Myocardial and cerebral oxygen delivery are not adversely affected by cocaine administration to early-gestation fetal sheep.

Abstract

Cocaine administration to near-term pregnant sheep causes fetal hypoxemia, but oxygen delivery to the heart and brain are preserved because of increased blood flow. We hypothesized that cocaine administration during earlier fetal gestation impairs oxygen delivery to the heart and brain. Ten pregnant ewes and fetuses at 0.7 term gestation underwent surgical instrumentation. After 48 hours of recovery fetal blood pressure, heart rate, cerebral and myocardial blood flow, and arterial oxygen content were determined before and during cocaine administration to the ewe. Fetal hypoxemia was not noted in these animals. Fetal myocardial blood flow increased from 220 +/- 100 ml per 100 gm per minute to 349 +/- 183 ml per 100 gm per minute (p=0.03), and oxygen delivery increased from 16 +/- 5 ml of oxygen per 100 gm per minute to 22 +/- ml of oxygen per 100 gm per minute (p=0.02). Fetal cerebral blood flow and oxygen delivery remained unchanged. Cerebral and myocardial oxygen delivery are unimpeded by maternal cocaine administration in 0.7 term gestation ovine fetuses.