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Oxygen conserving devices, the TTO catheters, electronic pulsed DODS and reservoir cannulas, increase efficacy of oxygen delivery; TTO also improves cosmetic appearance, comfort and compliance. We speculated that pulsing of oxygen transtracheally can increase efficiency of TTO. We modified the DODS to include settable delays and a rapid pre-inspiratory trigger. The first part of the study was performed with nasal oxygen on seven subjects and the second part, with TTO on 17 subjects. Nasal oxygen results indicate improved delivery efficiency with more rapid response. The TTO results indicate no significant change for each delay setting, but there was improvement in delivery efficiency when DODS was combined with TTO vs continuous flow TTO. Thus, early inspiratory delivery increases efficiency of oxygen therapy. Small delays in response time are critical in nasal delivery but not important in TTO. Pulsed TTO is more efficient than continuous flow TTO and merits long-term studies.

Eight patients with chronic severe and refractory hypoxemia were treated with a new transtracheal oxygen catheter. All patients demonstrated an arterial oxygen partial pressure of less than 55 mm Hg on high-flow nasal cannula therapy. Refractory hypoxemia was successfully treated in all eight patients following initiation of transtracheal oxygen therapy at 2.5 to 6.0 L/min. Arterial oxygen partial pressure was 50% greater and oxygen flow requirements were 72% less with transtracheal oxygen. There were no complications related to the procedure and oxygen flow rates up to 6 L/min were well tolerated. Although four patients died, four remain clinically stable with adequate oxygenation at up to 20 months' follow-up. All eight patients experienced an improvement in quality of life with transtracheal oxygen.

Over a 2-year period, the safety and efficacy of a program specifically designed for transtracheal oxygen therapy were evaluated in 100 patients with chronic hypoxemia. The four clinically defined phases of the program included patient orientation, evaluation, and selection (phase I); a new needle-wire guide-dilator transtracheal procedure and stent week (phase II); transtracheal oxygen delivery with an immature tract (phase III); and transtracheal oxygen delivery with a mature tract (phase IV). Sequelae and complications were minor, and patient acceptance was high. As compared with the nasal cannula, the transtracheal catheter was associated with a significant reduction in oxygen flow requirement during both rest and exercise. Adequate oxygenation was maintained over time, and erythrocythemia was alleviated with transtracheal delivery. We conclude that transtracheal oxygenation by this method has a low, acceptable morbidity; it is more efficient than nasal cannula delivery and may be more effective in some patients.