POSTBYPASS EFFECTS OF DELAYED REWARMING OM CEREBRAL BLOOD-FLOW VELOCITIES IN INFANTS AFTER TOTAL CIRCULATORY ARREST

Cerebral perfusion is reduced after prolonged periods of total circula tory arrest in infants, Methods of rewarming after arrest may modify t he flow pattern of recovery, and a single report has suggested that us ing cold reperfusion to delay rewarming could mitigate abnormalities i n cerebral blood how Cerebral perfusion was evaluated by transcranial Doppler sonography in 16 infants who required periods of total circula tory arrest of 35 minutes or more, In group A (n = 9) rewarming was be gun immediately on reperfusion, whereas in group B (n = 7) a 10-minute period of cold reperfusion was instituted before rewarming was begun, The mean and end-diastolic flow velocities were measured before incis ion (baseline) and at 20, 45, and 90 minutes after conclusion of cardi opulmonary bypass, Mean arterial pressure, hematocrit value, and arter ial carbon dioxide tension were controlled, with no significant differ ences between the two groups (p > 0.05), In group A, the mean cerebral blood how velocity was below the baseline level at all three postbypa ss measurements (p < 0.001), In group B, however, mean velocity did no t differ significantly from the baseline value (p > 0.05), Twenty minu tes after bypass, 89% of the patients in group A had no diastolic Dopp ler signal, indicating absence of perfusion during diastole, compared with only 28% in group B (p = 0.02), These preliminary results suggest that a delay in rewarming on reperfusion may be beneficial in infants after circulatory arrest.