A study of out-of-hospital cardiac arrest patients has shown that they have better neurological outcomes if a protective cerebrovascular regulation system reasserts itself. The research, published in the Journal of Cerebral Blood Flow and Metabolism, shows that this information can be used to assign more intensive rehabilitation, and also can be used to develop new interventions to improve cerebral perfusion.
Despite advances in treatment for out-of-hospital cardiopulmonary arrest and efforts to improve outcomes, many patients still suffer neurological sequelae (hypoxic-ischaemic brain injury, HIBI) even after return of spontaneous circulation. It is known that if brain function is maintained normally, there is a mechanism, cerebrovascular autoregulation (CVAR), that tries to maintain cerebral blood flow at a constant level even with changes in systemic blood pressure, but until now, it was unclear whether such a reaction occurs in the brain after resuscitation. Cerebral regional oxygen saturation (crSO2), a measure of oxygen supply and demand balance in the brain, is affected by blood pressure, and we focused on a method to evaluate the presence or absence of CVAR using this correlation. The researchers used this correlation to evaluate the presence or absence of CVAR in the post-resuscitated brain and assessed its relationship to life expectancy.
In this study, the research group analysed 100 patients with out-of-hospital cardiac arrest who were transported to the trauma and acute critical care centre of the Osaka University Graduate School of Medicine. CVAR was determined by calculating the moving Pearson correlation coefficient and by continuously monitoring crSO2 and mean blood pressure for 96 hours after return of spontaneous circulation. Assuming undetected CVAR time as a bad exposure for the organism (time-dependent covariate), the researchers evaluated the association of life prognosis using Cox proportional hazards model. CVAR was detected in all 24 patients with good neuroprognosis (Cerebral Performance Scale5: CPC 1-2) out of 100 analysed subjects and in 65 (88%) of 76 patients with poor neuroprognosis (CPC 3-5). The analysis using the Cox proportional hazards model showed that the survival rate decreased significantly as the undetected time of CVAR increased.
The results of this study have two major implications. First, the ability to identify subgroups with high mortality from early post-resuscitation clinical data can help identify populations that should receive enhanced therapeutic intervention. In addition, it may help to avoid early withdrawal of treatment from those who may recover. Secondly, we believe that intensive therapeutic management that maintains proper cerebral perfusion suggests improved life outcomes, and that developing a systemic management approach based on cerebral perfusion may be a breakthrough in reducing post-resuscitation neurological sequelae.
Source: EurekAlert!
