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Cerebral vascular reactivity to hypercapnia is unchanged in apnea divers
Author(s) -
Ivancev Vladimir,
Valic Zoran,
Palada Ivan,
Obad Ante,
Bakovic Darija,
Dietz Niki M,
Joyner Michael J,
Dujic Zeljko
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1360-a
Subject(s) - hypercapnia , medicine , anesthesia , middle cerebral artery , hypoxia (environmental) , apnea , cerebral blood flow , obstructive sleep apnea , cardiology , acidosis , ischemia , chemistry , oxygen , organic chemistry
Hypercapnic cerebrovascular reactivity is decreased in obstructive sleep apnea and congestive heart disease patients. Ventilatory response to hypercapnia and/or hypoxia is blunted in apnea divers, whereas cerebrovascular reactivity to hypercapnia is presently unknown. We hypothesized that cerebrovascular reactivity to hypercapnia is increased in elite apnea divers, compared to control subjects, as a part of the O 2 conserving mechanism to maintain adequate brain O 2 supply. In the present study we determined cerebrovascular reactivity by measuring change in middle cerebral artery velocity per mmHg change in P ET CO 2 in response to two hyperoxic hypercapnia rebreathing maneuvers in seven elite apnea divers and seven control subjects. Ventilatory response to hypercapnia was blunted in divers compared to controls. Hypercapnia‐induced ventilation increase was significantly lower in divers due to lower respiratory frequency. Cerebrovascular reactivity was unchanged in both groups (3.7±1.4 vs 3.4±1.3 %/mmHg P ET CO 2 in divers and controls) and the same was found for cerebral vascular resistance and a time for middle cerebral artery velocity recovery to baseline value. Results indicate that the regulation of the cerebral circulation in response to hypercapnia shows no difference between divers and controls serving as protective mechanism against chronic intermittent cerebral hypoxia/hypercapnia. This study was supported by Croatian Ministry of Science, Education and Sports.