Decreases in organ blood flows associated with increases in sublingual PCO2 during hemorrhagic shock

Earlier studies demonstrated that not only the stomach but also the esophag eal wall served as an appropriate site for estimating the severity of circu latory shock by using tonometric methods. We then conceived of the option o f sublingual tonometry. In the present study, we tested the hypothesis that the changes in sublingual PCO2 serve as indicators of decreases in blood f low to sublingual and visceral tissue. In Sprague-Dawley rats, sublingual P CO2 increased from 50 to 127 Torr and arterial blood lactate increased from 0.9 to 11.2 mmol/l during bleeding. Sublingual blood flow simultaneously d ecreased to similar to 32% of preshock values. After reinfusion of shed blo od, organ blood flows and sublingual PCO2 were promptly restored to near-ba seline values. There were corresponding decreases in blood flows in the ton gue, stomach, jejunum, colon, and kidneys during hemorrhagic shock. Increas es in sublingual PCO2 were highly correlated with decreases in sublingual b lood flow (r = 0.80), tongue blood flow (r = 0.81), gastric blood flow (r = 0.74), jejunal blood flow (r = 0.65), colon blood flow (r = 0.80), and ren al blood flow (r = 0.75). Unbled control animals demonstrated no significan t changes. Therefore, we anticipate that sublingual tonometry will provide a useful, noninvasive alternative for monitoring visceral PCO2.