Document Detail

Hypercapnic ventilatory response in humans before, during, and after 23 days of low level CO2 exposure.
MedLine Citation:
PMID:  9561287     Owner:  NLM     Status:  MEDLINE    
Alterations in ventilation and the chemoreceptor response to CO2 during 23 d of 1.2% inspired CO2 were studied in four male subjects. Resting ventilation (VE), tidal volume (VT), respiratory frequency (fR), inspired and end tidal O2 and CO2 and the hypercapnic ventilatory response (HCVR) measured by CO2 rebreathing were measured once before entering the chamber, on days 2, 5, 11, and 22 of CO2 exposure, and one day after. Resting VE slightly increased (5%) on day 2 of exposure and significantly increased (22%) by day 5 followed by a progressive decrease to pre-chamber levels by day 22 and on the first day of recovery. Tidal volume and fR were not statistically different. During the exposure PetCO2 was significantly elevated with day 2 having the largest increase (19.6%). PetCO2 returned to normal within 24 h post exposure. The HCVR was characterized by the slope (SHCVR), intercept at zero ventilation (B), and the ventilation at a PCO2 = 60 mmHg (VE60). The SHCVR decreased (14%) on day 2, but was not significant; the SHCVR on the other exposure days were also not different. The SHCVR on the first recovery day significantly increased (37%). The HCVR B was shifted to the right on day 2 by 5.2 mmHg, then progressively returned to the pre-exposure position. On recovery the B significantly shifted 6.9 mmHg to the right of pre-exposure B. The VE60 decreased by approximately 32% and 16% on day 2 and 5, respectively, then returned within pre-exposure range for the remainder of the exposure and during recovery. During the early phase and one day after the exposure the HCVR was right shifted. One day after exposure chemoreceptor sensitivity to elevated CO2 was increased but, the B was right shifted resulting in a reduced HCVR below PCO2 of 60 mmHg and a greater HCVR above 60 mmHg.
A R Elliott; G K Prisk; C Schöllmann; U Hoffmann
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  69     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  1998 Apr 
Date Detail:
Created Date:  1998-06-04     Completed Date:  1998-06-04     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  391-6     Citation Subset:  IM; S    
Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
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MeSH Terms
Adaptation, Physiological
Blood Gas Analysis
Carbon Dioxide / poisoning*
Chemoreceptor Cells / physiopathology
Chronic Disease
Ecological Systems, Closed
Hypercapnia / chemically induced*,  metabolism,  physiopathology*
Linear Models
Pulmonary Ventilation / physiology*
Space Flight
Time Factors
Reg. No./Substance:
124-38-9/Carbon Dioxide
G K Prisk / U CA San Diego, La Jolla

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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