This prospective observational study aimed to examine the pharmacokinetics of ropivacaine in patients with chronic kidney disease after sciatic nerve block.

Sciatic nerve block for foot and ankle surgery will be performed using ropivacaine under ultrasound-guidance, and arterial blood test will be taken for total plasma ropivacaine concentration at 2.5, 5, 15, 30, 60 minutes and 2, 6, 24 hours after sciatic nerve block.

Inclusion Criteria:

• Patients scheduled for foot and ankle surgery
• Patients with chronic kidney disease (glomerular filtration rate < 60 ml/min/1.73m2) (changed from 30 ml/min/1.73m2 to facilitate patient recruitment)
• Patients who are thought to be clinically helpful to receive sciatic nerve block rather than general anesthesia because of comorbidities such as cardiopulmonary dysfunction and cerebral dysfunction

Exclusion Criteria:

• Patients who need to renal replacement therapy, such as hemodialysis
• Patients with liver disease (aspartate transaminase OR alanine transaminase > 80 IU/L)
• Patients with allergic disease
• Patients with previous history of drug allery
• Patients with chronic pain persisting 3 months

Patients scheduled for foot and ankle surgery under sciatic nerve block and who had chronic kidney disease