ABSTRACT
Objective To measure the leakage rate in the process of expansion in vivo and in normal saline and the over-expansion property of the expander.Methods We chose 17 cases that were treated with the skin expansion.We recorded total injected saline volume intentionally in these cases before the second surgery,and recorded the remainder of the volume of saline postoperatively.We injected normal saline into 8 expanders,respectively,exceeding 50％ of the volume-rating;and subsequently put these expanders into plastic bucket filled with saline.30 days after,we measured the remaining volume of the normal saline.We injected 100 ml normal saline into 4 expanders,respectively,of which nominal volume was 100 ml,and then left these expanders in saline and measured the remainder volume of the saline 30 days later.In the second time,we injected 150 ml and repeated the abovementioned process.It was repeated 7 times until the injection volume reached 400 ml.We processed the data and depicted a curve of effective expansion.Results The results showed that the leakage rate reached (29.0+12.5) ％ in vivo.Experiments in vitro confirmed that 85.0％ (8.0/9.4) of the saline leaked through the injection port and 14.8％ (1.4/9.4) leaked through the membrane of the expander.In addition,over-expansion performance index test confirmed that the over-expansion property of an expander was about twice the nominal volume.Conclusions The expander is not completely sealed structure.Normal saline can leak through the injection part and the membrane of the expander.The over-expansion property of an expander is limited.When the volume injected into the expander exceeds a certain value,the effective expansion performance is not increased with it.