To investigate the relationship between the expression level of matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase inhibitor-1(TIMP-1) and the healing of pressure ulcer in the exudate of stage IV pressure ulcer.

A total of 39 patients (59 wounds) with stage IV pressure ulcers from July 2017 to April 2018 in Hebei General Hospital were selected.The patients were divided into 2 groups according to the difference between receiving and the fourth weekend pressure ulcer scale for healing (PUSH) score. The difference >2 points was a good healing group (n=26) and ≤2 points was a poor healing group(n=13). After evaluation, cleaning and debridement in accordance with the unified method, appropriate therapeutic regimen was selected to change dressings and track for four weeks. Collect the wound exudate at different time points: the time of diagnosis, the first weekend of treatment, the second weekend of treatment, the third weekend of treatment and the fourth weekend of treatment. The changes of MMP-9, TIMP-1 expression level and MMP-9 / TIMP-1 ratio in wound effusion of the two groups were detected by enzyme-linked immuno sorbent assay. Date were compared by t test.

There was no significant difference in MMP-9 expression between the two groups at the time of diagnosis and the first weekend of treatment (t=1.262, 1.944, with P values above 0.05). At the second weekend, the third weekend, the fourth weekend of treatment, the expression level of MMP-9 in the poor healing group was (189.27±90.15) ng/L, (176.95±75.47) ng/L, (149.30±63.08) ng/L, which was significantly higher than that in the good healing group [(114.97±70.06) ng/L, (93.75±55.15) ng/L, (71.62±41.66) ng/L], the difference was statistically significant (t=2.835, 3.921, 4.608, with P values below 0.05). There was no statistically significant difference in TIMP-1 expression between the good healing group and the poor healing group at different time points (t=0.346, 0.292, 0.047, 0.395, 0.999, with P values below 0.05). There was no significant difference in the ratio of MMP-9 /TIMP-1 between the two groups at the time of diagnosis and the first weekend of treatment(t=1.023, 1.134, with P values above 0.05). At the second, third and fourth weekends of treatment, MMP-9 / TIMP-1 ratio in the poor healing group was (38.42±9.25), (33.74±9.58), (29.53±8.04), which was significantly higher than that in the good healing group [(30.04±10.67), (25.35±10.18), (21.54±9.29)], the difference was statistically significant (t=2.411, 2.473, 2.642, with P values below 0.05).

The changes of MMP-9 expression level and MMP-9/TIMP-1 ratio in wound exudate were related to the healing of pressure ulcer, while high level of expression of MMP-9 and MMP-9/TIMP-1 were not conducive to the healing of pressure ulcer.