Is the flutter valve good for COPD?

Could you please elaborate on the potential benefits and drawbacks of using a flutter valve for the treatment of Chronic Obstructive Pulmonary Disease (COPD)? Are there any clinical studies or research findings that support its effectiveness in managing symptoms and improving lung function in COPD patients? Also, is there a specific group of COPD patients who may benefit more from using a flutter valve compared to others? Lastly, are there any precautions or side effects that patients should be aware of when using a flutter valve for COPD?