Periodic limb movements during sedation and general anesthesia in elderly patients: a prospective observational study

Dexmedetomidine sedation in elderly patients is associated with cognitive benefits due to its biomimetic non-rapid eye movement (NREM) sleep–like state. However, this state may predispose patients to periodic limb movements (PLMs), which can cause unintended procedural risk during sedation. We aimed to determine the incidence of PLMs during dexmedetomidine-based multimodal sedation for transcatheter aortic valve implantation (TAVI) and explore associations with the need for conversion to general anesthesia. In this prospective observational study, 35 consecutive patients (mean age 81 ± 6 years; 17 female, 18 male) undergoing TAVI over a two-month period from October 2021 to the end of November 2021 were monitored using standard anesthesia monitoring, processed electroencephalography (pEEG) monitoring using Narcotrend 3-lead frontal EEGs (Narcotrend, Hannover, Germany), and bilateral ankle actimetry (SOMNOwatch™ plus). Sedation was administered according to our institutional protocol, beginning with a dexmedetomidine loading dose (0.5 µg kg⁻¹), followed by titration of the infusion between 0.2 and 1.5 µg kg⁻¹ h⁻¹. Additional propofol or fentanyl boluses were administered as clinically indicated by the responsible anesthesiologist. Actimetry, EEG patterns, and intraoperative events were analyzed. PLMs (2–6 movements/min; most commonly 3–5 movements/min) were observed in 20 of 35 patients (57%) and all conversions to general anesthesia (5/5, 100%) occurred in the PLM-positive group, highlighting a potential clinical impact on procedural stability. In the 19 patients with complete EEG datasets, Narcotrend indices during dexmedetomidine-only sedation averaged 96.6 ± 2.6, consistent with an awake–sedate EEG pattern. Following propofol administration, the index decreased to 39.3 ± 20.0, corresponding to a very large effect size (Cohen’s d = 2.85). Five conversions to general anesthesia were necessary in patients with PLMs, because of restlessness, although the severity of PLMs did not predict conversion. No patient had a known history of restless legs syndrome (RLS); prior neurological disease showed no consistent association with PLM occurrence. PLMs are common during dexmedetomidine sedation for TAVI in elderly patients and may need conversion to general anesthesia. While dexmedetomidine offers cognitive benefits, the potential for movement-related procedural risk warrants increased monitoring and consideration during patient selection and anesthetic planning. Further studies comparing sedation-induced and natural sleep PLMs are needed.