Exclusion of a patient assessment interval and extension of the CPR interval both mitigate post-resuscitation myocardial dysfunction in a swine model of cardiac arrest.
OBJECTIVE
Interruptions in cardiopulmonary resuscitation (CPR), particularly as guided by automated external defibrillators, have been implicated in poor survival from cardiac arrest. Interruptions of CPR may be reduced by eliminating repetition of shocks between periods of CPR, elimination of the interval for patient assessment before CPR, and extension of the periods of CPR.


METHODS
The effects of exclusion of a 30s post-shock assessment interval prior to CPR and use of a longer interval (180s versus 90s) of CPR on resuscitation and post-resuscitation function were assessed in a factorial design using an established swine model of cardiac arrest. Repetitive shocks were excluded. Ventricular fibrillation was induced ischemically and maintained untreated for 5min.


RESULTS
All subjects were resuscitated, 95% survived 3 days, and 97% of survivors had full neurological recovery. Exclusion of the assessment interval reduced the delay to first return of spontaneous circulation by 33.1s (P=0.004) and the delay to sustained resuscitation by 99.2s (P=0.004), reduced post-resuscitation ECG ST elevation by 0.12mV (P=0.03), and alleviated transient post-resuscitation ejection fraction reduction (P<0.0001). Extension of the CPR interval reduced transient post-resuscitation fractional area change impairment (P=0.003).


CONCLUSIONS
Exclusion of an interval for assessment of airway, breathing and signs of circulation mitigates post-resuscitation dysfunction in a swine model of cardiac arrest. Extension of the period of CPR independently provides measurable, though less comprehensive, mitigation as well.
Chang
Yun-Te
YT
Weil Institute of Critical Care Medicine, Rancho Mirage, CA 92270-1761, USA.
Tang
Wanchun
W
Russell
James K
JK
Ristagno
Giuseppe
G
Sun
Shijie
S
Weil
Max Harry
MH
D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects / Q000379:methods*; D047548:Defibrillators; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000009:adverse effects / Q000295:instrumentation*; D004562:Electrocardiography; D004632:Emergency Medical Services; D006323:Heart Arrest / Q000401:mortality / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D015996:Survival Rate; D013552:Swine; D016896:Treatment Outcome; D018754:Ventricular Dysfunction / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology