Document Detail

Effects of age and exercise on physiological dead space during simulated dives at 2.8 ATA.
MedLine Citation:
PMID:  12391136     Owner:  NLM     Status:  MEDLINE    
Physiological dead space (Vds), end-tidal CO(2) (Pet(CO(2))), and arterial CO(2) (Pa(CO(2))) were measured at 1 and 2.8 ATA in a dry hyperbaric chamber in 10 older (58-74 yr) and 10 younger (19-39 yr) air-breathing subjects during rest and two levels of upright exercise on a cycle ergometer. At pressure, Vd (liters btps) increased from 0.34 +/- 0.09 (mean +/- SD of all subjects for normally distributed data, median +/- interquartile range otherwise) to 0.40 +/- 0.09 (P = 0.0060) at rest, 0.35 +/- 0.13 to 0.45 +/- 0.11 (P = 0.0003) during light exercise, and 0.38 +/- 0.17 to 0.45 +/- 0.13 (P = 0.0497) during heavier exercise. During these conditions, Pa(CO(2)) (Torr) increased from 33.8 +/- 4.2 to 35.7 +/- 4.4 (P = 0.0059), 35.3 +/- 3.2 to 39.4 +/- 3.1 (P < 0.0001), and 29.6 +/- 5.6 to 37.4 +/- 6.5 (P < 0.0001), respectively. During exercise, Pet(CO(2)) overestimated Pa(CO(2)), although the absolute difference was less at pressure. Capnography poorly estimated Pa(CO(2)) during exercise at 1 and 2.8 ATA because of wide variability. Older subjects had higher Vd at 1 ATA but similar changes in Vd, Pa(CO(2)), and Pet(CO(2)) at pressure. These results are consistent with an effect of increased gas density.
H J Mummery; B W Stolp; G deL Dear; P O Doar; M J Natoli; A E Boso; J D Archibald; G W Hobbs; H E El-Moalem; R E Moon
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2002-10-11
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  94     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2003 Feb 
Date Detail:
Created Date:  2003-01-17     Completed Date:  2003-07-21     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  507-17     Citation Subset:  IM    
Department of Anesthesiology, Center for Hyperbaric Medicine and Environmental Physiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
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MeSH Terms
Aging / physiology*
Atmospheric Pressure*
Carbon Dioxide / blood
Diving / physiology*
Exercise / physiology*
Hydrogen-Ion Concentration
Oxygen / blood,  metabolism
Pulmonary Alveoli / metabolism
Respiratory Dead Space*
Sex Characteristics
Tidal Volume
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen

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