Transtracheal needle catheter ventilation in complete airway obstruction: an animal model

Transtracheal needle catheter ventilation (TNCV) may be used as an alternative airway when contraindications to endotracheal intubation exist. A feline model tested the efficacy of low-flow oxygen delivery, and initial data were gathered to define proper catheter calibers to effect adequate oxygenation and ventilation. Cats were anesthetized, trachea intubated, and ventilated for 30 minutes with a pressure-regulated ventilator. Arterial and venous pressures were monitored, and a chest tube was inserted to measure intrathoracic pressures. Arterial blood gas analysis was performed every five minutes during the baseline period. The endotracheal tube was then removed, the trachea cross-clamped, and TNCV instituted. Oxygen flow rates of 1, 3, and 5 L/min were varied with catheter sizes of 14, 16, and 18 g. Data demonstrated that TNCV provided adequate oxygenation and ventilation with flow rates of 3 and 5 L/min with the 14- and 16-g catheters. Satisfactory oxygenation could be obtained with these flow rates with the 18-g catheter, but ventilation was inadequate. Ventilation was unsatisfactory with the 1 L/min flow rate in all catheter sizes. These preliminary data indicate that a minimum catheter:trachea cross-sectional area ratio of 0.03 may be required to obtain oxygenation and ventilation with low-flow oxygen rates of 3 to 5 L/min in cats.