Effects of chloral hydrate on the cardiorespiratory response to hypoxia in newborn piglets.

To assess the effects of chloral hydrate (CH) on the cardiorespiratory response to hypoxia in the neonate, 17 newborn piglets were chronically instrumented 48-72 h before study and randomly assigned to a CH group (100 mg/kg, i.p.) or saline group. The animals were intubated and studied under quiet sleep which was determined by behavioral states, and continuous electro-oculographic and electroencephalographic monitoring. Minute ventilation (VE), tidal volume, respiratory rate, arterial blood gases (ABG), oxygen consumption (VO2), arterial blood pressure (ABP) and heart rate (HR) were measured before and after CH or saline administration during room air and after 10 min of hypoxia (fraction of inspired oxygen concentration = 0.10). Cardiorespiratory response to hypoxia was similar before and after saline infusion. Basal VE and the ventilatory response to hypoxia were similar before and after CH administration. In contrast, the basal ABP decreased significantly (p < 0.05) after CH administration, but the ABP response to hypoxia was similar before and after CH. A significant increase in both basal HR and HR with hypoxia was observed after CH administration. In addition, VO2 and ABG were not modified by CH treatment during normoxia and hypoxia. These data demonstrate that a sedative dose of CH does not significantly modify the ventilatory response to hypoxia in newborn piglets. However, CH produced some changes in the cardiovascular system which should be considered when using it in infants with hemodynamic derangements.