New method detects endotracheal tube obstruction during mechanical ventilation
In mechanically ventilated patients, airway pressure (Paw) is measured at the ventilator, but the pressure that actually reaches the patient is the tracheal pressure (Ptrach). The two can differ substantially because the endotracheal tube has a very high flow resistance, comparable to the airway resistance of a patient with severe asthma.
This resistance can increase rapidly after intubation due to mucus deposition, biofilm formation, or kinking. Clinical studies have reported increases of about 70% within three days, while doubling or tripling of tube resistance is not uncommon. Yet tracheal pressure is rarely measured because this requires an additional catheter or miniature pressure sensor.
We have developed a method that estimates the actual tube resistance from naturally occurring pressure and flow fluctuations generated by the ventilator. The approach requires neither a tracheal pressure sensor nor externally applied forced oscillations.
In a laboratory lung model, the method estimated tube resistance with less than 10% mean error and less than 2% bias. It detected progressive obstruction caused by inserting a bronchoscope into the tube and can estimate resistance from a single breath, allowing changes to be tracked continuously.
The method could enable early detection of tube obstruction and allow Automatic Tube Compensation to adapt to the actual, rather than nominal, tube resistance.
The study is available as a medRxiv preprint:
https://doi.org/10.64898/2026.05.01.26352226