PNEUMOMEDIASTINUM FROM SPIROMETRY AND RESPIRATORY FUNCTION TESTING AFTER MEDIAN STERNOTOMY AND THYMECTOMY: A CASE REPORT

Abstract

SESSION TITLE: Global Case Report Posters SESSION TYPE: Global Case Reports PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Pneumomediastinum is the presence of air within the mediastinum. Causes include parenchymal lung disease, violent coughing, and vomiting and chest surgery. Spirometry testing is a rare cause of pneumomediastinum. We report a case of pneumomediastinum due to pulmonary function testing and spirometry in a man who underwent thymic surgery. CASE PRESENTATION: A 52 year old man underwent median sternotomy and thymectomy for a 9x7cm thymoma discovered after diagnosis of myasthenia gravis. Chest drains were removed by post-operative day (POD) 2. The patient received chest physiotherapy, incentive spirometry and twice daily negative inspiratory force (NIF) and forced vital capacity (FVC) measurements as recommended by Neurology. On POD 5, he reported a change in voice quality and facial swelling. Subcutaneous crepitus was palpable over the right chest, neck and cheek. A computed tomographic (CT) study of the thorax showed extensive pneumomediastinum, pneumopericardium and subcutaneous emphysema extending to the right temporal fossa. Upon review of our patient’s NIF and FVC measurements, he was found to have an increased FVC daily with an FVC of 3L prior to the onset of his symptoms. The patient was commenced on bed rest with limited ambulation around his cubicle. Spirometry and the NIF and FVC measurements were stopped and he was commenced on empirical antibiotics. He reported improvement of his facial swelling within 24 hours and daily chest radiographs demonstrated improvement in the subcutaneous emphysema. The patient remained clinically well and was discharged on POD 8 with a course of oral antibiotics. DISCUSSION: The pathophysiology of pneumomediastinum suggests that following alveolar rupture, air enters the perivascular adventitia and dissects proximally into the mediastinum. Pneumomediastinum following chest surgery should prompt the clinician to rule out pneumothorax and mediastinitis and monitor for obstructive symptoms, air embolism and subcutaneous emphysema. When significant pathology has been excluded, treatment is directed towards symptom relief. In our patient, we postulate that the rapid increase in lung volume and pressure changes in the alveolus from the inspiratory function tests and incentive spirometry, coupled with breaches of the pleura and pericardium during surgery, had caused air to dissect into the subcutaneous plane, mediastinum and pericardial space. CONCLUSIONS: Incentive spirometry helps prevent postoperative pulmonary complications and aids recovery of pulmonary function in patients undergoing thoracic surgery. Our case highlights the need to be aware of potential complications of spirometry and pulmonary function testing in motivated patients, especially following thoracic surgery. Reference #1: Manco, JC, Terra-Filho, J, and Silva, GA. Pneumomediastinum, pneumothorax and subcutaneous emphysema following the measurement of maximal expiratory pressure in a normal subject. Chest. 1990; 98: 1530–1532 DISCLOSURES: No relevant relationships by Atasha Asmat, source=Web Response No relevant relationships by Shaun Chan, source=Web Response No relevant relationships by Jacqueline Chua, source=Web Response