Effect of arrest time on the hemodynamic efficacy of precordial compression.

OBJECTIVES

To evaluate the efficacy of conventional threshold levels of coronary perfusion pressure and end-tidal CO2 as predictors of resuscitability after prolonged cardiac arrest.

DESIGN

Prospective, randomized, controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Twenty-one Sprague-Dawley rats, including three groups of seven animals in each group.

INTERVENTIONS

Ventricular fibrillation was untreated for 9, 12, or 15 mins. After an additional 5-min interval of precordial compression, external direct current defibrillation was attempted.

MEASUREMENTS AND MAIN RESULTS

All animals were successfully resuscitated after 9 mins of ventricular fibrillation but less than one half of the animals were successfully resuscitated after 15 mins of ventricular fibrillation. Each of seven animals survived for 24 hrs after 9 mins of untreated ventricular fibrillation but none of the animals survived after 15 mins of ventricular fibrillation. In this experimental setting, neither coronary perfusion pressure nor end-tidal CO2 produced by precordial compression was predictive of outcomes when the animals underwent progressively longer intervals of untreated cardiac arrest.

CONCLUSIONS

The efficacy of precordial compression--as measured by coronary perfusion pressure and end-tidal CO2 concentration after prolongation of untreated cardiac arrest--was not overtly compromised. However, the previously established critical threshold levels of coronary perfusion pressure and end-tidal CO2 failed as predictors of resuscitability after prolonged intervals of untreated cardiac arrest.