Tracheal pressure and endotracheal tube obstruction can be detected by continuous cuff pressure monitoring: in vitro pilot study

To evaluate whether the degree of endotracheal tube (ETT) obstruction can be predicted by changes of ETT cuff pressure (P (c)) as a function of peak inspiratory pressure. The study was conducted in three phases: phase I evaluated the correlation between peak tracheal pressure (P (tr)) and P (c); phase II evaluated the relation between P (c) versus ventilator pressure (P (v)) and ETT obstruction (range of obstruction 0-58%). In phase III the analytical model developed in phase II was used to predict the degree of obstruction of five ETTs removed from intensive care unit (ICU) patients. All measurements were conducted on a tracheal-lung simulator. In phases I and II it was found that P (c) correlates significantly with P (tr). The gradient (dP (c)/dP (v)) reflects the degree of ETT obstruction according to the formula: obstruction (%) = -553 x (dP (c)/dP (v))(2) + 672.5 x (dP (c)/dP (v)) - 142.81. Using this formula, the degree of obstruction of the ETTs could be predicted in ICU patients during controlled mechanical ventilation (r (2) = 0.98, p < 0.001). This study proposes a new method to predict the degree of ETT obstruction based on differences between P (c) and P (v). The method was proved accurate on simulator, and further studies are needed on intubated patients.