Effect of Ambulatory Oxygen on the Walking Test in Patients With Pulmonary Fibrosis

Pulmonary Fibrosis

Oxygen therapy

Patients with pulmonary fibrosis often desaturate on exercise. There are no data showing whether ambulatory oxygen can be useful to improve exercise capacity in this condition. Ambulatory ambulatory oxygen is often denied to these patients based on studies conducted on patients with chronic obstructive pulmonary disease, a completely different condition for physiopathology, prognosis, and response to therapy. We therefore planned a controlled study to verify the usefulness of ambulatory oxygen in patients with pulmonary fibrosis

Criteria for inclusion: Patients with a diagnosis of pulmonary fibrosis of any kind, with oxygen saturation \>90% in ambient air at rest, showing a desaturation \<88% during a preliminary 6 minutes walking test Criteria for exclusion: Inability to give consent, age \<18 or \>85 years, walking problems from causes different from pulmonary disease Procedure: In a preliminary session, the flow of oxygen needed to prevent desaturation during walking is established according to a validated protocol Guyatt et al, Am J Respir Crit Care Med 2001,163:,942-946.) Two 6 minutes walking tests are then performed in a corridor, at least 30' apart, during administration of oxygen or medical air, in random order and double blind, at the same pre-determined flow, administered through a nasal cannula connected to a wall outlet (concealed from sight, being in a side rum at about mid distance in the corridor) through a 10 mt plastic tubing. Oxygen saturation and pulse rate are monitored through a dedicated recording oximeter (Minoxy, Cosmed) , whose display is concealed to both the patient and the operator, with an alarm set for oxygen saturation \<70%, to stop the test in case severe desaturation would occur Data are then transferred to computer for analysis only after both test are performed. Walked distance is recorded by the operator unaware of treatment. At the end of each test, a short questionnaire is administered with 10 cm Visual Analogue Scales (VAS) for dyspnoea, fatigue, and preference compared to performing the test without any treatment. At the end of the second test a further scale is submitted, asking about the preference between the two treatments. Primary outcomes are the distance walked and the difference in preference of the two treatments compared o no treatment. Secondary outcomes are differences in minimal saturation level and maximal pulse rate during the test and in the report of dyspnea and fatigue at the end of the test, and the reported preference between the two treatments. Statistical analysis to evaluate the effect of the treatment on walking distance, heart frequency and oxygen saturation is performed using generalized linear model with a gaussian family and identity link and including order of treatment as a fixed effect. Parameters evaluated using VAS are analyzed using Koch adaptation of Wilkoxon rank test (Senn SS. Cross-over Trials in Clinical Research, 2nd Edition. Wiley 2002)