Affiliations: Department of Dermatology, University of Tübingen, Liebermeisterstr. 25, 72076 Tübingen, Germany | Department of Medical Biometry, University of Tübingen, Westbahnhofstr. 55, 72070 Tübingen, Germany | Department of Dermatology, University of Greifswald, Fleischmannstr. 42‐44, 17487 Greifswald, Germany
Note: [] Corresponding author: Prof. Dr. M. Jünger, Universitäts‐Hautklinik, Fleischmannstr. 42‐44, 17487 Greifswald, Germany. Tel.: +49 3834 866770; Fax: +49 3834 866772; E‐mail: juenger@uni‐greifswald.de.
Abstract: Emla® cream is frequently used in surgical dermatology and in anesthesiology, for instance, during vascular surgery procedures. Because local anesthetics can have a vasoactive effect in addition to producing analgesia, we decided to document the effect of 5% Emla® cream on cutaneous circulation in a prospective, placebo‐controlled study. Skin circulation was monitored continuously under standardized conditions using video capillaroscopy, laser Doppler flowmetry and skin temperature. Recordings were made at the nailfold of the fourth finger (DIV) of the left hand of 12 volunteers with healthy veins over an observation period of 60 minutes under either Emla® occlusive dressing or an occlusive dressing with placebo. Mean capillary red blood cell velocity changed only minimally under the Emla® occlusive dressing, while placebo occlusive dressing led to a reduction of mean capillary red blood cell velocity from 0.21 mm/s to 0.12 mm/s (p<0.01). There was no statistically significant change of arterial capillary diameter under Emla® or placebo occlusive dressing. Skin temperature dropped after 60 minutes of Emla® cream occlusive dressing from an initial 26.7 to 24.0°C (−10.1%; p<0.02). The same duration of placebo caused skin temperature to drop from 27.6 to 23.0°C (−16.7%; p<0.001). Laser Doppler flux (543 nm) rose 13% with Emla® (p=0.9) and dropped 41.9% under placebo occlusive dressing (p<0.03). Emla® cream upregulated nutritive perfusion. No clinically relevant vasoconstrictive effects are expected from an application period of 60 minutes.
Keywords: Local anesthesia, capillaroscopy, laser Doppler flux, lidocaine, prilocaine
