Diabetic foot is one of the chronic complications of diabetes mellitus, which was defined by WHO in 1999 as infection, ulcer formation and/or destruction of deep tissues in the lower extremities of diabetic patients due to combined neuropathy and various degrees of peripheral vasculopathy. The prevalence of this disorder is high in Europe and the United States, at approximately 10% of diabetic patients and 2.37% in Japan. Although there is no complete epidemiological data in China, the literature reports that it is about 1% to 2% of diabetic patients. Diabetic foot eventually often leads to lower limb amputation, which increases the disability rate and mortality rate of diabetic patients.
I. Pathogenesis
Diabetic vasculopathy, neuropathy, local mechanical injury and infection are the main mechanisms of diabetic foot formation. Among them, vascular and nerve damage is the pathophysiological basis for the formation of diabetic foot, while local mechanical injury and infection are the causative factors.
Vascular damage in diabetes is divided into macro- and mesangiopathy and microangiopathy, and the pathophysiological mechanisms of these two types of vascular damage are different. Among them, macrovascular lesions cannot be distinguished from non-diabetic lesions causing peripheral arterial thrombo-occlusion, which are commonly seen in type 2 diabetes. Microvascular lesions are specific to diabetes and can be distinguished from non-diabetic conditions, mostly seen in type 1 diabetes.
The reason for this difference is unclear, and it is thought that macro- and mesangiopathy is mainly related to elevated fibrinogen activator inhibitor (PAI) and dyslipidemia due to hyperinsulin or hyperinsulinogenemia caused by insulin resistance, while microangiopathy is mainly due to simultaneous reduction of insulin and C-peptide caused by islet damage, and especially C-peptide reduction is thought to be a factor causing worsening of microvascular complications One of them.
The corresponding diabetic foot is also divided into these two conditions. The one with thrombo-occlusive large and medium vascular lesions is called “vascular foot”, which is mostly characterized by dry gangrene, weakened or absent dorsal foot artery pulsation, reduced blood flow to the foot, and cool skin temperature. In contrast, microvascular lesions are mainly microcirculatory disorders, sensory-motor nerve fiber dysfunction and local edema caused by decline, but the dorsal foot artery pulsation is good, the skin temperature is normal dorsal foot ulcers, infection, etc., known as “neurological foot ulcers”.
Lack of general knowledge of diabetic foot care, sensory disorders caused by diabetic nerve damage, and neuropathic arthropathy (Charcot’s joint) and plantar ulcers caused by motor nerve damage are all important causes of diabetic foot.
Second, classification and grading: the purpose of classification and grading is to treat and judge the prognosis.
Generally, according to the above pathogenesis of diabetic foot is divided into dry gangrene, wet gangrene and mixed gangrene between the two. However, this classification does not reflect the factor of infection. In order to better assess and judge the prognosis, some new diagnostic and classification criteria have been proposed, and the more common one is the University of Texas diabetic foot classification, which is divided into grades 0 to 3 according to the depth of ulcers: grade 0 with only a history of ulcers, grade 1 superficial ulcers, grade 2 deep to the tendons, and grade 3 ulcers deep to the bone tissue affecting the bone and joints.
On this basis, they were also classified according to the presence or absence of infection and ischemia: no infection and ischemia, infection only, ischemia only, and infection and ischemia. The classification is more comprehensive and descriptive.
Third, diagnostic and evaluation means.
1, nerve examination: including the examination of nerve conduction velocity, temperature sensation, pain sensation, vibration sensation. Patients with no sensation in S-W nylon filament (Simmes Weinsteine monofilament) pressure 10g should be classified as protective sensory loss and should be given the necessary prophylactic treatment in time.
2.Circulatory examination.
① Blood pressure index: i.e. ankle blood pressure/brachial blood pressure ratio [ankle-brachial ratio (API)], which can assist in determining the circulatory status of the large middle artery. Normal value: 1.0~1.4. API<0.9: mild ischemia; API<0.7~0.5: moderate ischemia, may be accompanied by claudication; API<0.5~0.3: severe ischemia, may have resting pain; API<0.3: gangrenous ischemia, gangrene may occur at any time.
②Lower limb posture test: elevate the lower limb 45°, generally within 30-60 seconds the skin of the foot is seen to be significantly pale, after the limb drops down and observes the venous filling time >15 seconds, the local foot is seen to gradually become purplish red, indicating that the blood supply to the lower limb is significantly insufficient. The examination should pay attention to have a normal control in order to judge.
③ Color ultrasound of large and medium-sized arteries and veins in the extremities and neck: the blood flow status and intima status can be observed, the vessel wall thickness and diameter should be measured, and the acoustic description of the plaque should be available if there is atherosclerotic plaque. The purpose is to judge the vascular status and blood flow signal, which is limited to large and medium-sized vessels.
④Vascular MRI examination of extremities: The significance is the same as vascular ultrasound, but the vascular images are clearer and easier to measure and describe.
⑤ Selective angiography: The clearest, but it can also aggravate limb ischemia due to vasospasm caused by interventional trauma or stimulation of angiography. Therefore, it is not preferred and is only used as a judgment of amputation plane before amputation surgery.
(6) Microcirculation examination: It can check the microcirculation, microvascular structure, and microvascular peritubular status in the sclera and nail fold, and indirectly determine the status of microcirculation.
(⑦) Laser hemocytometer: It can be used to evaluate the movement status of red blood cells in superficial skin capillaries and to evaluate the presence of neurological and microcirculatory disorders.
(8) The difference between the arteriovenous partial pressure of oxygen between the arteriovenous blood gas analysis of the upper limbs and the arteriovenous blood gas analysis of the feet can reflect the utilization of oxygen in peripheral tissues.
3.Measurement of blood glucose control, lipid level and blood rheology and degradation products of fibrinogen or D-dimer in blood: glycated hemoglobin is more significant than blood glucose measurement in blood glucose control, blood lipid should be checked several times, fibrinogen or D-dimer can help determine the tendency of thrombosis, and PAI can be checked when available.
4. Determination of the risk site of foot ulcers.
①Parameter of metatarsal head: Measure the pressure and contact time of certain parts of the foot bone to calculate the pressure time fraction (PTI), and an increase in the ratio of PTI applied to the metatarsal head and PTI applied to the big toe indicates an increased risk of foot ulcers in the metatarsal head area.
② Plantar pressure determination: The determination of plantar pressure points in a total of five sites can clearly distinguish the common sites of forefoot ulcers, with an accuracy rate of up to 72.7%.
5, assessment of infection: special attention should be paid to potential infections (fungal) caused by skin chafing with intact epidermis, more so for elderly people of advanced age. Bacterial culture of local secretions and drug sensitivity tests can help determine the type of infecting microorganism, usually multiple pathogens. x-ray examination can help determine the extent and depth of infection. If there is a Charcot’s joint combined with purulent secretions, it is more likely that the ulcer and the depth of infection are large.
IV. Treatment strategies and treatment methods meta.
First of all, it should be clear that once the diabetic foot is diagnosed, it means that the vasculopathy and neuropathy of the patient’s lower limbs have progressed to a fairly serious degree and can be said to be close to the end-stage level, even if the blood glucose is strictly controlled again, it will not help and all treatments are expedient. Therefore, the focus should be on early diagnosis and preventive treatment. In addition, the overall complications of the patient should be evaluated before treatment.
1, conventional medical treatment: including blood glucose control, improve the overall nutritional status, lipid and blood pressure control, etc., although these treatments can not help the complete recovery of the lesion, but at least can slow down the rate of progression of the lesion.
2, the selection strategy of targeted treatment methods: accurate evaluation of the type and classification of diabetic foot before treatment is very important, different types and levels of treatment methods and prognosis are very different, and the effectiveness ratio is also different.
(1) Dry gangrene with predominantly large and medium-sized vessels, with relatively rare chance of complicating infection, often occurs with dry gangrene and detachment in the area of the corresponding occluded vessel. In the early stage of ischemia, vascular bypass, endarterectomy, tipped large omentum graft or interventional radiotherapy methods such as percutaneous transluminal angioplasty, endovascular stenting, intravascular thrombus capsule removal, atherosclerotic spinotomy, laser endovascular angioplasty, etc. can be performed by surgical methods.
However, indications and contraindications should be strictly selected. Common complications include local hematoma, vessel wall rupture, arterial coarctation aneurysm or embolization of distal small vessels.
(2) Mixed gangrene and wet gangrene, which is generally considered to be associated with microcirculatory disorders and microangiopathy, and is mostly associated with infection. The above surgical approaches are difficult to address such problems. All that surgery can do is to assist with local debridement and eventual amputation. The treatment here should reflect the basic ideas of medical treatment, namely: improving neurotrophy, strict control of blood sugar, improving microcirculation to relieve tissue hypoxia, active anti-infection, and systemic nutritional support.
Including.
①Improve neurotropism: Micronutrients, 654-2, energy combination, nerve growth factor, prostaglandin E1,, capsaicin, pegylated, low molecular heparin, etc.
② systemic support to ensure caloric supply, pay attention to water-electrolyte balance, pay attention to heart, liver, kidney, lung and other organs for corresponding complications.
③Anti-infection: to combine systemic and local, use drugs according to bacterial culture results, especially attention should be paid to anaerobic bacteria and fungal infections.
④Local oxygen therapy or hyperbaric oxygen therapy: increase local tissue oxygen supply and inhibit the growth of anaerobic bacteria through pathways other than microcirculation.
⑤ Human skin substitute: Dermagraft is the world’s first human skin substitute for the treatment of neuropathic foot ulcers and contains epidermal growth factor, insulin-like growth factor, keratinocyte growth factor, platelet-derived growth factor, vascular endothelial growth factor, alphaand betatransport growth factors, and matrix proteins such as collagen 1, collagen 2, and fibronectin and some other components present in normal skin. It has a significant effect on promoting ulcer healing, has a good economic-benefit ratio, and has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of lower extremity venous ulcers and diabetes mellitus.
Tender Wet is a multi-layer wound pad produced by the German manufacturer Buchmann: it mainly contains a core (central part) made of polypropylene with super absorbent capacity, which can be activated by injecting the dressing with Ringer’s solution before use and the “absorber” with super absorbent capacity can be maintained on the wound surface for 24 hours. It can be maintained on the wound surface for 24 hours and can absorb tissue containing bacterial secretions into the “absorber”.
The main mechanism is that the “absorber” has a higher affinity for proteins than for salts. In this way, the treatment process is actually an exchange of protein exudate and Ringer’s fluid, i.e., microorganisms, debris, and toxins from deep in the wound are continuously sucked out, while the pre-injected Ringer’s fluid is continuously exchanged from the dressing to play the role of washing the wound, nourishing the wound, and promoting granulation tissue production. Zhang Guoying et al [4] had an effective rate of 96% for one month of treatment, and their grading was reasonable, with two conditions, dry gangrene and wet gangrene, subdivided into mild, moderate, and severe.
(7) The commonly used formula for wet gangrene wet dressing: hypertonic saline + antibiotics + potassium chloride + insulin + drugs to improve microcirculation + B vitamins.
3, other treatment: for the treatment of Charcot’s joint, mainly rely on orthopedic appliance braking, decompression, surgical treatment is poor. The purpose of amputation surgery is to avoid more serious sepsis and remedy those who fail other surgical treatments. Indications: Severe diabetic foot, ulceration to the depth of bone tissue may be accompanied by osteomyelitis, severe soft tissue infection, tendency to sepsis, failure of other surgical procedures and failure of conventional medical treatment.
Precautions.
①Preoperative evaluation of the vascular and circulatory status must be carried out carefully, and the amputation plane should be determined through various examinations;
(2) Intraoperative tourniquet should not be used so that the blood supply to the skin and muscles in the amputation plane can be dynamically observed;
Local anesthesia is not suitable, because local anesthesia is not conducive to the observation of local tissue circulation, and the local edema caused by local anesthesia may not be conducive to wound healing after amputation;
④The postoperative wound suture should not be under too much tension, so as not to affect the blood supply and the wound will not heal easily.