Abstract
Noninvasive ventilation in chronic obstructive pulmonary disease (COPD) has been shown to improve arterial blood gases but its long-term role has not been established. We retrospectively studied 26 consecutive patients with hypercapnic ventilatory failure due to COPD in whom oxygen therapy caused worsening hypercapnia (defined as a rise in the daytime arterial carbon dioxide tension (Pa,CO2) to >8.0 kPa or nocturnal transcutaneous carbon dioxide tension (Ptc,CO2) to >9 kPa). All were treated with mask ventilation (15 with nasal and 11 face masks) at night and during daytime naps. Additional oxygen therapy was required in 15 patients. The mean annualized death rate was 10.8% with a 1 and 3 yr survival of 92 and 68%, respectively. After 1 yr the median daytime Pa,CO2 had fallen by 1.35 kPa and the arterial oxygen tension (Pa,O2) had risen by 2.4 kPa. In subjects not using additional oxygen the median overnight Sa,O2 rose by 12% and the Ptc,CO2 fell by 2.8 kPa after 1 yr. The haematocrit was significantly less than pretreatment at 6 months and 1 yr. Quality of life in the domain of role limitation by physical health (measured using the SF-36 questionnaire) improved significantly at 6 months. Survival in this selected group with clinically stable airflow obstruction unable to tolerate oxygen therapy and treated with noninvasive mask ventilation is better than historical controls and is comparable to those able to tolerate oxygen therapy. Poor survival was associated with a low forced expiratory volume in one second, a low body mass index and a high nocturnal transcutaneous carbon dioxide tension. No difference in survival was found between those treated with mask intermittent positive pressure ventilation alone or with mask intermittent positive pressure and supplementary oxygen therapy.
