Comparison of the Analgesic Duration Using Ultrasound-guided Popliteal Sciatic Nerve Block between Diabetics with Neuropathy and Nondiabetics without Neuropathy.

Introduction: In India, the prevalence of diabetes mellitus neuropathy was reported to be as high as 30%. Eight percentage of the diabetic population suffer from foot ulceration and 1.8% have amputations. Popliteal nerve block can be potentially used for foot and ankle surgery with several advantages.

Aim: To compare analgesic duration of an ultrasound (US)-guided popliteal sciatic nerve block between diabetics with neuropathy and nondiabetics without neuropathy.

Patients and methods: Participants were allocated into two groups for popliteal sciatic nerve blocks under US guidance. The primary outcome was the duration to onset of sensory and motor blockade. The secondary outcome was the duration to rescue analgesic and the visual analog scale scoring within 24 h. Hemodynamic outcomes were also monitored along with the above variables.

Results: It was observed that the onset of sensory blockade was faster in participants with diabetes mellitus with peripheral neuropathy as compared to the nondiabetic participants and the duration for onset of motor blockade in dorsiflexion was faster in diabetic patients as compared to the nondiabetic patients (17.48 ± 3.21 min). However, there was no significant changes when comparing the onset of duration to loss of plantar flexion, in diabetics (17.86 ± 2.29 min) versus in nondiabetics (18.51 ± 3.32 min). The duration for rescue analgesics was found to be longer in diabetic participants (13.19 ± 2.14 h) as compared to the nondiabetic participants (11.44 ± 1.86 h). No differences were observed in the hemodynamic changes and the complications associated with local anesthetics in either group.

Conclusion: Diabetic patients with neuropathy have faster onset of blockade when compared to nondiabetic patients without neuropathy which may be due to the degenerative condition of the peripheral nerves in them. The hemodynamic parameters do not play a role in defining the outcome of the block.