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Continuous ventilation during tracheal dilatation using a novel, non-occlusive tracheal balloon dilator in an ovine model

      Introduction

      Subglottic and tracheal stenosis pose a challenge to surgeons and anaesthesiologists. Although common aetiologies differ in adults and children, post-intubation injury is universally the leading cause. Tracheal stenosis often presents as an airway emergency, and is difficult and costly to treat. Definitive surgical correction requires tracheal resection and reconstruction, but may be avoided with dilatation. This requires bougies of increasing diameter, or balloon dilatation. Balloon dilatation is effective and low risk compared to reconstruction, but may require multiple procedures. Traditional balloon dilators cause complete occlusion of the trachea, which prevents ongoing oxygenation and ventilation, limits the safe duration of dilatation, and increases the risk of barotrauma. We investigated the performance of a novel, non-occlusive tracheal dilatation balloon in anaesthetised sheep, to assess whether continuous ventilation is possible with this device.

      Method

      With institutional animal research ethics approval, eight adult anaesthetised sheep were included in the study. After induction of anaesthesia, each subject was intubated with a 9.0 mm internal diameter endotracheal tube (ETT), and ventilated using volume control. Pulse oximetry, electrocardiograph, airway pressures and volumes, and continuous waveform capnography were continuously measured. Using a bronchial blocker adaptor, a 3.7 mm flexible fibreoptic bronchoscope and the study device were introduced through the ETT, advanced to a mid-tracheal position, and the balloon inflated. Without altering ventilator settings, tidal volume (Vt), peak and plateau airway pressures (Ppeak/Pplat) were recorded with the ETT alone, with the deflated balloon and bronchoscope in the trachea, and with the balloon inflated.

      Results

      All subjects could be ventilated continuously. At no time during balloon deployment and inflation was there a loss of capnograph waveform or arterial desaturation. There were no clinically relevant changes in ventilatory parameters, (see figure). The median(range) at each time point were Vt of 565(370-780), 560 (330-830) and 550(320-830) ml, Ppeak of 11(9-22), 14(11-17) and 14(13-17), and Pplat of 9(7-17), 11(9-14) and 11(9-14) cmH₂O.