Dependence of Early Cerebral Reperfusion and Long-Term Outcome on Resuscitation Efficiency After Cardiac Arrest in Rats

Abstract

Background and Purpose — While it is well known that longer duration of cardiac arrest (CA) is often associated with poorer long-term outcome, the influence of resuscitation efficacy on postischemia recovery is less clear. The objective of the present study is to investigate whether an inadequate and prolonged resuscitation after a shorter CA can lead to worse long-term outcomes than an effective resuscitation after a longer CA, provided that the total time from the onset of CA to the return of spontaneous circulation is comparable. Methods — Thirty-eight rats were randomized into 2 groups with nominal 9 minutes (group 1) and 15 minutes (group 2) of normothermic asphyxial CA. Each group was further divided into 2 subgroups on the basis of the duration of resuscitation efforts (labeled as S and L for short and long, respectively). Thus, the asphyxia and nominal resuscitation times were 8 and 1 minute, respectively, for group 1S, 5 and 4 minutes for group 1L, 14 and 1 minute for group 2S, and 11 and 4 minutes for group 2L. Cerebral perfusion was measured continuously at the dorsal hippocampus level before, during, and after the CA, with the use of the arterial spin labeling MRI technique. The survival time, histological damage, and neurological deficit were evaluated 5 days after resuscitation. Results — Groups 1S and 1L had nearly the same duration of CA (9.02±0.17 minutes, n=6 versus 8.58±0.80 minutes, n=6). The same is true for groups 2S and 2L (15.51±0.59 minutes, n=11 versus 15.65±1.25 minutes, n=15). Despite longer asphyxia, shorter and more effective resuscitation was associated with significantly improved long-term outcomes and higher cerebral perfusion at the early stage of reperfusion. Conclusions — Effective resuscitation increased early reperfusion and improved survival after CA. The clinical implication is that inadequate and prolonged resuscitation may have detrimental effects on the recovery of CA patients.