngeal tube (LT), endotracheal intubation (ETI)) using continuous (t-test), non-parametric (Wilcoxon Rank-Sum test - WRS), count (negative binomial - NB) and survival models (Cox proportional hazards (CPH) and competing risks regression (CRR)). We conducted bootstrapped simulations to estimate statistical power. MAIN ResultsICU-free days was skewed; median 0 days (IQR 0, 0), survivors only 24 (18, 27). Ventilator-free days was skewed; median 0 (IQR 0, 0) days, survivors only 27 (IQR 23, 28). ICU-free and ventilator-free days correlated with MRS (Spearman’s ρ = -0.95 and -0.97). LT was associated with higher ICU-free days using t-test (p = 0.001), WRS (p = 0.003), CPH (p = 0.02) and CRR (p = 0.04), but not NB (p = 0.13). LT was associated with higher ventilator-free days using t-test (p = 0.001), WRS (p = 0.001) and CRR (p = 0.03), but not NB (p = 0.13) or CPH (p = 0.13). Simulations suggested that t-test and WRS would have had the greatest power to detect the observed ICU- and ventilator-free days differences. ConclusionICU-free and ventilator-free days correlated with MRS and differentiated trial interventions. ICU-free and ventilator-free days may have utility in the design of OHCA trials.

Airway strategy and ventilation rates in the pragmatic airway resuscitation trial

BackgroundWe sought to describe ventilation rates during out-of-hospital cardiac arrest (OHCA) resuscitation and their associations with airway management strategy and outcomes. MethodsWe analyzed continuous end-tidal carbon dioxide capnography data from adult OHCA enrolled in the Pragmatic Airway Resuscitation Trial (PART). Using automated signal processing techniques, we determined continuous ventilation rates for consecutive 10-second epochs after airway insertion. We defined hypoventilation as a ventilation rate < 6 breaths/min. We defined hyperventilation as a ventilation rate > 12 breaths/min. We compared differences in total and percentage post-airway hyper- and hypoventilation between airway interventions (laryngeal tube (LT) vs. endotracheal intubation (ETI)). We also determined associations between hypo-/hyperventilation and OHCA outcomes (ROSC, 72-hour survival, hospital survival, hospital survival with favorable neurologic status). ResultsAdequate post-airway capnography were available for 1,010 (LT n = 714, ETI n = 296) of 3,004 patients. Median ventilation rates were: LT 8.0 (IQR 6.5–9.6) breaths/min, ETI 7.9 (6.5–9.7) breaths/min. Total duration and percentage of post-airway time with hypoventilation were similar between LT and ETI: median 1.8 vs. 1.7 minutes, p = 0.94; median 10.5% vs. 11.5%, p = 0.60. Total duration and percentage of post-airway time with hyperventilation were similar between LT and ETI: median 0.4 vs. 0.4 minutes, p = 0.91; median 2.1% vs. 1.9%, p = 0.99. Hypo- and hyperventilation exhibited limited associations with OHCA outcomes. ConclusionIn the PART Trial, EMS personnel delivered post-airway ventilations at rates satisfying international guidelines, with only limited hypo- or hyperventilation. Hypo- and hyperventilation durations did not differ between airway management strategy and exhibited uncertain associations with OCHA outcomes.

The association of race with CPR quality following out-of-hospital cardiac arrest

IntroductionPrevious studies have shown racial disparities in outcomes after out-of-hospital cardiac arrest. Although several treatment factors may account for these differences, there is limited information regarding differences in CPR quality and its effect on survival in underrepresented racial populations. MethodsWe conducted a secondary analysis of data from patients enrolled in the Pragmatic Airway Resuscitation Trial (PART). We calculated compliance rates with AHA 2015 high quality CPR metrics as well as compliance to intended CPR strategy (30:2 or continuous chest compression) based on the protocol in place for the first responding EMS agency. The primary analysis used general estimating equations logistic regression to examine differences between black and white patients based on EMS-assessed race after adjustment for potential confounders. Sensitivity analyses examined differences using alternate race definitions. ResultsThere were 3004 patients enrolled in PART of which 1734 had > 2 minutes of recorded CPR data and an EMS-assessed race (1003 white, 555 black, 176 other). Black patients had higher adjusted odds of compression rate compliance (OR: 1.36, 95% CI: 1.02–1.81) and lower adjusted odds of intended CPR strategy compliance (OR: 0.78, 95% CI: 0.63–0.98) compared to white patients. Of 974 transported to the hospital, there was no difference in compliance metric estimates based on ED-reported race. ConclusionCompression rate compliance was higher in black patients however compliance with intended strategy was lower based on EMS-assessed race. The remaining metrics showed no difference suggesting that CPR quality differences are not important contributors to the observed outcome disparities by race.

Abstract 13110: Novel Application of Thoracic Impedance to Characterize Ventilations During Cardiopulmonary Resuscitation in the Pragmatic Airway Resuscitation Trial

Introduction: Controlled ventilation is important in OHCA resuscitation, but there are few validated methods for accurate detection of ventilations. We sought to utilize changes in thoracic impedance (TI) to characterize resuscitation ventilations in the Pragmatic Airway Resuscitation Trial (PART). Methods: We analyzed CPR process files collected from adult OHCA enrolled in PART. We limited the analysis to cases with simultaneous capnography ventilation recordings at the Dallas-Ft Worth site. We identified ventilation waveforms in the thoracic impedance signal by applying automated signal processing with adaptive filtering techniques to remove overlying artifacts from chest compressions. We correlated detected ventilations with the end-tidal capnography signal. We determined the amplitudes (Ai, Ae) and durations (Di, De) of both insufflation and exhalation phases of the ventilation impedance signal (Figure 1). We compared differences between laryngeal tube (LT) and endotracheal intubation (ETI) airway management during mechanical or manual chest compressions using Mann-Whitney U-test. Results: We included 303 CPR process cases in the analysis; 209 manual (77 ETI, 132 LT), 94 mechanical (41 ETI, 53 LT). Ventilation Ai and Ae were higher for ETI than LT in both manual (ETI: Ai 0.71Ω, Ae 0.70Ω vs LT: Ai 0.46Ω Ae 0.45Ω, p&lt;0.01 respectively) and mechanical chest compressions (ETI: Ai 1.22Ω, Ae 1.14Ω VS LT: Ai 0.74Ω, Ae 0.68Ω, p&lt;0.01 respectively). Ventilations per minute, duration of TI amplitude insufflation and exhalation did not differ among groups. Conclusion: Compared with LT, ETI thoracic impedance ventilation insufflation and exhalation amplitude were higher while duration did not differ. TI may provide a novel approach to characterizing ventilation during OHCA.

Abstract 10874: Evaluation of Intensive Care Unit and Ventilator-free Days as Alternative Outcomes in Out-of-Hospital Cardiac Arrest Trials

Objective: Compared with traditional out-of-hospital cardiac arrest (OHCA) trial outcomes such as hospital survival, alternative outcomes such as intensive care unit-free (IFD) and ventilator-free days (VFD) have potential advantages including requiring smaller sample sizes to detect significant differences. Few studies have evaluated these outcomes in OHCA. We sought to evaluate the utility and validity of IFD and VFD as candidate outcomes for OHCA trials. Methods: We analyzed data from the Pragmatic Airway Resuscitation Trial (PART), which tested laryngeal tube (LT) vs. endotracheal intubation (ETI) airway strategies in adult OHCA. We defined IFD as the number of days alive and permanently out of ICU during the first 30 days after the OHCA event. We examined IFD distribution and correlation with Modified Rankin Scale (MRS). To test associations with trial interventions, we applied a range of analytic strategies, including modeling IFD as continuous (Generalized Estimating Equations - GEE), non-parametric (Wilcoxon Rank-Sum test - WRS) and count (zero-inflated negative binomial regression - ZINB) data. We also modeled time-to-ICU discharge using a survival model with death as a competing risk. We repeated the analysis assessing VFD. Results: IFD was available for 2,898 of 3,004 patients. IFD was skewed and J-shaped; 91% IFD=0 and 5.3% IFD≥22. Mean (±SD) IFD was 2.0±6.6 days; 21.2±7.5 days for survivors. IFD varied by intervention (LT 2.4±7.2, ETI 1.6±5.8 days). IFD and VFD strongly correlated with MRS (ρ= -0.88, -0.89). LT was associated with increased IFD using GEE, WRS, and ZINB, but not competing risks model. (Table) LT was associated with increased VFD using GEE and WRS, but not ZINB or competing risks models. Conclusion: IFD and VFD differentiated OHCA interventions, suggesting their utility. IFD and VFD were highly correlated with MRS, suggesting validity. IFD and VFD have important features that may influence OHCA trial design.

Association of Advanced Airway Insertion Timing and Outcomes After Out-of-Hospital Cardiac Arrest

While often prioritized in the resuscitation of patients with out-of-hospital cardiac arrest, the optimal timing of advanced airway insertion is unknown. We evaluated the association between the timing of advanced airway (laryngeal tube and endotracheal intubation) insertion attempt and survival to hospital discharge in adult out-of-hospital cardiac arrest. We performed a secondary analysis of the Pragmatic Airway Resuscitation Trial (PART), a clinical trial comparing the effects of laryngeal tube and endotracheal intubation on outcomes after adult out-of-hospital cardiac arrest. We stratified the cohort by randomized airway strategy (laryngeal tube or endotracheal intubation). Within each subset, we defined a time-dependent propensity score using patients, arrest, and emergency medical services systems characteristics. Using the propensity score, we matched each patient receiving an initial attempt of laryngeal tube or endotracheal intubation with a patient at risk of receiving laryngeal tube or endotracheal intubation attempt within the same minute. Of 2,146 eligible patients, 1,091 (50.8%) and 1,055 (49.2%) were assigned to initial laryngeal tube and endotracheal intubation strategies, respectively. In the propensity score-matched cohort, timing of laryngeal tube insertion attempt was not associated with survival to hospital discharge: 0 to lesser than 5 minutes (risk ratio [RR]=1.35, 95% confidence interval [CI] 0.53 to 3.44); 5 to lesser than10 minutes (RR=1.07, 95% CI 0.66 to 1.73); 10 to lesser than 15 minutes (RR=1.17, 95% CI 0.60 to 2.31); or 15 to lesser than 20 minutes (RR=2.09, 95% CI 0.35 to 12.47) after advanced life support arrival. Timing of endotracheal intubation attempt was also not associated with survival: 0 to lesser than 5 minutes (RR=0.50, 95% CI 0.05 to 4.87); 5 to lesser than10 minutes (RR=1.20, 95% CI 0.51 to 2.81); 10 to lesser than15 minutes (RR=1.03, 95% CI 0.49 to 2.14); 15 to lesser than 20 minutes (RR=0.85, 95% CI 0.30 to 2.42); or more than/equal to 20 minutes (RR=0.71, 95% CI 0.07 to 7.14). In the PART, timing of advanced airway insertion attempt was not associated with survival to hospital discharge.

Novel application of thoracic impedance to characterize ventilations during cardiopulmonary resuscitation in the pragmatic airway resuscitation trial

BackgroundSignificant challenges exist in measuring ventilation quality during out-of-hospital cardiopulmonary arrest (OHCA) outcomes. Since ventilation is associated with outcomes in cardiac arrest, tools that objectively describe ventilation dynamics are needed. We sought to characterize thoracic impedance (TI) oscillations associated with ventilation waveforms in the Pragmatic Airway Resuscitation Trial (PART). MethodsWe analyzed CPR process files collected from adult OHCA enrolled in PART. We limited the analysis to cases with simultaneous capnography ventilation recordings at the Dallas-Fort Worth site. We identified ventilation waveforms in the thoracic impedance signal by applying automated signal processing with adaptive filtering techniques to remove overlying artifacts from chest compressions. We correlated detected ventilations with the end-tidal capnography signals. We determined the amplitudes (Ai, Ae) and durations (Di, De) of both insufflation and exhalation phases. We compared differences between laryngeal tube (LT) and endotracheal intubation (ETI) airway management during mechanical or manual chest compressions using Mann-Whitney U-test. ResultsWe included 303 CPR process cases in the analysis; 209 manual (77 ETI, 132 LT), 94 mechanical (41 ETI, 53 LT). Ventilation Ai and Ae were higher for ETI than LT in both manual (ETI: Ai 0.71 Ω, Ae 0.70 Ω vs LT: Ai 0.46 Ω, Ae 0.45 Ω; p < 0.01 respectively) and mechanical chest compressions (ETI: Ai 1.22 Ω, Ae 1.14 Ω VS LT: Ai 0.74 Ω, Ae 0.68 Ω; p < 0.01 respectively). Ventilations per minute, duration of TI amplitude insufflation and exhalation did not differ among groups. ConclusionCompared with LT, ETI thoracic impedance ventilation insufflation and exhalation amplitude were higher while duration did not differ. TI may provide a novel approach to characterizing ventilation during OHCA.

Airway strategy and chest compression quality in the Pragmatic Airway Resuscitation Trial

BackgroundChest compression (CC) quality is associated with improved out-of-hospital cardiopulmonary arrest (OHCA) outcomes. Airway management efforts may adversely influence CC quality. We sought to compare the effects of initial laryngeal tube (LT) and initial endotracheal intubation (ETI) airway management strategies upon chest compression fraction (CCF), rate and interruptions in the Pragmatic Airway Resuscitation Trial (PART). MethodsWe analyzed CPR process files collected from adult OHCA enrolled in PART. We used automated signal processing techniques and a graphical user interface to calculate CC quality measures and defined interruptions as pauses in chest compressions longer than 3 s. We determined CC fraction, rate and interruptions (number and total duration) for the entire resuscitation and compared differences between LT and ETI using t-tests. We repeated the analysis stratified by time before, during and after airway insertion as well as by successive 3-min time segments. We also compared CC quality between single vs. multiple airway insertion attempts, as well as between bag-valve-mask (BVM-only) vs. ETI or LT. ResultsOf 3004 patients enrolled in PART, CPR process data were available for 1996 (1001 LT, 995 ETI). Mean CPR analysis duration were: LT 22.6 ± 10.8 min vs. ETI 25.3 ± 11.3 min (p < 0.001). Mean CC fraction (LT 88% vs. ETI 87%, p = 0.05) and rate (LT 114 vs. ETI 114 compressions per minute (cpm), p = 0.59) were similar between LT and ETI. Median number of CC interruptions were: LT 11 vs. ETI 12 (p = 0.001). Total CC interruption duration was lower for LT than ETI (LT 160 vs. ETI 181 s, p = 0.002); this difference was larger before airway insertion (LT 56 vs. ETI 78 s, p < 0.001). There were no differences in CC quality when stratified by 3-min time epochs. ConclusionIn the PART trial, compared with ETI, LT was associated with shorter total CC interruption duration but not other CC quality measures. CC quality may be associated with OHCA airway management.

Airway insertion first pass success and patient outcomes in adult out-of-hospital cardiac arrest: The Pragmatic Airway Resuscitation Trial

ObjectiveWhile emphasized in clinical practice, the association between advanced airway insertion first-pass success (FPS) and patient outcomes is incompletely understood. We sought to determine the association of airway insertion FPS with adult out-of-hospital cardiac arrest (OHCA) outcomes in the Pragmatic Airway Resuscitation Trial (PART). MethodsWe performed a secondary analysis of PART, a multicenter clinical trial comparing LT and ETI upon adult OHCA outcomes. We defined FPS as successful LT insertion or ETI on the first attempt as reported by EMS personnel. We examined the outcomes return of spontaneous circulation (ROSC), 72-h survival, hospital survival, and hospital survival with favorable neurologic status (Modified Rankin Scale ≤3). Using multivariable GEE (generalized estimating equations), we determined the association between FPS and OHCA outcomes, adjusting for age, sex, witnessed arrest, bystander CPR, initial rhythm, and initial airway type. ResultsOf 3004 patients enrolled in the trial, 1423 received LT, 1227 received ETI, 354 received bag-valve-mask ventilation only. FPS was: LT 86.2% and ETI 46.7%. FPS was associated with increased ROSC (aOR 1.23; 95%CI: 1.07–1.41)), but not 72-h survival (1.22; 0.94–1.58), hospital survival (0.90; 0.68–1.19) or hospital survival with favorable neurologic status (0.66; 0.37–1.19). ConclusionIn adult OHCA, airway insertion FPS was associated with increased ROSC but not other OHCA outcomes. The influence of airway insertion FPS upon OHCA outcomes is unclear.

Abstract 206: Effect of Airway Strategy Upon Chest Compression Quality in the Pragmatic Airway Resuscitation Trial

Background: Chest compression (CC) quality is associated with improved out-of-hospital (OHCA) outcomes. Airway management efforts may adversely influence CC quality. We sought to compare the effects of initial laryngeal tube (LT) and initial endotracheal intubation (ETI) airway management strategies upon chest compression fraction (CCF), rate and interruptions in the Pragmatic Airway Resuscitation Trial (PART). Methods: We analyzed CPR process files collected from adult OHCA enrolled in PART. We used automated signal processing techniques (MATLAB) to identify and calculate CC quality measures. We defined a CC interruption as ≥3 second pause in chest compressions. We determined CC fraction, rate and interruptions (number and total duration) in 1-minute epochs for the entire resuscitation. We compared differences in CC quality between LT and ETI using t-tests. We repeated the analysis stratified by time before/after airway insertion as well as by successive 3-minute time segments. We also compared CC quality between single vs. multiple airway insertion attempts, as well as between BVM-only vs. ETI or LT. Results: Of 3,004 patients enrolled in PART, CPR process data were available for 1,996 (1,001 LT, 995 ETI). Mean resuscitation duration was: LT 22.6±10.8 min, ETI 25.3±11.3 min. Mean CC fraction (88% vs. 87%, p=0.045) and rate (114 vs. 114 bpm, p=0.59) were similar between LT and ETI. Median number of CC interruptions was similar between LT and ETI (11 vs. 12). Total CC interruption duration was lower for LT than ETI (160 vs. 181 sec, p=0.002); this difference was largest before airway insertion (56 vs. 78 sec, p=0.001). There were no differences in CC quality when stratified by 3-min time epochs. Total CC interruption duration was shorter for single than multiple airway insertion attempts (127 vs. 153 sec, p=0.005). Total CC interruption duration was shorter for BVM-only than LT or ETI (104 vs. 135 sec, p&lt;0.001). Conclusion: In PART, compared with ETI, LT was associated with shorter total CC interruption duration but not other CC quality measures. Single-attempt airway insertion and BVM-only were associated with shorter total CC interruption duration. OHCA airway management may influence CC quality.

Abstract 201: Bougie-Assisted Endotracheal Intubation in the Pragmatic Airway Resuscitation Trial

Objective: Paramedics often perform endotracheal intubation (ETI) in the management of out-of-hospital cardiac arrest (OHCA). While ETI assisted by use of the gum elastic Bougie has been associated with improved first-pass intubation success in the emergency department, its influence upon out-of-hospital cardiac arrest (OHCA) ETI is unknown. We compared success rates and outcomes between Bougie-assisted and standard ETI in the Pragmatic Airway Resuscitation Trial (PART). Methods: We conducted a secondary analysis of PART, a clinical trial comparing initial-ETI vs. initial-laryngeal tube airway management strategies in adult OHCA. We included only patients receiving initial ETI attempts. The primary exposure was Bougie-assisted vs. standard ETI. The primary outcome was first-pass ETI success. Secondary outcomes included overall ETI success, time to successful ETI, 72-hour survival, hospital survival and hospital survival with favorable neurologic status. We assessed the associations between Bougie-assistance and ETI outcomes using Generalized Estimating Equations and Cox Regression, adjusting for for age, sex, race, witnessed arrest, bystander CPR and initial rhythm. Results: Of the 3,004 patients enrolled in PART, 1,227 received initial ETI, including 440 Bougie-assisted and 787 standard ETI. First-pass ETI success did not differ between Bougie-assisted and standard ETI (53.1% vs. 42.8%; adjusted OR 1.12, 95% CI: 0.97 to 1.39). Overall ETI success was slightly higher for Bougie-assisted ETI (56.2% vs. 49.1%; adjusted OR 1.19, 95% CI: 1.01 to 1.32). Time to ETI was longer for Bougie-assisted than standard ETI (median 13 vs. 11 min; adjusted HR 0.63, 95% CI: 0.45 to 0.90). While survival to hospital discharge was lower for Bougie-assisted than standard ETI (3.6% vs. 7.5%; adjusted OR 0.94, 95% CI: 0.92 to 0.96), there were no differences in 72-hour survival or hospital survival with favorable neurologic status. Conclusion: In the PART trial, Bougie assistance resulted in slightly higher overall ETI success but with longer airway placement time. Bougie assistance was not associated with first-pass ETI success. The association between Bougie-assisted ETI and OHCA survival was unclear. The role of Bougie-assisted ETI in OHCA is uncertain.

Abstract 203: Thoracic Impedance Reflects Differences Between Endotracheal and Laryngeal Advanced Airway During Mechanical Chest Compressions

Background: Ventilations during out-of-hospital cardiac arrest (OHCA) produce thoracic impedance(TI) waveforms due to air volume changes in the lungs. Different airway management techniques, i.e. laryngeal tube (LT) and endotracheal intubation (ETI), may produce distinct TI waveforms as a result of different air flows and dead space volumes. Methods: Adult OHCA cases from the Pragmatic Airway Resuscitation Trial were analyzed. Cases recorded with Philips MRx monitor-defibrillators and treated with LUCAS mechanical CPR devices were considered, ensuring homogeneous TI acquisition and compression therapy. Impedance and capnogram signal intervals were extracted after successful airway insertion and during ongoing chest compressions. Ventilations were confirmed in the capnogram, and the associated TI waveforms were analyzed. Adaptive filtering was applied to remove compression artifacts, and the amplitudes (A i , A e ) and durations (D i , D e ) of the insufflation and exhalation phases were computed (see Figure). Each case was characterized by its observed median values. Differences between airway groups were assessed with a Wilcoxon rank sum test. Results: Data from 100 OHCA cases (57 LT and 43 ETI) were analyzed, totaling 10348 ventilations, with median (IQR) of 87 (51 - 146) ventilations per case. Median TI amplitudes for ETI and LT groups showed significant differences (p&lt;0.05), with 1.1 (0.7 - 1.8) Ω and 0.7 (0.3 - 1.3) Ω for A i , and 1.0 (0.7 - 1.6) Ω and 0.6 (0.3 - 1.2) Ω for A e . No significant differences were observed for phase durations, 1.6 (1.3 - 2.0) s and 1.6 (1.2 - 1.8) s for D i , and 2.3 (1.8 - 3.3) s and 2.6 (2.0 - 3.3) s for D e . Conclusions: Significant differences on ventilation impedance waveform amplitudes were observed between patients treated with ETI and LT. This might be related to higher insufflated air volumes for ETI or larger dead space volumes for LT.

Bougie-assisted endotracheal intubation in the pragmatic airway resuscitation trial

ObjectiveParamedics may perform endotracheal intubation (ETI) while treating patients with out-of-hospital cardiac arrest (OHCA). The gum elastic Bougie (Bougie) is an intubation adjunct that may optimize intubation success. There are few reports of Bougie-assisted intubation in OHCA nor its association with outcomes. We compared intubation success rates and OHCA outcomes between Bougie-assisted and non-Bougie ETI in the out-of-hospital Pragmatic Airway Resuscitation Trial (PART). MethodsThis was a secondary analysis of patients receiving ETI enrolled in the Pragmatic Airway Resuscitation Trial (PART), a multicenter clinical trial comparing intubation-first vs. laryngeal tube-first strategies of airway management in adult OHCA. The primary exposure was use of Bougie for ETI-assistance. The primary endpoint was first-pass ETI success. Secondary endpoints included overall ETI success, time to successful ETI, return of spontaneous circulation, 72-h survival, hospital survival and hospital survival with favorable neurologic status (Modified Rankin Score ≤3). We analyzed the data using Generalized Estimating Equations and Cox Regression, adjusting for known confounders. ResultsOf the 3004 patients enrolled in PART, 1227 received ETI, including 440 (35.9%) Bougie-assisted and 787 (64.1%) non-Bougie ETIs. First-pass ETI success did not differ between Bougie-assisted and non-Bougie ETI (53.1% vs. 42.8%; adjusted OR 1.12, 95% CI: 0.97–1.39). ETI overall success was slightly higher in the Bougie-assisted group (56.2% vs. 49.1%; adjusted OR 1.19, 95% CI: 1.01–1.32). Time to endotracheal tube placement or abandonment was longer for Bougie-assisted than non-Bougie ETI (median 13 vs. 11 min; adjusted HR 0.63, 95% CI: 0.45–0.90). While survival to hospital discharge was lower for Bougie-assisted than non-Bougie ETI (3.6% vs. 7.5%; adjusted OR 0.94, 95% CI: 0.92–0.96), there were no differences in ROSC, 72-h survival or hospital survival or hospital survival with favorable neurologic status. ConclusionWhile exhibiting slightly higher ETI overall success rates, Bougie-assisted ETI entailed longer airway placement times and potentially lower survival. The role of the Bougie assistance in ETI of OHCA remains unclear.

Racial disparities in out-of-hospital cardiac arrest interventions and survival in the Pragmatic Airway Resuscitation Trial

BackgroundPrior studies have reported racial disparities in survival from out-of-hospital cardiac arrest (OHCA). However, these studies did not evaluate the association of race with OHCA course of care and outcomes. The purpose of this study was to evaluate racial disparities in OHCA airway placement success and patient outcomes in the multicenter Pragmatic Airway Resuscitation Trial (PART). MethodWe conducted a secondary analysis of adult OHCA patients enrolled in PART. The parent trial randomized subjects to initial advanced airway management with laryngeal tube or endotracheal intubation. For this analysis, the primary independent variable was patient race categorized by emergency medical services (EMS) as white, black, Hispanic, other, and unknown. We used general estimating equations to examine the association of race with airway attempt success, 72-h survival, and survival to hospital discharge, adjusting for sex, age, witness status, bystander cardiopulmonary resuscitation (CPR), initial rhythm, arrest location, and PART randomization cluster. ResultsOf 3002 patients, EMS-assessed race as 1537 white, 860 black, 163 Hispanic, 90 other, and 352 unknown. Initial shockable rhythms (13.8% vs. 21.5%, p < 0.001), bystander CPR (35.6% vs. 51.4%, p < 0.001), and survival to hospital discharge (7.6% vs. 10.8%, p = 0.011) were lower for black compared to white patients. After adjustment for confounders, no difference was seen in airway success, 72-h survival, and survival to hospital discharge by race. ConclusionsIn one of the largest studies evaluating differences in prehospital airway interventions and outcomes by EMS-assessed race for OHCA patients, we found no significant adjusted differences between airway success or survival outcomes.

Outcomes With the Use of Bag-Valve-Mask Ventilation During Out-of-hospital Cardiac Arrest in the Pragmatic Airway Resuscitation Trial.

While emergency medical services (EMS) often use endotracheal intubation (ETI) or supraglottic airways (SGA), some patients receive only bag-valve-mask (BVM) ventilation during out-of-hospital cardiac arrests (OHCA). Our objective was to compare patient characteristics and outcomes for BVM ventilation to advanced airway management (AAM) in adults with OHCA. Using data from the Pragmatic Airway Resuscitation Trial, we identified patients receiving AAM (ETI or a SGA), BVM ventilation only (BVM-only), and BVM ventilation as a rescue after at least one failed attempt at advanced airway placement (BVM-rescue). The outcomes were return of spontaneous circulation (ROSC), 72-hour survival, survival to hospital discharge, neurologically intact survival (Modified Rankin Scale≤3), and the presence of aspiration on a chest radiograph. Comparisons were made using generalized mixed-effects models while adjusting for age, sex, initial rhythm, EMS-witnessed status, bystander cardiopulmonary resuscitation, response time, study cluster, and advanced life support first on scene. Of 3,004 patients enrolled, there were 282 BVM-only, 2,129 AAM, and 156 BVM-rescue patients with complete covariates. Shockable initial rhythms (34% vs. 18.6%) and EMS-witnessed arrests (21.6% vs. 11.3%) were more likely in BVM-only than AAM but similar between BVM-rescue and AAM. Compared to AAM, BVM-only patients had similar ROSC (odds ratio [OR]= 1.29, 95% confidence interval [CI]= 0.96 to 1.73), but higher 72-hour survival (OR= 1.96, 95% CI= 1.42 to 2.69), survival to discharge (OR= 4.47, 95% CI= 3.03 to 6.59), and neurologically intact survival (OR= 7.05, 95% CI= 4.40 to 11.3). Compared to AAM, BVM-rescue patients had similar ROSC (OR= 0.73, 95% CI= 0.47 to 1.12) and 72-hour survival (OR= 1.08, 95% CI= 0.66 to 1.77) but higher survival to discharge (OR= 2.15, 95% CI= 1.17 to 3.95) and neurologically intact survival (OR= 2.64, 95% CI= 1.20 to 5.81). Aspiration incidence was similar. Bag-valve-mask-only ventilation is associated with improved OHCA outcomes. Despite similar rates of ROSC and 72-hour survival, BVM-rescue ventilation was associated with improved survival to discharge and neurologically intact survival compared to successful AAM.