A prototype small-bore ventilation catheter with a cuff: cuff inflation optimizes ventilation with the Ventrain.

Abstract

Ventilation through small-diameter tubes typically precludes use of a cuff as this will impede the necessary passive outflow of gas alongside the tube's outer surface. Ventrain assists expiration and enables oxygenation and normoventilation through small-bore cannulas or catheters, particularly in obstructed airways. A small-bore ventilation catheter (SBVC; 40 cm long, 2.2 mm inner diameter) with a separate pressure monitoring lumen and a cuff was developed. Efficacy of oxygenation and ventilation with Ventrain through this catheter was investigated in sealed and open airways in a porcine cross-over study. Six pigs were ventilated with Ventrain (15 l/min oxygen, frequency 30 breaths per min, I : E-ratio 1 : 1) through the SBVC, both with the cuff inflated and deflated. Prior to each test they were ventilated conventionally until steady state was achieved. With an inflated cuff, PaO₂ rose instantly and remained elevated (median [range] PaO₂ 61 [52-69] kPa after 30 min; P = 0.027 compared to baseline). PaCO₂ remained stable at 4.9 [4.2-6.2] kPa. After cuff deflation, PaO₂ was significantly lower (9 [5-28] kPa at 10 min, P = 0.028) and interventional ventilation had to be stopped prematurely in five pigs as PaCO₂ exceeded 10.6 kPa. Pulmonary artery pressures increased markedly in these pigs. Intratracheal pressures were kept between 5 and 20 cmH₂ O with the cuff inflated, but never exceeded 2 cmH₂ O after cuff deflation. The SBVC combines the benefits of a small diameter airway and a cuff. Cuff inflation optimizes oxygenation and ventilation with Ventrain.