Cerebral blood flow pattern and autoregulation during open-heart surgery in infants and young children: a transcranial, Doppler ultrasound study.

Abstract

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. Operating room. Prospective study. Thirteen newborn infants and young children undergoing open-heart surgery. 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. 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 less than .0001). During steady-state cardiopulmonary bypass, cerebral blood flow velocity showed a correlation with MAP (p less than .01). The nasopharyngeal temperature influenced this relationship: at lower (absolute) nasopharyngeal temperatures, lack of cerebral autoregulation was more common. 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.