The efficacy of three different methods of transtracheal ventilation

The ability of three different techniques of transtracheal ventilation to reverse hypoxia and provide pulmonary ventilation were examined. Five swine were anaesthetized with isoflurane in oxygen, their tracheas were intubated, and their lungs mechanically ventilated to produce a PaCO ₂ of 35-40 mmHg. A 14-gauge catheter was inserted percutaneously into the trachea caudad to the tip of the tracheal tube. The animals were then left apnoeic until their oxygen saturation fell to 60 per cent. At this point, attempts were made to ventilate and oxygenate the animals through the tracheal catheter with one of three systems (Jet -50 psi [2585 mmHg] driving pressure controlled with a thumb operated valve, Flush -fresh gas outlet of an anaesthetic machine with flow controlled by the flush button, or Circle -standard anaesthesia circle system with pressures greater than 60 mmHg). Arterial blood gas determinations were made every minute for five minutes after beginning transtracheal ventilation. Both the Jet and Flush modes resulted in a mean PaO ₂ greater than 250 mmHg within one minute of their initiation whereas the PaO₂ with the Circle system never exceeded 180 mmHg even at five minutes. The Flush and Jet modes produced a decrease in the PaCO ₂ (from 80 mmHg to 35-45 mmHg) over the five minutes. In contrast, it was not possible to provide adequate ventilation with the Circle system as evidenced by an increasing PaCO ₂ (from 80 mmHg to > 110 mmHg at five minutes). This study suggests that preexisting hypoxia can be reversed by the administration of oxygen via a tracheal catheter connected to an anaesthesia circuit. Ventilation, however, can be achieved only if the tracheal catheter is connected to a high pressure source of oxygen.