Influence of positive end-expiratory pressure ventilation on peripheral tissue perfusion evaluated by measurements of tissue gases and pH - An experimental study in pigs with oleic acid lung injury

Measurements of subcutaneous oxygen tension (PscO(2)), subcutaneous carbon dioxide tension (PscCO(2)) and subcutaneous pH (pHsc) were used for evaluat ion of peripheral oxygenation in pigs subjected to oleic acid-induced lung injury during ventilation with increasing levels of positive end-expiratory pressure (PEEP). Lung injury resulted in a decrease of arterial oxygen ten sion (PaO2) from 93 to 37 mm Hg (p < 0.01) with maintained cardiac output. PscO(2) decreased from 45 to 17 mm Hg (p < 0.01) and pHsc from 7.47 to 7.39 (p < 0.05), and PscCO(2) increased from 46 to 59 mm Hg (p < 0.05). Increas e of PEEP level between 5 and 20 cm H2O resulted in a continuous increase o f PaO2 from 45 to 145 mm Hg and a decrease of cardiac output from 4.1 to 2. 0 liters/min (p < 0.01). PscO(2) increased up to a PEEP level of 15 cm H2O, reaching 26 mm Hg. Further increase of PEEP level up to 20 cm H2O resulted in an increase of PscCO(2) from 65 to 71 mm Hg (p < 0.05) and a decrease o f pHsc from 7.31 to 7.29 (p < 0.05). In conclusion: measurements of tissue gases and pH can be used to evaluate optimum peripheral tissue oxygenation during titration of PEEP level. Whether these measurements can be used as t he only indicator to guide therapy in an individual case remains to be stud ied. Copyright (C) 2000 S. Karger AG, Basel.