EDITOR:
Negative pressure pulmonary oedema is a medical emergency that usually arises from attempted ventilations against an acutely obstructed upper airway, such as the one that occurs during laryngospasm, resulting in transudation of fluid from pulmonary capillaries to the interstitium. Frequently, this occurs in the perioperative period when general anaesthesia is used. Clinicians should promptly recognize this complication and commence appropriate management as early as possible [Reference Louis and Fernandes1–Reference Willms and Shure4].
Case
A 65-yr-old male was encountered at home by paramedics in respiratory distress. The paramedics immediately administered dexamethasone 12 mg intravenously and xylometazoline nebuliser to treat a suspected upper airway obstruction. He was transported to the emergency room of our hospital. His medical history revealed hypertension, hypercholesterolaemia and an acute myocardial infarction in 1999. He complained of a sore throat and was dyspnoeic. Physical examination revealed an inspiratory stridor and a temperature of 38.7°C. Infection parameters were white blood cells (WBC) 15.7 × 103 g L−1 (4–11) and C-reactive protein (CRP) 95 mg L−1 (0–5). Arterial blood gas showed pH 7.43 (7.35–7.45), PCO2 4.3 kPa (4.5–6.0), PO2 16.1 kPa (9.5–13.0) and SaO2 99% (92–99) with oxygen mask. A chest X-ray showed no infiltrations.
In order to inspect the oral cavity and throat, the patient was put into the supine position. Suddenly the patient lost consciousness due to a complete upper airway obstruction. Despite respiratory efforts, no effective breathing was possible. An emergency cricothyrotomy was performed. The trachea was canulated and positive-pressure ventilation was started. A chest-X-ray, 2 h after the first X-ray, showed typical negative pressure pulmonary oedema (Fig. 1). The patient was sedated and ventilated overnight. The next morning, a percutaneous tracheostomy was inserted. A chest X-ray showed resolving oedema. A computed tomography scan of the head and chest showed an oedematous epiglottis.
Negative pressure pulmonary oedema after upper airway obstruction.
Discussion
This case illustrates the rapid onset of negative pressure pulmonary oedema and its resolution with appropriate interventions. Laryngospasm during intubation or after anaesthesia is the most common cause of upper airway obstruction leading to negative pressure pulmonary oedema, but there are several other causes such as epiglottitis, foreign-body aspiration, thyroid goitre, croup, obstructive sleep apnoea and upper airway tumour. Negative pressure pulmonary oedema is a rare entity with a high degree of morbidity; its rarity may lead to the failure of early recognition or to misdiagnosis. The cornerstones of management comprises early diagnosis with re-establishment of the airway, adequate oxygenation and application of positive airway pressure [Reference Louis and Fernandes1–Reference Willms and Shure4].
