Assessing the correct inflation of the endotracheal tube cuff: a larger pilot balloon increases the sensitivity of the 'finger-pressure' technique, but it remains poorly reliable in clinical practice.

The pilot balloon palpation (or 'finger-pressure') method is still widely used to assess the endotracheal tube cuff inflation, despite consistent evidence of its poor sensitivity in recognizing cuff overinflation. It was recently speculated that this may be related to the lower wall tension (due to the smaller radius) of the pilot balloon as compared with the cuff, according to Laplace's law. To verify this hypothesis and, secondarily, to assess whether the use of a 'large' pilot balloon (identical to the cuff) increases the reliability of this technique, 62 anesthetists (41 experienced anesthesiologists and 21 residents) were asked to estimate the pressure of a cuff inflated to 88 mmHg into a simulated trachea by feeling both a usual and a modified 'large' pilot balloon. A similar test was repeated at 40 mmHg. After palpation of the usual pilot balloon, only 35% of participants (49% of experienced anesthesiologists and 10% of residents) recognized considerable overinflation (88 mmHg), as compared with 87% of participants (95% of experienced anesthesiologists and 71% of residents) after palpation of the 'large' pilot balloon. Moreover, 89% of participants (85% of experienced anesthesiologists and 95% of residents) believed that pressure was higher in the 'large' balloon than in the normal one. However, only 32% of participants (51% of experienced anesthesiologists and none of residents) recognized slight overinflation (40 mmHg) after feeling the 'large' balloon. The pilot balloon size affects the sensitivity of the 'finger-pressure' technique, but it remains poorly reliable with a larger pilot balloon.