In recent years, new types of wound dressings have become increasingly available, giving us a large choice when doing wound management, but due to the wide variety of wound conditions, there is no one dressing that can be applied to all types of wounds. We must therefore make the appropriate dressing selection according to the type of wound and the period in which it is located, and many of these dressings for infected wounds play a useful role in controlling infection. For example, the silver-containing dressings-Kang Shu Ling Gel and Kang Hui Er Foam Patch; Mepore Wet Yum Cream and Mepore Healing Patch are convenient to use.
However, no matter what dressing is chosen, it is important to follow the best treatment method based on practical scientific evidence to promote wound healing. Three landmark advances in the field of modern chronic wound treatment provide a strong scientific theoretical basis for clinical practice.
The first milestone, which occurred in the 1960s and 1970s, was the first discovery by the British scholar Dr. Winter, who studied a porcine trauma model; that wound epithelium formed faster in wounds covered with plastic film than in exposed wounds, as confirmed by Hinman and Maibach in 1963; that human wet wounds heal faster than dry wounds; and that in 1972 In 1972, Roveeti proposed the theory of “wet wound healing”, in which the wet wound environment accelerates the rate of epithelial cell proliferation and migration to promote wound healing. The “wet wound healing” theory led to the development of a series of new dressings since the 1970s, including hydrocolloid dressings, hydrogel dressings, alginate dressings, and artificial skin, which are still widely used in clinical practice.
The second milestone, which appeared in the 1980s, was the recognition that a variety of growth factors exist in the body, including platelet-derived growth factor (PDGF), epidermal growth factor (EGF), keratin growth factor (KGF-2), etc., have strong pro-repair effects on wounds, and they have gradually been widely used in clinical practice with promising results.
The third milestone is the concept of “trauma bed preparation”, which is based on the pathological healing process of chronic wounds: that is, the implementation of a comprehensive assessment of the trauma, including systemic and local assessment of the trauma, focusing on the removal of bacterial, necrotic and cellular loads and the application of dressings, growth factors, enzymes, etc. Growth factors, enzymes, etc. actively create a relatively suitable trauma microenvironment to accelerate healing or prepare the trauma for further surgical treatment in a series of processes. The concept of “trabecular bed preparation” is a new systemic concept that examines the overall process of pathological healing of chronic wounds in general, but also takes into account the conditions required for each period of healing, emphasizing the appearance of the trabecular bed and the state required to achieve healing. Most importantly, the introduction of this concept distinguishes the local management of chronic trauma from acute trauma as a relatively independent yet systematic process.
In fact, if the above three theories can be grasped, flexibly applied and consistently implemented throughout the trauma evolution process, even the most difficult trauma can have the hope of healing. This is also my deepest experience in more than ten years of clinical dressing exchange!
The treatment of chronic wounds has always been a medical problem, especially the treatment of chronic wounds with poor blood supply is even more difficult. How to increase local blood flow is the key point of treatment. In recent years, it has been found that, in addition to closed wounds, supplemented by continuous or intermittent negative pressure suction, can significantly improve the local blood supply, which is conducive to wound healing.
I. Research progress of closed negative pressure suction technology
Wound closure negative pressure suction technique (Vacuum-Sealing Technique, VST) was proposed less than 10 years ago, it is different from the traditional negative pressure drainage method in the surgical clinic, in addition to the use of negative pressure, but also to close the wound, the drainage tube wrapped with sponge does not come into direct contact with the wound tissue. There are two types of suction, intermittent negative pressure suction and continuous negative pressure suction, which have been recommended for the treatment of chronic wounds, total wounds, and wounds with deep cavities or sinus tracts.
(i) Research on the role of closed negative pressure suction technique
1, foreign research reports: in recent years for the role of closed negative pressure suction treatment wound research has made significant progress. 1997 Morykwas et al. first reported the application of laser Doppler flowmetry, the study of negative pressure on the impact of fresh skin defects in pigs wound bed blood flow, found -16KPa under the wound bed blood flow blood flow increased rapidly, its peak reached four times the baseline blood flow, 5-7min after The local blood flow started to decrease and gradually returned to the baseline level. If negative pressure was given intermittently, the blood flow showed a square wave-like curve, i.e., the local blood flow increased when negative pressure was given for suction and recovered to the baseline level soon after the negative pressure was removed. In the same year, Argenta reported the treatment results of 300 cases of various types of wounds and observed that -16KPa (-125mmHg) pressure can eliminate chronic edema faster, increase local blood flow and promote granulation tissue growth.
2.Domestic research progress
(1) When -8KPa was given to fresh wounds, the blood flow in the wound bed increased significantly; when -12KPa was given, the wound blood flow continued at about 2 times the baseline blood flow; when -16KPa was given, the peak blood flow was close to 4 times the baseline blood flow; the local blood flow gradually decreased 10-12min after negative pressure suction and was maintained at 2 times the baseline blood flow after 30min. When intermittent negative pressure suction was applied, the local blood flow showed a square wave-like curve.
(2) When -16KPa was given to the sarcoid trauma, the local blood flow increased and then decreased insignificantly, and it was still maintained at the peak blood flow level (close to 4 times of the baseline blood flow) after 15min.
3. Mechanistic study: Further findings of recent studies on the mechanism of blood flow increase showed that the microcirculatory flow rate in the wound bed was accelerated after -19.2 kPa (-150 mmHg), -14.1 kPa (-110 mmHg) and -0.96 kPa (-75 mmHg) pressure suction, with the most significant acceleration of blood flow rate at -14.1 kPa pressure, and the sustained suction The higher level was maintained for 15 min. Negative pressure suction at -19.2kPa and -14.1kPa can simultaneously cause an increase in microvascular caliber and thus an increase in blood flow. According to the results of the study, some people in China believe that the negative pressure is not less than -16kPa for fresh wounds and -16kPa for granulation wounds can effectively increase the trauma blood flow, and point out that VST technology has the effect of improving local blood flow, eliminating inflammation and rapidly forming granulation tissue, which is expected to solve the problem of poor blood flow in chronic hard-to-heal wounds, so the clinical application is promising.
(II) Mechanism of action of closed negative pressure suction technique
Numerous studies have shown that the mechanism of negative pressure to increase blood flow in the wound bed may be related to the following factors.
1, the wound bed exudate is sucked out, the tissue swelling subsides, and the small vessel afterload is reduced.
2, After negative pressure suction, the pressure difference formed between local and surrounding tissue surface can promote blood perfusion in the wound bed.
3.The mechanical effect of negative pressure helps to overcome the tension contraction of blood vessels themselves, causing microvascular dilation and promoting the opening of capillary beds and arteriovenous traffic branches.
4.The negative pressure effect is local confinement, and the low oxygen environment causes acidic metabolites such as lactic acid, carbon dioxide and histamine to focus, causing microvascular dilation and stimulating the opening of capillary beds.
Second, the application of closed negative pressure suction technology in wound treatment
(A) Application method
1, indications: Although VST technology was first proposed for the treatment of chronic wounds, with the in-depth research on the role of VST and its mechanism, VST technology has been expanded for acute and subacute wounds and wounds with serious infections.
2, clinical application reports: domestic newly reported the application of VST technology for the treatment of skin avulsion with infection in 56 cases to achieve significant results, 5 to 21 days the wound bed clean, fresh granulation, and effective control of infection. One week after negative pressure suction, most of the wounds healed, sinus tracts were closed or the wounds were reduced in size and depth, which created good conditions for skin implantation and shortened the hospital stay.
In the past 3 years, we have applied the modified VST technique to 5 cases of cave-like wounds formed by skin cancer causing extensive tissue necrosis, pressure ulcers with sinus tract formation, and diabetic foot ulcers with abscess formation in Wagner grade III. We designed our own inlet and outlet pipes for the characteristics of a large, deep wound, heavy infection, difficult drainage, strong odor and hyperthermia, etc. The specific method: wrap two 16-gauge catheters with sterile gauze, cut two to three side holes at the head end of the catheter under aseptic operation, one of which is the inlet pipe, connected to an infusion set and 500 ml of saline, and continuously drip saline to flush the wound; the other The other one is the outlet pipe, which is connected to the negative pressure drainage bottle and the central negative pressure suction device.
The wound surface was closed with homemade closed dressing; trimmed plastic film larger than the wound edge 0.5M, plus a piece of dry gauze or absorbent towel, larger than the wound edge 2-3M, surrounded by waterproof film paste firmly, if there is contamination or moisture timely replacement. A set of inlet and outlet pipes were placed at each sinus tract or deep hole to maintain adequate drainage, and the negative pressure was -16～-20kPa. Two cases of skin cancer wounds with malodor and necrotic secretions were given intermittent suction. Results: After 3 days of suction, except for one case of sepsis, the body temperature did not drop, but all other cases had decreased; two cases of skin cancer wounds had good granulation growth after 29 days of the above treatment, the wounds became shallow and reduced in size, the malodor was eliminated, and they were cured after flap transfer. IV. Pressure ulcers and diabetic foot ulcer wounds were closed with pus cavities and sinus tracts in 48 to 51 days after negative pressure suction, with fresh granulation tissue and good growth, creating conditions for surgical treatment.
(B) Advantages and precautions of VST technique
1. VST technique is an effective means of treating refractory wounds. To summarize the advantages of VST technique mainly include.
(1) Favorable control of infection: the wound is closed so that foreign bacteria cannot enter, and negative pressure attraction removes bacteria and substances that are conducive to bacterial growth and reproduction, thus favoring the control of infection.
(2) Good drainage effectiveness: negative pressure increases the drainage effectiveness, the drainage range is wide and uniform, especially for sinus tracts and cavities, the inlet pipe can maintain continuous flushing effectiveness, the outlet pipe ensures the effectiveness of continuous drainage, and the exudate is not easily blocked by sponge or gauze filtration.
(3) Easy to operate, save time, effort and materials, and less pain for patients.
(4) The suction tube can be placed according to the size, depth and lumen characteristics of the wound, and it is also possible to decide whether continuous or intermittent suction should be applied according to the amount of wound secretions and the growth of granulation, so it can be used differently according to the person and ensure the drainage effect.
(5) While ensuring drainage effect and wound cleaning, negative pressure can increase local blood flow and promote granulation growth.
2.Cautions
(1) Correctly connect the negative pressure drainage device to ensure that the negative suction pressure is -16~-20Kpa, and assess the suction condition every 2~4h and adjust it at any time.
(2) Keep the wound closure intact: the dressing should be firmly and tightly attached to the skin, and should be changed immediately once the dressing is found to be loose, wet or contaminated.
(3) Fix the tube properly, keep the drainage flowing smoothly, prevent the tube from dislodging, and replace and reinsert it in time if it is found to be dislodged.
(4) Pay attention to the color, nature and amount of drainage fluid: drainage fluid mixed with a large amount of protein can have a fishy smell, drainage fluid from infected wounds has a putrid smell, and when there is bloody fluid, attention needs to be paid to the presence of fresh bleeding, open the dressing when necessary and check the position of the wound bed and the inlet and outlet pipes.
(5) Each time the dressing is changed, attention needs to be paid to observe the color, secretion and odor of the wound, and timely adjust the negative pressure and the way of attraction, both to fully drain the wound and not to injure the fresh granulation.
(C) Attach a typical case
A male, 75 years old, was bedridden for more than two months due to dementia after cerebral infarction and acute myelitis resulting in paralysis in the plane below chest 12. 10cm×15cm×3cm IV appeared in the sacrococcygeal region. 5cm and 8cm deep sinus tracts were found in the 1 o’clock and 7 o’clock directions, respectively, and more pus flowed from the sinus tracts, which were golden yellow, and the secretions from the wound bed were green and smelly, and the secretions were taken for bacterial culture, respectively. A set of inlet and outlet pipes were placed deep in the wound and in the two sinus tracts, with 3 holes cut at the head end, wrapped with gauze, connected to a negative pressure drainage bottle, negative pressure was adjusted to -20 Kpa, and 500 ml of saline was connected to the top for flushing and negative pressure suction, which was continued every 2 h for 4 h during the day and stopped after 21:00 at night until 8:00 the next morning. After 3 days, the bacterial culture results suggested triple infection of Staphylococcus aureus, Metacoccus aureus and Enterococcus faecalis, and continued flushing and suctioning, the foul odor was reduced, and “granulation islands” appeared scattered in the wound bed. Although the patient died after 1 week due to the aggravation of the original disease, the local wound was treated by VST technology with the following results.
1.Wound secretions were fully drained, avoiding local maceration and irritation.
2.Removal of odor.
3, increased local blood flow, ten granulation appeared “island” growth.
4. Infection was controlled: on the 7th day after drainage, the wound secretion culture was redone, and the results showed that only Enterococcus faecalis was growing, which provided a good environment for the growth of wound granulation.