NASAL INTERMITTENT POSITIVE PRESSURE VENTILATION - ANALYSIS OF ITS WITHDRAWAL

Nasal intermittent positive pressure ventilation (NIPPV) applied durin g sleep has been demonstrated to be useful in the treatment of restric tive thoracic diseases (RTD). The purpose of this study was to evaluat e the repercussions of a withdrawal period from NIPPV of 15 days. This would be sufficient time for patients to go on trips without the resp irator. It was hypothesized that once daytime improvement was achieved and was stable, it could be maintained for this period of time. Five volunteer patients with severe RTD who had been receiving treatment wi th nocturnal NIPPV for at least 2 months before and who had improved a t least 5 mm Hg in daytime Po-2 and Pco(2) were included in the study. No significant differences were disclosed clinically or with arterial blood gas levels, spirometry results, lung volumes, airway resistance s, or maximal muscle pressures 15 days following the withdrawal. Howev er, in the sleep studies, a severe worsening of gas exchange was obser ved, mainly during rapid eye movement (REM) sleep, as well as a trend toward a more disturbed sleep pattern and more important alterations i n cardiac rhythm. Consequently, withdrawing the treatment with nocturn al NIPPV cannot be recommended, at least for this particular removal p eriod. Moreover, alterations in daytime gas exchange were found to ori ginate in those produced during REM sleep through the blunting of the respiratory center to CO2. The NIPPV obstructs this mechanism, prevent ing the deterioration of gas exchange during sleep.