Objective: Leakage of fluid from the subglottic space to the lungs occurs along the longitudinal folds within the wall of an inflated high-volume, low-pressure (HVLP) cuff. The low-volume, low-pressure (LVLP) cuff does not have these folds yet allows for convenient and reliable control of tracheal wall pressure. Pulmonary aspiration during anesthesia has been linked with postoperative pneumonia and during critical illness causes ventilator-associated pneumonia.
Design: Prospective, blinded, randomized controlled trial; prospective observational study; and benchtop models.
Setting: Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital.
Patients: Anesthetized patients (n=38) and critically ill patients with either an LVLP or HVLP cuffed tracheostomy tube following swallow assessments (n=67).
Interventions: The LVLP cuff was compared with HVLP cuffs for leakage of dye placed in the subglottic space to the tracheobronchial tree in a rigid tracheal model and a benchtop pig trachea model (before and after a standardized cuff movement).
Measurements and main results: In the rigid tracheal model, the incidence of leakage was 0% in the LVLP group and 100% in the HVLP group (p<.01). Dye leakage in the pig tracheal model with HVLP cuffs was 44% before tube movement, increasing to 79% afterward. The LVLP cuff did not leak in the pig tracheal model. Dye leakage in anesthetized patients was 0% before movement and 5% after in the LVLP group and in the HVLP group 22% increasing to 67% after movement (p<.001). Forty-nine percent of swallow assessments were scored as failed in the critical care patients with HVLP tracheostomy tube cuffs, and there were no episodes of aspiration following swallow assessment in the LVLP group (p<.05).
Conclusions: The LVLP cuffed tracheal and tracheostomy tubes reduced pulmonary aspiration in the benchtop models and in anesthetized and critically ill patients. The single failure of the LVLP cuff in the anesthesia group was probably associated with accidental endobronchial intubation following tube movement.