Fazal Hameed Khan

Use of the Laryngeal Mask AirwayTM in mucopolysaccharidoses

mucopolysaccharidoses SIR—The mucopolysaccharidoses are a group of inherited metabolic disorders in which an enzymatic abnormality leads to abnormal accumulation of mucopolysaccharides in different body tissues. One of the major anaesthetic problems in these patients is difficulty in airway management and tracheal intubation. They have a short neck, high larynx, a small hypopharynx, limited atlantoaxial mobility, macroglossia, thickened oral soft tissues, long immobile epiglottis and a narrow larynx and trachea (1,2). The Laryngeal mask airway (LMA) has been used in difficult intubations and has earned a place in the difficult airway algorithm (3). Its role in the above group of patients has not yet been defined (2). Our experience relates to a 9-year-old, partially deaf and blind female child with Hurler’s syndrome, weighing 16 kg, who presented with hoarseness and obstructive sleep apnoea and was scheduled for bilateral nasal polypectomy. Awake fibreoptic intubation was ruled out because of mental retardation. The child was not given any premedication and was induced with 100 oxygen and sevoflurane. Deepening of anaesthesia resulted in complete loss of airway. Attempts to lift the jaw were unsuccessful. Insertion of a size 2 LMA resulted in an adequate airway and a good PECO2 tracing, but positive pressure ventilation was unsuccessful through this. Exchange of the LMA to a larger size (2.5) again led to the loss of airway. After deepening the anaesthesia, a direct laryngoscopy was attempted but structures could not be identified due to folds of mucosa. A thin gum elastic bougie when inserted through the LMA resulted in oesophageal intubation. On insertion of the fibreoptic laryngoscope through the LMA, the laryngeal inlet could not be identified and there was suspicion of the presence of a mucosal polyp above the opening. A decision was taken to perform tracheostomy and a size 4.5 tube was inserted in a relatively narrow trachea. After tracheostomy, the surgeon attempted direct laryngoscopy using a straight blade, at which a very anterior epiglottis and large arytenoids covered with folds of mucosa were seen but the vocal cords or larynx could not be visualized. It appears that although the anterior part of the LMA was sitting on the laryngeal inlet, the posterior part was not fitting snugly because of the narrowness of the inlet. This resulted in the bougie slipping into the oesophagus. Positive pressure ventilation was probably not possible because of the folds of mucosa covering the larynx and large floppy arytenoids acting as ball valves during positive pressure ventilation. It appears that LMA has a limited but crucial place in the airway management of Hurler’s syndrome cases. Although intubation was not possible through an LMA, it allowed time for other alternate measures to be instituted in a controlled manner.

Total intravenous anaesthesia with propofol and buprenorphine

A combination of propofol infusion and two bolus doses of buprenorphine, 2.5 or 5.0 μg/kg were evaluated in a total intravenous anaesthesia technique in 36 patients of ASA grade 1 or 2 undergoing cholecystectomy. Additional boluses of propofol were given intravenously if needed. Systolic blood pressure after tracheal intubation increased significantly only in those who received the smaller dose of buprenorphine. Patients in both groups remained haemodynamically stable throughout surgery with minimal side effects. Recovery was fast even with prolonged infusions and without major side effects. No patient reported awareness on postoperative questioning.