Document Detail


Tissue oxygenation response to mild hypercapnia during cardiopulmonary bypass with constant pump output.
MedLine Citation:
PMID:  16675511     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Tissue oxygenation is the primary determinant of wound infection risk. Mild hypercapnia markedly improves cutaneous, subcutaneous (s.c.), and muscular tissue oxygenation in volunteers and patients. However, relative contributions of increased cardiac output and peripheral vasodilation to this response remains unknown. We thus tested the hypothesis that increased cardiac output is the dominant mechanism. METHODS: We recruited 10 ASA III patients, aged 40-65 yr, undergoing cardiopulmonary bypass for this crossover trial. After induction of anaesthesia, a Silastic tonometer was inserted s.c. in the upper arm. S.C. tissue oxygen tension was measured with both polarographic electrode and fluorescence-based systems. Oximeter probes were placed bilaterally on the forehead to monitor cerebral oxygenation. After initiation of cardiopulmonary bypass, in random order patients were exposed to two arterial CO(2) partial pressures for 30 min each: 35 (normocapnia) or 50 mm Hg (hypercapnia). Bypass pump flow was kept constant throughout the measurement periods. RESULTS: Hypercapnia during bypass had essentially no effect on Pa(CO(2)) , mean arterial pressure, or tissue temperature. Pa(CO(2)) and pH differed significantly. S.C. tissue oxygenation was virtually identical during the two Pa(CO(2)) periods [139 (50-163) vs 145 (38-158), P=0.335] [median (range)]. In contrast, cerebral oxygen saturation (our positive control measurement) was significantly less during normocapnia [57 (28-67)%] than hypercapnia [64 (37-89)%, P=0.025]. CONCLUSIONS: Mild hypercapnia, which normally markedly increases tissue oxygenation, did not do so during cardiopulmonary bypass with fixed pump output. This suggests that hypercapnia normally increases tissue oxygenation by increasing cardiac output rather than direct dilation of peripheral vessels.
Authors:
O Akça; D I Sessler; D Delong; R Keijner; B Ganzel; A G Doufas
Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't; Validation Studies     Date:  2006-05-04
Journal Detail:
Title:  British journal of anaesthesia     Volume:  96     ISSN:  0007-0912     ISO Abbreviation:  Br J Anaesth     Publication Date:  2006 Jun 
Date Detail:
Created Date:  2006-05-15     Completed Date:  2006-07-12     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0372541     Medline TA:  Br J Anaesth     Country:  England    
Other Details:
Languages:  eng     Pagination:  708-14     Citation Subset:  IM    
Affiliation:
Outcomes Research Institute, University of Louisville, KY 40202, USA. ozan.akca@louisville.edu
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MeSH Terms
Descriptor/Qualifier:
Adult
Carbon Dioxide / blood
Cardiac Output
Cardiopulmonary Bypass*
Cerebrovascular Circulation
Cross-Over Studies
Female
Humans
Hypercapnia / blood,  physiopathology*
Intraoperative Period
Male
Middle Aged
Monitoring, Intraoperative / instrumentation,  methods
Oximetry / instrumentation
Oxygen / blood
Oxygen Consumption*
Partial Pressure
Regional Blood Flow
Reproducibility of Results
Skin / blood supply
Subcutaneous Tissue / blood supply*
Grant Support
ID/Acronym/Agency:
DE 14879-01A1/DE/NIDCR NIH HHS; GM 61655/GM/NIGMS NIH HHS; R01 GM061655-03/GM/NIGMS NIH HHS; R03 DE014879-01A1/DE/NIDCR NIH HHS
Chemical
Reg. No./Substance:
124-38-9/Carbon Dioxide; 7782-44-7/Oxygen
Comments/Corrections

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