Application of negative pressure closed drainage in the treatment of venous ulcer of lower limbs

Shi-Meng Yan, Ren-Yan Huang, Guo-Bin Liu

1. Department of Vascular Surgery, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine

Keywords:

A BSTRACT

Venous leg ulcers (VLU) are one of the complications in the late stage of venous insuきciency of lower limbs, and the incidence rate can reach 3% of the total population [1]. Studies have shown that 60% of patients heal within 3-6 months, 33% within 1 year, and 7% of patients have an ulcer that is diきcult to heal for life. However, the probability of relapse within 3-5 months after recovery is as high as 70%[2]. Thus, venous ulcer of lower limbs is a health problem accompanying a lifetime[3]. This disease is most common in elderly patients. It is easy to relapse, diきcult to heal and has a long treatment period. With the progress of the disease, it eventually forms refractory ulcer. Therefore, the treatment of venous ulcer of lower limbs has become an arduous task in clinical work[4]. According to survey statistics, VLU patients account for 1% ～ 2% of the world's total population[5], and the medical and health care costs for treating venous leg ulcers in some western European countries are as high as more than 1 billion US dollars[6], which has brought a heavy burden to both the patient's family and the whole society. Chronic venous disease (CVD) is a chronic debilitating disease that aあects millions of people. CVD patients suあer from venous obstruction, weakened venous wall and valve function or impaired calf muscle pump function, resulting in increased venous pressure and decreased venous reflux in lower limbs. The symptoms of CVD begin to be mild, accompanied by telangiectasia or varicose veins. However, they can progress to more serious symptoms, such as edema, changes in skin color, and eventually develop into VLU[7]. VLU mainly occurs in patients over 50 years old. However, not all CVD patients develop VLU[8]. VSD is a commonly used treatment method in clinic, which can eあectively avoid infection, reduce pain and improve the patient's condition [9].

1. Overview of VSD

1.1 Definition

VSD refers to a method of covering and sealing the wound surface with a special material, which can continuously drain the wound surface under the action of continuous negative pressure and promote wound healing[10]. On the one hand, negative pressure suction can remove wound exudate in time and reduce infection rate； On the other hand, sealing is a prerequisite for continuous negative pressure, which also insulates the wound from the outside world.

1.2 Origin and development

VSD was first applied in the former Soviet Union in the 1970s[11]. In 1993, Germany doctor ULM Fleischman[12] and others applied negative pressure technology to treat soft tissue wound infection for the first time, end in good results. The following year, Professor Qiu Huade and others[13] brought the technology into China and named it vacuum sealing drainage, VSD), which began to be widely used in infectious wounds and common surgical operations, creating a new pattern of wound treatment.

1.3 Material composition

Vacuum sealing drainage materials mainly include sterile dressing, semitransparent membrane and drainage tube, wherein the tee joint on the drainage tube can be connected with each drainage tube at will to achieve the eあect of preventing backflow. Aseptic dressing is made of transparent polyurethane film, which has the eあect of "molecular valve" and can realize one-way ventilation and oxygen permeability to prevent water and bacteria invasion [14-16].

2. Principle of vacuum sealing drainage in treating venous ulcer of lower limbs

VSD device can eあectively ensure continuous negative pressure, promote local blood circulation metabolism of patients, accelerate the speed of removing necrosis factor, and thus promote tissue regeneration[17]. The medical permeable adhesive biomembrane has strong permeability, can fully block and seal the invasion of external bacteria, and at the same time can ensure the water leakage from normal skin surface and ulcer surface tissue, which is beneficial to the effective recovery of nerve endings[18]. For chronic ulcer complicated with infection and wound surface with more exudate, it can play a therapeutic role in temporarily increasing blood flow, strengthening granulation tissue formation and improving bacterial clearance rate[19], and its relevant mechanisms can be summarized as follows.

2.1 Reduce tissue edema on ulcer surface

Among the factors that make the wound of venous ulcer of lower limbs diきcult to heal, the more common one is wound tissue edema. On the one hand, if edema occurs in the wound surface, it will compress the blood vessels and lymphatic system in the deep part of ulcer tissue, thus increasing the tension of the wound surface, eventually leading to a significant increase in the spacing between cells and tissues, making it diきcult to complete the exchange of substances between cells. On the other hand, microvascular afterload of ulcer surface also increases with wound tissue edema, blood supply of skin valve decreases, perfusion diきculty between ulcer tissues increases, substance exchange between cells cannot proceed normally, ischemia and hypoxia of wound surface further intensify, resulting in accumulation of a large amount of harmful substances. VSD can eあectively drain wound exudate and necrotic substances, reduce tissue edema, increase blood supply, reduce microvascular afterload, etc. Through reducing accumulation around wound surface, it can reduce inflammatory factor concentration, relieve tissue edema, and reduce capillary permeability[20]. Bassetto and other researchers[21]concluded by histological evaluation method that edema in patients with venous ulcer of lower limbs can be significantly reduced after VSD treatment.

2.2 Regulate inflammatory reaction and control infection

Ulcer infection is an important factor leading to delayed healing or non-healing of VLU. The massive growth and reproduction of bacteria consume oxygen and nutrients of tissue cells, hindering the normal tissue growth. Secondly, pathogen infection can produce a large amount of toxins in the body. The combined action of endotoxin and exotoxin on related cells will produce a large number of inflammatory mediators, which will lead to the aggravation of ischemia and hypoxia in wound surface[22]. The negative pressure sealing drainage device isolates the ulcer surface from the air, effectively blocking the invasion path of foreign bacteria[23]. Li Shanyou, and other [24] found that the number of bacteria in ulcer surface of negative pressure treatment group was much lower than that of conventional dressing change group. VSD can reduce the levels of inflammatory cytokines such as IL-6 and TNF-α, increase neutrophil infiltration and IL-1β expression, thus regulating inflammatory response and promoting wound healing[25]. Wiegand and other[26] Studies show that oxygen content can be increased in acidic environment, and the number of bacteria in ulcer surface with PH=5 is reduced by 10% compared with PH=7, which is more conducive to wound healing.

2.3 Promote blood circulation, accelerate granulation growth and wound healing

Poor blood supply is an important factor leading to prolonged ulcer surface, and adequate blood circulation is an essential condition for granulation growth[27]. The application of VSD equipment provides good conditions for the growth of fresh granulation: ① Provide a moist environment for the ulcer surface to prevent the dry dehydration and necrosis of the epidermis and deep tissues of the wound surface. (2) Strengthen the interaction between naturally occurring cytokines on the ulcer surface, target cells and growth factors, and then achieve the eあects of wound contraction and reepithelialization. ③ Promoting the regeneration of blood vessels and granulation tissue. ④ Promoting the degradation of necrotic tissue and fibrin. Zhang Guangzhen and other[28,29] Experiments show that continuous negative pressure drainage can expand local blood vessels, stimulate cell growth and improve local blood supply on ulcer surface, which is more conducive to the growth of new granulation tissue.

3. Research progress of vacuum sealing drainage in treatment of venous ulcer of lower limbs at home and abroad

3.1 Domestic application progress

Chen Kui[30]and other applied negative pressure drainage combined with debridement to treat 40 cases of varicose ulcer of lower limbs. It was found that VSD treatment can promote wound healing, shorten the course of treatment, achieve satisfactory ulcer healing eあect, and the curative eあect is significantly better than that of ordinary dressing change group. Qin Lihong[31]and others also reached a similar conclusion when treating 78 patients with varicose ulcer of lower limbs. Negative pressure technology combined with free skin grafting is more conducive to VLU healing and ulcer surface recovery, and the clinical efficiency and safety are higher. Yuan Yijia[32]and others have respectively studied 50 cases and 50 cases of chronic refractory wound patients. The results show that the clinical application of VSD is simple, safe and eあective, reduces the pain of patients, saves the treatment cost, and has high popularization and application value. Yang Jing[33] and other reports also show that vacuum sealing drainage combined with skin grafting has a definite curative eあect on venous stasis ulcer of lower limbs, which can accelerate the formation of new granulation tissue and promote wound healing.

3.2 Application progress abroad

Chopra Karan[34]and other applied negative pressure therapy to abdominal wall reconstruction wounds and found that the infection in the surgical site was significantly reduced statistically. Compared with standard dressings, negative pressure therapy saved a lot of medical resources and was an economical and effective choice. Semsarzadeh[35] and other used VSD to reduce the incidence of infection at the surgical site. Fixed eあect model was used to evaluate the location, subgroup heterogeneity and eあect size between studies and incisions. Compared with the control group, VSD treatment group has significantly reduced the possibility of infection at the surgical site, which is a potential and eあective method to reduce infection at the surgical site. Renno[36]and other observed the shortterm eあects of VSD treatment on wound skin perfusion patterns after weight loss. Patients in the study group received VSD treatment with continuous negative pressure of -125mmHg for 5 days. The blood oxygen saturation (SO2), hemoglobin content (RHb) and perfusion mode were measured twice during and after the operation respectively by combining laser Doppler spectrophotometer and ICG angiography system. Research shows that VSD treatment has a positive eあect on wound oxygen saturation and tissue perfusion, and is closely related to wound healing process. Therefore, the use of this technique will reduce the risk of wound healing complications.

4. Matters needing attention when VSD is applied to the treatment of venous ulcer of lower limbs

4.1 Keep drainage smooth

Fixing the drainage tube position and keeping the drainage tube unobstructed are the basis of drainage. After installing VSD equipment, carefully check whether the connection head of the drainage tube is loose, whether there is slippage between pipelines, whether the drainage tube is folded, compressed, damaged, etc. The above factors will directly aあect the drainage eあect[37]. If there is a large amount of secretion on the ulcer surface, the drainage tube will be blocked by the drainage substance. At this time, normal saline should be injected retrograde under sterile environment to make the secretion soft and suck out. The drainage tube can also be dredged with the help of guide wire, and the drainage tube should be replaced if necessary.

4.2 Select the appropriate negative pressure

Appropriate negative pressure value is the key to successful drainage. The change of negative pressure directly aあects the growth of granulation tissue. At present, the internationally recommended pressure value is -125mmHg. Morykwas and other[38] Research shows that a pressure value of -125mmHg is more conducive to wound healing and the growth of new granulation tissue. Continuous clinical practice shows that it is the most eあective to select a negative pressure value suitable for the patient's condition, considering comprehensively the location, size, depth of ulcer and tolerance of patients to pain[39].

4.3 Aseptic operation of ulcer surface

Before VSD is performed, the wound surface must be strictly sterilized to avoid reinfection. When infection occurs on the wound surface, necrotic substances or foreign bodies can be seen exuding from the dressing. In more serious cases, grayish green and brown deposits can be found, and even peculiar smell can be heard. At this time, the drainage equipment needs to be replaced again.

4.4 Prevention of ulcer bleeding

The drainage tube is used to drain secretions and necrotic tissues on the ulcer surface. When there is a large amount of blood in the drainage tube, the negative pressure equipment should be removed in time to carefully check the cause of bleeding. In order to reduce excessive bleeding of wound surface and avoid excessive debridement. Stop using anticoagulants after negative pressure suction to reduce the risk of wound bleeding.

4.5 Protect healthy skin around the wound surface

VSD equipment uses medical biological semi-permeable membrane, which is not only conducive to wound healing, but also convenient for wound observation. Under normal circumstances, this material seldom causes skin redness, rash, itching and other discomfort. If the above symptoms occur clinically, the equipment shall be removed in time, the causes shall be checked, and new negative pressure equipment shall be replaced.

4.6 Humanistic care

Venous ulcers of the lower limbs are mostly of long course and prone to recurrent attacks. Ulcers are accompanied by severe pain, and lower limb activities are greatly limited. Factors such as higher treatment costs often lead to a series of negative emotions such as anxiety, inferiority and depression, further aggravating the psychological burden of patients and aあecting the prognosis. Medical staあ should pay more attention to the emotional changes of patients, and preach a positive and optimistic attitude to help improve the disease and improve the prognosis confidence of patients[40].

5. Summary and prospect

Venous ulcer of lower limb is caused by a series of venous diseases of lower limb. Blood reflux of deep vein and superficial vein is blocked for a long time, and lower limb vein is in a state of continuous high-pressure congestion, which leads to increased fibrin and capillary exudation in blood, decreased oxygen content in blood, and aあected cell metabolism, eventually leading to skin ulcer[41].Venous ulcer of lower limbs is a recurrent ulcer that is diきcult to heal. No matter patients, medical workers or even the whole society pay more attention to its treatment. The clinical application of VSD has become an indispensable method for modern treatment of venous ulcer of lower limbs. By reducing wound tissue edema, inhibiting inflammatory reaction, controlling infection, improving vascular microcirculation, promoting the growth of new granulation tissue and wound healing, the wound healing rate of venous ulcer of lower limbs is significantly improved, and the quality of life of patients is improved. Through the review of relevant literatures, compared with the foreign medical environment, VSD is mostly applied at one's own expense in China, which cannot be included in the scope of medical insurance, and patients bear more treatment costs. In addition, when VSD treatment is carried out, the patient's walking activities are limited to a certain extent, and the daily life of the patient is inconvenient. If the equipment can be simplified, the patient can be treated in daily life at home without hospitalization, which will bring great convenience to the patient, not only can the treatment cost be saved, the curative eあect can be improved, but also the recurrence probability can be greatly reduced. It is believed that in the near future, vacuum sealing drainage products with better curative eあect, simpler equipment and lower price will be applied clinically, bringing greater benefits to patients.