Endotracheal intubation is a common procedure performed approximately 15–20 million times annually in the United States. During this procedure, a healthcare provider uses a laryngoscope to guide an endotracheal tube (ETT) through the mouth or nose, past the voice box, and into the trachea. The tube maintains an open airway, ensuring air can reach the lungs. Intubation typically occurs in a hospital setting during emergencies or before surgery. In the perioperative setting, endotracheal tubes may be used in various clinical situations, such as patients undergoing general anesthesia, surgeries involving or near the airway, unconscious patients needing airway protection, or surgeries requiring unusual positioning. An important element of patient safety and comfort is appropriate airway cuff pressure when utilizing intubation in the OR.
There are two types of ETTs: cuffed and uncuffed. In clinical practice, anesthesia providers predominantly use cuffed ETTs. The cuff is an inflatable “balloon” surrounding the shaft of the tube near its distal end. When inflated, the cuff presses against the tracheal wall, preventing air leakage and pressure loss from the lungs. It also reduces the risk of aspiration during mechanical ventilation. The advantages of using a cuffed ETT are extensive. Proper cuff inflation facilitates positive pressure ventilation, administration of anesthetic gases, positive end-expiratory pressure, reduced risk of airway injury from multiple laryngoscopy attempts, and protection against aspiration of gastric contents. Once inflated, the cuff pressure directly correlates with the pressure exerted on the tracheal mucosa wall. The recommended range for ETT cuff pressure is 20–30 cm H2O. This narrow range ensures the cuff pressure is sufficient to seal the airway while maintaining tracheal capillary perfusion pressure.
Cuff pressures fall outside the recommended range 60%–80% of the time in clinical settings, which can lead to injuries in patients. Injuries related to endotracheal intubation can potentially extend the average length of stay and increase readmission rates, thereby raising healthcare costs. Cuff overinflation is directly linked to airway complications such as sore throat, cough, edema, inflammation, and more severe issues like nerve injury, tracheal stenosis, tracheal fistulas, granulations, ulcerations, and tracheal rupture. Even a short duration of excess cuff pressure can impair local blood supply and cause hyperemia and hemorrhage in the tracheal wall at the cuff contact area.
On the flip side, maintaining airway cuff pressure above 20 cm H2O is crucial to prevent the leakage of contaminated supraglottic secretions past the cuff. Underinflated ETT cuffs may expose the patient to risks of aspiration and inadequate ventilation. A major consequence of underinflated ETTs is ventilator-associated pneumonia (VAP). Several factors contribute to VAP, including impaired host defense, reduced mucociliary clearance, gastric and upper respiratory tract colonization, and microorganism virulence. Nonetheless, the leakage of contaminated secretions past the cuff is the primary etiologic factor for VAP. VAP is one of the most common infections in ICU patients, with a prevalence ranging from 10% to 27%. Preventing the aspiration of respiratory secretions from the supraglottic space and monitoring cuff pressure are proven techniques to prevent VAP. Insufficient airway cuff pressure also can impair ventilation efforts and lead to leakage of anesthetic gases.
Monitoring ETT cuff pressure with a cuff manometer is the gold standard for airway cuff pressure management. However, this device is seldom used in the operating room due to issues like unintentional leaks, increased costs, and the need for cleaning between patients. Despite manometry being the standard, most practitioners do not use them. Instead, many anesthesia providers rely on “estimation techniques” to inflate the ETT cuff. These methods are employed 98% of the time in clinical settings but are subjective and not consistently accurate.
Ensuring proper airway cuff pressure management through consistent use of accurate monitoring techniques is essential for improving patient outcomes and reducing the risks associated with endotracheal intubation.
References
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