In a recent clinical study, four different techniques for sealing an endotracheal tube cuff were evaluated. Eighty client-owned dogs were used in the study. Once intubated, each had its cuff inflated four times, by four different people. After each inflation, the cuff pressure was measured, the cuff deflated, and then the next technique was evaluated.
Spoiler alert: [I always jump ahead to the results.] None of the methods evaluated in this study consistently resulted in cuff pressures within a recommended range.
Each of the four anesthetists attempted one of these four techniques: (A) feeling the tension of the pilot balloon; (B) feeling the tension of the pilot balloon after a week’s practice inflating the cuff to a known pressure; (C) inflating the cuff to occlude at an airway pressure of 20 cmH2O; (D) incrementally deflating the cuff until a leak could be heard at an airway pressure of 25 cmH2O. Although the results showed none of the techniques adequate, it was encouraging to see that technique (B) approached success. It affirms the value of practice.
The article makes me wonder how effective my favorite techniques are at achieving an appropriate cuff pressure. Fortunately, it gives me the method to test them. I was also surprised at the techniques they chose to test. I was sure that by testing four different methods, I would see at least one of my favorites on the list.
The first method I learned was fast and easy. I would over-inflate the cuff, and then take my thumb off the syringe plunger and allow the pressure in the cuff to push the plunger back. When the plunger stopped moving backward, I would then add 1ml of air back into the cuff and disconnect the syringe.
In subsequent years, I learned a more precise method. It’s similar to technique (C) and (D), in that I use airway pressure to determine the cuff seal, rather than pilot balloon pressure. I seal the cuff at 15 cmH2O, but adjust so it leaks at 20 cmH2O pressure.
And now my interest in piqued. What is your favorite method for inflating an endotracheal tube cuff?The clinical study: Evaluation of the endotracheal tube cuff pressure resulting from four different methods of inflation in dogs. Vet Anaesth Analg. 2012 Sep;39(5):488-94