Changes in cerebral blood flow and oxygen extraction during post-resuscitation syndrome

SummaryIntroductionMost survivors of out-of-hospital cardiac arrest (OHCA) will die subsequently from post-anoxic encephalopathy. In animals, the severity of brain damage is mainly influenced by the duration of cardiac arrest and also by the cerebral blood flow (CBF) and oxygen extraction (CEO2) abnormalities observed during the post-resuscitation period. The aim of our study was to describe CBF and CEO2 modifications during the first 72 h in OHCA patients treated by induced mild hypothermia.MethodsConsecutive OHCA patients were studied every 12 h over 72 h. Diastolic flow velocities (dFV), mean flow velocities (mFV) and pulsatility index (PI) were assessed by transcranial doppler (TCD) as an estimate of CBF changes. Simultaneous measurements of CEO2 were obtained using retrograde jugular catheterisation.ResultsEighteen patients (61 [47–74] years) were studied (12 non-survivors and 6 survivors). At admission, mFV values were low (27.3 [21.5–33.6] cm/s) but reached normal values after 72 h (50.5 [36.7–58.1] cm/s). Initial PI values were high (1.6 [1.3–1.9]) but reached normal values after 72 h (1.04 [0.82–1.2]). No differences were found between survivors and non-survivors regarding these CBF estimates. CEO2 values were quite normal at admission (20.4 [11–27%]) but decreased over time in non-survivors until H72 (25.8% [19.3–31.1] versus 5.7% [5.1–11.5], p = 0.02).ConclusionCerebral haemodynamic and oxygenation values are altered considerably but evolve during the first 72 h following resuscitation after cardiac arrest. In particular, these changes may lead to a mismatch between CBF and CEO2 leading to a “luxurous perfusion” in non-survivors.