Document Detail


Physiological mechanisms of hyperventilation during human pregnancy.
MedLine Citation:
PMID:  18289946     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study examined the role of pregnancy-induced changes in wakefulness (or non-chemoreflex) and central chemoreflex drives to breathe, acid-base balance and female sex hormones in the hyperventilation of human pregnancy. Thirty-five healthy women were studied in the third trimester (TM(3); 36.3+/-1.0 weeks gestation; mean+/-S.D.) and again 20.2+/-7.8 weeks post-partum (PP). An iso-oxic hyperoxic rebreathing procedure was used to evaluate wakefulness and central chemoreflex drives to breathe. At rest, arterialized venous blood was obtained for the estimation of arterial PCO(2) (PaCO(2)) and [H(+)]. Blood for the determination of plasma strong ion difference ([SID]), albumin ([Alb]), as well as serum progesterone ([P(4)]) and 17beta-estradiol ([E(2)]) concentrations was also obtained at rest. Wakefulness and central chemoreflex drives to breathe, [P(4)] and [E(2)], ventilation and V CO(2) increased, whereas PaCO(2) and the central chemoreflex ventilatory recruitment threshold for PCO(2) (VRTCO(2)) decreased from PP to TM(3) (all p<0.01). The reductions in PaCO(2) were not related to the increases in [P(4)] and [E(2)]. The alkalinizing effects of reductions in PaCO(2) and [Alb] were partly offset by the acidifying effects of a reduced [SID], such that arterial [H(+)] was still reduced in TM(3) vs. PP (all p<0.001). A mathematical model of ventilatory control demonstrated that pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, V CO(2) and cerebral blood flow account for the reductions in PaCO(2), [H(+)] and VRTCO(2). This is the first study to demonstrate that the hyperventilation and attendant hypocapnia/alkalosis of human pregnancy results from a complex interaction of pregnancy-induced changes in wakefulness and central chemoreflex drives to breathe, acid-base balance, metabolic rate and cerebral blood flow.
Authors:
Dennis Jensen; James Duffin; Yuk-Miu Lam; Katherine A Webb; Jeremy A Simpson; Gregory A L Davies; Larry A Wolfe; Denis E O'Donnell
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-01-12
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  161     ISSN:  1569-9048     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2008 Mar 
Date Detail:
Created Date:  2008-03-10     Completed Date:  2008-06-24     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  76-86     Citation Subset:  IM    
Affiliation:
School of Kinesiology and Health Studies, Queen's University, Kingston, Ontorio, Canada K7L 3N6. Odj@queensu.ca
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MeSH Terms
Descriptor/Qualifier:
Acid-Base Equilibrium / physiology*
Adult
Carbon Dioxide / blood,  cerebrospinal fluid
Estradiol / blood
Female
Humans
Hydrogen-Ion Concentration
Hyperventilation*
Models, Theoretical
Pregnancy / physiology*
Progesterone / blood
Pulmonary Ventilation / physiology*
Serum Albumin
Wakefulness
Chemical
Reg. No./Substance:
0/Serum Albumin; 124-38-9/Carbon Dioxide; 50-28-2/Estradiol; 57-83-0/Progesterone

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


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