BACKGROUND Hyperventilation should speed up elimination of volatile anaesthetic agents from the body, but hyperventilation usually results in hypocapnia. We compared recovery from isoflurane anaesthesia in patients allowed to recover with assisted spontaneous ventilation (control) and those treated with isocapnic hyperpnoea. METHODS Fourteen patients were studied after approximately 1 h of an...

Previous research has shown an inconsistent effect of hypoxia on dynamic cerebral autoregulation (dCA), which may be explained by concurrent CO2 control. To test the hypothesis that hypoxic dCA is mediated by CO2, we assessed dCA (transcranial Doppler) during and following acute normobaric isocapnic and poikilocapnic hypoxic exposures. On 2 separate days, the squat-stand maneuver was used to de...

It has been proposed that exercise provokes bronchoconstriction in asthma by inducing mast cell degranulation, and that this occurs secondary to the hyperpnoea of exercise causing hypertonicity of the airway lining fluid. We investigated the contribution of the mast cell products, histamine and prostaglandins, to the bronchoconstriction induced by isocapnic hyperventilation (ISH) using single d...

Previous reports indicate roles for acid-sensing ion channels (ASICs) in both peripheral and central chemoreception, but the contributions of ASICs to ventilatory drive in conscious, unrestrained animals remain largely unknown. We tested the hypotheses that ASICs contribute to hypoxic- and hypercapnic-ventilatory responses. Blood samples taken from conscious, unrestrained mice chronically instr...

Clar, Christine, Keith L. Dorrington, and Peter A. Robbins. Ventilatory effects of 8 h of isocapnic hypoxia with and without b-blockade in humans. J. Appl. Physiol. 86(6): 1897–1904, 1999.—This study investigated whether changing sympathetic activity, acting via b-receptors, might induce the progressive ventilatory changes observed in response to prolonged hypoxia. The responses of 10 human sub...

Nocturnal hypoxia is a major pathological factor associated with cardiorespiratory disease. During wakefulness, a decrease in arterial O2 tension results in a decrease in cerebral vascular tone and a consequent increase in cerebral blood flow; however, the cerebral vascular response to hypoxia during sleep is unknown. In the present study, we determined the cerebral vascular reactivity to isoca...

Chemoreflex stimulation elicits both hyperventilation and sympathetic activation, each of which may have different influences on oscillatory characteristics of cardiovascular variability. We examined the influence of hyperventilation on the interactions between changes in R-R interval (RR) and muscle sympathetic nerve activity (MSNA) and changes in neurocirculatory variability, in 14 healthy su...

Effect of 8 Hours of Isocapnic/Poikilocapnic Hypoxia on the Ventilatory Response to CO[subscript 2] p. 17 Ventilatory Responses to Hypoxia after 6 Hours Passive Hyperventilation in Humans p. 21 Ventilatory Effects of 8 Hours of Isocapnic Hypoxia with and without [beta]-Blockade p. 25 Modulation of Ventilatory Sensitivity to Hypoxia by Dopamine and Domperidone before and after Prolonged Exposure...

Key points We investigated the influence of arterial () with and without acutely elevated pH bicarbonate ([HCO3–]) on cerebral blood flow (CBF) regulation in internal carotid artery vertebral artery. assessed stepwise iso-oxic alterations (i.e. cerebrovascular CO2 reactivity) prior to following i.v. sodium infusion (NaHCO3–) elevate [HCO3–]. Total CBF was unchanged irrespective a higher at each...