Double Lumen Endotracheal Tube for Percutaneous Tracheostomy

BACKGROUND: Percutaneous dilational tracheostomy is normally a bronchoscope-guided procedure. The insertion of a bronchoscope into an endotracheal tube (ETT) affects resistance, flow, and alveolar pressure. To improve airway management and ventilation during percutaneous tracheostomy, we developed a double lumen endotracheal tube (DLET). The aim of this in vitro study was to compare the linear constant of the Rohrer equation (K-1), the nonlinear constant of the Rohrer equation (K-2), the inspiratory and expiratory airway resistance, and ventilatory and airway pressures using the DLET with different standard sized ETTs. METHODS: A trachea and lung model was used to compare the DLET to ETTs with 7, 7.5, and 8 mm inner diameters with and without a bronchoscope (4.5 mm external diameter), and 4 and 5 mm inner diameter ventilation tubes (F-4, F-5) of a translaryngeal tracheostomy. For each device, the pressure drop across the device and the Rohrer equation linear constant (K-1) and nonlinear constant (K-2) were calculated during a continuous flow of 10-90 L/min, the inspiratory and expiratory airway resistance values were calculated during volume controlled mechanical ventilation, and respiratory airway pressure values were calculated during volume and pressure controlled mechanical ventilation. RESULTS: DLET had lower K-2, pressure drop, and inspiratory and expiratory airway resistance compared with conventional ETTs plus fiberoptic bronchoscope. Furthermore, during mechanical ventilation, DLET had a lower value of peak pressure, mean pressure, and intrinsic PEEP than the other ETTs plus fiberoptic bronchoscope. CONCLUSIONS: Use of the DLET during percutaneous dilational tracheostomy allows fiberoptic bronchoscopy without imposing excessive airway resistance. Reduced tube resistance during this procedure may confer additional safety in what is well known to be a hazardous procedure.