Out-of-Hospital Cardiac Arrest Survival after the Sequential Implementation of 2005 AHA Guidelines for Compressions, Ventilations, and Induced HypothermiaJ. Brent Myers, MD MPHMedical DirectorWake County EMS System

AuthorsPaul Hinchey, MD MBA, WakeMed/Wake EMSBrent Myers, MD MPH, Wake EMS/WakeMedRyan Lewis, EMT-P, Wake EMSValerie De Maio, MD MSc, WakeMedEric Reyer, RN, WakeMedGraham Synder, MD, WakeMedGerald Maccioli, MD, Rex HealthcareDaniel Licastese, RN, Rex HealthcareRobert Lee, MS MA, WakeMed

DisclosurePaul Hinchey, Eric Reyer, and Brent Myers serve on the speakers bureau for Alsius Corporation

Capital County Research ConsortiumCommunity-based research group representing Rex Healthcare, Wake County EMS System, and WakeMed Health and Hospitals

Includes nurses, physicians, paramedics, and research support

Community Wide ProjectMulti-phase before and after clinical trial

All out-of-hospital cardiac arrests (OOH-CA) on a community wide basis were eligible for inclusion

Protocol Revision TimelineBaseline [Jan 2004-Apr 2005]: Traditional CPR, focus on airwayNew CPR [Apr 2005-Apr 2006]: Continuous compressions, delayed intubation for VF/VTImpedance Threshold Device (ITD) [Apr 2006-Oct 2006]Induced Hypothermia [Oct 2006-Oct 2007]

MethodsAll EMS records are maintained in an electronic databaseRecords with any of the following characteristics are reviewed to determine if cardiac arrest occurred:EMS Patient Disposition = cardiac arrestCPR procedure is recordedDefibrillation is recorded

Age less than 16Obvious traumatic origin of arrestEMS witnessed arrestArrest not in EMS controlPrison facilitiesOut-of-system interceptArrests under direction of non-EMS physician

Cases Excluded from Review

MethodsData were analyzed using logistic regression Covariates offered for the regression:AgeGenderResponse time for the first defibrillatorWitnessed statusLocation

MethodsPrimary outcome was the proportion of OOH-CA patients for whom resuscitation was attempted that survived to discharge in baseline vs. hypothermia phasesSecondary outcomes include (by phase):Pulse at emergency department, survival to admission, neurological intact survival to dischargeAdditionally, results were stratified by initial rhythm

MethodsNeurologically intact survival was defined as CPC 1 or 2 at time of hospital discharge or discharge from rehabilitation if transferred directly from hospital2 blinded physician reviewers from each hospital independently assigned CPC scores based on patient records

Results3124 OOH-CA occurred during the study period1442 obvious deaths (no resuscitation attempted)1682 attempted resuscitations484 of 1682 were excluded due to:119 not under EMS control/not a code109 obvious traumatic origin 70 under the age of 16206 EMS witnessed1198 met inclusion criteria

Results

Total OOH-CAN= 1198Baseline N = 372New CPRN= 319ITDN= 148HypothermiaN= 359

NOTE: no statistically significant difference between study periods

Mean Age65Percent male58%Private Residence81%Witnessed Status36%Bystander CPR 36%Mean Defibrillator Response5.3 6.1 minsInitially VF/VT26%

Survival All Rhythms4.6%7.3%8.2%11.6%* when compared with baselineP

Survival VF/VT12%22%29%37%* When compared with baselineP

Percentage of All Attempted Resuscitations Neuro Intact1.9%4.4%6.2%7.8%* When compared with baselineP

Neurologically intact VF/VT10%17%20%28%* When compared with baselineP

Comparison of Outcomes Hypothermia vs. Baseline* P

Multivariate Odds of Survival

FactorOdds95% CIAge0.970.96-0.98Residence0.500.31-0.82Bystander CPR2.181.34-3.54New CPR2.371.10-4.96ITD2.991.29-6.95Hypothermia3.671.86-7.26

DiscussionConfoundersRemoval of stacked defibrillationsProtocol-driven pre- and post-resuscitation cardiac arrest careImprovement with procedures due to repetitionHawthorne effectIntention-to-treat analysis

ConclusionThe sequential implementation of 2005 AHA guidelines for compressions, ventilations, and induced hypothermia lead to significant improvements in neurologically intact survival for cardiac arrest in this urban/suburban community.

www.wakeems.com/saem

Criteria for Induced HypothermiaROSC after cardiac arrest not related to trauma or hemorrhageAge 16 years or greaterFemale without obviously gravid uterusInitial temperature >34 CPatient is intubated (no RSI)Patient remains comatose without purposeful response to pain

Multivariate Odds of Neuro Intact Survival

FactorOdds95% CIAge0.970.96-0.98Bystander CPR2.651.49-4.71New CPR3.191.10-9.26ITD4.951.61-15.21Hypothermia6.212.35-16.41

Sample Database Entry

BackgroundWake County/Raleigh, NC:Single, 3rd service EMS System with 65,000 calls/yearReliable firefighter first responseResident population of ~825,000 (add 100 per day)Post-resuscitation patients are selectively transported to one of 2 high volume PCI centers

Cardiac Arrest ResponseAll calls receive EMD from a single, high-volume centerFire first response with AED and compressionsParamedic response with transport ambulancesSupervisory response at paramedic level

*C=0.74