Postoperative Delirium After Total Knee Arthroplasty Under Regional Anesthesia

Postoperative Delirium After Total Knee Arthroplasty Under Regional Anesthesia: a Comparison Between Intraoperative Sedation With Fentanyl, Fentanyl-dexmedetomidine and Fentanyl-propofol

Postoperative delirium after total knee replacement surgery has been related to significant morbidity and mortality among high risk patients. Anesthetic care might play a role in the development of postoperative delirium.

The purpose of this study is to compare the incidence of postoperative delirium between different intraoperative sedation regimen. Delirium assessment using standardized screening tools will be done every 8 hours after surgery.

• In this randomized controlled trial, the investigator will compare the incidence of postoperative delirium after total knee arthroplasty between 3 intraoperative sedation regimens including (1) propofol-fentanyl (2) dexmedetomidine -fentanyl (3) fentanyl alone
• Anesthesia techniques include spinal anesthesia and adductor canal block for postoperative analgesia. Sedation will be provide per group assignment.
• After performance of regional anesthesia, sedation protocols will be used as followed: (1) target-controlled infusion of Propofol to achieve MOAA/S of 3-4 (2) incremental titration of Dexmedetomidine to achieve MOAA/S of 3-4 (3) supplemental fentanyl for anxiolysis.
• Delirium will be screened by trained physicians, registered nurses every 8 hours postoperatively with validated Thai-version CAM-ICU (Confusion Assessment Method-Intensive Care Unit) until patient discharge.
• Serum Interleukins (IL-1, IL-6) Tumor necrosis factor-Alpha and S100B protein from preoperative period will be compared with serum from postoperative period between delirium and non-delirium group. The level of serum biomarkers will be acquired in a 6-hour interval for 5 measurement points during the first postoperative day in the first 12 participants. The subsequent participants will have 1 measurement of serum biomarker during the first postoperative day.
• Genetic profile for ApolipoproteinE genotype will be acquired and compared between delirium and non-delirium group.

Inclusion Criteria:

• Age 65 year or older
• Scheduled for elective primary total knee arthroplasty

Exclusion Criteria:

• Contraindication for spinal anesthesia
• Contraindication for adductor canal block
• Allergy to fentanyl or propofol or dexmedetomidine or bupivacaine
• Cognitive impairment
• NSQIP database risk calculator > 10% overall complication
• Unable to communicate in Thai language
• Significant visual and hearing impairment