IS ENDOTOXIN AND CYTOKINE RELEASE RELATED TO A DECREASE IN GASTRIC INTRAMUCOSAL PH AFTER HEMORRHAGIC-SHOCK

Objectives: (a) To investigate the relationship between gut ischemia p arameters (gastric intramucosal pH [pHi]: mucosal-arterial carbon diox ide difference [PCO2-gap]), and endotoxin or cytokine release during h emorrhagic shock; (b) to compare the predictive value of pHi, PCO2-gap and arterial lactate concentrations. Design: Prospective study. Setti ng: Surgical intensive care unit of a university hospital. Patients: 2 0 multiple trauma patients with severe hemorrhagic shock. Intervention s: Intramucosal measurements and blood samples were obtained on admiss ion to the emergency room and repeatedly over 48 h. Measurements and r esults: Endotoxin was measured using a chromogenic limulus amoebocyte assay Cytokine [tumor necrosis factor-alpha (TNF alpha) and interleuki n-6 (IL-6)] values were evaluated by immunoradiometric assays. Only 3 patients had positive blood cultures but endotoxins were detected at l east once in all patients. Endotoxin levels were similar in survivors and nonsurvivors over the study period and were not related to pHi or PCO2-gap. Initially high levels of IL-6 were observed in both, nonsurv ivors and survivors [median 1778 pg/ml (range 435-44 540) vs 2068 pg/m l (range 996-92 300)]. IL-6 levels progressively decreased In the surv ivors but-not significantly. On admission, TNF alpha concentrations we re similar in nonsurvivors and survivors (42 +/- 35 vs 46 +/- 27 pg/ml ). From the. 24th h, TNF alpha values were higher in the nonsurvivors than in the survivors (24 h: 72 +/- 38 vs 34 +/- 17 pg/ml, p < 0.05). The greatest IL-6 levels were found for a pHi < 7.20 (28.5 +/- 36.5 vs 1.8 +/- 1.3 ng/ml, p < 0.05) or a PCO2-gap > 7.5 mmHg (1 kPa) (32.5 /- 37.5 vs 1.7 +/- 1.3 ng/ml, p < 0.01). With the same pHi threshold, no difference was found in endotoxin levels, The lactate concentration s were predictive for outcome from the 12th h (9.5 +/- 5.9 vs 3.6 +/- 2.3 mmol/l, p < 0.05), Conclusions: h)wing severe hemorrhagic shock, e ndotoxin translocation from the gut was a common phenomenon that seeme d independent of both pHi values and outcome. It could not explain IL- 6 and TNF alpha release. In severe hemorrhagic shock, neither pHi nor PCO2-gap provides additional information to the lactate measurements.