Abstract
We studied the interrelationships among myocardial oxygenation, cardiac output, and systemic oxygenation during acute progressive hypoxemia in the paralyzed and mechanically ventilated lamb. Fractional inspired concentration of oxygen was reduced in five steps to a minimum of 0.05, decreasing arterial oxygen content (CaO2) from 10.9 +/- 2.4 to 2.8 +/- 0.5 ml/dl. Heart rate and stroke volume did not change at any step so that systemic oxygen transport decreased with CaO2. Systemic oxygen consumption fell at CaO2 less than 6 ml/dl. Left ventricular blood flow at maximal hypoxemia increased 277% (249 +/- 27 to 938 +/- 118 ml.min-1.100 g-1) so that left ventricular oxygen delivery and oxygen consumption were maintained. Evidence of anaerobic metabolism occurred when CaO2 was less than four (increase in arterial lactate and hypoxanthine), whereas at this level there was no evidence of inadequate myocardial oxygenation as determined by normal subepicardial: subendocardial blood flow and absence of net lactate production, although coronary sinus PO2 decreased. Although myocardial, cerebral, and adrenal blood flows increased, there was no redistribution of blood flow away from the viscera and skin.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: American Journal of Physiology-Heart and Circulatory Physiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
