In vitro evaluation of diffusion of lidocaine and alkalinized lidocaine through the polyurethane membrane of the endotracheal tube

Abstract

Objectives: Endotracheal tube (ETT) and its inflated cuff are likely to induce specific reactivity at the emergence time. In ICU, the tolerance of the ETT cuff could be a part of patient agitation and increased of sedation.

Materials and methods: Using specific ICU ETT cuff (thin polyurethane cuff), we perform an in vitro evaluation of diffusion of lidocaine and alkalinized lidocaine (L-B) across the PU cuff for a long duration. We evaluate the safety of this procedure by a daily injection into the cuff.

Results: With lidocaine alone, we observed a low rate of diffusion through the cuff (<8% over 24h), whereas the L-B solution had a high diffusion (>90% over 24h). The released profiles were similar from day 0 to day 8, and no cuff rupture was reported over the 8-day study.

Conclusion: The safety, controlled release, and lack of deleterious effects on cuff membrane were confirmed. In case of unexpected cuff rupture, an adequate determination of the mixture allows to obtain a safe solution with the achievement of a physiological pH (7.4) and the small dose of lidocaine (40 mg).

Keywords: Alcalinisation; Alkalinized lidocaine; Ballonnet de sonde d’intubation; Bicarbonate; Cuff; Diffusion in vitro; Endotracheal tube; In vitro; Lidocaine; Lidocaïne; Polyurethane; Polyuréthane.