Objective:To study on quantity-effect relationship of vacuum-assisted closure(VAC)techniques on free skin graft of limbs.Methods:According to skin wound size

chronic wound bed preparation on 120 patients with skin graft of limbs in surgical ward of emergency department of The Second Affiliated Hospital of Chongqing Medical University from 2014 January to 2015 March was completed. All patients were divided into small-

medium-

large- level(each level having 40 cases of wound).Each area within the group was randomly divided into four treatment groups(each group having 10 cases). All groups were treated with continuous VAC under 10

20

30

40 k Pa negative pressure. The dressings under positive pressure and b-viability of free skin graft changes were measured. Results:Negative pressure strength and skin grafting wound area values for the dressings under positive pressure and viability of free skin graft were significantly different(P<0.001)and the interaction between the two was also significantly different(P<0.001). Statistically significant quantity-effect relationship existed between the dressings under positive pressure and viability of free skin graft

between wound areas

between negative pressure strength and the dressings under positive pressure. Conclusion:The model could explain reasonably well quantityeffect relationship of VAC intervention on free skin graft of limbs

with high goodness-of-fit

robustness

and practicability

able to provide a scientific basis for clinical application.