Preterm infants with volume- and pressor-resistant hypotension respond to hydrocortisone with rapid normalization of the cardiovascular status and sustained decreases in volume and pressor requirement.

Buffering of alpha-receptor-mediated pressor responses by beta-adrenergic or cholinergic vasodilation in tranquilized, chronically instrumented gos was investigated. Increases in aortic pressure were produced in the same animal by intravenous injections of phenylephrine in the control state and in three successive experimental states by 1) pacing the heart to remove the reflex capability to lower heart rate, 2) pacing the heart and beta-blockade to remove beta-adrenergic vascular buffering, and 3) beta-blockade plus atropine to also remove cholinergic vascular buffering. The pressor response in each experimental state was greater than that in the state preceding it. With the combined beta-adrenergic and cholinergic blockade, the pressor response to an alpha-receptor stimulation was three times greater than that of the control state. From an analysis of the components of the pressor response, cardiac output, and peripheral resistance, it is suggested that normal buffering of an alpha-mediated pressor response may include beta-adrenergic and cholinergic vascular dilation in addition to a decrease in heart rate.

Doxapram hydrochloride as a 2% aqueous solution (Dopram V, A. H. Robins) was administered intravenously to cats anaesthetized with either Saffan (Glaxo) or 2 5% thiopentone sodium. A dose of 7 5 mg per kg resulted in an immediate and marked increase in respiratory rate and depth, and the heart rate also increased significantly. The administration of doxapram to cats anaesthetized with Saffan resulted in an average initial increase in minute volume of 181%; although the effect diminished rapidly, the tidal volume remained elevated for many minutes compared with controls. Doxapram hydrochloride would appear to be of value in the treatment of respiratory depression during anesthesia with either Saffan or thiopentone.