Sympathetic responses in out-of-hospital cardiac arrest.

To determine the clinical relevance of the sympathetic response to out-of-hospital cardiac arrest, we measured plasma concentrations of catecholamine and cortisol in ten such arrested patients on their arrival. The duration of cardiac arrest was estimated from 9 to 200 min before basic life support was initiated by ambulance personnel. Two of the patients developed spontaneous pulses in response to ALS and were resuscitated, and the others were not, although the length and the extent of ALS were not different between the two groups. Plasma concentrations of epinephrine (EN), norepinephrine (NE) and cortisol prior to ALS in both groups were markedly elevated. In particular, the patients who never regained spontaneous pulses showed 58-fold and 12-fold increase in the plasma EN and NE levels, respectively, which were much higher than those in the resuscitated cases; 8- and 1.7-fold increase, respectively. These massive EN and NE discharges correlated well with the arrest time (r = 0.96 and 0.94, respectively) and the degree of acidosis (r = -0.82 and -0.82, respectively).