Hemodynamic Assessment with SPY-Indocyanine Green Angiography in Expansion Period: A Study for Expansion Capsule Pressure Optimization

Tissue expansion-related severe complication exists, and the poor blood supply is one of the causes. After decades of negative correlation between capsule pressure and blood flow was verified, the widely recognized expansion capsule pressure is still absent. A prospective randomized controlled trial was performed to explore the optimal expanding capsule pressure. Thirty subjects were randomly divided into 5 groups, received a weekly expanding on 60-, 70-, 80-, 90-, and 100-mm Hg capsule pressure, respectively. All patients achieved 8-week follow-up; hemodynamic assessment by SPY-indocyanine green (ICG) angiography was taken every 2 weeks. Standardized indexes from SPY-ICG angiography were used to assess the blood supply, in which the ratio of ingress rate and the ingress rate of normal skin (IR/NIR) reflects the arterial perfusion level, and the ratio of Engress Rate and IR (ER/IR) indicates the venous reflux level. The expansion-related adverse events during the trial were recorded. The IR/NIR and the ER/IR are both obviously negatively correlated to the capsule pressure of tissue expander (P ≤ 0.05, the ER/IR's correlation coefficient = −0.453; the IR/NIR's correlation coefficient = −0.482). The post-expansion IR/NIR increased significantly after 8 weeks of expansion (P ≤ 0.05) in 90-mm Hg group. And the post-expansion ER/IR was significantly elevated (P ≤ 0.05) in 80 and 90-mmHg groups. There were 2 expansion-related complications reported in 100-mm Hg group, whereas no complication occurred in 4 other lower groups. SPY-ICG angiography is an objective measurement for tissue expansion hemodynamic monitoring. The expanding capsule pressure of 80 to 90 mm Hg is a reasonable upper limit.

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