Norman, Robert G., Roberta M. Goldring, Jeremy M. Clain, Beno W. Oppenheimer, Alan N. Charney, David M. Rapoport, and Kenneth I. Berger. Transition from acute to chronic hypercapnia in patients with periodic breathing: predictions from a computer model. J Appl Physiol 100: 1733–1741, 2006. First published December 29, 2005; doi:10.1152/japplphysiol.00502.2005.—Acute hypercapnia may develop duri...

The relative contributions of hypoxia and hypercapnia in causing persistent sympathoexcitation after exposure to the combined stimuli were assessed in nine healthy human subjects during wakefulness. Subjects were exposed to 20 min of isocapnic hypoxia (arterial O(2) saturation, 77-87%) and 20 min of normoxic hypercapnia (end-tidal P(CO)(2), +5.3-8.6 Torr above eupnea) in random order on 2 separ...

Acute respiratory disorders and permissive hypercapnic strategy may lead to alveolar hypoxia and hypercapnic acidosis. However, the effects of hypercapnia with or without acidosis on hypoxic pulmonary vasoconstriction (HPV) and oxygen diffusion capacity of the lung are controversial. We investigated the effects of hypercapnic acidosis and hypercapnia with normal pH (pH corrected with sodium bic...

INTRODUCTION While tissue hypoxia is known to play a critical role in the process of vascular injury and repair, the effect of hypercapnia on this process remains uncertain. We investigated whether hypercapnia might influence endothelial cell wound healing under the influence of hypoxia. MATERIALS AND METHODOLOGY Monolayers of human umbilical venous endothelial cells (HUVECs) were scratch-wou...

Elevated CO(2) levels (hypercapnia) frequently occur in patients with obstructive pulmonary diseases and are associated with increased mortality. However, the effects of hypercapnia on non-neuronal tissues and the mechanisms that mediate these effects are largely unknown. Here, we develop Drosophila as a genetically tractable model for defining non-neuronal CO(2) responses and response pathways...

PURPOSE To investigate whether nitric oxide (NO) contributes to the regulation of retinal circulation during hypercapnia in cats. METHODS NG-nitro-L-arginine-methylester (L-NAME; n=8), a NOS inhibitor; NG-nitro-D-arginine-methylester (D-NAME; n=6), the inactive isomer; or phosphate-buffered saline (PBS; n=8) was injected intravitreously into the cat's eye. A selective neuronal nitric oxide sy...

STUDY OBJECTIVE The inotropic, lusitropic, and electrophysiologic effects of acute hypercapnia in humans are not known. Although the effects of hypercapnia on the systemic circulation have been well documented, there is still some debate as to whether hypercapnia causes true pulmonary vasoconstriction in vivo. We have therefore evaluated the effects of acute hypercapnia on these cardiac indices...

purpose: hypercapnia increases minute ventilation (v’e) with little effect on heart rate (hr), whereas hypoxia may increase hr without affecting v’e. however, the effects of hypercapnia and hypoxia on both heart rate variability (hrv) and the clustering of heart beats during spontaneous breathing (respiratory sinus arrhythmia – rsa), are not clear. methods: in this study, 10 human volunteers br...

Adult freshwater rainbow trout (Oncorhynchus mykiss) were exposed acutely (approximately 20 min) in a stepwise manner to increasing levels of environmental carbon dioxide ranging between 1.7 and 9.0 mmHg (0.23-1.2 kPa). Experiments were performed to examine, for the first time, the influence of hypercapnic acidosis on aspects of cardiovascular physiology including blood pressure, cardiac output...

Neonates with respiratory distress syndrome (RDS), who are treated according to INSURE protocol; require arterial blood gas (ABG) analysis to decide on appropriate management. We conducted this study to investigate the validity of pulse oximetry instead of frequent ABG analysis in the evaluation of these patients. From a total of 193 blood samples obtained from 30 neonates <1500 grams with RDS,...