Nasotracheal intubation with the McGrath videolaryngoscope in patients with difficult airway

Abstract

Nasotracheal intubation (NTI) is frequently indicated for maxillofacial surgery and the patients usually have difficult airway1. NTI may be complicated by trauma, failure, haemorrhage, sinusitis and glottic palsy. Fibreoptic laryngoscopy is useful, but expensive, bulky and requires experience. The McGrath videolaryngoscope (Aircraft Medical, Edinburgh, UK) is a portable, indirect laryngoscope designed to improve glottic view and orotracheal intubation in patients with difficult airways 2. There is no previous report of McGrath videolaryngoscopy to facilitate NTI. This report is a prospective evaluation of the McGrath for NTI in a cohort of maxillofacial surgery patients with difficult airways. Following the initial successful use of the McGrath for NTI in a patient with previous difficult laryngoscopic and fibreoptic intubation, we conducted a clinical evaluation of this device for NTI. Twenty-five adults, who underwent maxillofacial surgery under general anaesthesia and NTI, were studied. Preoperative airway assessment included Mallampati score, mandibular protrusion, thyromental distance and neck mobility. The study was approved in January 2010, by the research department and audit committee of Central Manchester University Hospital, Manchester, UK. The study was a prospective observational clinical evaluation in adult patients. All the patients gave informed consent to general anaesthesia, laryngoscopy and NTI. Perioperative patient monitoring included electrocardiography, pulse oximetry, blood pressure and respiratory gas measurement. Patients’ nostrils were sprayed with 5% lidocaine and phenylephrine. After preoxygenation, anaesthesia was induced with remifentanil 0.2 mcg/kg/min, propofol 2–3 mg/kg and atracurium 0.5 mg/kg. A lubricated 6 mm cuffed nasotracheal tube was inserted through a nostril into the pharynx. Initial Macintosh laryngoscopy was performed and the Cormack–Lehane grade of laryngoscopic view was noted. Final laryngoscopy was promptly performed with the McGrath, and the grade of glottic view was noted before NTI. Magill forceps were not required for NTI. After intubation, anaesthesia was maintained with 2% sevoflurane and 50% N2O in O2. An observer measured time to intubation, as time from first insertion of the McGrath into patients’ mouth, until first ventilation via nasotracheal tube. Other measurements included number of intubation attempts (withdrawal of laryngoscope and reinsertion), ease of NTI (measured as 1 = easy, 2 = difficult), anaesthetists’ satisfaction with McGrath videolaryngoscopy (measured as 1 = satisfied, 2 = dissatisfied) and complications. Twenty-five patients underwent general anaesthesia and NTI for maxillofacial surgery. Mean age was 45 years, mean BMI was 27 kg m−2, male : female ratio was 1 : 1 and 84% were American Society of Anesthesiologists class 1 or 2. About 80% of patients had known preoperative risk factors for difficult intubation. The frequency distribution of Mallampati airway assessment showed that 24% were grade 1, 36% were grade 2, 28% were grade 3 and 12% were grade 4. The frequency distribution of Macintosh laryngoscopic views showed that 28% were Cormack–Lehane grade 1, 32% were grade 2, 24% were grade 3 and 16% were grade 4. Compared with the mostly difficult Macintosh laryngoscopic views in the majority of patients; the McGrath provided grade 1 laryngoscopic views in all patients and NTI was accomplished at first attempt in 96% of cases. The mean time to NTI was 18 (±8) s. There were no complications. In 96% of cases, NTI was rated as easy; and 100% of anaesthetists were satisfied with McGrath videolaryngoscopy. The prediction of difficult airways, using the measures in our study, is reliable 3,4. However, our study showed no association between predictors of difficult airways and NTI using McGrath videolaryngoscopy. Previous studies showed the benefit of the GlideScope (Verathon, Bothell, Washington, USA) for NTI,5,6. Our study is the first to show the benefit of the McGrath for NTI and also suggests shorter intubation time relative to the Macintosh or GlideScope. McGrath videolaryngoscopy avoids the use of Magill forceps for NTI, thereby reducing intubation time and complications, as shown in our study. In conclusion, the McGrath videolaryngoscope is useful for NTI, especially in patients with a difficult airway. Further evaluation for NTI, in randomised comparison with other videolaryngoscopes, would be useful.