CONTRIBUTION OF WATER CONDENSATION IN ENDOTRACHEAL-TUBES TO CONTAMINATION OF THE LUNGS

We postulated that water condensate in endotracheal tubes (ETTs) trans ports bacteria in the ETTs into the lungs during mechanical ventilatio n. Thirty-two ETTs obtained from freshly extubated patients were studi ed under wet and dry conditions using a physiologic lung model. All ba cteria expelled from the ETTs were collected on culture plates positio ned beneath the ETT. The lung model was ventilated with saturated air at 37-degrees-C over two time periods (60 min each), one in which cond ensation formation was prevented and the second in which condensation formed within the ETT. A mean of 457.6 colony-forming units (CFU)/h we re expelled with condensation compared to a mean of 2.4 CFU/h without condensation. We concluded that bacteria were continuously transported from the ETT into the lungs during mechanical ventilation in water dr oplets. Prevention of water condensation abolishes this constant bacte rial inoculation in a lung model.