RT Journal Article SR Electronic T1 Mechanisms underlying effects of nocturnal ventilation on daytime blood gases in neuromuscular diseases JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 157 OP 162 DO 10.1183/09031936.99.13115799 VO 13 IS 1 A1 D Annane A1 MA Quera-Salva A1 F Lofaso A1 JB Vercken A1 O Lesieur A1 C Fromageot A1 B Clair A1 P Gajdos A1 JC Raphael YR 1999 UL http://erj.ersjournals.com/content/13/1/157.abstract AB The hypothesis that, in neuromuscular and chest wall diseases, improvement in central respiratory drive explains the effects of night-time ventilation on diurnal gas exchanges was tested. The effects at 6 months, 1, 2 and 3 yrs of intermittent positive pressure ventilation (IPPV) on arterial blood gas tension, pulmonary function, muscle strength, sleep parameters, respiratory parameters during sleep and ventilatory response to CO2 were evaluated in 16 consecutive patients with neuromuscular or chest wall disorders. As compared with baseline, after IPPV daytime arterial oxygen tension (Pa,O2) increased (+2.3 kPa at peak effect) and arterial carbon dioxide tension (Pa,CO2) and total bicarbonate decreased (-1.8 kPa and -5 mmol x L(-1), respectively) significantly; vital capacity, total lung capacity, maximal inspiratory and expiratory pressures and alveolar-arterial oxygen gradient did not change; the apnoea-hypo-opnoea index and the time spent with an arterial oxygen saturation (Sa,O2) value <90% decreased (-24 and -101 min, respectively), sleep efficiency and mean Sa,O2 increased (+16% and +5%, respectively); and ventilatory response to CO2 increased (+4.56 L x min(-1) x kPa(-1)) significantly. The reduction in Pa,CO2 observed after IPPV correlated solely with the increase in the slope of ventilatory response to the CO2 curve (r=-0.68, p=0.008). In neuromuscular or chest wall diseases, improvement of daytime hypoventilation with nocturnal intermittent positive pressure ventilation may represent an adaptation of the central chemoreceptors to the reduction of profound hypercapnia during sleep or reflect change in the quality of sleep.