Cerebral Blood Flow Velocity Changes After Bovine Natural Surfactant Instillation

Abstract

OBJECTIVE:To determine the effects of bovine natural surfactant (beractant) instillation on cerebral hemodynamics in preterm infants with respiratory distress syndrome (RDS). STUDY DESIGN:Preterm infants who required surfactant for RDS were enrolled. Cerebral blood flow velocity (CBFV) waveforms from the pericallosal artery were analyzed by pulsed Doppler ultrasonography with the anterior fontanel serving as an acoustic window. CBFV was measured before and at 5, 10, 20, and 30 minutes after the first dose of a bolus instillation of surfactant in four aliquots. Simultaneously with CBFV measurements, mean blood pressure (MBP), heart rate, and ventilator settings were recorded. pH, PACO 2 , and PAO 2 before and at 30 minutes after surfactant administration were also determined. RESULTS:The 30 enrolled preterm infants had a mean birth weight of 973 gm (513 to 1996 gm) and a mean gestational age of 27 weeks (23 to 33 weeks). Mean postnatal age at surfactant administration was 4.7 Ϯ 2.7 hours. There were no significant changes in pH and PACO 2 before and at 30 minutes after surfactant (before surfactant: mean pH of 7.29 Ϯ 0.07 and mean PACO 2 of 44.4 Ϯ 7.1 torr; after surfactant: mean pH of 7.31 Ϯ 0.07 and mean PACO 2 of 42.7 Ϯ 8.3 torr). PAO 2 increased significantly from a pre-surfactant mean of 83 torr to 130 torr at 30 minutes after surfactant (p Ͻ 0.05), with no significant changes in mean airway pressure. There were no significant changes in MBP, heart rate, mean CBFV, peak systolic flow velocity, and diastolic flow velocity before and after surfactant instillation regardless of gestational age. Individ--ual changes in mean CBFV were related to MBP changes (p Ͻ 0.001, linear mixed models with random effects).

Patent ductus arteriosus hemodynamics in very premature infants treated with poractant alfa or beractant for respiratory distress syndrome

“…8,9 Differences in surfactant preparations, volume and timing of administration probably explain the widely different cerebral blood flow responses to surfactant. Previous studies reported that cerebral blood flow decreased, 10-13 increased 9,14 -18 and remained unchanged [19][20][21][22][23][24] following various surfactant preparations, administered under varying conditions. Thus, as with the cerebral circulation, we believe that the differential pulmonary effects of beractant and poractant alfa may be responsible for indirect effects on PDAs and PDA hemodynamics.…”

Surfactant administration acutely affects cerebral and systemic hemodynamics and gas exchange in very-low-birth-weight infants

“…Previous studies examining the effects of natural bovine surfactant on cerebral hemodynamics 8,9 used intermittent monitoring protocols and failed to find any study sample changes in CBFv, PaCO 2 , and MABP, although some individuals had changes in CBFv during surfactant administration. The discrepancy between these studies and ours may be due to aggressive ventilator management after surfactant instillation, the lower dose volume (1.1 mL/kg) used by Jorch et al, 8 and intermittent monitoring in which transient changes could have been overlooked.…”

“…Disturbances of arterial blood gases (ABGs) after surfactant also may have deleterious effects on CBF, since carbon dioxide and oxygen are potent mediators of cerebral vascular tone. 7 Studies of the acute effects of surfactant on cerebral hemodynamics have reported decreased, 2 unchanged, 5,8,9 or increased 3,4 CBF variables. Discrepancies in these results may be due to use of different surfactant preparations, differences in administration protocols, use of diverse CBF measurement techniques and indirect ABG measures, intermittent physiologic monitoring, and inclusion of heterogeneous populations.…”

Acute side effects of surfactant treatment

“…However, results from experimental and clinical trials are equivocal: Decrease of arterial blood pressure resulted in a consecutive drop of CBFV in three studies [4, 31,36], in another study CBFV increased as a result of increased blood pressure and increase of pO 2 [41]. Rey and colleagues found a decrease of CBFV without a change of mean arterial blood pressure [33].…”