Document Detail

Ventilatory responses to inhaled carbon dioxide, hypoxia, and exercise in idiopathic hyperventilation.
MedLine Citation:
PMID:  15059786     Owner:  NLM     Status:  MEDLINE    
Idiopathic hyperventilation (IH) is a poorly understood condition of sustained hypocapnia and controversial etiology. Although behavioral/emotional factors may contribute, it is uncertain whether chemosensitivity is altered, hyperventilation is maintained during exercise, and the associated breathlessness reflects the hyperventilation. In 39 patients with IH and 23 control subjects, we described ventilatory responses to isocapnic-hypoxia, hyperoxic-hypercapnia, and exercise; breath-hold tolerance; breathlessness; and psychologic status. Patients demonstrated hyperventilation at rest, with hypocapnia (28 +/- 3.8 mm Hg), a normal (slightly alkaline) arterial pH and [H(+)]a, and a significant base excess (-4.5 +/- 2.7 mEq/L), consistent with compensated respiratory alkalosis. Hyperventilation was sustained during exercise, despite hyperoxic-hypercapnic ventilatory responsiveness being normal and isocapnic-hypoxic ventilatory responsiveness being low relative to control (but exceeding control [2.4 +/- 1.0 vs. 1.6 +/- 0.5 L/min/%, p < 0.05] with acute restoration to normocapnia). Hyperventilation was maintained during exercise, at the resting CO(2) "setpoint." Relative to control, the breath-hold tolerance was attenuated, and dyspnea during exercise was significantly greater and not simply ascribable to the high ventilation. These observations suggest that patients with IH have a sustained hyperventilatory and dyspneic drive that, although not attributable to central chemosensitivity, may possibly have peripheral chemoreflex contributions. The nature and etiology of this chronic hyperventilatory drive remain unclear.
Sandy Jack; Harry B Rossiter; Michael G Pearson; Susan A Ward; Christopher J Warburton; Brian J Whipp
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2004-04-01
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  170     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2004 Jul 
Date Detail:
Created Date:  2004-07-09     Completed Date:  2004-08-19     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  118-25     Citation Subset:  AIM; IM    
Aintree Chest Centre, University Hospital Aintree, Liverpool L9 7AL, UK.
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MeSH Terms
Administration, Inhalation
Anoxia / complications,  physiopathology*
Carbon Dioxide / administration & dosage*,  metabolism
Chronic Disease
Dyspnea / etiology,  physiopathology
Exercise / physiology*
Hypercapnia / complications,  physiopathology
Hyperventilation / complications,  metabolism,  physiopathology*
Middle Aged
Pulmonary Gas Exchange / physiology
Pulmonary Ventilation / physiology*
Reference Values
Rest / physiology
Reg. No./Substance:
124-38-9/Carbon Dioxide
Comment In:
Am J Respir Crit Care Med. 2004 Jul 15;170(2):105-6   [PMID:  15242848 ]

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