Efforts to reduce acute lung injury by using smaller tidal volumes and lower pressures have been suggested along with sedation vacations to facilitate weaning. Recently, Schweickert and coworkers evaluated seven complications in 128 patients receiving mechanical ventilation and continuous infusions of sedative drug who were randomized to daily interruption of sedative infusions (n = 66) vs sedation directed by the medical ICU team without this strategy (n = 60). Daily interrupted sedative infusions reduced ICU length of stay (6.2 days vs 9.9, p < 0.01), duration of mechanical ventilation (4.8 vs 7.3 days, p < 0.003), and the incidence of complications per patient (13 complications in 12 patients vs 26 complications in 19 patients, p < 0.04).
Weaning protocols are recommended to limit the duration of mechanical ventilation. Dries and co-workers, using a standardized weaning protocol, reduced days of mechanical ventilation (ventilator days/ICU days) from 0.47 to 0.33, numbers of patients failing ventilation (25 vs 43), and reduced rates of VAP (15% to 5%). Although there are a number of confounding variables with the study design, efforts to remove the endotracheal tube without reintubation should be encouraged.
Continuous aspiration of subglottic secretions (CASS), through use of specially designed endotracheal tubes with wider, elliptic holes, helps facilitate drainage. In a recent metaanalysis, CASS reduced the incidence of VAP by half (RR, 0.51; 95% CI, 1.7 to 2.3), shortened ICU stay by 3 days (95% CI, 2.1 to 3.9), and delayed the onset of VAP by 6 days. CASS was also cost-effective, saving $4,992/ case of VAP prevented or $1,872/patient, but mortality was not affected. However, when CASS was combined with semirecumbent positioning, no clinical benefit was observed, which underscores the importance of interactive prevention strategies.
Ventilator circuit issues and methods of humidifi-cation in relation to VAP were recently summarized by Branson. Frequency of circuit changes does not prevent VAP and is an area for substantial cost saving. Condensate collecting in the ventilator circuit can become contaminated from patient secretions or by opening the circuit; vigilance is needed to prevent inadvertently flushing the condensate into the lower airway or in-line nebulizers at the bedside or during patient transport. Metered-dose inhalers may be safer for the delivery of bronchodilators than nebulizers, which if contaminated, may produce bacterial aerosols.