Decision regarding surgery in a case of hemothorax due to blunt trauma chest should be based on:

The nature of chest tube drainage and the Hemodynamic status, both provide vital clues that may form an indication for Thoracotomy. But only the Hemodynamic status can decide the need for a surgery. Ref: Trauma Manual: Companion to trauma, 4th Edition, Page 165; Bailey and Love's Sho Practice of Surgery, 25th Edition, Page 345