Although apnea is a common neonatal problem, its impact on the cerebral circulation is unknown. CBFV was measured with the transcutaneous Doppler technique at the anterior fontanel. Determination of area under the velocity curve (A.U.V.C.) was utilized to quantitate CBFV. The objective of this study was to examine the effects of apnea on CBFV. Ten infants <1500 gm were studied at rest and during apnea. Apnea was defined as cessation of respiration for >15 sec. In each patient, the effects were similar. Initially, a decrease in diastolic flow velocity (DFV) occurred as the heart rate decreased. With marked bradycardia (heart rate (80). a decrease in systolic flow velocity (SFV) developed and a further decrease in DFV was noted. SFV and DFV returned to baseline within sec. following the onset of spontaneous respiration, but with a delay in those requiring resuscitation. Simultaneous intra-arterial blood pressure ( Med. 309:204, 1983).Paralysis with pancuronium was shown to convert the fluc. CBFV to a stable CBFV pattern. The objectives of this prospective, randomized study in intubated preterm infants with RDS and fluc. CBFV was to examine the effects of pancuronium on the occurrence of IVH. Seventeen infants