RECOVERY OF CEREBRAL BLOOD FLOW VELOCITY IN
INFANTS WITH HYPOTHERMIC CARDIOPULMONARY
BYPASS. DR Qin*, RN
Justo, CJ Burke, PB Colditz, PG Pohlner, H Jalali. Queensland
Centre for Congenital Heart Disease, Prince Charles Hospital, Brisbane, Qld. Background: Reduced cerebral blood
flow velocity (CBFV) in infants after profound hypothermic cardiopulmonary
bypass (HCPB) has been reported. Blood haemoglobin level may affect the
recovery of cerebral blood flow velocity in infants with open heart surgery. Methods: CBFV in the anterior
cerebral artery was measured by pulsed Doppler intermittently throughout the
operation until 5 hours post-reperfusion in 28 infants undergoing cardiac
surgery. Arterial haemoglobin was measured at the same time. The patients were
divided into three groups according to the degree of intraoperative
hypothermia: mild (30-32°C, n=8),
moderate (22-28°C, n=16) and deep (17-18°, n=4). Results: Peak CBFV decreased significantly (p<0.01) in all the groups to
less than 50% of the preoperative level during HCPB and returned to more than
65% of the prebypass level after reperfusion. However, compared to the moderate
group, both mild and deep groups had a lower peak CBFV recovery at 1 hour
(p<0.001), 2 hours (p<0.01) and 3 hours (p<0.05) after reperfusion
with a higher haemoglobin level (p<0.05). It was also found that there was a
negative correlation between peak CBFV and haemoglobin level at 1 and 2 hours
after reperfusion in the whole cohort of patients (r=-0.56, p=0.002 and
r=-0.57, p=0.0017, respectively). Conclusion: The recovery of cerebral blood flow velocity in infants with HCPB
may be affected by both the degree of hypothermia and haemoglobin level. There
is an inverse relationship between cerebral blood flow velocity and haemoglobin
level following infant cardiac surgery. Therefore, an optimal correction of
haemodilution after infant cardiac surgery should be considered for cerebral
protection.
