Nasal Positive Pressure Ventilation in Patients with Acute Respiratory Failure (8)
The impression was that some kind of ventilatory support was necessary, lest potentially lethal respiratory acidosis eventually develop, but that the degree of emergency allowed sufficient time for a trial of NPPV The latter was therefore initiated; initial PaC02 levels of 10.5 kPa (79 mm Hg) decreased rapidly, and 5 h later was at 6.3 kPa (47 mm Hg), whereas the Sa02 was more than 90 percent (FIo2, 28 percent). The patient’s neurologic status rapidly improved; and on the following day, she was alert and cooperative.
Wfe decided to introduce a prolonged period of NPPV (8 h per 24 h) up to a weight loss of 50 kg (110 lb); our aim was to interrupt NPPV when sufficient weight loss would entail the disappearance of the obesity-associated hypoventilation. During the following six months the patient lost 60 kg (132 lb); when NPPV was interrupted, after 15 days without mechanical ventilation, the PlaCO* was 6 to 6.5 kPa (45 to 50 mm Hg), and the patient remained Well oriented and alert.
This 50-year-old man had been a heavy smoker for more than 30 years and could be considered as having COPD, with severe airflow obstruction (Table 2). In addition, he was obese (body weight, 110 kg [242 lb]; height, 169 cm [5 ft 614 in]), suffered from numerous obstructive sleep apneas, and was chronically hypercapnic (PaC02, 6.5 kPa [49 mm Hg]).