GASTRIC INTRAMUCOSAL PH - A PREDICTOR OF SURVIVAL IN CARDIAC-SURGERY PATIENTS WITH LOW CARDIAC-OUTPUT

Objective: To assess the value of gastric intramucosal pH measurement in patients with low output after cardiac surgery, Design: Prospective clinical study. Setting: University hospital. Participants: Fifteen p atients with low output after cardiac surgery were included. Those who survived the first postoperative day (n = 14) remained in the study. Interventions: Gastric intramucosal pH and arterial lactate concentrat ions were measured 6, 12, and 24 hours after admission to the intensiv e care unit. Intravenous infusion of buffer solutions was strictly avo ided during the equilibration period and in the half hour before injec tion of saline into the gastric balloon of the tonometer. Measurements and Main Results: Eight patients survived during the 28-day observati on period, and six patients died. On admission to the intensive care u nit, no difference in cardiac index (1.56 v 1.54 L/min/m(2)) or pulmon ary capillary wedge pressure (17.3 v 17.7 mmHg) was found between surv ivors and nonsurvivors. During the first 24 hours after surgery arteri al lactate was significantly higher in the nonsurvivor group (61 v 23 mg/dL), but there was net difference between the gastric intramucosal pH of survivors and nonsurvivors (7.41 v 7.42 on admission). Conclusio ns: Calculated gastric mucosal pH is not an early predicter of surviva l in cardiac surgery patients with postoperative low cardiac output sy ndrome. Further studies are required to assess whether the gradient be tween arterial and intramucosal partial pressure of carbon dioxide (Pc o(2)) might be a more useful predictive value. Copyright (C) 1997 by W .B. Saunders Company.