Transtracheal oxygen (TTO) therapy refers to the delivery of long-term oxygen therapy (LTOT) through a transtracheal catheter (picture 1). It is an alternative to conventional LTOT, which is delivered through a nasal cannula.
The benefits of TTO therapy, patient selection, complications, and reimbursement are discussed in this topic review. Other issues related to LTOT are discussed separately. (See "Long-term supplemental oxygen therapy" and "Traveling with oxygen aboard commercial air carriers" and "Oxygen conserving devices" and "Use of oxygen in patients with hypercapnia".)
TTO therapy offers several potential benefits . Most studies that have examined the efficacy of TTO have used the subject as his or her own control. In the short-term physiologic studies, patients with an existing transtracheocutaneous fistula usually received interventions related to tracheal gas delivery in a random order, and then were compared to controls with no tracheal flow [2,3]. In the long-term clinical studies, data collected after initiation of TTO therapy were compared to data collected while the patient was receiving LTOT by nasal cannula [4-8]. One trial randomized 43 patients to receive TTO or LTOT via nasal cannula for the duration of the trial .
TTO was found to have the following effects when compared to LTOT delivered via nasal cannula (table 1):
- Reduces the oxygen flow that is required to achieve the same arterial oxyhemoglobin saturation, both at rest (55 percent reduction) and during exercise (30 percent reduction) 
- Improved exercise capacity was observed in two studies; however a third study found no increase in exercise capacity with TTO compared to nasal cannula, when controlled for oxygen saturation [3,5,9]
- Improves the room air alveolar to arterial oxygen tension gradient (ie, A-a gradient) [6,9]
- Reduces erythrocytosis and improves cor pulmonale [4,7,9]
- Reduces or maintains arterial carbon dioxide tension (PaCO2) 
- Corrects hypoxemia that was refractory to LTOT delivered by nasal cannula 
- Improves activity and mobility 
- Improves physical, social, and psychological function 
- Improves compliance (daily duration of oxygen use) 
- Reduces days of hospitalization