The goal of this randomized, double-blind, placebo-controlled, 2×2 factorial trial is to evaluate the effect of intraoperative dexmedetomidine combined with either femoral nerve block (FNB) or adductor canal block (ACB) on postoperative sleep quality in patients aged 18-85 years with ASA I-III undergoing elective knee arthroscopy under general anesthesia.
The main questions it aims to answer are:
1. Does intraoperative dexmedetomidine infusion (0.5 μg/kg/h) improve postoperative sleep quality as measured by the Pittsburgh Sleep Quality Index (PSQI) at 24 h and 48 h after surgery? 2. Is there an interaction between the type of nerve block (FNB vs. ACB) and the use of dexmedetomidine on postoperative sleep quality?
Age 18 to 85 years.
American Society of Anesthesiologists (ASA) physical status I to III.
Body Mass Index (BMI) between 18 and 30 kg/m² and body weight > 50 kg.
Scheduled for elective knee arthroscopy under general anesthesia.
Refusal to participate in the study.
Inability to communicate effectively.
Known allergy or contraindication to any study drug (ropivacaine, dexmedetomidine, propofol, sufentanil, remifentanil, vecuronium, or sevoflurane).
History of knee trauma or knee surgery; diagnosed with immune system disorders (e.g., rheumatoid arthritis, systemic lupus erythematosus); neuromuscular diseases or psychiatric disorders; restless legs syndrome (RLS); periodic limb movement disorder (PLMD).
Factorial
ropivacaine (local infiltration)
Drug0.375% ropivacaine solution, 20 mL, administered as a single-shot peripheral nerve block prior to anesthesia induction.
Dexmedetomidine
Drug0.5 μg/(kg·h) continuous intravenous infusion, initiated after anesthesia induction and discontinued 30 minutes before the end of surgery.
Normal saline placebo
Drug0.9% normal saline solution, administered as a continuous intravenous infusion at a volume rate matching the dexmedetomidine group (0.5 μg/kg/h equivalent), started after induction and stopped 30 minutes before surgery end.
Femoral Nerve Block
Procedure/SurgeryUltrasound-guided femoral nerve block performed at the inguinal region (approximately 2 cm distal to the inguinal ligament) using an in-plane technique. A total of 20 mL of 0.375% ropivacaine is injected 1-2 mm anterior to the femoral nerve.
Adductor canal block
Procedure/SurgeryUltrasound-guided adductor canal block performed via the distal approach at the mid-to-lower third of the medial thigh, targeting the adductor hiatus. A total of 20 mL of 0.375% ropivacaine is injected.
Pittsburgh Sleep Quality Index (PSQI) scores at 24 hours after surgery
Sleep quality at 24 hours after surgery will be assessed using the Pittsburgh Sleep Quality Index. The unit of measure is points on a scale. The Pittsburgh Sleep Quality Index includes 7 component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Each component score ranges from 0 to 3. The global Pittsburgh Sleep Quality Index score is calculated as the sum of the 7 component scores, resulting in a total score ranging from 0 to 21. Higher scores indicate poorer sleep quality.
Pittsburgh Sleep Quality Index (PSQI) scores at 48 hours after surgery
Sleep quality at 48 hours after surgery will be assessed using the Pittsburgh Sleep Quality Index. The unit of measure is points on a scale. The Pittsburgh Sleep Quality Index includes 7 component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Each component score ranges from 0 to 3. The global Pittsburgh Sleep Quality Index score is calculated as the sum of the 7 component scores, resulting in a total score ranging from 0 to 21. Higher scores indicate poorer sleep quality.
Richards-Campbell Sleep Questionnaire (RCSQ) Score at 24 Hours After Surgery
Subjective sleep quality at 24 hours after surgery will be assessed using the Richards-Campbell Sleep Questionnaire. The unit of measure is points on a scale. The questionnaire includes 5 items assessing sleep depth, sleep latency, number of awakenings, time spent awake, and overall sleep quality. Each item is scored from 0 to 100. The final Richards-Campbell Sleep Questionnaire score is calculated as the mean of the 5 item scores. The final score ranges from 0 to 100, with higher scores indicating better sleep quality.
Richards-Campbell Sleep Questionnaire (RCSQ) Score at 48 Hours After Surgery
Subjective sleep quality at 48 hours after surgery will be assessed using the Richards-Campbell Sleep Questionnaire. The unit of measure is points on a scale. The questionnaire includes 5 items assessing sleep depth, sleep latency, number of awakenings, time spent awake, and overall sleep quality. Each item is scored from 0 to 100. The final Richards-Campbell Sleep Questionnaire score is calculated as the mean of the 5 item scores. The final score ranges from 0 to 100, with higher scores indicating better sleep quality.
Resting Pain Numeric Rating Scale Score at 6 Hours After Surgery
Resting pain intensity will be assessed using an 11-point Numeric Rating Scale. The score ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate more severe pain.
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