Secondary failure of nasal intermittent positive pressure ventilation using the Monnal D: effects of changing ventilator.

BACKGROUND Some patients started on nasal intermittent positive pressure ventilation (NIPPV) with the Monnal D ventilator deteriorate after a period. The effects of changing them to the Nippy ventilator were investigated. METHODS The records of such patients were examined retrospectively. Comparisons were made between blood gas tensions and overnight oximetry records before NIPPV, 12 weeks after the initiation of NIPPV with the Monnal D, at the time of deterioration, and 12 weeks after initiation of treatment with the Nippy ventilator. RESULTS Ten patients (seven women) were identified. Prior to starting NIPPV their mean (SD) age was 59.6 (8.39) years and their mean arterial oxygen and carbon dioxide tensions (PaO2 and PaCO2) while breathing air were 6.1 (1.79) and 9.6 (3.28) kPa, respectively. All were started on NIPPV with the Monnal D with improvements in symptoms, PaO2, PaCO2, and overnight oximetry after 12 weeks of treatment. After a mean interval of 118 (69.0) weeks all measures of ventilation had deteriorated and the patients were converted to the Nippy ventilator. Twelve weeks after initiation of treatment with the Nippy ventilator symptoms and overnight oximetry were improved again and the mean PaO2 and PaCO2 were 8.9 (1.27) and 6.9 (0.45) kPa, respectively. After a total mean period of 59 (26.9) weeks on the Nippy all but one of the patients have maintained this improvement. CONCLUSIONS Support with NIPPV using the Monnal D ventilator may fail after an interval and changing to the Nippy ventilator can reverse this deterioration, probably because of its superior responsiveness to leaks and patient effort. The regular follow up of patients on long term NIPPV is necessary if secondary treatment failure is to be identified and effectively treated.