Do not Overinflate the Endotracheal Cuff
Gregory Dalencourt MD
Elizabeth A. Martinez MD, MHS
A large percentage of patients who are cared for in the intensive care unit (ICU) are intubated with an endotracheal tube. Regardless of the reason for requiring intubation, key factors must be understood when caring for such patients. The endotracheal tube (ETT) is typically placed orally using a laryngoscope and is advanced just past the vocal cords until the cuff disappears (to the view of the operator). The cuff is then inflated. The distension of the pilot balloon, next to the injection port, reflects inflation of the ETT cuff. The appropriate position of the ETT cuff is distal to the cords with the tip 4 cm above the carina. Confirmation of ETT placement in the trachea is best accomplished with the use of end-tidal carbon dioxide confirmation. Auscultation of bilateral breath sounds may confirm placement in the trachea and is useful in evaluating whether the ETT is too deep, resulting in endobronchial intubation. This is clinically indicated by loss of breath sounds in one of the lung fields, typically the left because of the straight path to the right main-stem bronchus compared with the sharp angle to the left. The ETT is then secured with tape or other ETT-securing devices.
Watch Out For
The purpose of the ETT cuff is to facilitate positive-pressure ventilation and prevent aspiration of secretions by forming a seal within the trachea. The current practice is use of a low-pressure, high-volume cuff. The risk of high-pressure cuffs is that the pressure transmitted to the underlying tracheal mucosa can cause ischemia when the cuff pressure exceeds the capillary arteriolar pressure (approximately 32 mm Hg). The low-pressure cuffs are preferred to limit this risk of ischemia and the recommended maximum pressure of the cuff is 25 mm HG. Low-pressure, high-volume cuffs inflate more symmetrically than high-pressure cuffs, which may also decrease the risk of tracheal dilatation, and they can inflate to the shape of the patient’s trachea, optimizing the seal.