The effect of blue-light phototherapy on cardiac output and brain and kidney perfusion was studied in 12 term infants with pulsed Doppler ultrasound. Mean (+/-SD) gestational age and birth weight were 39.0 (+/-1.6) weeks and 3438 (+/-533) g respectively. Mean (+/-SD) age of the infants at which phototherapy was initiated was 3.5 (+/-0.8) days. Left ventricular output (LVO), mean left pulmonary artery blood flow (LPA), mean blood flow velocities of the internal carotid (CBFV) and renal (RBFV) arteries were studied in all infants prior to the onset of phototherapy, 30 min, 2 h, and 12 h after initiation of phototherapy, and before and 12-24 h after discontinuation of phototherapy. LVO decreased immediately after the onset of phototherapy. However, after 12 h, LVO returned to pre-phototherapy values. LPA increased significantly after 12 h of exposure. LPA returned to pre-phototherapy values after discontinuation of phototherapy. CBFV increased, whereas RBFV decreased significantly after 2 h of exposure. After discontinuation of phototherapy CBFV as well as RBFV values returned to pre-phototherapy values.
Conclusion: Phototherapy does affect cardiac output and organ blood flow velocity in term infants. After termination of phototherapy the effect of phototherapy disappears.