pleurax catheter for pleural effusion drainage

Anyone familiar with this type of drainage for malignant pleural effusions. One is being put in my Mom on Monday because the drainage is building so often now. I know it should help her comfort because she will not have to go into the hospital as often for the drainage and will not have to be stuck every time. How often  and how much should drain each time. Each time we drain her with thoracentesis now it is at least 1500cc's and has developed to twice a week. What's next? any advice, suggestions, prognosis outcomes etc would be welcome.