Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves.
Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (p<0.001, ANOVA repeated measures design) and mean tissue fractions of 1.6% (cytochrome aa3) and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B), a left ventricular assistive device (LVAD pump) was implanted. Oxygen saturation in group B animals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.
Lindbergh
Tobias
T
Linkoping University, Department of Biomedical Engineering, Division of Biomedical Instrumentation, Linkoping, 58185 Sweden. tobi@imt.liu.se
Larsson
Marcus
M
Szabó
Zoltán
Z
Casimir-Ahn
Henrik
H
Strömberg
Tomas
T
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology; D002417:Cattle; D009206:Myocardium / Q000378:metabolism*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*
D010100:Oxygen