Continuous control of endotracheal cuff pressure and tracheal wall damage: a randomized controlled animal study
Authors: Nseir Saad , Duguet Alexandre , Copin Marie-Christine , De Jonckheere Julien , Zhang Mao , Similowski Thomas , Marquette Charles-Hugo 
Published: October 2007

Abstract
Background
Intubation is frequently performed in intensive care unit patients. Overinflation of the endotracheal tube cuff is a risk factor for tracheal ischemia and subsequent complications. Despite manual control of the cuff pressure, overinflation of the endotracheal cuff is common in intensive care unit patients. We hypothesized that efficient continuous control of the endotracheal cuff pressure using a pneumatic device would reduce tracheal ischemic lesions in piglets ventilated for 48 hours through a high-volume, low-pressure endotracheal tube.

Materials and methods
Twelve piglets were intubated and mechanically ventilated for 48 hours. Animals were randomized to manual control of the endotracheal cuff pressure (n = 6) or to continuous control of the endotracheal cuff pressure using a pneumatic device (n = 6). In the two groups, we inflated the endotracheal cuff with 50 ml air for 30 minutes, eight times daily. This hyperinflation of the endotracheal cuff aimed at mimicking high-pressure periods observed in intubated critically ill patients. In all animals, the cuff pressure and the airway pressure were continuously recorded for 48 hours. After sacrifice of the study animals, the trachea was removed and opened longitudinally for gross and histological examination. A pathologist evaluated the slides without knowledge of treatment group assignment.

Results
The cuff pressure was significantly lower in piglets with the pneumatic device than in piglets without the pneumatic device (median (interquartile range), 18.6 (11–19.4) cmH2O versus 26 (20–56) cmH2O, P = 0.009). No significant difference was found in the percentage of time spent with a cuff pressure <15 cmH2O and that with a cuff pressure between 30 and 50 cmH2O. The percentage of time between 15 and 30 cmH2O of cuff pressure, however, was significantly higher in piglets with the pneumatic device than in piglets without the pneumatic device (98% (95–99%) versus 65% (44–80%), P = 0.002). In addition, the percentage of time with cuff pressure >50 cmH2O was significantly lower in piglets with the pneumatic device than in piglets without the pneumatic device (0% versus 19% (12–41%), P = 0.002).
In all animals, hyperemia and hemorrhages were observed at the cuff contact area. Histological examination showed no difference in tracheal lesions between animals with and without the pneumatic device. These lesions included deep mucous ulceration, squamous metaplasia and intense mucosal inflammation. No cartilage lesions were observed.

Conclusion
The pneumatic device provided effective continuous control of high-volume, low-pressure endotracheal cuff pressure in piglets mechanically ventilated for 48 hours. In the present model, however, no significant difference was found in tracheal mucosal lesions of animals with or without a pneumatic device. Further studies are needed to determine the impact of continuous control of cuff pressure over a longer duration of mechanical ventilation.