Postoperative Pulmonary Edema: Vocal Cord Dysfunction as a Potential Risk Factor

Abstract

INTRODUCTION: Vocal Cord Dysfunction (VCD) usually presents with dyspnea, often mistaken for severe asthma attacks. This case describes postoperative respiratory failure with negative pressure pulmonary edema in a patient with history of VCD. To our knowledge this is the first case of negative pressure pulmonary edema associated with VCD. CASE PRESENTATION: A 41 year-old white female patient with history of anxiety disorder and Vocal Cord Dysfunction diagnosed by direct laryngoscopy. She has history of multiple emergency room visits with asthma-like attacks. Otolaryngologist evaluation for hoarseness confirmed the diagnosis of VCD, but also revealed a nodule in her left thyroid. Ultrasound of her thyroid gland showed a 3 centimeter nodule in her left thyroid lobe. Aspirate of the nodule was suspicious for papillary cancer and the patient was referred for thyroidectomy. The patient had an uneventful surgery, no complications noted during intubation. The procedure lasted 3 hours and she did not require blood transfusion. Immediately after postoperative extubation, she went into severe distress with associated stridor/hypoxemia and required reintubation. The patientas chest x-ray revealed bilateral parenchymal densities. We suspected negative pressure pulmonary edema. The patient had a normal electrocardiogram and echocardiography. She was kept on assisted-controlled mechanical ventilation with lung protective strategy. We did not use diuretics, antibiotics or corticosteroids. The patient achieved excellent recovery over the next 2 days. Thyroid pathology was consistent with Hashimoto's thyroiditis. DISCUSSION: Postoperative Pulmonary Edema usually results from laryngospasm with sustained vocal cord adduction. It is thought that this condition results from forced inspiration against closed upper airways. High negative intrathoracic pressure will shift capillary interstitial fluid inward via increase in hydrostatic pressure. This will result in pulmonary edema. Unlike cardiogenic edema, patients with Negative Pressure Pulmonary Edema (NPPE) have normal cardiac filling pressures. Also, they have rapid radiological resolution and clinical recovery compared to patients with aspiration. Postoperative laryngospasm is a potentially life threatening condition. It is imperative to immediately improve oxygenation and reestablish airways. Management of respiratory failure secondary to NPPE includes supportive care. Low tidal volumes or lung protective strategy seems appropriate. Diuretics are not beneficial and antibiotics are not indicated. It is recommended to obtain an echocardiogram. CONCLUSIONS: The occurrence of high negative pressure during laryngospasm may be exaggerated in patients with chronic VCD. We recommend careful postoperative monitoring for patients with VCD.