Sir,We report an unusual airway challenge in a 32-year-old male acromegalic planned for endoscopic trans-sphenoidal resection of a pituitary macroadenoma. Airway examination showed a large jaw and an enlarged tongue, with a Class III modified Mallampati score. Anesthesia was induced using fentanyl, propofol, and rocuronium. Laryngoscopy revealed a Cormack-Lehane Grade I view and a large laryngeal inlet. Orotracheal intubation was performed with size 8.5 mm cuffed endotracheal tube (ETT). There was an audible leak during positive pressure ventilation, and the peak airway pressure was 15 cmH2O. On further inflation of the cuff with up to 10 ml of air, the leak reduced but was persistent. The pilot balloon was distended. There was a volume loss of 150 ml during ventilation resulting in fogging of the endoscope lens. The throat was packed with ribbon gauze and the audible leak as well as fogging of the lens ceased. The rest of the procedure was uneventful, and the patient's trachea was extubated on table. After extubation, we confirmed that the cuff of the ETT was intact and inflating normally. Subsequently, the tracheal diameter was measured using the computed tomography (CT) scan of the para-nasal sinus and neck. The sagittal diameter (SD) and coronal diameter (CD) of the trachea were 25.7 mm and 19.4 mm, respectively [Figures 1 and 2], at the level where the ETT cuff rests (30 mm below the glottis).
Figure 1
Computed tomography scan of the paranasal sinus and neck (sagittal section) showing coronal tracheal diameter 30 mm below the glottis
Figure 2
Computed tomography scan of the paranasal sinus and neck (axial section) showing coronal and sagittal diameter of the trachea 30 mm below the glottis
Computed tomography scan of the paranasal sinus and neck (sagittal section) showing coronal tracheal diameter 30 mm below the glottisComputed tomography scan of the paranasal sinus and neck (axial section) showing coronal and sagittal diameter of the trachea 30 mm below the glottisThe abnormal anatomy of larynx in acromegalics may result from soft-tissue hypertrophy and bony alterations. Jackson reported four acromegalics who had laryngeal abnormality caused by overgrowth of soft tissue and cartilages.[1] Other authors[23] have reported laryngeal stenosis and generally thickened tissues of the upper airway. Hassan et al.[4] measured the cricoid width and anterior-posterior diameter of cords and showed for the first time that they were narrower in acromegalypatients compared to normal patients and showed the need for smaller size tubes in these patients due to airway mucosal hypertrophy. In contrast to the above studies, our patient required a larger size ETT. The mean SD of 17.4 ± 3.1 (18.1–14.8) and CD of 17.7 ± 2.6 (18.3–15.2) of the trachea measured from CT scans in adult Indian population[5] were significantly smaller than in our patient, in whom the large tracheal diameter resulted in inability to achieve a seal despite over inflating the ETT cuff. No studies have documented an air leak following use of a standard size ETT in acromegalics. Thus, knowing the tracheal diameter preoperatively will be helpful in these patients to predict the size of ETT. Anesthesiologists must be aware that though literature cautions that a smaller size ETT is required in acromegalics due to airway mucosal hypertrophy, a larger size ETT may occasionally be required. Chest X-ray tends to overestimate the tracheal diameter.[6] A CT scan if available should be examined or ultrasound performed to measure the tracheal diameter before surgery, to predict the ETT size required. In case both are unavailable, one should keep larger size ETTs ready.
Figure 1
Figure 2