Comparison of neostigmine vs. sugammadex for recovery of muscle function after neuromuscular block by means of diaphragm ultrasonography in microlaryngeal surgery: A randomised controlled trial BACKGROUND Postoperative residual neuromuscular blockade or curarisation (PORC) is a risk directly related to the use of neuromuscular blocking agents during surgical procedures. Acceleromyography is distressing for conscious patients when assessing PORC. Diaphragm ultrasonography could be a valid alternative. OBJECTIVES The primary objective was to achieve a 28% lower incidence of PORC in patients who, after rocuronium administration, received neostigmine or sugammadex at 30 min after surgery. To assess PORC, diaphragm ultrasonography was used, and thickening fractioning [the difference of thickness at the end of inspiration (TEI) and at the end of expiration (TEE), normalised for TEE (TEI − TEE/TEE)] was measured. PORC was defined as thickening fractioning of 0.36 or less. The secondary object was the comparison, in the two treatment groups, of the return to baseline thickening fractioning at 30 min after surgery (ΔTF30). DESIGN Prospective, double-blind, single-centre randomised study. SETTING University Hospital Careggi, Florence, Italy. PATIENTS Patients of American Society Anesthesiologists’ physical status 1 or 2, 18 to 80 years, receiving rocuronium during microlaryngeal surgery. INTERVENTIONS At the end of surgery participants were randomised to receive neostigmine (NEO group) or sugammadex (SUG group) as the reversal drug. Thickening fractioning and ΔTF30 were evaluated at baseline and at 0, 10 and 30 min after surgery. MAIN OUTCOME MEASURES TEE and TEI at each time point. RESULTS A total of 59 patients with similar demographic characteristics were enrolled. An association between lack of recovery (thickening fractioning ≤0.36) and drug treatment was only observed at 0 min (SUG vs. NEO, P < 0.05). Concerning ΔTF, at 30 min more patients in the SUG group returned to baseline than those in the NEO group (P < 0.001), after adjusting for side (P = 0.52), baseline thickening fractioning (P < 0.0001) and time of measurement (P < 0.01). CONCLUSION We found an early (0 min) but not long-lasting (30 min) association between diaphragm failure and treatment allocation; a full recovery in baseline diaphragm function was observed only in patients receiving sugammadex. We cannot exclude that further differences have not been found due to interpatients variability in assessing diaphragm contractility by ultrasonography. TRIAL REGISTRATION EudraCT Identifier: 2013-004787-62, Clinicaltrials.gov Identifier: NCT02698969. Correspondence to Iacopo Cappellini, Section of Anesthesiology and Intensive Care, Department of Health Sciences, University of Florence, Largo Brambilla 3, 50134 Florence, Italy E-mail: jacopocappellini@gmail.com © 2019 European Society of Anaesthesiology