Document Detail


Ventilation is greater in women than men, but the increase during acute altitude hypoxia is the same.
MedLine Citation:
PMID:  11282389     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We wished to determine whether the previously reported lower arterial or alveolar P(CO2) in women than men, and in luteal (LUT) compared with follicular (FOL) menstrual cycle phase would persist during normal oral contraceptive use and during early altitude exposure. Ventilation and blood gases were measured at baseline (636 mmHg approximately 5400 ft, 1650 m) and during simulated altitude at 426 mmHg ( approximately 16000 ft, 4880 m), after 1 h (A1) and during the 12th h (A12), in 18 men (once) and in 19 women twice, during LUT and FOL and in 20 women twice while on placebo (PLA) or highest progestin dose (PIL) oral contraceptives. At baseline, Pa(CO2) was significantly higher in men than all women by 3.3 mmHg. When progesterone-progestin (PRO) was elevated in women, Pa(CO2) was significantly lower than in FOL and PLA, but the latter were still significantly lower than men. At altitude the P(CO2) differences between men and women and PRO levels persisted, with PA(CO2) falling by 3.6 and 7.3 mmHg at A1 and A12 in all, indicating an equivalent increase in alveolar ventilation. The mean arterial-end tidal P(CO2) difference was never >2 mmHg in the groups, indicating no VA/Q mismatch related to gender, PRO levels or altitude. All women had higher breathing frequency than men, resulting in greater deadspace ventilation. At altitude, the mean Pa(O2) was approximately 44 mmHg (Sa(O2) approximately 79%) for all, indicating equivalent oxygenation, but alveolar-arterial P(O2) differences were greater in women than men and higher when PRO was elevated. These results show that, relative to men, women have a compensated respiratory alkalosis, accentuated with elevated PRO. However, the ventilation response to acute altitude is the same in women and men.
Authors:
J A Loeppky; P Scotto; G C Charlton; L Gates; M Icenogle; R C Roach
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Respiration physiology     Volume:  125     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-04-03     Completed Date:  2001-06-28     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  225-37     Citation Subset:  IM    
Affiliation:
New Mexico Resonance, C-1, 2301 Yale Blvd SE, Albuquerque, NM 87106, USA. loeppky@unm.edu
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MeSH Terms
Descriptor/Qualifier:
Acid-Base Equilibrium / drug effects
Acute Disease
Adult
Altitude Sickness / physiopathology*
Carbon Dioxide / blood,  physiology
Contraceptives, Oral / pharmacology
Female
Follicular Phase / blood,  physiology
Humans
Luteal Phase / blood,  physiology
Male
Pulmonary Gas Exchange / drug effects,  physiology
Respiratory Physiological Phenomena* / drug effects
Sex Characteristics
Chemical
Reg. No./Substance:
0/Contraceptives, Oral; 124-38-9/Carbon Dioxide

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


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