. . "1555" . . . . "341" . "10.1016/0140-6736(93)90696-e" . . "341" . "1993-06"^^ . "Elsevier BV" . . . . "1557" . . . . "10.1016/0140-6736(93)90696-e" . . "1555" . "Randomised controlled trial of nasal ventilation in acute ventilatory failure due to chronic obstructive airways disease" . "10.1016/0140-6736(93)90696-e" . . . "1557" . . .