Endotracheal tubes for critically ill patients : an in vivo analysis of associated tracheal injury, mucociliary clearance, and sealing efficacy

BACKGROUND: Improvements in the design of the endotracheal tube (ETT) have been achieved in recent years. We evaluated tracheal injury associated with ETTs with novel high-volume low-pressure (HVLP) cuff s and subglottic secretions aspiration (SSA) and the eff ects on mucociliary clearance (MCC). METHODS: Twenty-nine pigs were intubated with ETTs comprising cylindrical or tapered cuff s and made of polyvinylchloride (PVC) or polyurethane. In specifi c ETTs, SSA was performed every 2 h. Following 76 h of mechanical ventilation, pigs were weaned and extubated. Images of the tracheal wall were recorded before intubation, at extubation, and 24 and 96 h thereaft er through a fl uorescence bronchoscope. We calculated the red-to-green intensity ratio (R/G), an index of tracheal injury, and the green-plus-blue (G 1 B) intensity, an index of normalcy, of the most injured tracheal regions. MCC was assessed through fl uoroscopic tracking of radiopaque markers. Aft er 96 h from extubation, pigs were killed, and a pathologist scored injury. RESULTS: Cylindrical cuff s presented a smaller increase in R/G vs tapered cuff s ( P=.011). Additionally, cuff s made of polyurethane produced a minor increase in R/G ( P=.012) and less G 1 B intensity decline ( P=.022) vs PVC cuff s. Particularly, a cuff made of polyurethane and with a smaller outer diameter outperformed all cuff s. SSA-related histologic injury ranged from cilia loss to subepithelial infl ammation. MCC was 0.9 ± 1.8 and 0.4 ± 0.9 mm/min for polyurethane and PVC cuff s, respectively ( P < .001). CONCLUSIONS: HVLP cuff s and SSA produce tracheal injury, and the recovery is incomplete up to 96 h following extubation. Small, cylindrical-shaped cuff s made of polyurethane cause less injury. MCC decline is reduced with polyurethane cuffs.