Kinetic and reversibility of mechanical ventilation-associated pulmonary and systemic inflammatory response in patients with acute lung injury.

Abstract

To investigate the kinetic and reversibility of mechanical ventilation-associated pulmonary and systemic inflammatory response in patients with acute lung injury (ALI). Prospective observational cross-over study. Intensive care unit of a university hospital. Twelve mechanically ventilated patients with ALI. Mechanical ventilation was transiently changed from a lung protective setting with PEEP of 15 cmH(2)O and a V(T) of 5 ml/kg predicted body weight to a more conventional ventilatory setting with PEEP of 5 cmH(2)O and V(T) of 12 ml/kg predicted body weight for a period of 6 h. We examined the profile of interleukin (IL)-1beta, IL-1 receptor antagonist, IL-6, IL-10, and tumor necrosis factor in the plasma of all patients, and in the bronchoalveolar lavage (mini-BAL) fluid of six of these patients. Measurements were performed at baseline, 1 h, and 6 h after each change of the ventilatory setting. Switching to conventional mechanical ventilation was associated with a higher PaO(2) ( P < 0.05) and a marked increase ( P < 0.05) of measured plasma cytokines in patients with and without mini-BAL with a maximum after 1 h. Similarly, intraalveolar cytokine concentrations increased with conventional mechanical ventilation. While plasma cytokine levels returned to baseline values, intraalveolar cytokine concentrations further increased when lung protective mechanical ventilation was reestablished. In patients with ALI, initiation of low PEEP and high V(T) mechanical ventilation is associated with cytokine release into circulation which occurred within 1 h. It is independent from BAL procedures and can be reversed by reinstitution of lung protective mechanical ventilation.