Abstract
The characteristics of two types of oxygen concentrators, the molecular sieve type (DAM-2 and DAM-4, Osaka Oxygen Industries Ltd.) and the membrane type (TO-40, Teijin Ltd.), were studied and the results in 20 cases of long-term home oxygen therapy (LHOT) with the former are reported. In the molecular sieve type, approximateley 95% oxygen was supplied in quantities of up to 21/min in the DAM-2 and up to 41/min in the DAM-4. In the membrane type, approximateley 35% oxygen was supplied in quantities of up to 6L/min irrespective of flow rate. Although the concentration ratios of argon were the same as oxygen in both types of oxygen concentrators, the concentration was so low that it may be concluded that there is little effect on the human body if given by nasal cannula. Flow rate-PaO2 responses to these concentrators were studied in eighteen hospitalized patients with various pulmonary disorders. In the molecular sieve type flow is equivalent to pure oxygen while in the membrane type, 5L/min oxygen-enriched air corresponds to about 1L/min of pure oxygen.
The LHOT subjects consisted of 14 males and 6 females with a mean age of 57±11. They consisted of 13 COLD cases, 4 cases with sequelae of pulmonary tuberculosis, 2 cases of bronchiectasis and 1 case of pulmonary fibrosis. Their mean PaO2 when breathing room air was 48.0±7.6Torr and was significantly raised to 64.2±9.8Torr by the administration of oxygen with a nasal cannula at a flow rate from 0.5 to 3L/min (1.3±0.6L/min). No significant changes were found in PaCO2. Thirteen recieved continuous oxygen therapy and seven received nocturnal oxygen therapy. All were followed for an average of 13.3 months and the mean period, during which they were able to stay at home, was 11.5 months. In all cases, the oxygen concentrator worked well and, in 10 of them, functioned throughout more than 12 months. This oxygen delivery system proved satisfactory in practice. The introduction of this equipment makes LHOT more practical in terms of oxygen supply in the home because of its simplicity in operation and maintenance.
