Laser speckle contrast imaging (LSCI) allows real-time, non-invasive, quantitative measurements of regional blood flow. The aim of this prospective observational study was to evaluate the blood flow changes by LSCI after peripheral nerve block and determine whether this novel optical technique can be used as a reliable indicator of successful blocks.

Methods: One hundred adult patients scheduled for elective upper or lower limb surgery with peripheral nerve block will receive LSCI measurements and pinprick sensory tests before the block and at 5-min intervals till 30 min after the block. The sensitivity, specificity of LSCI as a diagnostic method will be determined by receiver operator characteristic analysis.

Clinical Implications: LSCI with quantitative data could be used as an indicator of successful blocks.

Inclusion Criteria:

• informed consent
• American Society of Anesthesiologists physical statusⅠ-Ⅱ
• Undergo elective upper or lower limb surgery with peripheral nerve block

Exclusion Criteria:

• refusal to participate in the study
• peripheral vascular disease
• digit injury or deficiency
• colored or infected fingernails/toenails
• BMI>35
• those who had taken vasodilatory drugs before surgery
• preoperative analgesic medications
• Any contraindications to peripheral nerve block such as coagulation abnormalities, allergy to local anaesthetics, peripheral neuropathy.

One hundred adult patients scheduled for elective upper or lower limb surgery with peripheral nerve block

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