effects of acute systemic hypoxia on the cardiovascular system (cys) and respiration of spontaneously breathing cats were studied in two conditions. 1): hypoxic air (6-8% 02 in n2) was given to the animal to induce systemic hypoxia for 20 minutes. hyperventilation at this condition lowered arterial c02 tension (pac02 hypocapnia). 2): in the second run, induction of hypocapnia was prevented by a...

Effects of acute systemic hypoxia on the cardiovascular system (CYS) and respiration of spontaneously breathing cats were studied in two conditions. 1): Hypoxic air (6-8% 02 in N2) was given to the animal to induce systemic hypoxia for 20 minutes. Hyperventilation at this condition lowered arterial C02 tension (PaC02 hypocapnia). 2): In the second run, induction of hypocapnia was prevented ...

BACKGROUND Hypocapnia induced following the accidental intravenous infusion of a local anesthetic can mitigate anesthetic toxicity, but the effects of hypocapnia induced prior to local anesthetic infusion are unknown. In this study, we examined the effects of prior hypocapnia on bupivacaine-induced cardiotoxicity in rats. METHODS Eighteen Sprague-Dawley rats were randomly divided into two gro...

During voluntary hyperventilation in unanesthetized humans, hypocapnia causes coronary vasoconstriction and decreased oxygen (O(2)) supply and availability to the heart. This can induce local epicardial coronary artery spasm in susceptible patients. Its diagnostic potential for detection of early heart disease is unclear. This is because such hypocapnia produces an inconsistent and irreproducib...

Mechanical ventilation can worsen morbidity and mortality by causing ventilator-associated lung injury, especially where adverse ventilatory strategies are employed. Adverse strategies commonly involve hyperventilation, which frequently results in hypocapnia. Although hypocapnia is associated with significant lung alterations (e.g., bronchospasm, airway edema), the effects on alveolar-capillary...

This study tested the hypothesis that hypocapnia superimposed upon hypotension produces a further reduction in cerebral blood flow velocity (CBFV). In 12 newborn piglets, CBFV was measured continuously by Doppler ultrasound through an artificial fontanelle. Hypotension was induced by removing 30 ml/kg of blood. Increasing the ventilator rate reduced the average arterial carbon dioxide tension f...

Specific carotid body (CB) hypocapnia in the-10-Torr (less than eupneic) range reduced ventilation in the awake and sleeping dog to the same degree as did CB hyperoxia [CB PO2 (PCBO2); > 500 Torr; C.A. Smith, K.W. Saupe, K. S. Henderson, and J. A. Dempsey. J. Appl. Physiol. 79:689-699, 1995], suggesting a powerful inhibitory effect of hypocapnia at the carotid chemosensor over a range of PCO2 e...

BACKGROUND At least half of all cases of early onset (<60) familial Alzheimer's disease (FAD) are caused by any of over 150 mutations in three genes: the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin 2 (PS2). Mutant forms of PS1 have been shown to sensitize cells to apoptotic cell death. OBJECTIVE We investigated the effects of hypocapnia, a risk factor for both cognitiv...

Hypercapnia induces cerebral vasodilation and increases cerebral blood flow (CBF), and hypocapnia induces cerebral vasoconstriction and decreases CBF. The relation between changes in CBF and cerebral blood volume (CBV) during hypercapnia and hypocapnia in humans, however, is not clear. Both CBF and CBV were measured at rest and during hypercapnia and hypocapnia in nine healthy subjects by posit...

Hypercapnia and hypocapnia commonly complicate conditions that are present in critically ill patients. Both conditions have important physiologic effects that may impact the clinical management of these patients. For instance, hypercapnia results in bronchodilation and enhanced hypoxic vasoconstriction, leading to improved ventilation/perfusion matching. Hypocapnia reduces cerebral blood volume...