Reduced effectiveness of hypothermia in patients lacking the wave V in auditory brainstem responses immediately following resuscitation from cardiac arrest.

Aims: Therapeutic hypothermia appears to improve the outcome of pre-hospital cardio-pulmonary arrest (CPA) in patients with an initial cardiac rhythm of ventricular fibrillation or nonperfusing ventricular tachycardia (VF/VT). Notwithstanding, the outcome of this procedure is certainly difficult to predict based solely on the initial rhythm. The aim of the present study was to predict the outcome using auditory brainstem responses (ABRs) in CPA patients treated with therapeutic hypothermia.

Design And Setting: A prospective observational study in the intensive care unit of a university hospital.

Patients: The study included 26 patients resuscitated from out-of-hospital CPA.

Interventions: Basic and advanced cardiac life support, intensive care and post-resuscitative hypothermia.

Measurement And Results: ABRs were recorded immediately after the return of spontaneous circulation (ROSC). An ABR wave V was recorded in 16 patients. Among 8 patients with a favourable outcome, the initial rhythms were VF/VT in 6 patients and other rhythms in 2. All 10 patients without a detectable ABR wave V had an unfavourable outcome. The VF/VT as the initial arrest rhythm and the presence of wave V were significantly (p = 0.0095) correlated with a favourable outcome. The presence of wave V had a 100% sensitivity to a favourable outcome.

Conclusion: The absence of the ABR wave V in the early phase after ROSC wave indicated a reduced effect of therapeutic hypothermia, even in cases that underwent hypothermia promptly after out-of-hospital CPA. Measurement of ABRs appears to be useful as a predictor of effectiveness and as a criterion for determining the indication for therapeutic hypothermia.