Systemic phospholipase A2 and cachectin levels in adult respiratory distress syndrome and multiple-organ failure.

In this clinical study we have prospectively measured plasma phospholipase A2 (PLA2) activity and tumor necrosis factor (TNF) levels in ventilated intensive care unit (ICU) patients with (n = 9) and without (n = 12) evidence of respiratory distress syndrome (ARDS) and multiple-organ failure (MOF). The median peak TNF concentration in control patients was 40 ng/L (range less than 40-100 ng/L) and in ARDS patients 231 ng/L (range 100-2550 ng/L; p less than 0.001). All of the control patients were discharged alive from the ICU, whereas 6 of 9 ARDS patients died in the ICU. In 6 ARDS patients, it was possible to measure more than 4 consecutive plasma TNF levels. Of these 6 patients, the 3 with persistent elevations in systemic TNF above 230 ng/L succumbed (p less than 0.05, one-tailed). Patients with ARDS also had parallel elevations in plasma PLA2 activity above controls. These elevations were significant for arterial PLA2 activity but not for venous PLA2 activity. Our study suggests that serial measurement of plasma (arterial or venous) TNF levels may have (1) prognostic and (2) etiologic significance in ICU patients with ARDS and MOF.