科研之友
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摘要
Although low doses of oxygen (FiO(2) %26lt; 0.50) are considered nontoxic, recent studies have shown that even lower doses increase pulmonary inflammatory mediators. We aimed to evaluate the acute effects of reducing FiO(2) on pulmonary inflammation in mechanically ventilated patients without respiratory failure. %26lt;br%26gt;This study was a prospective, single-center crossover study in a medical/surgical intensive care unit at a university hospital. Hemodynamically stable patients under mechanical ventilation for %26gt; 24 h without severe respiratory failure (PaO2/FiO(2) %26gt; 250). A basal FiO(2) of 0.40 was reduced to 0.21 provided SpO(2) remained higher than 90 %. Patients who could not tolerate the reduction in FiO(2) to 0.21 were excluded. %26lt;br%26gt;We screened 40 patients, but only 28 (70 %) tolerated FiO(2) 0.21. We measured common clinical variables and inflammatory mediators in plasma and in exhaled breath condensate (EBC) at the end of three 4-h periods: (1) basal (FiO(2) 0.40), (2) after FiO(2) reduction to 0.21, and (3) after returning FiO(2) 0.40. We used one-way ANOVA for repeated measurements with FiO(2) as the grouping variable. Median values of inflammatory mediators in EBC showed nonsignificant changes among the three periods: NO2 + NO3 17.1, 14.1 and 11.0 mu mol/L (p = 0.2), and 8-isoprostane 4.4, 8.2 and 5.3 pg/ml (p = 0.6) for the three periods, respectively. Plasma levels also showed nonsignificant changes during the period of the study: NO2 + NO3 12.6, 16.3 and 15.0 mu mol/L (p = 0.9), TNF alpha 13.5, 18.0 and 14.5 pg/ml (p = 0.8), IL-4 12.9, 18.7 and 23.9 pg/ml (p = 0.1), IL-6 50.9, 35.1 and 28.3 pg/ml (p = 0.6), and IL-10 15.2, 22.2 and 22.2 pg/ml (p = 0.7) for the three periods, respectively. %26lt;br%26gt;FiO(2) 0.40 in mechanically ventilated patients without severe respiratory failure did not increase systemic or pulmonary inflammation.
- 出版日期2013-4
