Reflection spectroscopy of analgesized skin

Area of Science:

• Dermatology
• Physiology
• Biomedical Optics

Background:

• Analgesic creams like EMLA are used to reduce skin pain.
• Heat stimuli can affect skin perfusion, but the precise mechanisms are debated.
• Understanding skin blood flow changes is crucial for various dermatological applications.

Purpose of the Study:

• To investigate changes in blood chromophore content in response to heat stimuli in analgesized skin.
• To correlate changes in oxyhemoglobin and deoxyhemoglobin with increased skin perfusion.
• To determine if increased perfusion originates from superficial capillaries or deeper vessels.

Main Methods:

• Reflection spectroscopy was used to measure blood chromophore content.
• Laser Doppler blood flowmetry assessed skin perfusion.
• Eleven subjects received EMLA or placebo, followed by local heating at various time points.
• Responses were defined as exceeding 2 standard deviations of normal variation.

Main Results:

• Increased skin perfusion was associated with elevated absorption, mainly due to oxyhemoglobin.
• The number of positive responses to EMLA treatment increased with longer application times.
• Good agreement was observed between reflection spectroscopy and laser Doppler measurements.

Conclusions:

• Analgesized forearm skin subjected to local heating exhibits elevated perfusion with oxygenated blood.
• The findings support the hypothesis that increased skin blood flow involves dilation of larger, deeper vessels, not capillaries.
• This study provides insights into the physiological effects of topical analgesics on skin vasculature.