Sugammadex as Rescue Therapy

Neuromuscular blocking (NMB) agents are commonly used in the practice of anesthesiology for skeletal muscle relaxation to facilitate tracheal intubation, and may require reversal in order to prevent residual NMB. This was historically done using an anticholinesterase such as neostigmine, which has many adverse effects and may not effectively reverse a deep NMB. However, the introduction of sugammadex was instrumental in allowing the rapid return of neuromuscular function. The FDA has only approved three doses of sugammadex (2 mg/kg, 4 mg/kg and 16 mg/kg) depending on the train of four (TOF) count, which is a qualitative measure of the depth of NMB and ranges from 0 to 4 twitches. Conversely, the TOF ratio is a quantitative measure, is calculated using the ratio of the amplitude of the fourth twitch to the first twitch, and ranges from 0 to 1. A TOF ratio of 0.9 is generally accepted as the minimum threshold to safely extubate a patient, but this information is not always readily accessible as many anesthesia providers do not have a quantitative NMB monitor.

In 2020, Carvalho et al. conducted a meta-analysis of 53 studies (12,664 adult patients) where the pooled residual NMB incidence ranged from 0.115 when quantitative neuromuscular monitoring was used to 0.331 where no neuromuscular monitoring was used. Ravel et al. conducted a meta-analysis of 20 randomized controlled trials (1,923 adult patients), where residual NMB was found in 2.8% of patients who received sugammadex compared to 39% of those who received neostigmine 15 minutes post administration. Concerningly, 60 minutes after administration, 2.1% of the sugammadex group versus 19% of the neostigmine group still had NMB. When expanded to observational studies (58 studies with 25,277 adult patients), the incidence of residual NMB ranged from 0% to 90.5% (median 30%), which was significantly lower (0% to 16%) in the sugammadex group compared to 3.5% to 90.5% in the neostigmine group and 15% to 89% in the spontaneous recovery group.

This project is a double-blind randomized placebo-controlled dose-response trial that aims to determine the time taken to achieve adequate reversal comparing five doses of sugammadex as rescue therapy following inadequate reversal with neostigmine. The study team will recruit patients aged 18 years and above from the main operating room and outpatient surgery center at Grady Memorial Hospital who are undergoing elective surgery under general anesthesia, who has received NMB, received neostigmine for NMB reversal, and achieved a TOF count ≥ 3 twitches but not a TOF ratio of 0.9 fifteen minutes after neostigmine was given. Those with a TOF count < 3 twitches will drop out of the study as there are already specified doses of sugammadex for that level of NMB.

These patients will then be randomized to six groups: 2 mg/kg (the lowest dose approved by the FDA), 1 mg/kg, 0.5 mg/kg, 0.25 mg/kg, 0.125 mg/kg of sugammadex, and placebo. The time taken to reach a TOF ratio of 0.9 thereafter would be measured and compared for statistically significant differences.