OBJECTIVETo evaluate the therapeutic effects of VSD combined with irrigation of oxygen loaded fluid on chronic wounds in diabetic patients.

METHODSTwenty-six diabetic patients hospitalized in Nanfang Hospital of Southern Medical University from September 2010 to June 2013, with chronic ulcers on lower extremities conforming to the inclusive criteria, were divided into group VSD (n = 8), VSD + irrigation control group (VSD + IC, n = 9), VSD + oxygen loaded fluid irrigation group (VSD OLI, n = 9) according to the random number table. After gross observation was conducted and wound secretion was sent for bacterial culturing right after admission, debridement was performed. During the debridement, granulation tissue of wound center was harvested for determination of the activity of lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) with ELISA. After debridement, the patients in group VSD were treated with VSD (negative pressure from -30 to -25 kPa, the same below); the patients in group VSD + IC were treated with VSD combining irrigation of normal saline; the patients in group VSD + OLI were treated with VSD combining normal saline loaded with oxygen (flow of 1 L/min ) irrigation. Drainage tube blockage was recorded and its incidence rate was recorded during the treatment. On post treatment day (PTD) 7, tissue exudates were collected and analyzed with blood gas analyzer for determining the partial pressure of oxygen of the exudate. After the VSD was terminated, bacterial culture was conducted as before, and the bacterial clearance rate was calculated. After the calculation of granulation tissue coverage rate, the granulation tissue in the center of the wound was harvested for histopathological observation with HE staining; morphological characteristics and density of mitochondria were observed with transmission electron microscopy; the activity of LDH and SDH was estimated as before; microvascular density (MVD) was counted after CD31 antibody immunohistochemical staining. Then the second stage operation was performed. The method of second stage operation was recorded and survival rate of grafted skin or flap was calculated. Data were processed with one-way analysis of variance, LSD- t test, rank sum test, or Fisher's exact test.

RESULTS(1) The gross observation showed that before debridement there was only necrotic tissue without granulation tissue in the wounds of patients in all the 3 groups. On PTD 7, granulation tissue was found in the wounds of patients in all the 3 groups. HE staining showed that there were more abundant newborn microvessels and regularly arranged fibroblasts in the wounds of group VSD + OLI; less newborn microvessels and relatively sparsely fibroblasts were observed in the wounds of group VSD + IC. There were only sparse newborn microvessels and fibroblasts in the wounds of group VSD. (2) Rates of drainage tube blockage, granulation tissue coverage, and bacterial clearance showed significant differences among the 3 groups (with F values from 10.98 to 770.24, P values below 0.01). The drainage tube blockage rate was significantly lower in groups VSD + IC and VSD + OLI [(2.0 ± 0.4)% and (1.9 ± 0.6)%] than in group VSD [(16.0 ± 1.3)%, with t values respectively 28.77 and 29.20, P values below 0.01]. (3) On PTD 7, the partial pressure values of oxygen of the exudate in groups VSD + IC, VSD + OLI, and VSD were respectively (111 ± 4), (43 ± 4), and (40 ± 4) mmHg (1 mmHg = 0.133 kPa, F = 882.76, P < 0.01). (4) The density of mitochondria in group VSD + OLI was obviously higher than that of the other 2 groups, full in shape, with complete outer membrane and no vacuolization. (5) During debridement, the activity of LDH and SDH in 3 groups showed no significant differences (with F values respectively 0.08 and 1.03, P values above 0.05). On PTD 7, the activity of LDH was lower in group VSD + OLI [(103 ± 15) U/L] than in group VSD + IC [(136 ± 16) U/L, t = 4.49, P < 0.01], while it was higher in group VSD [(155 ± 16) U/L] than in group VSD + IC (t = 2.47, P < 0.05). The activity of SDH was higher in group VSD + OLI [(2.93 ± 0.27) U/L] than that in group VSD + IC [(1.77 ± 0.22) U/L] or group VSD [(1.61 ± 0.19) U/L, with t values respectively 10.21 and 11.65, P values below 0.01]. (6) On PTD 7, there was more positive expression of CD31 in group VSD + OLI than in the other 2 groups. The MVD of groups VSD, VSD + IC, and VSD + OLI were respectively (109 ± 5), (124 ± 5), (141 ± 6) per 400 times visual field (F = 68.78, P < 0.01). (7) The patients in 3 groups mainly received skin or flap grafting as the second stage operation. The survival rates of skin and flap in group VSD + OLI were higher than those of groups VSD + IC and VSD (with t values from 3.32 to 8.26, P < 0.05 or P < 0.01), and the rates were higher in group VSD + IC than in group VSD (with t values respectively 2.67 and 3.18, P values below 0.05).

CONCLUSIONSVSD + OLI is effective in reducing drainage tube blockage, removing necrotic tissue and bacteria, ameliorating ischemia and hypoxia of wound tissue, providing fresh wound bed for wound healing, and improving skin or flap graft survival rates.