Background. This study research that the recovery from deep neuromuscular block with small dose of sugammadex is slower and incidence of recurarization is higher in elderly patients than non-elderly patients. This study purpose to reveal the risk factors of recurarization by comparing the changes of the train-of-four ratio (TOFR) during spontaneous and sugammadex-induced recovery from deep muscle paralysis in elderly and non-elderly patients. 

Methods. Twenty elderly (70-yr; elderly group) and twenty non-elderly (20-69yr; non-elderly group) patients were enrolled in this non-randomized, parallel-arm observation study. Before induction of anaesthesia, an acceleromyograph neuromuscular monitor was put on the thumb and the ulnar nerve. Under propofol anaesthesia, the ulnar nerve was stimulated with the automatic calibration mode and TOF stimulation was repeated throughout the experiment. All patients received rocuronium 0.6mg kg-1 intravenously. After measuring spontaneous recovery of the neuromuscular block, rocuronium 0.4mg kg-1 was intravenously administered. When the PTCs 2-10 was achieved, sugammadex was continuously infused at a rate of 50µg kg-1 min-1 but stopped at an insufficient dose when the TOFC 3 was achieved. The recovery of the TOFR was measured after cessation of the sugammadex infusion.

Results. The spontaneous TOFR recovery speed is significantly slower in the elderly group (median (25 percentile, 75 percentile):1.89(1.22, 2.90) %/min) than non-elderly group (3.45 (1.96, 4.25) %/min, p=0.002). After inadequate dose of sugammadex administration, there was no significant difference in early-phase TOFR recovery speed (elderly 8.10(6.18, 12.9) %/min, non-elderly 10.5(7.45, 12.1) %/min, p=0.607) but in late-phase, the TOFR recovery speed is significantly slower in elderly group (0.55(-0.29, 1.54) %/min) than non-elderly group (1.68(0.73, 3.13) %/min, p=0.006). There were 7 cases of occurring recurarization in elderly group and only one case in non-elderly group. A multiple regression model indicates slower spontaneous TOFR recovery speed, impaired renal function and higher serum rocuronium during TOFR recovery are the three most contributing factors for decreasing the late-SGX TOFR recovery speed. 

Conclusions. The elderly group is one of the risk factor of recurarization when administration of inadequate dose of sugammadex. In the high-risk group such as the elderly, proper management using a muscle relaxation monitor and administrating a sufficient dose of sugammadex are more important.

11 / Elderly patients are one of the high-risk groups of recurarization due to insufficient dose of sugammadex