GASTRIC INTRAMUCOSAL PH AS A THERAPEUTIC INDEX OF TISSUE OXYGENATION IN CRITICALLY ILL PATIENTS

Falls in gastric intramucosal pH (pH(i)) are associated with morbidity and mortality in patients admitted to intensive-care units (ICU). We tested the hypothesis that ICU outcome can be improved by therapy guided by changes in pH(i) and aimed at improving systemic oxygen availability. We studied 260 patients admitted to ICUs with APACHE II scores of 15-25. After insertion of a gastric tonometer, each patient was randomly assigned to a control or protocol group within the admission pH(i) category (normal = 7.35 or higher, low = below 7.35). The control groups were treated according to standard ICU practices. The protocol groups received, in addition, treatment to increase systemic oxygen transport or to reduce oxygen demand, whenever the pH(i) fell below 7.35 or by more than 0.10 units from the previous measurement. The protocol was used, because pH(i) fell, in 67 (85%) of the protocol group with normal pH(i) on admission. There were no significant differences between protocol and control groups in demographic characteristics, admission blood gases or haemoglobin concentration, number or type of organ system failures, or the intensity of ICU care. For patients admitted with low pH(i), survival was similar in the protocol and control groups (37% vs 36%), whereas for those admitted with normal pH(i), survival was significantly greater in the protocol than in the control group (58% vs 42%; p < 0.01). Therapy guided by pH(i) measurements improved survival in patients whose pH(i) on admission to ICU was normal. pH(i)-guided resuscitation may help improve outcome in such patients by preventing splanchnic organ hypoxia and the development of a systemic oxygen deficit.