Document Detail


Cardiovascular neuroregulation during acute exposure to 40, 70, and 100% oxygen at sea level.
MedLine Citation:
PMID:  16370259     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Humans encounter increased partial pressures of inspired oxygen in some kinds of diving as well as during use of hyperoxic mixtures to shorten decompression times and hyperbaric oxygen therapy for decompression sickness or other clinical conditions. Although it is known that hyperoxia may affect cardiovascular regulation, such effects are generally obscured by stress and the diving reflex. In this study, we evaluated cardiovascular neuroregulation for various levels of hyperoxia in a laboratory setting. METHODS:There were 10 healthy adults who were exposed to 21, 40, 70, and 100% oxygen administered via mask as a series of stepwise increases. Subjects breathed at a fixed respiratory rate of 15 breaths x min(-1) while their heart rate (HR) and blood pressure (BP) were measured continuously over 5-min intervals. RESULTS: HR decreased with increasing fraction of inspired oxygen (FIO2) (21%: 65 +/- 9, 40%: 63 +/- 9, 70%: 61 +/- 8, 100%: 60 +/- 8 bpm) and the high-frequency power of HR variability (an index of cardiac parasympathetic activity) increased as FIO2 rose (21%: 773 +/- 565, 40%: 880 +/- 590, 70%: 966 +/- 681, 100%: 1114 +/- 715 ms2); both changes were significant at the 70% and 100% oxygen levels. The low-frequency power of systolic BP variability (an index of vasomotor sympathetic activity) did not change. Low- and high-frequency transfer function gains (indices of arterial-cardiac baroreflex function) increased with FIO2. CONCLUSION: Parasympathetic activity and arterial-cardiac baroreflex function increased with hyperoxia in a dose-dependent manner. This increase may help reduce the likelihood of arrhythmias during diving.
Authors:
Shigeki Shibata; Ken-Ichi Iwasaki; Yojiro Ogawa; Jitsu Kato; Setsuro Ogawa
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  76     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-12-22     Completed Date:  2006-02-16     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1105-10     Citation Subset:  IM; S    
Affiliation:
Department of Anesthesiology, Nihon University School of Medicine, 30-1 Oyaguchi-Kamimachi, Itabashi-Ku, Tokyo 173-8610, Japan.
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MeSH Terms
Descriptor/Qualifier:
Administration, Inhalation
Adult
Analysis of Variance
Baroreflex / physiology*
Blood Pressure / physiology
Cardiovascular System / innervation*
Female
Heart Rate / physiology
Hemodynamics / physiology
Humans
Hyperoxia / physiopathology*
Linear Models
Male
Oxygen / administration & dosage*
Parasympathetic Nervous System / physiology*
Chemical
Reg. No./Substance:
7782-44-7/Oxygen

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


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