Wednesday, July 30, 2008

Inhaled furosemide for dyspnea RCT

Thorax has a randomized, placebo controlled trial of inhaled furosemide for dyspnea in patients with COPD. Specifically, it was a randomized, double-blind, placebo controlled cross-over trial of inhaled furosemide in 20 patients with moderate to severe COPD. Subjects (mean age 61 years; mean FEV1 45% of predicted) were given inhaled furosemide or placebo on two different days and then a bunch of tests were performed (spirometry, exercise capacity using a cycle ergometer, etc.) about 30 minutes after the treatment. The specific treatment was inhalation of a 4 ml solution containing 40mg of furosemide (10mg/ml) or saline placebo, nebulized over 15 minutes.

Results: there were minimal differences in spirometry findings between groups. Those receiving furosemide had some statistically significant but modest improvements in exercise capacity (could tolerate an extra ~1.5 minutes of exertion) and exertional dyspnea (~1 point on a 10 point scale). They performed several subgroup analyses: essentially there were no clear-cut predictors of who responded. Of note, there were 7 patients whose dyspnea improved with furosemide but whose exercise capacity didn't. The authors discuss the multitude of hypotheses as to why inhaled furosemide could be effective.

My gloss on this is that this is some supporting data for further studies, but it is not compelling evidence for adopting this, particularly in a 'palliative care' COPD population. The outcomes looked at here were exertional dyspnea under controlled conditions within a very short time-frame of receiving a single treatment - and the magnitude of the treatment effects was not great. This is not dyspnea at rest or a clinical setting which resembles real life. I know inhaled furosemide for refractory dyspnea has been discussed anecdotally in the palliative care literature: anyone out there using it or know of other research supporting its use, particularly in refractory/rest dyspnea (from COPD or other causes)?

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