Mechanical ventilation strategies and inflammatory responses to cardiac surgery: a prospective randomized clinical trial
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To examine whether postoperative mechanical ventilation with lower tidal volumes (VT) has protective effects on inflammatory responses induced by cardiopulmonary bypass (CPB) surgery in smokers and nonsmokers.
Design and setting
Prospective, randomized, controlled clinical trial in the intensive care unit of a university hospital.
Patients and participants
We examined 44 patients (22 smokers, 22 nonsmokers) immediately after uncomplicated CPB surgery.
Ventilation was applied for 6 h with either VT of either 6 or 12 ml/kg ideal body weight.
Measurements and results
The time course of serum tumor necrosis factor (TNF) α, interleukin (IL) 6, and IL-8 determined 0, 2, 4, and 6 h after randomization did not differ significantly between the ventilatory strategies. By contrast, in bronchoalveolar lavage fluids sampled after 6 h only TNF-α levels were significantly higher in the high VT group than the low VT group (50±111 pg/ml vs. 1±7 pg/ml). IL-6 and IL-8 concentrations did not differ between groups. Subgroup analysis of patients with serum TNF-α level higher than 0 pg/ml after surgery revealed lower TNF-α serum levels during lower VT ventilation. All observed effects were small, independent of patients’ history of smoking, and were not correlated with duration of ventilation and ICU stay.
Ventilation with lower VT had no or only minor effect on systemic and pulmonary inflammatory responses in patients with healthy lungs after uncomplicated CPB surgery. Our data do not suggest a clinical benefit of using low VT ventilation in these selected patients.