Massive subcutaneous emphysema after off-pump coronary bypass surgery.

Subcutaneous emphysema is a condition when air gets accumulated into the tissues under the skin and in the soft tissues of the chest wall or neck but can also spread to other parts of the body. It generally causes minimal symptoms and nonlethal; sometimes, it may be severe and life-threatening if deeper tissues of the thoracic outlet and chest are involved. It is essential to know the mechanisms of subcutaneous emphysema after cardiac surgery.

A 55-year-old female patient presented with chest discomfort for few days. She had no other comorbid conditions. However, the coronary angiographic evaluation revealed a triple vessel coronary artery disease. She underwent off-pump coronary artery bypass grafting surgery (left internal mammary artery to left anterior descending artery, 2 saphenous venous grafts to obtuse marginal and posterior descending artery) uneventfully. Only mediastinal and not pleural drain was inserted while closing the sternum as pleural cavity was not opened. The patient was extubated in a stable condition 8 h after the surgery. Immediate postoperative chest X-ray did not reveal any abnormal finding. On postoperative day 1, patient's face, chest wall and abdomen were swollen with crepitus on palpation. Chest X-ray and computed tomography scan suggested massive subcutaneous emphysema (SE) [Figure 1]. Bilateral pleural drain tubes were inserted, and gradually the SE subsided.

Figure 1

(a) Chest X-ray showing extensive bilateral subcutaneous emphysema in a postoperative patient of coronary artery bypass grafting surgery. (b-d) Computed tomography scan image showing pneumomediastinum and massive bilateral subcutaneous emphysema

SE is a condition when air gets accumulated into the tissues under the skin and in the soft tissues of the chest wall or neck but can also spread to other parts of the body.[12] It can be due to blunt or penetrating trauma, barotrauma, pneumothorax, malignancy, infection, iatrogenic complication, and even spontaneous SE.[2]

In SE after cardiac surgery, air originating from the lung may get into subcutaneous space by two mechanisms.[3] Air in pleural space in case of pneumothorax can pass directly into the chest wall and subcutaneous tissues if the parietal pleura is breached.

Other mechanism can be tracking of alveolar air proximally within the bronchovascular sheath towards the hilum of the lungs and then it may pass superficial to the endothoracic fascia along with the path of least resistance producing SE.[4] Similarly, it may also travel along the mediastinal and then into the cervical visceral space investing the trachea and esophagus.[5] This could have been the possible mechanism in the present case as the patient did not have pneumothorax.

Although SE generally causes minimal symptoms and nonlethal; sometimes, it may be severe and life-threatening if deeper tissues of the thoracic outlet and chest are involved resulting in respiratory impediments and tension phenomena. Various approaches have been elaborated in the management of SE such as the use of subcutaneous incisions, needles, drains, or cervical mediastinotomy.[16]

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