1585 AUTOREGULATION OF BRAIN BLOOD FLOW (BBF): REGIONAL DIFFERENCES IN REDUCED BBP WITH HYPOTENSION

Abstract

The potential use of a piglet as a model for investigation of brain blood flow (BBF) was evaluated by assessing the presence of autoregulation in 11 spontaneously breathing newborn piglets. MABP was altered by phlebotomy. Within the normotensive range (MABP=51-105 mmHg) no significant change in BBF (measured by the microsphere technique)occurred (r=0.03) indicating the presence of autoregulation. During hypotension (MABP=15-50 mmHg), a pressure passive relation exists between BBF and MABP (r=0.59). However, since the piglets breathed spontaneously and hyperventilated during hypotension, both the MABP and PaCO₂ fell and both correlated with BBF during hypotension. Thus, it is uncertain which factor is responsible for the loss of autoregulation. The blood flow (BF) to three specific regions of the brain (cerebrum, cerebellum, brainstem) and MABP also showed no correlation during normotension. During hypotension each region demonstrates significant pressure passive relationships, but the reduction in BF is most pronounced in the cerebrum, less in the cerebellum, and least in the brainstem, (M±SE, 58±7%, 34±12%, 27±11% reduction from control respectively, p<.05). The study indicates that a newborn piglet may serve as an appropriate model for the study of brain hemodynamics particularly with regard to autoregulation. Furthermore, during hypotension, preferential protection of vital regions of the brain (cerebellum and brainstem) occur which may have important implication in interpreting the effect of hypotension on the newborn central nervous system.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD