TISSUE OXYGENATION IN HYPOVOLEMIC SHOCK

Bowel mucosal ischemia may be related to the development of systemic sepsis. Traditional indices of oxygen metabolism are flow-weighted averages which do not reflect tissue-specific oxygen concentration. We undertook this study to examine the relationship between systemic oxygen delivery (DO2) and tissue oxygen tension (TPO2) in hypovolemic shock. A modified Wiggers model was used to produce hypotension in five swine. TPO2 was measured continuously with fluorescence-quenching 1-mm probes placed in the submucosa of the terminal ileum and subcutaneously in an axillary fold. Shock was maintained for 1 hr, followed by resuscitation. Cardiac output, systemic and pulmonary arterial pressures, and arterial and mixed venous blood gases were measured every 15 min. Data were analyzed by nonparametric ANOVA and rank coefficients, with logarithmic curve fitting and linear regression. DO2 decreased with phlebotomy (P < 0.003) as did skin TPO2 (P < 0.001) and bowel TPO2 (P < 0.0004). Skin and bowel TPO2 varied with DO2 and each other (P < 0.05). TPO2 remained low throughout the shock period and returned to or exceeded baseline levels with resuscitation (P < 0.05). The following were concluded: (1) Hypovolemic shock produces a significant and rapid decrease in subcutaneous and bowel TPO2 with concomitant change in DO2. (2) The degree of bowel ischemia, clinically inaccessible for quantitation, is paralleled by subcutaneous TPO2. (3) TPO2 provides information about oxygen availability in shock and resuscitation not available from traditional parameters of oxygen transport. © 1993 Academic Press, Inc.