User: Guest  Login
Original title:
Cerebral blood flow and cerebrovascular response to intermittent hypercapnia during hyperbaric oxygenation treatment 
Translated title:
Zerebraler Blutfluss und zerebrovaskulaere Reaktivitaet bei intermittierender Hyperkapnie waehrend der hyperbaren Oxygenierungstherapie 
Document type:
Fakultät für Medizin 
Hipp, R. (apl Prof Dr med) 
Tempel, G. (Univ-Prof Dr med) 
Subject group:
MED Medizin 
Cerebral blood flow; hyperbaric oxygenation; transcranial Doppler sonography; cerebrovascular reactivity 
Translated keywords:
Hirndurchblutung; hyperbare Oxygenierung; transkranielle Dopplersonographie; zerebrovaskulaere Reaktivitaet 
TUM classification:
MED 411d; MED 606d 
Background and purpose: The decrease in cerebral blood flow (CBF) through cerebral vasoconstriction caused by extreme hyperoxia could promote the onset of central nervous system oxygen toxicity during hyperbaric oxygenation (HBO). CBF increases with hypercapnia, but the effects of intermittent hypercapnia during HBO exposure on CBF have not been determined. The aim of the study is to evaluate CBF and cerebrovascular reactivity to hypercapnia during HBO at 2.5 atmospheres absolute (ATA) for 70 min using transcranial doppler sonography (TCD) in healthy volunteers. Methods: 29 adult subjects were studied during a routine compression profile: 2.5 ATA for 70 min. Fifteen subjects received 100% oxygen simulating a HBO treatment, 14 subjects breathed room air. TCD with a 2 MHz probe was used to continuously measure mean blood flow velocities (Vmean) in the middle cerebral artery. Cerebrovascular reactivity was assessed by response to hypercapnia induced by standardized rebreathing. Results: Vmean decreased by 19% during HBO at 2.5 ATA for 70 min, P<0.0001, and returned to baseline within 10 min after end of exposure. Hyperbaric exposure alone did not change Vmean. Heart rate and blood pressure did not differ between groups over time. Hypercapnic cerebral vasodilation tended to be less pronounced in the HBO group, P=0.02 after 30 min at 2.5 ATA, but reversible with termination of hypercapnia. Conclusions: HBO at 2.5 ATA for 70 minutes causes a sustained decrease in CBF, which is reversible within 10 min after end of exposure. Cerebral hypercapnic vasodilation is slightly reduced during HBO and reversible with normocapnia. 
Translated abstract:
Die Auswirkungen der Behandlung mit Sauerstoff unter Überdruck (HBO) bei 2,5 bar während 70 min auf den cerebralen Blutfluss und die CO2-Reaktivität wurde an gesunden Freiwilligen mittels transcranieller Dopplersonographie untersucht. Die mittlere Blutflussgeschwindigkeit in der arteria cerebri media fällt um 19% und erreichte 10 min nach der Behandlung wieder den Ausgangswert. Bei alleiniger Überdruckexposition blieb die Blutflussgeschwindigkeit unverändert. Die Gefässerweiterung bei Hypercapni...    »
Publication :
Universitätsbibliothek der TU München 
Oral examination:
Controlled terms:
Hirngefäß Hämatogene Oxidationstherapie Hyperkapnie Gehirn Durchblutung Doppler-Sonographie 
File size:
161006 bytes 
Last change: