CHRONIC RESPIRATORY-FAILURE - ASSESSMENT, EVOLUTION, PROGNOSIS

Chronic respiratory failure (CRF) is a major cause of morbidity and mo rtality. II is estimated that in France at least 60 000 patients exhib it severe CRF and that about 15 000 patients die each year from CRF. C hronic obstructive pulmonary disease (COPD) (chronic obstructive bronc hitis, emphysema and their association) is by far the first cause of C RF (90% of the cases). The clinical picture of CRF depends on the caus al disease, but exertional dyspnea is observed in almost all patients. Pulmonary function testing allows to assess whether the ventilatory d efect is obstructive (COPD), restrictive or mixed. Severe CRF is usual ly defined by a Pa02 < 55 mmHg, in a stable state of the disease, with or without hypercapnia (PaC02 > 45 mmHg). The two major complications of CRF since the 5 year survival rate is of 50 % in COPD patients. Un der long-term oxygen therapy (LTOT) the survival rate has been somewha t improved, being of 60-65 % at 5 years. The best prognostic indices i n CRF complicating COPD are the level of FEV1, Pa02, PaC02, the level of pulmonary artery mean pressure (PAP) and age. In COPD patients unde r LTOT the best prognostic indices are PAP and age.