Automated Compressions During CPR; Severe TBI Patient Destinations
Automated Compressions, Contrasting Results
Hallstrom A, Rea TD, Sayre MR, et al. Manual chest compression vs. use of an automated chest-compression device during resuscitation following out-of-hospital cardiac arrest: A randomized trial. JAMA 295(22):2,620-8, Jun 14, 2006.
Abstract: Context/objective-To compare resuscitation outcomes following out-of-hospital cardiac arrest when an automated load-distributing band (LDB) CPR device was added to standard emergency medical services (EMS) care with manual CPR. Design, setting and patients-Multicenter, randomized trial of patients experiencing out-of-hospital cardiac arrest in the United States and Canada. The a priori primary population was patients with cardiac arrest that was presumed to be of cardiac origin and that had occurred prior to the arrival of EMS personnel. Initial study enrollment varied by site, ranging from late July to mid-November 2004; all sites halted study enrollment on March 31, 2005. Intervention-Standard EMS care for cardiac arrest with an LDB CPR device (n=554) or manual CPR (n=517). Main outcome measures-The primary endpoint was survival to four hours after the 9-1-1 call. Secondary endpoints were survival to hospital discharge and neurological status among survivors.
Results-Following the first planned interim monitoring conducted by an independent data and safety monitoring board, study enrollment was terminated. No difference existed in the primary endpoint of survival to four hours between the manual CPR group and the LDB CPR group overall (n=1,071; 29.5% vs. 28.5%, p=0.74) or among the primary study population (n=767; 24.7% vs. 26.4%, p=0.62). However, among the primary population, survival to hospital discharge was 9.9% in the manual CPR group and 5.8% in the LDB CPR group (p=0.06). A cerebral performance category of 1 or 2 at hospital discharge was recorded in 7.5% of patients in the manual CPR group and 3.1% of the LDB CPR group (p=0.006). Conclusions-Use of an automated LDB CPR device as implemented in this study was associated with worse neurological outcomes and a trend toward worse survival than manual CPR. Device design or implementation strategies require further evaluation.
Ong ME, Ornato JP, Edwards DP, et al. Use of an automated, load-distributing band chest-compression device for out-of-hospital cardiac arrest resuscitation. JAMA 295(22):2,629-37, Jun 14, 2006.
Abstract: Objective-To compare resuscitation outcomes before and after an urban emergency medical services system switched from manual cardiopulmonary resuscitation to LDB CPR. Design-A phased, observational cohort evaluation with intention-to-treat analysis of 783 adults with out-of-hospital nontraumatic cardiac arrest. A total of 499 patients were included in the manual CPR phase (Jan. 1, 2001-March 31, 2003), and 284 patients in the LDB CPR phase (Dec. 20, 2003-March 31, 2005); of these patients, the LDB device was applied in 210 patients. Intervention-Urban EMS system change from manual CPR to LDB CPR. Main outcome measures-Return of spontaneous circulation (ROSC), with secondary outcome measures of survival to hospital admission and hospital discharge, and neurological outcome at discharge.
Results-Patients in the manual CPR and LDB CPR phases were comparable except for a faster response time interval (mean difference: 26 seconds) and more EMS-witnessed arrests (18.7% vs. 12.6%) with LDB. Rates for ROSC and survival were increased with LDB CPR compared with manual CPR (for ROSC, 34.5% [95% CI, 29.2%-40.3%] vs. 20.2% [95% CI, 16.9%-24.0%], adjusted odds ratio 1.94 [95% CI, 1.38-2.72]; for survival to hospital admission, 20.9% vs. 11.1%; and for survival to hospital discharge, 9.7% vs. 2.9%). In secondary analysis of the 210 patients for whom the LDB device was applied, 38 (18.1%) survived to hospital admission, and 12 (5.7%) survived to hospital discharge. Among patients in the manual CPR and LDB CPR groups who survived to hospital discharge, there was no significant difference in cerebral performance category (p=0.36) or overall performance category (p=0.40). The number needed to treat for the adjusted outcome survival to discharge was 15. Conclusion-Compared with resuscitation using manual CPR, a resuscitation strategy using LDB CPR on EMS ambulances is associated with improved survival to hospital discharge in adults with out-of-hospital nontraumatic cardiac arrest.
Comment: Here is a nice example of how complex and confusing prehospital research can be. These two studies, published in the same issue of a well-respected medical journal, using the same device on the same patients, come up with the exact opposite conclusions.
CPR may improve both cardiac and brain resuscitation in patients with cardiac arrest. Moreover, it appears that properly performed CPR (correct compression depth and rate, minimal interruptions) is even better. It would make sense, then, that a device that could compress the chest circumferentially at an exact and unwavering rate and depth would at least be as good as manual CPR, and quite likely better.
The ZOLL AutoPulse is an automated load-distributing band (LDB) chest-compression device that performs excellent and consistent CPR. However, when it was compared to manual CPR in the first study, the patients on whom the AutoPulse was used did worse-decreased survival and worse neurological outcomes. But in the second study, the AutoPulse patients did better. Why? This was most likely due to the differences in study design. In scientific experiments, it is essential that all variables other than the one being studied are the same in the control and experimental groups. In EMS this is exceedingly difficult, as patients, prehospital personnel, response times and many other factors all vary. Here, addressing those complexities differently caused the opposing findings.
So, which is the "correct" answer? At this point we do not know, as neither study was clearly superior.
Trauma-Center Transport for Patients With Severe TBI
Hartl R, Gerber LM, Iacono L, et al. Direct transport within an organized state trauma system reduces mortality in patients with severe traumatic brain injury. J Trauma 60(6):1,250-6, Jun 2006.
Abstract: This multicenter study was conducted to explore the effect of prehospital management decisions on early mortality after severe TBI. Methods-This report is based on 1,449 patients with severe TBI (GCS<9) treated at 22 trauma centers enrolled in a New York state quality improvement (QI) program between 2000-04. The prehospital data collected on these patients included time of injury, time of arrival to the trauma center, mode of transport, type of EMS provider, direct or indirect transport, blood pressure and pulse oximetry values, GCS score, pupillary assessment and airway management procedures. Results-After exclusion criteria were applied, a total of 1,123 patients were eligible for analysis. The majority were male (75%), with a mean age of 36 years. After controlling for arterial hypotension, age, pupillary status and initial GCS score, direct transport was found to result in significantly lower mortality than indirect transport. Transport mode, time to admission and prehospital intubation were not found to be related to two-week mortality. Conclusions-The study provides class II evidence that demonstrates a 50% increase in mortality associated with indirect transfer of TBI patients. Patients with severe TBI should be transported directly to a Level I or Level II trauma center with capabilities as delineated in the Guidelines for the Prehospital Management of Traumatic Brain Injury, even if this center may not be the closest hospital.
Comment: As we gain more experience with trauma systems, we are able to better determine how they can best improve care. There are essentially two mechanisms to get trauma patients to definitive care. One is to transport them to the closest hospital for evaluation and stabilization (when possible) and then secondarily transfer those who need a higher level of care to a trauma center. The second is to identify those who are likely to require the expertise of a trauma center in the field and triage them directly to a trauma center. This report provides good evidence that with those patients for whom findings indicate a severe brain injury, it may be better to triage them directly to a trauma center. EMS systems should consider this in the design of their systems.
