Israel Medical Association Journal

Objectives: To suggest a simple outpatient technique for evaluating the response of arterial oxygen saturation to exercise for use as a marker of disease severity.

Patients and methods: Ninety-six patients with various degrees of COPD¹ were divided into three groups: mild (forced expiratory volume in 1 sec >65%), moderate (FEV1² between 50 and 65%), and severe (FEV1 <50%). Using continuous oximeter recording we measured oxygen saturation during 15 steps of climbing, and quantified  oxygen desaturation by measuring the “desaturation area”, defined as the area under the curve of oxygen saturation from the beginning of exercise through the lowest desaturarion point and until after recovery to the baseline level of oxygen percent saturation. Desaturation was correlated to spirometry, lung gas volumes, blood gas analysis, and 6 min walking distance.

Results A good correlation was found between severity of COPD and baseline SaO2³, lowest SaO2, recovery time, and desaturation area.  A negative correlation was found between desaturation area and FEV1 (r=-0.65), FEV1/forced vital capacity (r=-0.58), residual volume to total lung capacity (r=0.52), and diffusing lung capacity for carbon monoxide (r=-0.52). In stepwise multiple regression analysis only FEV1 correlated significantly to desaturation area.  A good correlation was noted between 6 min walking distance and desaturation area with the 15 steps technique (r=0.56).

Conclusions: In patients with severe COPD, arterial hypoxemia during exercise can be assessed by simple 15 steps oximetry. This method can serve both as a marker for disease severity and to determine the need for oxygen supplementation.

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COPD = chronic obstructive pulmonary disease

FEV1 = forced expiratory volume in 1 sec

SaO2 = arterial oxygen saturation

Objective: To examine to what extent and for how long nedocromil sodium prevents exercise-induced asthma when given immediately before exertion compared to chronic administration.

Patients and Methods: Eighteen asthmatic patients were given 4 mg NS at 30 min or 3.5 hours before exertion. We compared the resultant effect with that of the same protocol measured after 2 and 4 weeks of continuous treatment with the drug.

Results: Nedocromil sodium decreased exercise-induced asthma similarly at both points when given acutely. Chronic treatment of up to 4 weeks did not improve this protective effect at either interval following the inhalation.

Conclusion: Nedocromil sodium most likely reaches its maximal effect on exercise-induced asthma upon the first administration, although treatment for longer than 4 weeks might be required to prove a chronic effect of the drug.