Control of perioperative muscle strength during ambulatory surgery

Purpose of review This review describes strategies to control perioperative muscle strength in patients undergoing ambulatory surgery. Recent findings Although it is impossible to improve muscle relaxation (defined as absence of electrical activity) of intact resting muscle by hypnotics, analgesia is required to prevent pain-evoked muscular contractions during surgery. Regional anesthesia, as well as hypnotics and opioids, promotes intraoperative muscle relaxation. Neuromuscular blocking agents (NMBAs) induce dose-dependent muscle relaxation, but their effects vary widely between individuals, and postoperative residual curarization (PORC) exposes patients to additional risk. Low doses of NMBAs should, therefore, be used, effects be monitored quantitatively by acceleromyography, and residual neuromuscular block be reversed. Acetylcholinesterase inhibitor reversal can cause respiratory side effects, so the lowest efficacious dose should be used: as little as 0.015-0.025 mg kg ^-1 of neostigmine is required at a train-of-four count of four with minimal fade. Sugammadex encapsulates steroidal NMBAs. Sugammadex reversal is a viable approach to rapidly antagonize deep levels of neuromuscular block. Summary Optimal muscle relaxation for ambulatory surgery results from a judicious combination of regional anesthesia, opioids, and low doses of NMBAs. The effects of NMBAs should be monitored quantitatively by acceleromyography and reversed appropriately.