CEREBRAL BLOOD-FLOW PATTERN AND AUTOREGULATION DURING OPEN-HEART-SURGERY IN INFANTS AND YOUNG-CHILDREN - A TRANSCRANIAL, DOPPLER ULTRASOUND STUDY

Objectives: To elucidate the effect of cardiopulmonary bypass on cerebral perfusion and on the autoregulatory ability of the cerebral vascular bed of infants and young children. Setting: Operating room. Design: Prospective study. Patients: Thirteen newborn infants and young children undergoing open-heart surgery. Interventions: Cerebral blood flow velocity was monitored in the patients undergoing open-heart surgery from just before the induction of anesthesia until the discontinuation of anesthesia after completion of the surgery. Measurements and Main Results: Cerebral blood flow velocity was assessed by semicontinuous measurement of temporal mean blood flow velocity in the middle cerebral artery using a range-gated, pulsed Doppler flowmeter with a transducer that was firmly attached to the left temporal region of the head. Mean arterial pressure (MAP) and nasopharyngeal temperature were continuously monitored. During hypothermic (18.4-degrees-C to 31.9-degrees-C) cardiopulmonary bypass, cerebral blood flow velocity decreased and showed a close relationship with nasopharyngeal temperature (p < .0001). During steady-state cardiopulmonary bypass, cerebral blood flow velocity showed a correlation with MAP (p < .01). The nasopharyngeal temperature influenced this relationship: at lower (absolute) nasopharyngeal temperatures, lack of cerebral autoregulation was more common. Conclusions: The finding suggests that cerebral blood flow decreases with decreasing nasopharyngeal temperature. During hypothermic cardiopulmonary bypass, cerebral autoregulation seems to be easily disturbed, especially at low nasopharyngeal temperatures.