Optical Brain Monitoring of the Cerebrovascular Effects Induced by Acute Cocaine Exposure in Neonatal Pigs

> Objective: The purpose of this study was to assess the direct effects of cocaine on cerebral blood flow and oxygenation in newborn piglets using optical spectroscopy. Optical spectroscopy is capable of monitoring changes in cerebral oxyhemoglobin, deoxyhemoglobin, and total hemoglobin continuously, noninvasively, and in real time. Methods: Five anesthetized and ventilated newborn piglets were injected intravenously with 1 mg/kg cocaine through a central venous catheter over 60 seconds. Cerebral blood flow and oxygenation were assessed by optical spectroscopy and standard physiologic monitoring: mean arterial pressure, carotid blood flow, cerebrovascular resistance, and arterial hemoglobin oxygen saturation (by pulse oximetry). Results: Cocaine induced a profound increase in cerebrovascular resistance, a decrease in carotid blood flow, and a decrease in mean arterial pressure and heart rate. Cerebrovascular changes were detected readily by optical spectroscopy (i.e. a decrease in cerebral oxyhemoglobin was associated with an increase in deoxyhemoglobin). The hypotensive response augmented the cerebral vasoconstriction effect on carotid blood flow. A good correlation existed between the changes in carotid Doppler blood flow and total hemoglobin in each animal and for all animals combined. Peripheral arterial hemoglobin oxygen saturation measured by pulse oximetry remained normal throughout the experiment. Conclusions: The cause for the apparent idiosyncratic hypotensive response to intravenous injections of cocaine is uncertain and requires further investigation. Our study clearly demonstrates that optical spectroscopy might become an extremely useful tool for monitoring cerebral hemodynamics and oxygenation in cocaine-exposed fetuses and infants.