Effects of partial liquid ventilation on cerebral blood flow and cerebral metabolism in neonatal lambs

Background/Purpose: Liquid ventilation is a promising therapy for respiratory failure. The effects of perfluorochemical on cardiac output have not been well described. The purpose of this study was to compare cerebral blood flow (Q_CAROTID) and cerebral metabolic rates (CMR) during conventional ventilation (CV) and partial liquid ventilation (PLV). Methods: Five 2-week-old lambs underwent tracheostomy and central venous, aortic, and postcerebral venous catheter placement. Doppler flow probes were placed around the common ovine trunk, and the lambs underwent CV for 1 hour. Ventilation was adjusted to maintain physiologic blood gases. Pre- and postcerebral blood gas, glucose, and lactate samples were obtained every 15 minutes. Perfluorodecalin then was instilled endotracheally. The lambs underwent 1 hour of PLV with similar sampling. Data were analyzed using the Wilcoxon matched pairs test, significance at P ≤ .05. Results: The authors observed no difference in mean Q_CAROTID or carotid vascular resistance between CV and PLV (P = .35 and .34, respectively). The CMR of oxygen, glucose, and lactate were calculated using the Fick principle. CMR was unchanged between modes (P = .5). Conclusions: PLV did not adversely alter Q_CAROTID or CMR in lambs, implying that this mode of ventilation should be safe in neonatal patients at risk for neurologic injury.