SECONDARY FAILURE OF NASAL INTERMITTENT POSITIVE PRESSURE VENTILATIONUSING THE MONNAL-D - EFFECTS OF CHANGING VENTILATOR

Background - Some patients started on nasal intermittent positive pres sure ventilation (NIPPV) with the Monnal D ventilator deteriorate afte r a period. The effects of changing them to the Nippy ventilator were investigated. Methods - The records of such patients were examined ret rospectively, Comparisons were made between blood gas tensions and ove rnight oximetry records before NIPPV, 12 weeks after the initiation of NIPPV with the Monnal D, at the time of deterioration, and 12 weeks a fter 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 (Pao(2) and Paco(2)) while breathing air were 6.1 (1.79) and 9.6 (3.28) kPa, respectively. All were started on NIPP V with the Monnal D with improvements in symptoms, Pao(2), Paco(2), an d overnight oximetry after 12 weeks of treatment. After a mean interva l of 118 (69.0) weeks all measures of ventilation had deteriorated and the patients were converted to the Nippy ventilator. Twelve weeks aft er initiation of treatment with the Nippy ventilator symptoms and over night oximetry were improved again and the mean Pao(2) and Paco(2) wer e 8.9 (1.27) and 6.9 (0.45) kPa, respectively. After a total mean peri od of 59 (26.9) weeks on the Nippy all but one of the patients have ma intained this improvement. Conclusions - Support with NIPPV using the Monnal D ventilator may fail after an interval and changing to the Nip py ventilator can reverse this deterioration, probably because of its superior responsiveness to leaks and patient effort. The regular follo w up of patients on long term NIPPV is necessary if secondary treatmen t failure is to be identified and effectively treated.