Topical anaesthesia of the upper airway following deliberate sulphuric acid ingestion

Abstract

A 36-year-old man presented to our trauma centre with significant mucosal burns, following a deliberate sulphuric acid ingestion. Initially we noted his voice was hoarse; however, this quickly progressed to aphonia. We decided to intubate his trachea to secure the airway and allow surgical intervention. Given the risk of difficult laryngoscopy, we decided to perform an awake fibreoptic intubation. However, given that the patient had ingested a large volume of highly concentrated sulphuric acid an hour before presentation, we were uncertain how long it would take for tissue pH to normalise again. Lidocaine, an amide local anaesthetic with a pKa of 7.9, may not be effective in such an acidic environment. We were also concerned that the airway burns could increase the risk of local anaesthetic systemic toxicity, as a result of an increased rate of absorption [1]. We transferred the patient to the operating theatre and undertook anaesthesia with noninvasive monitoring, intravenous lipid available and our surgical colleagues present. We achieved topical anaesthesia with 1 ml co-phenylcaine spray (5% lidocaine and phenylephrine) to one nostril and 10 ml lidocaine 2% to the pharynx using a Mucosal Atomisation Device (MADgic®, Wolfe Tory Medical, Utah, USA). We anaesthetised the supra and infraglottic areas with 2 ml lidocaine 4% via a cut epidural catheter. The patient did show signs of discomfort during application of the local anaesthetic. We then performed an uncomplicated upper airway endoscopy via the nostril without any discomfort or gag reflex. We observed extensive mucosal burns and swelling of the epiglottis and false vocal cords. Before topical anaesthesia of the glottic area, we noted that the vocal cords were non-mobile and in the abducted position. The patient did not cough and seemed comfortable during passage of a 6.5-mm reinforced tracheal tube through the glottis. The total lidocaine dose of 330 mg (approximately 4 mg.kg−1) did not lead to any symptoms of local anaesthetic toxicity. Over the next two days, the patient went on to have extensive surgery including a tracheostomy, oesophagogastrectomy, Whipple’s procedure with complete pancreatectomy and splenectomy. He has now been discharged from critical care and is awaiting further procedures for his laryngeal injuries. Acidic upper airway and gastrointestinal burns can have catastrophic consequences that need to be addressed in a timely fashion to avoid serious morbidity and mortality [2, 3]. This case highlights the plausibility and safety of topical airway anaesthesia and fibreoptic intubation in such caustic burns.