A Case of Negative Pressure Pulmonary Edema After Breast Implant Surgery

摘要

This case report concerns a 50 year old woman with no prior history of lung disease who exhibited respiratory distress, dyspnea and low oxygen saturations in the recovery room following breast implant surgery. The diagnosis of negative pressure pulmonary edema was made based on immediate history, radiographic exams, and testing that ruled out myocardial infarction and pulmonary embolus. High resolution CT scans revealed multiple non-calcified pulmonary nodules along with moderate-to-severe emphysema from a concealed smoking history. Introduction Negative pressure pulmonary edema (NPPE) is an uncommon but recognized complication of upper airway obstruction. It was first described in children in 1973 (1). This form of non-cardiogenic pulmonary edema occurs when the patient struggles to inhale against a partially or completely occluded upper airway. In a vigorous adult the inspiratory muscles can generate a negative intrapleural pressure in the range of -50 to -100 cm H2O (2). The high negative pressure gradient causes fluid to extravasate from the pulmonary capillaries into the interstitial and alveolar spaces (3). This fluid leak represents non-cardiogenic pulmonary edema, and it may result in immediate or delayed hypoxemia. Even after an upper airway obstruction is alleviated, pulmonary edema can develop immediately or up to six hours later (4). Upper airway compromise may be due to occlusion of an artificial airway, as when a patient bites down on an endotracheal tube. Or it may come from internal or external obstruction of the natural upper airway, as might happen in epiglottitis or strangulation.In the case presented below, the radiographic exam was complicated by the recent placement of bilateral breast implants. An under-reported smoking history and unrecognized moderate to severe emphysema were contributing factors. Case Report A 50 year old woman status post bilateral breast implant surgery exhibited dyspnea, wheezing, chest pressure, and low oxygen saturations after extubation in the post-anesthesia recovery room. Before extubation she was noted to be in respiratory distress with severe retractions. A pulmonary consult several hours later described her as pleasant, cooperative, alert and oriented, and speaking in full sentences with only mild dyspnea and some chest pressure. Physical exam at that time revealed clear lungs without wheeze or crackles and an SpO2 of 89% on 2 L/min oxygen by nasal cannula. Cardiac exam noted regular rate and rhythm without chest pain or palpitations. The patient had a history of rheumatoid arthritis treated with methotrexate and gold salts, but no history of pulmonary disease, hemoptysis or pleurisy. Family history was positive for coronary artery disease in both mother and father. Before surgery she had informed the anesthesiologist that she smoked one pack of cigarettes per week, but after the episode of hypoxemia she admitted to smoking more than a pack per day.The differential diagnosis included reaction to anesthesia, excessive IV fluids, myocardial infarction, pulmonary emboli, and negative pressure pulmonary edema.A-P portable chest X-ray (Figure 1, chest X-ray of 6/26) revealed bilateral diffuse perihilar infiltrates and right lower lobe atelectasis, but the presence of breast implants complicated the radiographic analysis of both lower lung fields. High resolution chest CT scans with contrast were used to rule out pulmonary emboli. Over a hundred sequential scans revealed no evidence of pulmonary emboli or pneumothorax, but did show pulmonary edema superimposed on moderate-to-marked emphysema with multiple non-calcified small pulmonary nodules (Figure 3, Chest CT #21, and Figure 4, chest CT #31). Subcutaneous emphysema and bilateral breast prostheses in the soft tissue of the anterior chest were consistent with the surgical history.