Article

Cerebral and peripheral hemodynamics and oxygenation during maximal dry breath-holds.

Department of Physiology, University of Split School of Medicine, Soltanska 2, 21000 Split, Croatia.
Respiratory Physiology & Neurobiology (impact factor: 2.24). 09/2007; 157(2-3):374-81. DOI:10.1016/j.resp.2007.02.002 pp.374-81
Source: PubMed

ABSTRACT The effects of maximal apneas on cerebral and brachial blood flow and oxygenation are unknown in humans. Middle cerebral artery blood velocity (MCAV), cerebral and muscle oxygenation (Sc(O2) and Sm(O2)) and brachial blood flow (BBF) were measured during apneas in breath-hold divers (BHD) and non-divers (ND). Brain oxyhemoglobin (O(2)Hb) was maintained in both groups until the end of apnea, whereas deoxyhemoglobin increased more in BHD. Therefore, Sc(O2) decreased more in BHD due to longer apnea duration and smaller initial MCAV increase. MCAV increased significantly more in BHD versus ND at the end of apnea. Cerebral desaturation for approximately 13% occurred at the end of apnea in BHD despite increased cerebral oxygen delivery for approximately 50%. Larger reduction in muscle O(2)Hb was found in BHD, with similar peripheral vasoconstriction. These data indicate that BHD have decreased Sc(O2) at the end of breath-hold despite large increases in MCAV. This is partly due delayed initial cerebral vasodilation. This study provides further evidence for the oxygen-conserving effect in elite divers.

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Keywords

apnea duration
 
apneas
 
BBF
 
brachial blood flow
 
breath-hold divers
 
Cerebral desaturation
 
cerebral oxygen delivery
 
deoxyhemoglobin
 
elite divers
 
initial cerebral vasodilation
 
large increases
 
Larger reduction
 
maximal apneas
 
Middle cerebral artery blood velocity
 
muscle oxygenation
 
non-divers
 
oxygen-conserving effect
 
oxygenation
 
similar peripheral vasoconstriction
 
smaller initial MCAV increase