PLASMA FATTY-ACID CHANGES AND INCREASED LIPID-PEROXIDATION IN PATIENTS WITH ADULT-RESPIRATORY-DISTRESS-SYNDROME

Objective: There is strong evidence that adult patients with acute res piratory distress syndrome (ARDS) are under severe oxidative stress, w hich leads to molecular damage. Using gas chromatography-mass spectrom etry, our objective was to sequentially monitor changes, in intensive care unit (ICU) patients, characteristic of the oxidative loss of plas ma unsaturated fatty acids and formation of the highly specific oxidat ion product of linoleic acid, 4-hydroxy-2-nonenal. Design: Prospective , nonintervention, descriptive study, Limited statistics were applied to facilitate interpretation of the data. Setting: ICU of a postgradua te teaching hospital. Patients: Eighteen critically ill patients with an established diagnosis of ARDS requiring high F10(2) administered by mechanical ventilation were compared with ten normal, healthy control s and ten patients pre- and postcardiopulmonary bypass surgery at risk for developing ARDS. Interventions: None. Measurements and Main Resul ts: Sixty percent of the patients with ARDS included in this study sur vived. Major changes in the plasma concentrations of fatty acids occur red in all patients during their stay in the ICU. Percentage decreases in plasma linoleic acid concentrations were accompanied by increases in plasma oleic and palmitoleic acid concentrations. Circulating linol eic acid concentrations were significantly (p = .0001) lower in patien ts with ARDS than in the two control groups, The patients with ARDS wh o did not survive had lower (p = .0056) plasma oleic acid values than normal healthy controls and patients at risk for ARDS as a consequence of undergoing cardiopulmonary bypass surgery. Changes in palmitoleic acid, however, did not reach significance within the different groups studied. Patients with ARDS showed higher plasma concentrations of 4-h ydroxy-2-nonenal (0.433 +/- 0.048 vs. 0.523 +/- 0.069 nmol/mL plasma f or survivors and nonsurvivors, respectively) when compared with normal healthy controls (0.205 +/- 0.03 nmol/mL, p = .0001) and cardiopulmon ary bypass patients at risk for developing ARDS (0.279 +/- 0.027 nmol/ mL, p = .034 prebypass). Conclusions: During intensive care treatment, patients with ARDS decrease their percentage plasma concentrations of total plasma linoleic acid, but increase their percentage concentrati ons of oleic and palmitoleic acids. As plasma linoleic acid concentrat ions decreased, there was usually an increase in plasma 4-hydroxy-2-no nenal values, one of its specific peroxidation products, suggestive of severe oxidative stress leading to molecular damage to lipids.