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

The Monnal D is among the most widely used home ventilators with worldwide sales in excess Background – Some patients started on nasal intermittent positive pressure ventof 10 000 units (Taema Ltd, Paris, France). Between 1988 and 1993 we started 112 patients ilation (NIPPV) with the Monnal D ventilator deteriorate after a period. The effects on long term nasal intermittent positive pressure ventilation (NIPPV) using the Monnal D. of changing them to the Nippy ventilator were investigated. Most initially responded well to treatment but a number have since deteriorated. The aim of Methods – The records of such patients were examined retrospectively. Comthe present investigation was to examine the effects of transferring these patients to another parisons were made between blood gas tensions and overnight oximetry records ventilator, the Nippy (Friday Medical, Herne Hill, UK). 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 ventilMethods ator. On the Monnal D the minute volume is preset. Results – Ten patients (seven women) were It operates in the assist/control mode with presidentified. Prior to starting NIPPV their sure triggering from expiration to inspiration. mean (SD) age was 59.6 (8.39) years and The maximum inspiratory pressure is aptheir mean arterial oxygen and carbon diproximately 120 cm H2O and the maximum oxide tensions (Pa2 and Pa2) while minute volume 20 l/min. On the Nippy the breathing air were 6.1 (1.79) and 9.6 peak inspiratory pressure is preset along with (3.28) kPa, respectively. All were started the inspiratory and maximum expiratory time. on NIPPV with the Monnal D with imThe maximum inspiratory pressure is approvements in symptoms, Pa2, Pa2, and proximately 32 cm H2O and the maximum overnight oximetry after 12 weeks of treatminute volume about 40 l/min. ment. After a mean interval of 118 (69.0) The records of all patients on long term weeks all measures of ventilation had deNIPPV transferred from the Monnal D to the teriorated and the patients were converted Nippy ventilator were examined. Patients who to the Nippy ventilator. Twelve weeks after changed ventilators during an acute interinitiation of treatment with the Nippy current illness were excluded. Ten patients ventilator symptoms and overnight ox(seven women) were identified who had initially imetry were improved again and the mean responded well to treatment on the Monnal D Pa2 and Pa2 were 8.9 (1.27) and 6.9 but after an interval had developed recurrent (0.45) kPa, respectively. After a total mean symptoms of ventilatory failure or poor sleep period of 59 (26.9) weeks on the Nippy all and deteriorating overnight oximetry (mean but one of the patients have maintained arterial oxygen saturation (Sa2) <90%) or daythis improvement. time arterial blood gas tensions (Pa2 >7 kPa The Respiratory Conclusions – Support with NIPPV using or Pa2 <8 kPa). In each case these features Support and Sleep the Monnal D ventilator may fail after an had been present for at least four weeks and Centre, Papworth interval and changing to the Nippy ventilHospital, Papworth had not responded to changes in the settings Everard, Cambridge ator can reverse this deterioration, probof the Monnal D (including timing and minute CB3 8RE, UK ably because of its superior responsiveness volume), attention to the mask fit, or to changes I E Smith to leaks and patient effort. The regular J M Shneerson in medical treatment. follow up of patients on long term NIPPV Details at initial referral (t0) were recorded Correspondence to: is necessary if secondary treatment failure Dr I E Smith. for age, diagnosis, daytime (between 09.00 and is to be identified and effectively treated. Received 30 January 1996 17.00 hours) arterial blood gas tensions with Returned to authors (Thorax 1997;52:89–91) the patient at rest breathing air, spirometric 10 May 1996 Revised version received parameters measured using a dry spirometer 20 June 1996 (Vitalograph, Bucks, UK), and static lung vol