Recovery of diaphragm function after neuromuscular block by means of diaphragm ultrasonography with comparison of neostigmine vs normal saline as reversal drugs

Background: Residual neuromuscular blockade (RNMB) is a well-known risk factor after general anesthesia for critical respiratory events and higher postoperative morbidity. Acetylcholinesterase inhibitors cannot completely avoid RNMB. Neuromuscular monitoring of the adductor pollicis is the gold standard for detecting RNMB, but it cannot be carried out on conscious patients. Ultrasonography of diaphragm excursion may reveal residual effects of neuromuscular blocking agents in conscious patients. Methods This prospective, double-blind, single-center randomized controlled study enrolled 150 patients, who belong to ASA physical status I and II, aged 18–65 years, and be scheduled to undergo neuromuscular block with cis-atracurium for neurosurgery. The primary objective will be to compare the difference in DE between groups. Patients will be extubated when the train-of-four ratio is ≥ 0.9. Diaphragm ultrasonography will be used to evaluate the diaphragm excursion. The Diaphragm ultrasonography will be performed before anesthesia induction, at one minute after extubation, and before being discharged from the PACU. The secondary objective was to compare the incidence of postoperative pulmonary complications after operation. Results After extubation, the DE of patients was significantly larger in the NEO group than in the NS group (14.14 ± 1.93 vs. 12.96 ± 1.62 mm, P < 0.05). The incidence of RNMB was higher in the NS group, when compared to the NEO group, after extubation (73.33% vs. 53.33%, P = 0.011) and when leaving the PACU (33.33% vs. 20%, P = 0.044). The incidence of respiratory insufficiency after extubation was higher in the NEO group (14.67%), when compared to the NS group (4%) (P = 0.046). Conclusion Residual neuromuscular blockade is still a problem to be solved. Diaphragm ultrasound may become a bedside tool in the neuromuscular monitoring field to detect underestimated residual neuromuscular blockade after neuromuscular block. Trial registration: The trial was registered prior to patient enrollment at ClinicalTrials.gov (ChiCTR1900021095, Date of registration: January 28, 2019).