THE COMPENSATORY RESERVE INDEX FOR PREDICTING HEMORRHAGIC SHOCK IN PREHOSPITAL TRAUMA.

ABSTRACT: Background: The compensatory reserve index (CRI) is a noninvasive, continuous measure designed to detect intravascular volume loss. CRI is derived from the pulse oximetry waveform and reflects the proportion of physiologic reserve remaining before clinical hemodynamic decompensation. Methods: In this prospective, observational, prehospital cohort study, we measured CRI in injured patients transported by emergency medical services (EMS) to a single Level I trauma center. We determined whether the rolling average of CRI values over 60 s (CRI trend [CRI-T]) predicts in-hospital diagnosis of hemorrhagic shock, defined as blood product administration in the prehospital setting or within 4 h of hospital arrival. We hypothesized that lower CRI-T values would be associated with an increased likelihood of hemorrhagic shock and better predict hemorrhagic shock than prehospital vital signs. Results: Prehospital CRI was collected on 696 adult trauma patients, 21% of whom met our definition of hemorrhagic shock. The minimum CRI-T was 0.14 (interquartile range [IQR], 0.08-0.31) in those with hemorrhagic shock and 0.31 (IQR 0.15-0.50) in those without ( P = <0.0001). The positive likelihood ratio of a CRI-T value <0.2 predicting hemorrhagic shock was 1.85 (95% confidence interval [CI], 1.55-2.22). The area under the ROC curve (AUC) for the minimum CRI-T predicting hemorrhagic shock was 0.65 (95% CI, 0.60-0.70), which outperformed initial prehospital HR (0.56; 95% CI, 0.50-0.62) but underperformed EMS systolic blood pressure and shock index (0.74; 95% CI, 0.70-0.79 and 0.72; 95% CI, 0.67-0.77, respectively). Conclusions: Low prehospital CRI-T predicts blood product transfusion by EMS or within 4 hours of hospital arrival but is less prognostic than EMS blood pressure or shock index. The evaluated version of CRI may be useful in an austere setting at identifying injured patients that require the most significant medical resources. CRI may be improved with noise filtering to attenuate the effects of vibration and patient movement.

Increase in end-tidal carbon dioxide after defibrillation predicts sustained return of spontaneous circulation during out-of-hospital cardiac arrest.

INTRODUCTION: Guidelines recommend monitoring end-tidal carbon dioxide (ETCO2) during out-of-hospital cardiac arrest (OHCA), though its prognostic value is poorly understood. This study investigated the relationship between ETCO2 and return of spontaneous circulation (ROSC) after defibrillation in intubated non-traumatic OHCA patients. METHODS: This retrospective, observational cohort analysis included adult OHCA patients who received a defibrillation shock during treatment by an urban EMS agency from 2015 to 2021. Peak ETCO2 values were determined for the 90-second periods before and after the first defibrillation in an intubated patient (shock of interest [SOI]). Values were analyzed for association between the change in ETCO2 from pre- to post-shock and the presence of ROSC on the subsequent pulse check. RESULTS: Of 518 eligible patients, mean age was 61, 72% were male, 50% had a bystander-witnessed arrest, and 62% had at least one episode of ROSC. The most common arrest etiology was medical (92%). Among all patients, peak ETCO2 during resuscitation prior to SOI was 36.8 mmHg (18.6). ETCO2 increased in patients who achieved ROSC immediately after SOI (from 38.3 to 47.6 mmHg; +9.3 CI: 6.5, 12.1); patients with sustained ROSC experienced the greatest increase in ETCO2 after SOI (from 37.8 to 48.2 mmHg; +10.4 CI: 7.2, 13.6), while ETCO2 in patients who did not achieve ROSC after SOI rose (from 36.4 to 37.8 mmHg; +1.4 CI: -0.1, 2.8). CONCLUSIONS: ETCO2 rises after defibrillation in most patients during cardiac arrest. Patients with sustained ROSC experience larger rises, though the majority experience rises of less than 10 mmHg.

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

AIM: We sought to determine if the difference between PaCO2 and ETCO2 is associated with hospital mortality and neurologic outcome following out-of-hospital cardiac arrest (OHCA). METHODS: This was a retrospective cohort study of adult patients who achieved return of spontaneous circulation (ROSC) after OHCA over 3 years. The primary exposure was the PaCO2-ETCO2 difference on hospital arrival. The primary outcome was survival to hospital discharge. The secondary outcome was favorable neurologic status at discharge. We used receiver operating characteristic (ROC) curves to determine discrimination threshold and multivariate logistic regression to examine the association between the PaCO2-ETCO2 difference and outcome. RESULTS: Of 698 OHCA patients transported to the hospitals, 381 had sustained ROSC and qualifying ETCO2 and PaCO2 values. Of these, 160 (42%) survived to hospital discharge. Mean ETCO2 was 39 mmHg among survivors and 43 mmHg among non-survivors. Mean PaCO2-ETCO2 was 6.8 mmHg and 9.0 mmHg (p < 0.05) for survivors and non-survivors. After adjustment for Utstein characteristics, a higher PaCO2-ETCO2 difference on hospital arrival was not associated with hospital mortality (OR 0.99, 95% CI: 0.97-1.0) or neurological outcome. Area under the ROC curve or PaCO2-ETCO2 difference was 0.56 (95% CI 0.51-0.62) compared with 0.58 (95% CI 0.52-0.64) for ETCO2. CONCLUSION: Neither PaCO2-ETCO2 nor ETCO2 were strong predictors of survival or neurologic status at hospital discharge. While they may be useful to guide ventilation and resuscitation, these measures should not be used for prognostication after OHCA.

Investigating the Airway Opening Index during cardiopulmonary resuscitation.

INTRODUCTION: Chest compressions during CPR induce oscillations in capnography (ETCO2) waveforms. Studies suggest ETCO2 oscillation characteristics are associated with intrathoracic airflow dependent on airway patency. Oscillations can be quantified by the Airway Opening Index (AOI). We sought to evaluate multiple methods of computing AOI and their association with return of spontaneous circulation (ROSC). METHODS: We conducted a retrospective study of 307 out-of-hospital cardiac arrest (OHCA) cases in Seattle, WA during 2019. ETCO2 and chest impedance waveforms were annotated for the presence of intubation and CPR. We developed four methods for computing AOI based on peak ETCO2 and the oscillations in ETCO2 during chest compressions (ΔETCO2). We examined the feasibility of automating ΔETCO2 and AOI calculation and evaluated differences in AOI across the methods using nonparametric testing (α = 0.05). RESULTS: Median [interquartile range] AOI across all cases using Methods 1-4 was 28.0 % [17.9-45.5 %], 20.6 % [13.0-36.6 %], 18.3 % [11.4-30.4 %], and 22.4 % [12.8-38.5 %], respectively (p < 0.001). Cases with ROSC had a higher median AOI than those without ROSC across all methods, though not statistically significant. Cases with ROSC had a significantly higher median [interquartile range] ΔETCO2 of 7.3 mmHg [4.5-13.6 mmHg] compared to those without ROSC (4.8 mmHg [2.6-9.1 mmHg], p < 0.001). CONCLUSION: We calculated AOI using four proposed methods resulting in significantly different AOI. Additionally, AOI and ΔETCO2 were larger in cases achieving ROSC. Further investigation is required to characterize AOI's ability to predict OHCA outcomes, and whether this information can improve resuscitation care.

Analysis of Epinephrine Dose, Targeted Temperature Management, and Neurologic and Survival Outcomes Among Adults With Out-of-Hospital Cardiac Arrest.

Importance: Epinephrine improves return of spontaneous circulation after out-of-hospital cardiac arrest (OHCA). These beneficial cardiac effects do not directly translate to better neurologic outcomes, possibly because of epinephrine-induced microvascular effects that produce critical brain ischemia. Objective: To examine whether targeted temperature management (TTM) modifies the adverse association between increasing prehospital epinephrine dose and neurologically favorable survival. Design, Setting, and Participants: This retrospective cohort study assessed 14 612 adults from Seattle and King County, Washington, with nontraumatic OHCA between January 1, 2008, and December 31, 2018, and included those who achieved return of spontaneous circulation and were unconscious at hospital admission. Data analysis was performed from April 2021 to May 2022. Exposures: Epinephrine dose and TTM during prehospital resuscitation. Main Outcomes and Measures: Favorable neurologic survival (Cerebral Performance Category [CPC] 1 or 2) and survival to hospital discharge. Results: Of the 14 612 assessed adults, 5253 (median age, 63 years; IQR, 51-74 years; 3460 [65.8%] male) were eligible for the study. The median epinephrine dose was 2.0 mg (IQR, 1.0-3.0 mg); 3052 patients (58.1%) received TTM. In all, 1889 patients (36.0%) survived with CPC 1 to 2, and 2177 (41.4%) survived to discharge. Increasing doses of epinephrine were associated with a decreasing likelihood of CPC 1 to 2 (odds ratio [OR], 0.46; 95% CI 0.42-0.50 for each additional milligram of epinephrine) and survival (OR, 0.47; 95% CI, 0.43-0.51). The dose-dependent epinephrine association was modified by TTM. After adjusting for Utstein covariates, TTM was associated with a relative stepwise improvement in odds of CPC 1 to 2 (interaction OR, 1.36; 95% CI, 1.22-1.51) and survival (interaction OR, 1.37; 95% CI, 1.24-1.51). A significant interaction was also observed when the analysis was stratified according to initial rhythm among shockable OHCA and nonshockable OHCA (shockable interaction OR, 1.20; 95% CI, 1.04-1.39; and nonshockable interaction OR, 1.24, 95% CI, 1.07-1.45). Conclusions and Relevance: This cohort study found an interaction between TTM and epinephrine dose such that the beneficial association of TTM increased with increasing epinephrine dose, suggesting that TTM may attenuate the adverse effects of higher-dose epinephrine.

Prehospital end-tidal carbon dioxide predicts hemorrhagic shock upon emergency department arrival.

BACKGROUND: In addition to reflecting gas exchange within the lungs, end-tidal carbon dioxide (ETCO2) also reflects cardiac output based on CO2 delivery to the pulmonary parenchyma. We hypothesized that low prehospital ETCO2 values would be predictive of hemorrhagic shock in intubated trauma patients. METHODS: A retrospective observational study of adult trauma patients intubated in the prehospital setting and transported to a single Level I trauma center from 2016 to 2019. Continuous prehospital ETCO2 data were linked with patient care registries. We developed a novel analytic approach that allows for reflection of prehospital ETCO2 over the entire prehospital course of care. The primary outcome was hemorrhagic shock on emergency department (ED) presentation, defined as either initial ED systolic blood pressure of 90 mm Hg or less or initial Shock Index (SI) > 0.9, and transfusion of at least one unit of blood product during their ED stay. Prehospital ETCO2 less than 25 mm Hg was evaluated for predictive value of hemorrhagic shock. RESULTS: Three hundred and seven patients (82% men, 34% penetrating injury, 42% in hemorrhagic shock on ED arrival, 27% mortality) were included in the study. Patients in hemorrhagic shock had lower median ETCO2 values (26.5 mm Hg vs. 32.5 mm Hg; p < 0.001) than those not in hemorrhagic shock. Patients with prehospital ETCO2 less than 25 mm Hg were 3.0 times (adjusted odds ratio = 3.0; 95% confidence interval, 1.1-7.9) more likely to be in hemorrhagic shock upon ED arrival than patients with ETCO2 ≥ 25 mm Hg. CONCLUSION: Intubated patients with hemorrhagic shock upon ED arrival had significantly lower prehospital ETCO2 values. Incorporating ETCO2 assessment into prehospital care for trauma patients could support decisions regarding prehospital blood transfusion, and triage to higher-level trauma centers, and trauma team activation. LEVEL OF EVIDENCE: Prognostic, level III.

Fewer tracheal intubation attempts are associated with improved neurologically intact survival following out-of-hospital cardiac arrest.

BACKGROUND: International guidelines emphasize advanced airway management during out-of-hospital cardiac arrest (OHCA). We hypothesized that increasing endotracheal intubation attempts during OHCA were associated with a lower likelihood of favorable neurologic survival at discharge. METHODS: This retrospective, observational cohort evaluated the relationship between number of intubation attempts and favorable neurologic survival among non-traumatic OHCA patients receiving cardiopulmonary resuscitation (CPR) from January 1, 2015-June 30, 2019 in a large urban emergency medical services (EMS) system. Favorable neurologic status at hospital discharge was defined as a Cerebral Performance Category score of 1 or 2. Multivariable logistic regression, adjusted for age, sex, witness status, bystander CPR, initial rhythm, and time of EMS arrival, was performed using the number of attempts as a continuous variable. RESULTS: Over 54 months, 1205 patients were included. Intubation attempts per case were 1 = 757(63%), 2 = 279(23%), 3 = 116(10%), ≥4 = 49(4%), and missing/unknown in 4(<1%). The mean (SD) time interval from paramedic arrival to intubation increased with the number of attempts: 1 = 4.9(2.4) min, 2 = 8.0(2.9) min, 3 = 10.9(3.3) min, and ≥4 = 15.5(4.4) min. Final advanced airway techniques employed were endotracheal intubation (97%), supraglottic devices (3%), and cricothyrotomy (<1%). Favorable neurologic outcome declined with each additional attempt: 11% with 1 attempt, 4% with 2 attempts, 3% with 3 attempts, and 2% with 4 or more attempts (AOR = 0.41, 95% CI 0.25-0.68). CONCLUSIONS: Increasing number of intubation attempts during OHCA resuscitation was associated with lower likelihood of favorable neurologic outcome.

Improving quality of life in nursing homes: the structured resident interview approach.

The quality of life (QOL) of the approximately 1.5 million nursing facility (NF) residents in the US is undoubtedly lower than desired by residents, families, providers, and policy makers. Although there have been important advances in defining and measuring QOL for this population, there is a need for interventions that are tied to standardized measurement and quality improvement programs. This paper describes the development and testing of a structured, tailored assessment and care planning process for improving the QOL of nursing home residents. The Quality of Life Structured Resident Interview and Care Plan (QOL.SRI/CP) builds on a decade of research on measuring QOL and is designed to be easily implemented in any US nursing home. The approach was developed through extensive and iterative pilot testing and then tested in a randomized controlled trial in three nursing homes. Residents were randomly assigned to receive the assessment alone or both the assessment and an individualized QOL care plan task. The results show that residents assigned to the intervention group experienced improved QOL at 90- and 180-day follow-up, while QOL of residents in the control group was unchanged.