Mark Wefers Bettink

Chapter 4 72 The additional effect of local pressure on the tissue with the COMET skin sensor on the deoxygenation kinetics compared to use of only a blood pressure cuff can clearly be seen in Figure 4. In the experiments shown in Figure 4b only an upper arm cuff was pressurized to stop the arterial blood flow. As a result, the mitoPO 2 stabilized at median of 30.0 [24.5 – 36.0] mmHg, greatly contrasting with the low mitoPO 2 3.0 [1.3 – 4.8] mmHg when pressure is also applied on the skin sensor itself. If pressure is applied to the skin sensor the decrease in oxygen tension is faster, 2.1 [1.0 – 2.9] mmHg/s compared to 1.3 [1.2 – 1.4] mmHg/s without pressure. Figure 5 : A) MitoPO 2 baseline measurement, at t=9 (sec) blood pressure cuff inflated to 50 mmHg above systolic blood pressure, t=17 (sec) manual pressure on the COMET skin sensor, at t=84 (sec) release of pressure from skin sensor and cuff. B) O2C microvascular blood flow (black) and tissue oxygenation SpO 2 (red) with the pressure cuff applied and pressure on the skin sensor. C) Cyanide was applied to the skin to block mitochondrial respiration. While pressure was applied no sudden drop was seen, indicating cyanide- induced blockage of mitochondrial respiration. D) Ten minutes after cyanide application a mitochondrial respirational check was done.