The aim of the study was to determine whether intermittent positive pressure ventilation (IPPV), delivered either by nasal mask or by tracheostomy, is able to improve alveolar gas exchange in kyphoscoliotic patients with respiratory failure. We evaluated 17 patients, 10 females and 7 males, aged 52 +/- 12 (mean +/- SD) yrs. Eight had severe respiratory failure (arterial oxygen tension (PaO2) 53.2 +/- 9.3 mmHg (7.1 +/- 1.2 kPa); arterial carbon dioxide tension (PaCO2) 73.3 +/- 12.5 mmHg (9.7 +/- 1.6 kPa), breathing supplemental oxygen), and were put on IPPV via tracheostomy (TIPPV). The others (PaO2 54.5 +/- 5.5 mmHg (7.3 +/- 0.7 kPa); PaCO2 57.9 +/- 7 mmHg (7.7 +/- 0.9 kPa), breathing air), were put on IPPV via nasal mask (NIPPV). Home mechanical ventilation (HMV) was performed at night (7 +/- 1 h) by means of a volume-cycled pressure respirator in control mode. The frequency was adapted to the patient's spontaneous respiratory rate, and then eventually modified according to blood gases. A silicone mask was moulded onto the patient's nose. Supplemental oxygen (to maintain arterial oxygen saturation (SaO2) > 90%) was used only for tracheostomized patients, whereas NIPPV was performed with fractional inspiratory oxygen (FIO2) 21%. Arterial blood samples were obtained for all patients in steady-state condition, 8 +/- 1 h from the withdrawal, breathing air, after 1 and 6 months of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)