USE OF TISSUE OXYGEN-TENSION MEASUREMENTS DURING RESUSCITATION FROM HEMORRHAGIC-SHOCK

Background: Tissue oxygen tension can be measured directly in selected organ beds, and these measurements may be more sensitive in assessing the adequacy of resuscitation than global physiologic parameters, We hypothesized that heart tissue oxygen tension would be an important ma sker for the severity of ischemic insult to the heart during hemorrhag ic shock, We further hypothesized that gut oxygen tension measured in the jejunum would prove to be a better measure of splanchnic hypoperfu sion than intramucosal pH (pHi). Methods: Tissue oxygen probes were in serted directly into the myocardium of the left ventricle and into the lumen of the proximal jejunum in 10 anesthetized swine, A pHi cathete r was introduced into the stomach, The animals were subjected to a con trolled hemorrhage of 50% of estimated blood volume, Gut and cardiac o xygen were monitored continuously during hemorrhage and resuscitation, which was performed with shed blood and crystalloid. Results: While g ut O-2 and pHi trended together, we were unable to establish a correla tion between changes in these two variables during hemorrhage and resu scitation. Heart Po-2 decreased significantly during hemorrhage, but s urpassed baseline values after resuscitation, a finding not seen in gu t Po-2. No standard physiologic variables reliably predicted changes i n heart Po-2 during these experiments. Conclusions: Tissue oxygen tens ions measurements are highly responsive to changes induced during grad ed hemorrhagic shock and resuscitation, Gut Po-2 and pHi appear to be measuring different physiologic processes in the gastrointestinal trac t, The compensatory ability of the heart far exceeds that of the gut a fter ischemic insult, This hemorrhagic shock model appears feasible fo r the study of various methods of resuscitation.