Phenobarbital and Cerebral Blood Flow during Hypotension in Newborn Pigs

Abstract

ABSTRACT. Phenobarbital sodium (PhS) has been used in anticonvulsant concentrations in premature newborns in attempts to prevent peri-and intraventricular hemorrhages (PIVH). Its effectiveness in preventing PIVH in clinical situations is still uncertain; however, PhS has reduced PIVH after hypertension in newborn beagles, and it has lowered cerebral blood flow (CBF) during hypertension in newborn beagles and piglets. We hypothesized that PhS might reduce CBF during systemic hypotension. Twelve control and 12 PhS-treated piglets (1 to 2 d old) were used for microsphere determinations of CBF during 1 ) steady state; 2) 30 min after PhS (treatment group) or saline infusion (controls); and 3 and 4) during two levels of graded hypotension. Mean arterial blood pressure (MABP) was 61 f 13 (SD) mm Hg (controls) and 57 f 13 (SD) mm Hg (PhS) during steady state. Thirty min after the PhS or saline infusion, MABP and CBF remained unchanged in both groups. CBF during hypotension at MABP of 41 f 5 (SD) mm Hg was significantly higher in controls than was CBF at MABP of 39 + 6 (SD) mm Hg in the PhS-treated group (p = 0.044); CBF in the two groups during the second hypotensive phase was not significantly different.

Postnatal development of the cerebral blood flow velocity response to changes in CO2 and mean arterial blood pressure in the piglet

“…In the present study we found that the MABP reactivity was age-dependent, being 1.1 % mmHg-' on days 0-3 and 0.0% mmHg-' for piglets older than 4 days. Our finding of reduced autoregulatory capacity in the very young piglet is supported by other studies (28,29). Calculating from their figures and tables the MABP reactivity displayed partial pressure passivity of 1 % mmHg-' for piglets aged 5 f l and 1-2 days.…”

“…We also examined the COz reactivity under pentobarbital anaesthesia and found the same age-dependent response for the two anaesthetics. The effect of phenobarbital on CBF during haemorrhagic hypotension was recently studied (29). The investigators found that phenobarbital affected the CBF response to MABP changes in 1-2day-old piglets by stabilizing CBF during hypotension.…”

Correlation of Near Infrared Spectroscopy Cerebral Blood Flow Estimations and Microsphere Quantitations in Newborn Piglets

“…A second femoral arterial line was placed and threaded into the abdominal aorta for reference sampling. From the left external carotid artery a catheter was threaded into the left cardiac ventricle; placement was assured by recording the left ventricular pressure tracing using a Statham transducer and Grass multi-channel recorder (it has been well documented that occluding a unilateral external carotid artery in this way has no effect upon blood flow to the ipsilateral hemisphere) [14][15][16]. One arterial line was connected to the transducer for continuous blood pressure monitoring; 0.4-cm 3 blood samples were withdrawn from the arterial line before each blood flow measurement for blood gas quantitations (Corning 170 blood gas analyzer, Corning Medical, Medfield, Mass., USA).…”

Brain Blood Flow Responses to Indomethacin during Hemorrhagic Hypotension in Newborn Piglets

“…This technique and the basis for the microsphere technique have been published several times [19][20][21][22]. Approximately 500,000 radiolabeled 15-pm micro spheres mixed with saline and 0.05% Tween-80 were injected into the left ventricle of the heart for each flow quantitation.…”