Regional cerebral blood flow after human cardiac arrest. A hexamethylpropyleneamine oxime single photon emission computed tomographic study.

We studied 30 patients 24 hours after out-of-hospital cardiac arrest and 13 age-matched normal controls with the use of technetium Tc 99m-hexamethylpropyleneamine oxime single photon emission computed tomography. All patients were followed up for 12 months or until death. Frontal hypoperfusion (anteroposterior perfusion ratio, less than 0.90) was observed in 23 patients (77%). In eight patients who remained comatose and died, the total size of perfusion defects was larger (38% +/- 20%) than in the 21 patients who recovered consciousness (24% +/- 14%), but the anteroposterior ratio was similar in both of these patient groups (0.83 +/- 0.09) and significantly lower than in the controls (0.96 +/- 0.03). During follow-up, both the anteroposterior perfusion ratio and the relative defect size improved, but frontal hypoperfusion was still observed in seven of 13 patients. After cardiac arrest, regional cerebral blood flow is characterized by frontal hypoperfusion that tends to improve over time but that persists in most patients.