Importance of real-time tissue oximetry: relationship to muscle oxygenation and tissue viability.
BACKGROUND
There is currently no efficient and reliable clinical means of assessing the degree of ischemia- and reperfusion-associated damage in microvascular transplants. The objective was to study correlation of tissue oxygen tension measurements with tissue oxygen saturation, cytochrome oxidase redox state, and tissue viability.


METHODS
Latissimus dorsi muscle was dissected and mobilized in New Zealand white rabbits (n = 30, 2.5 ± 0.5 kg). Muscles were exposed to warm ischemia in two groups with either 4 or 6 h, followed by reperfusion. Tissue PO(2) was measured with a miniature intramuscular oxygen sensor (Licox microprobe; Integra Neurosciences, Ratingen, Germany) all along with tissue hemoglobin saturation (rSO(2)) and cytochrome oxidase aa3 redox state (CytOx) by in vivo near-infrared spectroscopy. Linear correlation was performed between tissue PO(2) and rSO(2), CytOx and tissue viability.


RESULTS
After ischemia and reperfusion, tissue PO(2) and CytOx recovery was significantly decreased in both groups compared with control (4 h: P < 0.05; 6 h: P < 0.01). Significant correlations between changes in tissue PO(2) and rSO(2) (r = 0.92; P < 0.01), CytOx (r = 0.90; P < 0.01), wet-to-dry ratio (r = -0.97; P < 0.01), and mitochondrial viability index (r = 0.97; P < 0.01) were found.


CONCLUSIONS
Tissue oxygen tension measured with microprobes correlated closely with tissue oxygenation, cellular oxygen utilization, and the extent of ischemia reperfusion injury.
Troitzsch
Dirk
D
Department of Cardiac and Thoracic Vascular Surgery, Philipps University of Marburg, Marburg, Germany.
Moosdorf
Rainer
R
Vogt
Sebastian
S
D000818:Animals; D003576:Electron Transport Complex IV / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000378:metabolism*; D010084:Oxidation-Reduction; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000378:metabolism*; D011817:Rabbits; D015427:Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology; D013997:Time Factors; D014022:Tissue Survival / Q000502:physiology*
D006454:Hemoglobins; D003576:Electron Transport Complex IV; D010100:Oxygen