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

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.

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.

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.

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.