[Air seepage from endotracheal tube cuffs during anesthetic procedures. How to solve this problem without changing...

To demonstrate by an experimental model that a continuous medicinal airflow system giving a pressure of 30 cmH2O effectively stops leakage from endotracheal tubes.

Ten tracheas with their main bronchi were removed from cadavers with no pulmonary disease. The tracheas were placed vertically and tubes previously perforated with increasing caliber needles were inserted and connected to a continuous flow system. The flow of medicinal air generated in the cuff was monitored with a flow meter and pressure was measured with a manometer. When a pressure of 30 cmH2O was reached, the trachea was filled with saline. We then observed the moment at which, when pressure fell, the saline began to leak from the bronchi. The levels observed were expressed as arithmetic means and standard deviations.

No leakage was observed when the flow produced pressures above 10 cmH2O for 25 G caliber holes, above 15 cmH2O for 24 G holes, or above 20 cmH2O for 25 G, 21 G, 20 G, 18 G or 16 G holes. For 14 G holes, a flow producing pressures over 25 cmH2O were needed. Pressure up to 80 cmH2O was required to stop leakage from a scalpel cut.

We found that adjusting flow and pressure is a valid way to stop leakage from small holes. The method does not control leakage from large holes or cuts.