CUTANEOUS MICRODIALYSIS IN MAN - EFFECTS OF NEEDLE INSERTION TRAUMA AND ANESTHESIA ON SKIN PERFUSION, ERYTHEMA AND SKIN THICKNESS

Cutaneous microdialysis is a method of measuring endogenous and exogen ous compounds in the dermal interstitial fluid. The microdialysis prob e is inserted in the dermis using a guide cannula. The insertion traum a was studied in dorsal forearm skin in a total of 28 human health? vo lunteers. Twenty-four volunteers received local anaesthesia (Xylocain( R) 10 mg/ml) in both forearms and a microdialysis probe mas inserted i n one of the arms. In 12 volunteers the insertion trauma and the effec t of anaesthesia on skin blood flow and erythema were studied by laser Doppler perfusion imaging, Minolta Chromameter CR 200(R) and Dermaspe ctrometer(R). In the other 12 subjects trauma-induced oedema and effec ts on skin thickness were studied by ultrasound imaging. In addition, a microdialysis probe was inserted without prior anaesthesia in 4 volu nteers, and the effects on skin blood flow and erythema mere investiga ted. Significant increases in skin blood flow, erythema and skin thick ness mere found after insertion of the microdialysis probe. Local anae sthesia prior to the insertion reduced the effects of trauma. Probe de pth in dermis did not influence the effects of trauma. At least 90-120 min is required after insertion in order to allow the vascular reacti on to needle trauma to return to the baseline range.