[Proceedings: Home treatment of chronic respiratory insufficiency: criteria of disability].

The degree of disability of a patient with chronic respiratory failure must be determined on a theoretical basis. Using a water filled spirometer, VC and FEV1 tracings are observed several times until the maximal values are clearly reproduced. The percentage deficit of the patients' ventilatory capacity is determined by the formula (see article) and represents the first approximation of the degree of disability (in %). The result must now be corrected by arterial blood gas data obtained during 5 mon exhaustive work on a bicycle or tread-mill ergometer. The percentage disability results from a correction depending on the arterial pO2 and the pCO2 found during exercise: deterioration of the arterial hypoxemia and/or hypercapnia leads to an increase and their normalization to a decrease in the disability quota found during spirometry. Patients with unstable chronic obstructive lung disease and respiratory failure should be evaluated only after adequate rehabilitation at home and at work, and after cessation of smoking. Patients under tuberculostatic treatment must also be excluded from disability evaluation. The degree of disability determined on the basis of lung function tests is a theoretical one; the tests must be performed by trained staff in a pulmonary function laboratory.