The role of continuous popliteal sciatic block in a patient with acute on chronic limb-threatening ischemia: a case report

Abstract

Treating ischemic pain (IP) is challenging because of complex mechanisms involved in its pathogenesis. We report a case of pain management in a patient with acute on chronic limb-threatening ischemia (CLTI) treated with continuous popliteal sciatic block (CPSB). Microcirculation was measured using Near-Infrared Spectroscopy (NIRS). The patient was a 44-year-old male with acute exacerbation of CLTI of left leg. Excruciating pain was described as being stabbed in the left toe with burning sensation radiating to ankle (VAS score 9-10), 3 to 4 times a day with duration of 30 to 60 min each episode. CT Angiography showed wide arterial occlusions and thrombi in veins of left lower limb. ABI was 0,71. He was on heparin so we decided to do CPSB with patient controlled regional analgesia (PCRA) pump of ropivacaine 0.375%. Before catheter insertion, NIRS was measured on dorsum pedis. SrO₂ increased from 24 to 32% within 30 min after initial bolus. Episodes of severe pain still felt with only little relief when pressing PCRA pump. Daily chart showed increasing ropivacaine utilization with discrepancy between attempted and given dose. SrO₂ fluctuated between 25 to 32%. On the third day evaluation, we switched to multimodal analgesia. However, pain attacks increased in frequency, intensity and duration. Ischemic area in foot expanded rapidly. High dose methyl prednisolone was initiated. Amputation was suggested but refused by the patient.

Peripheral nerve block does not completely block ischemic pain, despite adequate motor block. However, it may be beneficial in cases of CLTI by maintaining blood flow, thus inhibiting the progression of ischemia. In this patient, it is evident that upon cessation of CPSB, the condition of the leg deteriorated rapidly.

Keywords: Chronic limb-threatening ischemia, Continuous popliteal sciatic block, Ischemic Pain

Citation: Tantri AR, Lawrence. The role of continuous popliteal sciatic block in a patient with acute on chronic limb-threatening ischemia: a case report. Anaesth. pain intensive care 2024;28(3):585−587; DOI: 10.35975/apic.v28i3.2454

Received: March 23, 2024; Reviewed: April 27, 2024; Accepted: April 27, 2024