Qiufeng Wei,1,* Heng Rong,1,* Guangying Zhang,1 Yubo Xie,2 Weixin Dai1 

1Department of Anesthesiology, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Province, 530021, People’s Republic of China; 2Guangxi Key Laboratory of Enhanced Recovery After Surgery for Gastrointestinal Cancer, The First Affiliated Hospital of Guangxi Medical University, Nanning, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Weixin Dai, Department of Anesthesiology, The First affiliated Hospital of Guangxi Medical University, No. 6 of Shuangyong Road, Nanning, 530021, Guangxi Province, People’s Republic of China, Tel +86 13507713016, Email yfy003902@sr.gxmu.edu.cn Yubo Xie, Guangxi Key Laboratory of Enhanced Recovery after Surgery for Gastrointestinal Cancer, The First Affiliated Hospital of Guangxi Medical University, No. 6 of Shuangyong Road, Nanning, 530021, Guangxi Province, People’s Republic of China, Tel +86 0771-5356250, Email yuboxie_gxmu@126.com

Objective: Research has revealed that patients with diabetes and peripheral neuropathy exhibit significantly elevated nerve stimulation thresholds. However, the minimum stimulation thresholds of peripheral nerves in patients with diabetic foot, along with the recovery of nerve function, remain undetermined. The aim of this study is to investigate the minimum stimulation thresholds of the femoral and sciatic nerves, as well as the duration of nerve block, in patients diagnosed with diabetic foot.
Methods: From July 2020 to March 2022, a prospective study was conducted involving patients aged 50– 80 scheduled for distal lower limb surgery. The study included 83 patients with diabetic foot and 48 individuals without diabetes. Prior to surgery, an ultrasound-guided approach combined with nerve stimulation was employed to administer a popliteal sciatic nerve block (20 mL of ropivacaine 5 mg/mL) and a femoral nerve block (20 mL of ropivacaine 5 mg/mL). During the ultrasound-guided femoral and popliteal sciatic nerve blocks, the electric current required to elicit motor activity in both the femoral and popliteal sciatic nerves was assessed.
Results: The study revealed that patients with diabetic foot exhibited significantly higher stimulation thresholds for femoral and sciatic nerve blocks, as well as a substantially longer duration of femoral and sciatic sensory and motor blocks (P < 0.01). Additionally, nerve injury was observed in 4 patients (4.8%) within the diabetes mellitus (DM) group.
Conclusion: Patients with diabetic foot exhibit higher minimum stimulus thresholds for the femoral and sciatic nerves and experience delayed recovery from ropivacaine block.

Keywords: diabetic foot, nerve damage, nerve blocks, minimal stimulation threshold, ultrasound