Ultrasound-guided ankle block in diabetic foot surgery: Association between glycemic control and block onset

Patients undergoing distal diabetic foot surgery commonly have diabetic peripheral neuropathy and substantial systemic comorbidity.

This study evaluated the association between preoperative glycated hemoglobin (HbA1c) level and ultrasound-guided ankle block onset.

Prospective observational study.

Adults with diabetic peripheral neuropathy undergoing wound debridement or toe amputation were grouped according to HbA1c level (<8.0% or ≥8.0%). The primary outcome was sensory block onset time. Postoperative pain, opioid consumption, and patient satisfaction were also evaluated.

Forty-two patients were analyzed. Sensory block onset was shorter in the HbA1c ≥8.0% group than in the HbA1c <8.0% group (4.9 ± 1.1 versus 7.4 ± 2.8 minutes; mean difference, -2.43 minutes; 95% confidence interval, -3.67 to -1.19; p < 0.001). Among patients who developed a measurable motor block, motor onset was also shorter (13.0 ± 3.4 versus 16.9 ± 3.5 minutes; mean difference, -3.89 minutes; 95% confidence interval, -6.36 to -1.43; p = 0.003). Postoperative pain, opioid consumption, and satisfaction were comparable between groups. Higher HbA1c remained associated with shorter sensory onset after covariate adjustment.

Poor glycemic control was associated with modestly faster ultrasound-guided ankle block onset in patients with diabetic peripheral neuropathy. The clinical importance of this finding and the potential effect of glycemic control on block duration require further investigation.