Open-heart surgery (OHS), which includes procedures like coronary artery bypass grafting (CABG) or valve repair, is a major operation requiring the chest cavity to be opened, often involving a sternotomy. The process is highly effective for treating various cardiac conditions but carries a temporary risk of complications affecting nearby organs, including the lungs. A “collapsed lung” refers to the loss of lung volume, which can range from a minor partial collapse of small airways to a full collapse of an entire lung. Understanding the differences between these conditions and their likelihood after OHS can help patients navigate the recovery period.
The Likelihood of Lung Complications After Open Heart Surgery
The likelihood of a lung complication after open-heart surgery depends significantly on the type and extent of the collapse. The most common form of volume loss is atelectasis, the partial collapse of the tiny air sacs (alveoli) in the lungs. This minor, partial collapse is exceptionally common following any procedure requiring general anesthesia and is observed to some degree in nearly all patients. Chest X-rays taken shortly after OHS frequently show evidence of atelectasis, with reported incidences ranging from 30% to over 70%.
The more serious complication, a complete collapse of the lung known as a pneumothorax, occurs when air leaks into the space between the lung and the chest wall. This is infrequent. Large retrospective analyses have consistently shown the incidence of a postoperative pneumothorax to be low, typically affecting only about 1.4% of patients. The distinction between the common, manageable atelectasis and the rare, serious pneumothorax is important for setting patient expectations.
Surgical and Physiological Causes of Lung Issues
The unique steps involved in open-heart surgery create specific physiological challenges that contribute to these lung complications.
Surgical Trauma and Pain
The initial cause stems from the surgical approach itself, which requires a sternotomy, the vertical incision and splitting of the breastbone. This trauma to the chest wall and the subsequent pain severely restrict a patient’s ability to take a deep, full breath. Patients often instinctively breathe shallowly, a defensive mechanism that prevents the alveoli from fully expanding, leading directly to the development of atelectasis.
Cardiopulmonary Bypass (CPB)
Another significant factor is the use of the heart-lung machine (CPB), which temporarily takes over the function of both organs. While on CPB, the lungs are not ventilated and can lose surfactant, a substance that helps keep the alveoli open, contributing to widespread alveolar collapse. The bypass process also triggers a systemic inflammatory response, which can increase fluid accumulation and impair gas exchange within the lungs.
Phrenic Nerve Injury
A specific nerve injury can impair the diaphragm, the primary muscle of breathing. During OHS, surgeons often apply cold saline slush or ice to the heart to slow its metabolism and protect it. This localized cooling can temporarily damage the phrenic nerve, which controls the movement of the diaphragm. Dysfunction of the diaphragm, particularly on the left side, reduces the efficiency of breathing and prevents the lower parts of the lung from fully expanding.
Recognizing the Signs of Respiratory Distress
Identifying potential lung complications early relies on recognizing a set of observable signs and symptoms. A patient may experience dyspnea, or shortness of breath, which is the most common early indicator of impaired lung function. They may also notice a sharp, localized chest pain that intensifies when they try to take a deep breath or cough. These respiratory symptoms are often accompanied by systemic signs, such as a rapid heart rate or a measurable drop in oxygen saturation levels in the blood.
Medical professionals confirm the presence and severity of a collapsed lung using specific diagnostic tools. The most common tool is a chest X-ray (CXR), which provides a quick image of the lungs. A CXR can visualize areas of opacification, indicating volume loss from atelectasis, or the presence of air outside the lung, indicating a pneumothorax. While a chest X-ray is often sufficient, a computed tomography (CT) scan may be used in more complex cases to provide a detailed, cross-sectional view of the chest.
Treatment and Recovery for Lung Complications
The treatment approach is tailored to whether the patient is experiencing atelectasis or a pneumothorax.
Treating Atelectasis
For atelectasis, the management focuses on non-invasive techniques designed to re-expand the collapsed alveoli. Patients are strongly encouraged to use an incentive spirometer, a handheld device that measures the depth of inhalation, prompting them to take slow, sustained deep breaths multiple times per hour. This active respiratory exercise helps reinflate the small airways.
Recovery also involves early mobilization and effective pain management, both of which allow for deeper breathing. Getting out of bed and walking, often within 24 hours of surgery, helps to redistribute air and fluid in the lungs. Appropriate pain medication reduces the guarding behavior that causes shallow breaths. These simple, active interventions are generally successful in resolving atelectasis within the first few days after surgery.
Treating Pneumothorax
If a significant pneumothorax occurs, a more direct medical intervention is required to remove the trapped air and allow the lung to fully re-inflate. This involves inserting a chest tube, known as thoracostomy, into the pleural space between the chest wall and the lung. The tube is connected to a suction device that helps to evacuate the air, restoring the negative pressure that keeps the lung expanded. The chest tube remains in place until the air leak has sealed and the lung remains fully inflated, which may extend the patient’s hospital stay, but typically leads to a successful resolution.