EFFECTS OF CHLORAL HYDRATE ORE 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 chronical ly instrumented 48-72 h before study and randomly assigned to a CH gro up (100 mg/kg, i.p.) or saline group. The animals were intubated and s tudied under quiet sleep which was determined by behavioral states, an d continuous electro-oculographic and electroencephalographic monitori ng. Minute ventilation (V-E, 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 a dministration 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 V-E and th e ventilatory response to hypoxia were similar before and after CH adm inistration. In contrast, the basal ABP decreased significantly (p < 0 .05) after CH administration, but the ABP response to hypoxia was simi lar before and after CH. A significant increase in both basal HR and H R 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 significan tly modify the ventilatory response to hypoxia in newborn piglets. How ever, CH produced some changes in the cardiovascular system which shou ld be considered when using it in infants with hemodynamic derangement s.