Impact of tracheal cuff shape on microaspiration of gastric contents in intubated critically ill patients: study protocol for a randomized controlled trial

Background: Ventilator-associated pneumonia (VAP) is the most common infection in intubated critically ill patients. Microaspiration of the contaminated gastric and oropharyngeal secretions is the main mechanism involved in the pathophysiology of VAP. Tracheal cuff plays an important role in stopping the progression of contaminated secretions into the lower respiratory tract. Previous in vitro studies suggested that conical cuff shape might be helpful in improving tracheal sealing. However, clinical studies found conflicting results. The aim of this study is to determine the impact of conical tracheal cuff shape on the microaspiration of gastric contents in critically ill patients. Methods/Design: This prospective cluster randomized controlled crossover open-label trial is currently being conducted in ten French intensive care units (ICUs). Patients are allocated to intubation with a polyvinyl chloride (PVC) standard (barrel)-shaped or a PVC conical-shaped tracheal tube. The primary objective is to determine the impact of the conical shaped tracheal cuff on abundant microaspiration of gastric contents. Secondary outcomes include the incidence of microaspiration of oropharyngeal secretions, tracheobronchial colonization, VAP and ventilator-associated events. Abundant microaspiration is defined as the presence of pepsin at significant level (>200 ng/ml) in at least 30 % of the tracheal aspirates. Pepsin and amylase are quantitatively measured in all tracheal aspirates during the 48 h following inclusion. Quantitative tracheal aspirate culture is performed at inclusion and twice weekly. We plan to recruit 312 patients in the participating ICUs. Discussion: BEST Cuff is the first randomized controlled study evaluating the impact of PVC tracheal-cuff shape on gastric microaspirations in patients receiving invasive mechanical ventilation. Enrollment began in June 2014 and is expected to end in October 2015.