Effects of low and high-cuff pressures on the incidence of ventilator associated pneumonia

Ventilator-associated pneumonia (VAP) is defined as nosocomial pneumonia, which develops after 48 hours of mechanical ventilatory support in a patient who doesn?t have pneumonia prior to entubation. The incidence of VAP in mechanically ventilated patients is between 9-27%. Mortality of VAP is reported to be 24% to 50%. Aspiration of subglottic secretions by the patient is a major risk factor for VAP. Adjustment of endotracheal tube cuff pressures at 20-30 cmH2O prevents aspiration of secretions without causing mucosal damage.The hypothesis of our study is that adjusting cuff pressures at 30 cmH2O results in a lower incidence of VAPOur study is a randomized controlled study. Twentysix patients were enrolled into the study prospectively. Patients were randomized into low-normal and high-normal cuff pressures. After randomization cuff pressures were measured and adjusted regularly. First group?s cuff pressures were adjusted at 20 cmH2O, second group?s cuff pressures were adjusted at 30 cmH2O and measured with readjustement every four hours after randomization.We used National Nosocomial Infection Surveillance System (NNIS) criteria for diagnosing VAP. There was no statistically significant difference in clinical and demographic variables on admission between the two groups. Because of tecnical diffuculties cuff pressures were not kept between predesignated levels. However, the difference in the median cuff pressures between two groups were statistically significant: median cuff pressure at low-normal group was 18.2 (16.0-21.4) cmH2O; it was 22 (20.1-24.8) cmH2O in high-normal group (p:0.02). The incidence of VAP was found to be 41.7% (64 in 1000 ventilator days) in the low-normal group; it was 21.4% (41 at 1000 ventilatory day) in the high-normal group. There was no statistically significant difference between the two groups in the incidence of VAP or mortality (p=0.27, p=0.56). There was microbial growth in 75% of tracheal aspirate cultures. Emprical antibiotic treatment was sufficient in only 12.5% of patients based on the results of antibiogram. The mortality of patients with VAP was 100%.Key words: VAP, Cuff pressure, İntensive care.