Is routine chest X-ray following mediastinal drain removal after cardiac surgery useful?

Objective: Mediastinal and pleural drains are routinely employed following open-heart surgery to prevent accumulation of blood and fluids in the mediastinum or the pleural cavities. Chest radiographs are obtained after removal of these drains to search for a pneumothorax. We hypothesised that clinical signs and symptoms are sensitive indicators of the presence of significant pneumothorax and routine use of radiographs in these patients is unnecessary.

Methods: A prospective study of 151 consecutive patients undergoing various cardiac surgical procedures over a 10-week period was undertaken. Chest X-rays were performed in all patients within 4h of drain removal. Patients were clinically monitored for development of any respiratory difficulties and the X-rays were evaluated for presence of a pneumothorax or any other abnormality necessitating intervention. The cost of a portable chest X-ray was calculated by taking into consideration the radiographer's time and the cost of an X-ray film.

Results: There were 113 males and 38 females with a mean age of 67.5 years. Fourteen patients (9%) had obstructive airway disease. The left and right pleurae were opened in 62% and 11% of patients respectively and a chest drain was inserted in all of them intraoperatively. Three patients (2%) developed pneumothorax following drain removal. Two of these patients had clinical signs and symptoms, which would have warranted a chest X-ray. One patient had a moderate pneumothorax but was not clinically compromised. Two patients needed chest drain reinsertion that was subsequently removed after 3 and 4 days. The third patient was monitored clinically and the pneumothorax resolved spontaneously on subsequent chest X-ray. In the remaining 148 patients, postdrain removal chest X-ray did not provide any additional information to alter the management. The cost saving of omitting an additional chest X-ray was calculated to be about pound10,000 per year.

Conclusions: Incidence of pneumothorax following mediastinal drain removal is very low. Clinical signs and symptoms almost always identify those few patients requiring intervention and the decision to obtain an X-ray could be based on clinical judgement alone. In addition, this approach may result in cost savings without compromising patient safety.