Transtracheal oxygen delivery

Tidal volume and airway pressure under percutaneous transtracheal ventilation without a jet ventilator: comparison of high-flow oxygen ventilation and manual ventilation in complete and incomplete upper airway obstruction models

PURPOSE

Percutaneous transtracheal ventilation (PTV) can be life-saving in a cannot ventilate, cannot intubate situation. The aim of this study was to investigate the efficacy of PTV by measuring tidal volumes (VTs) and airway pressure (Paw) in high-flow oxygen ventilation and manual ventilation using a model lung.

METHODS

We examined 14G, 16G, 18G, and 20G intravenous catheters and minitracheotomy catheters. In high-flow oxygen ventilation, the flow was set to 10 L/min, while the inspiratory:expiratory phases (I:E) were 1 s:4 s in the complete upper airway obstruction model and 1 s:1 s in the incomplete obstruction model. In manual ventilation, I:E were 2 s:4 s in the complete obstruction model and 2 s:3 s in the incomplete obstruction model. We ventilated through each catheter for 2 min and measured VT and Paw.

RESULTS

In high-flow ventilation, the average VTs were approximately 150 ml and <100 ml with 14G catheters in complete and incomplete upper airway obstruction, respectively. The VTs obtained were reduced when the bore size was decreased. In manual ventilation, the average VTs were over 300 ml and approximately 260 ml with 14G catheters in complete and incomplete upper airway obstruction, respectively. In high-flow ventilation, the airway pressure tended to be higher. The minitracheotomy catheters produced over 800 ml of VT and created almost no positive end-expiratory pressure.

CONCLUSIONS

High-flow ventilation tends to result in higher airway pressure despite a smaller VT, which is probably due to a PEEP effect caused by high flow.

Low-Flow Transtracheal Rescue Insufflation of Oxygen After Profound Desaturation

BACKGROUND

The objective of this study was to determine whether low-flow transtracheal insufflation of oxygen (TRIO) could rescue an animal from profound desaturation. This temporizing maneuver could be useful during cannot-intubate or -ventilate scenarios by resolving hypoxia without the morbidity associated with more invasive procedures.

METHODS

Seven swine for a total of 12 runs were studied. Animals were pharmacologically anesthetized, paralyzed, and mechanically ventilated with room air. After disconnection from the ventilator and desaturation to an Spo2 < 50%, low-flow TRIO (2 L/min) was administered for 1 hour.

RESULTS

All animals survived and Spo2 increased to greater than 90% in 23 seconds on average. Pao2 (mean, 183 mm Hg) remained elevated throughout the study. Hemodynamic stability was maintained for at least 15 minutes.

CONCLUSION

Low-flow TRIO rescued animals from profound hypoxia and maintained oxygenation for at least 1 hour. Low-flow TRIO did not prevent hypercarbia with its subsequent sympathetic activation.

Gas flow rates through transtracheal ventilation catheters

The purpose of the study was to measure gas flow rates using different methods of transtracheal ventilation. Wall oxygen flow (WOF) at 10 and 15L/min, and a self-inflating ventilation bag (SIVB) were used to deliver gas flow through three transtracheal catheters: 13, 14, and 16 gauge (5 trials each). WOF mean gas flow rates (L/min) through the 16G, 14G, 13G catheters, respectively were: 15.7, 15.7, 16.8 at 15L/min, 10.5, 10.5, 10.3 at 10 L/min, and 5.7, 7.5, 7.7 via SIVB. SIVB gas flow was not continuous since it required the bag to reinflate, which reduces its calculated flow rate. A 500 cc tidal volume can be delivered within 3 seconds (WOF) and 5 seconds (SIVB). Catheter size did not substantially affect gas flow rates (Poiseuille's law not applicable). Transtracheal ventilation is best done by using WOF, but if a device to perform this is not available, then an SIVB may still be sufficient.