Flexible reinforced laryngeal mask airway (FLMA®) has gained popularity in thyroid surgery, but air leak and displacement are still concerns.
In this randomized, single-blinded, noninferiority, controlled trial, we randomized patients scheduled for elective radical thyroidectomy to an endotracheal tube (ETT) group or a FLMA group. The primary outcomes were ventilation leak volume, peak airway pressure, and partial pressure of end-tidal carbon dioxide (PetCO2). Data for primary outcomes were collected after insertion of ETT/FLMA, at incision, and at 10-minute intervals during surgery. Ten milliliters, 5 cm H2O, and 10 mm Hg were used as the noninferiority deltas for ventilation leak volume, peak airway pressure, and PetCO2, respectively. We assessed noninferiority of FLMA to ETT on the primary outcomes over time using the results of a linear mixed-effects model. The position of FLMA mask was evaluated before and after surgery, and the airway complications were recorded.
A total of 132 patients were included: 65 in ETT group and 67 in FLMA group. Differences (FLMA group minus ETT group) of ventilation leak volume, peak airway pressure, and PetCO2 from the mixed-effects models were 2.09 mL (98.3% confidence interval [CI], -6.46 to 10.64), -0.60 cm H2O (98.3% CI, -2.15 to 0.96), and 1.02 mm Hg (98.3% CI, 0.04-1.99), respectively. Score of fiber-optic position of FLMA was significantly higher after surgery than before. There was no severe shift, loss of the mask seal, regurgitation, or aspiration in the FLMA group. One patient in the FLMA group experienced brief and easily controlled laryngospasm.
In thyroid surgery, FLMA is noninferior to ETT in the peak airway pressure and PetCO2 although mild to moderate mask shift could occur during surgical manipulation. There is no evidence for a higher complication rate when FLMA is used.