Oxygen therapy by transtracheal catheter (TTC), as described by Heimlich in 1982, was originally conceived to conserve oxygen but later proved to be truly useful as a treatment for chronic respiratory insufficiency, although the technique is little used in Spain. We conducted a one-year long prospective study of 10 patients with chronic respiratory insufficiency in whom a TTC was placed for ambulatory oxygen therapy. Complications appearing were bloody expectoration (100%), granulomas at the site of incision (20%) and accidental extubation (10%). The index of acceptance among our patients was 9%. The oxygen savings achieved amounted to 46%. The number of hospitalized days before and after insertion of the catheter amounted to 28 and 3, respectively (p < 0.001). PCO2 levels were 62 +/- 14 at baseline, 51.9 +/- 8.8 (p < 0.1) after one week, and 52.9 +/- 10 (NS) after one year. The hematocrit was 45.6 +/- 10.22 before TTC placement and 43.4 +/- 3.02 (NS) after one year. Changes in PO2, FVC and FEV1 were not statistically significant. No problems derived from TTC or liquid oxygen management.