Transcatheter Ventilation with a Modified Rapid-O2 Oxygen Insufflation Device

Rapid-O2™ oxygen insufflation device (Rapid-O2 ® ) has been primarily designed to provide rescue oxygenation; thus, hypercarbia is inevitable. We modified Rapid-O2 to augment ventilation by providing negative pressure during expiration. To determine the most effective combination between the 20 G, 18 G, 16 G, 14 G, or 2-mm internal diameter (ID) transtracheal catheter (TTC) (inner catheters) to create sub-atmospheric pressure and the 16 G, 14 G or 2-mm ID TTC to achieve insufflating flow (insufflating catheters), the corresponding insufflating and expiratory flows and pressures were measured using a gas flow analyzer. Insufflating and expiratory volumes were assessed using a trachea-lung model. Based on the flow measurements of combination between inner and insufflating catheters, the 18 G was chosen as the inner catheter. Insufflating pressures ranged from 97 (2-mm ID TTC) to 377 cmH 2 O (16 gauge) at oxygen flow rate of 15 L/min. During expiration, negative pressures of ~ 50 cmH 2 O were measured in three insufflating catheters at 15 L/min. At a lung compliance of 100 mL/cmH 2 O, with a rate of ~ 12 breathes/min, minute volumes through a 14 G or 2-mm ID TTC were 5.53 and 6.53 L/min, respectively, at 15 L/min. The modified Rapid-O2 could achieve adequate minute ventilation in adults.