Effect of direct cold atmospheric plasma (diCAP) on microcirculation of intact skin in a controlled mechanical environment

Abstract

Objective: The microcirculatory response of intact human skin to exposure with diCAP for different durations with a focus on the effect of implied mechanical pressure during plasma treatment was investigated.

Methods: Local relative hemoglobin, blood flow velocity, tissue oxygen saturation, and blood flow were monitored noninvasively for up to 1 hour in 1-2 mm depth by optical techniques, as well as temperature, pH values, and moisture before and after skin stimulation. The experimental protocol (N = 10) was set up to differentiate between pressure- and plasma-induced effects.

Results: Significant increases in microcirculation were only observed after plasma stimulation but not after pressure stimulus alone. For a period of 1 h after stimulation, local relative hemoglobin was increased by 5.1% after 270 seconds diCAP treatment. Tissue oxygen saturation increased by up to 9.4%, whereas blood flow was doubled (+106%). Skin pH decreased by 0.3 after 180 seconds and 270 seconds diCAP treatment, whereas skin temperature and moisture were not affected.

Conclusions: diCAP treatment of intact skin notably enhances microcirculation for a therapeutically relevant period. This effect is specific to the plasma treatment and not an effect of the applied pressure. Prolonged treatment durations lead to more pronounced effects.

Keywords: blood flow; cold atmospheric plasma; hemoglobin; microcirculation; plasma medicine; skin; tissue oxygen saturation; transcutaneous oxygen pressure; wound healing; wounds.

Figure 1

(A) Scheme of the customized mount for both reproducible plasma application and microcirculation measurements with an optical probe. (B) Photograph of the experimental setup with the optical probe (not visible) installed in the mount

Figure 2

Skin temperature of the dorsal forearms at the beginning of the experimental protocol, immediately after plasma treatment and after completion of the experimental protocol

Figure 3

Skin moisture of the dorsal forearms before and after completion of the experimental protocol

Figure 4

Skin pH value of the dorsal forearm before and after completion of the experimental protocol (*P < .05)

Figure 5

Time‐resolved characteristics of the cutaneous blood flow (N = 10) after stimulation with Pressure and with Pressure + Plasma for different treatment durations (indicated by gray bars). For clarity, SD data are only provided in Figure 9

Figure 6

Local relative hemoglobin in the ROI (1‐2 mm depth) at the beginning of the experimental protocol (Baseline; time average of 10 min), after pressure induction by the diCAP electrode (Pressure; time average of 10 min), and after operating the diCAP electrode at constant power density (Pressure + Plasma; time average of 1 h) (*P < .05)

Figure 7

Blood flow velocity in the ROI (1‐2 mm depth) at the beginning of the experimental protocol (Baseline; time average of 10 min), after pressure induction by the diCAP electrode (Pressure; time average of 10 min), and after operating the diCAP electrode at constant power density (Pressure + Plasma; time average of 1 h)

Figure 8

Tissue oxygen saturation in the ROI (1‐2 mm depth) at the beginning of the experimental protocol (Baseline; time average of 10 min), after pressure induction by the diCAP electrode (Pressure; time average of 10 min), and after operating the diCAP electrode at constant power density (Pressure + Plasma; time average of 1 h) (*P < .05, **P < .01)

Figure 9

Blood flow in the ROI (1‐2 mm depth) at the beginning of the experimental protocol (Baseline; time average of 10 min), after pressure induction by the diCAP electrode (Pressure; time average of 10 min), and after operating the diCAP electrode at constant power density (Pressure + Plasma; time average of 1 h) (**P < .01)