Effects of local anaesthesia on subdermal needle insertion pain and subsequent tests of microvascular function in human

Post-occlusive and local thermal hyperemia are currently used as integrated tests to study microvascular function in microvascular diseases. However, further pathophysiological insight would require its association with microdialysis. The major limitation remains the microinvasive approach as local anaesthesia prior to fiber insertion could lead to confounding effects. The objective of our study was to determine whether EMLA® cream treatment, applied for 20 min, 40 or 60 min, significantly decreases the pain related to intradermal needle insertions, while not decreasing the microvascular response to post-occlusive and thermal hyperemia 2 h after cream removal. EMLA® cream, when applied during 40 min, induces a significant 75% decrease in the pain following intradermal needle insertion, while not modifying skin post-occlusive and thermal hyperemia 2 h after cream removal. Therefore, we recommend its use in such conditions before performing microdialysis coupled with laser Doppler flowmetry in cohort studies aimed at studying microvascular dysfunction in patients with microvascular diseases.