Effects of internal pressure on blood flow in pig skin
Tissue expanders are inflated until the blanched skin and sluggish capillary refill imply poor perfusion. However, expander pressure and cutaneous blood flow immediately following inflation have not been measured. Thus, the purpose of this study was to identify the pressure in a tissue expander and the blood flow in the overlying skin. Tissue expanders were placed bilaterally using either conventional or minimally invasive techniques under the dorsal skin of eight 20kg pigs. Each expander was inflated in 50 ml increments until the skin appeared blanched with sluggish capillary refill, then 25 ml was evacuated from the expander. The expander pressure was then immediately measured with a manometer and the cutaneous blood flow was measured with a laser Doppler flowmeter. The pressure and blood flow measurements were repeated after three days, before the next inflation. Pressures ranged from 30 to 60 mmHg following expander inflation. There was a significant negative correlation between expander pressure and skin blood flow. However, the slope was much less than the estimated reduction in arterial-venous pressure difference, suggesting an autoregulation of blood flow by the skin. At expander pressures above 80 mmHg, the blood flow decreased rapidly to near zero. After the three day delay, the expander pressure had decreased to 10 mmHg or below in all cases and the blood flow returned toward normal. These data suggest that clinical criteria are safe to use and correlate quite closely with objective measures of perfusion.
Koger, KE; Levin, LS; Klitzman, B
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