Benchtop study of leakages across the Portex, TaperGuard and Microcuff Endotracheal tubes under simulated clinical conditions

Abstract

OBJECTIVES. To compare three endotracheal tubes for leakage across the cuff (microaspiration) under a comprehensive set of simulated clinical situations. These were the Mallinckrodt TaperGuard (Covidien, US) with a tapered polyvinyl chloride cuff; the KimVent Microcuff (Kimberly-Clark Health Care, US) with a cylindrical polyurethane cuff; and a conventional Portex (Smiths Medical International Ltd, UK) with a globular polyvinyl chloride cuff. DESIGN. A benchtop experimental study. SETTING AND MATERIALS. A silicone cylinder serving as the model trachea was intubated with each of the three endotracheal tubes, one at a time. A total of 20 mL of water were added above the cuff and leakage measured every minute for 20 minutes under five simulated mechanical ventilation scenarios, including different positive end-expiratory pressure levels, and disconnection with and without spontaneous breathing efforts. Each scenario was studied under three cuff pressures of 10, 20 and 30 cm H2O, and then repeated with the application of a continuous suction force of 200 cm H2O, and leakage measured every minute for 3 minutes. RESULTS. The outcome of interest was the cumulative amount of leakage. The Microcuff endotracheal tubes with an ultrathin polyurethane cuff consistently provided the best protection against microaspiration under all simulated clinical situations, followed by TaperGuard with a tapered cuff, and lastly Portex with a globular polyvinyl chloride cuff. Clinical scenarios associated with the greatest leakage were mechanical ventilation with zero positive end-expiratory pressure, circuit disconnection with spontaneous breathing efforts, application of suction, and a low cuff pressure. CONCLUSIONS. Microcuff endotracheal tubes outperformed TaperGuard and Portex endotracheal tubes in preventing microaspiration, which is one of the major mechanisms for ventilator-associated pneumonia.

The Vexing Problem of Ventilator-Associated Pneumonia: Observations on Pathophysiology, Public Policy, and Clinical Science

“…84 Laboratory studies have consistently demonstrated that polyurethane-cuffed ETTs (and similarly designed silicone cuffs) are superior to standard polyvinyl cuffs in minimizing fluid leakage. 70,71,75,[85][86][87] Significantly reduced microaspiration has been reproduced in clinical trials, 75,78 coinciding with significant reductions in VAP (26 -45% relative decrease). [88][89][90] However, others have not been able to demonstrate the superiority of polyurethane-cuffed ETTs in reducing microaspiration.…”

Current ventilation practice during general anaesthesia: a prospective audit in Melbourne, Australia

“…Previous evidence suggests that application of PEEP in itself may be lung protective independent of tidal volumes. PEEP may prevent atelectasis [ 41 ], micro-aspiration [ 42 ], and decrease the need for rescue therapies for hypoxia [ 19 ]. Low or absent PEEP may increase shear stress and lung injury independent of the absence of high plateau pressures due to the cyclic collapse and tidal recruitment of lung units referred to as “atelectatrauma” [ 43 ].…”

Prevention of ventilator-associated pneumonia

“…Our benchtop study showed that the Microcuff consistently outperformed the Portex and the TaperGuard in terms of leakage, especially during zero PEEP mechanical ventilation, laboured breathing, disconnection, and airway suction. 34 One disadvantage of the Microcuff is that the material is so thin that even moisture diffuses across, leading to fluid accumulation inside the cuff with resultant blockage of the pilot balloon tube. This can be solved by purging the tube with small amount of air.…”

“…Without positive pressure, leakage around the cuff is significant, especially if the conventional PVC cuff is used and the cuff pressure is less than 30 cm H 2 O. 34 During routine care, disconnections of the airway circuit are frequent, for instance, use of another ventilator for patient transport, change of the heat-and-moisture exchanger, spontaneous breathing trials, and change of ventilator tubing. Such disconnections should be avoided as far as possible.…”

“…34 Periodical manual checking of cuff pressure maintains adequate cuff pressure, but the benefit could be offset if the cuff pressure is accidentally released during checking.…”