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The Role of Technology in Managing Vascular Wounds 15
length of ulcer >10 cm, and previous recurrence are some examples that may indicate the need for surgical intervention. A systematic review of the role of supercial venous surgery in managing venous ulcers concluded that early surgical intervention does not shorten healing times signicantly; though recurrence rates were signicantly lower following surgery (Fowkes et al. 2017). The ESCHAR study from 2004 is a highly cited randomized trial comparing surgery and com­pression with compression alone in chronic venous ulceration. This is, to date, one of only a few studies with sound methodology and an adequate samp le size. Overall 24-week healing rates were similar in the compression and surgery and compres­sion alone groups (65% vs. 65%, p = 0.85), but 12-month ulcer recurrence rates were signicantly reduced in the compression and surgery group (12% vs. 28%, p <
0.0001) (Norgren et al. 2007).
While surgical intervention may not shorten the healing times signicantly when considering patients with venous leg ulcers as a whole group, surgery will often initiate healing in venous ulcers where compression alone has failed. Unfortunately, few studies address this issuewhat are the results of surgical intervention on recalcitrant venous ulcers rather than for venous ulcers in general?
Ideally, a vascular specialist should evaluate most patients with venous ulcers to determine whether surgical correction of venous insufciency is indicated. An evaluation by a specialist is also necessary to determine whether the etiology is a mixed ulcer rather than a venous ulcer alone.
In most cases, an ultrasound doppler examination of the lower extremity veins is sufcient to diagnose the level and extent of venous insufficiency. More advanced techniques like CT- or MRI-based studies may be required in cases with suspected deep insufciency, post-thrombotic syndrome, or anomalies of veins in the pelvic area. In low-resource areas of the world, a venogram using contrast agents and conventional X-ray methods may still be used.
This section will briey discuss the most common surgical procedures for supercial venous insufciency. Surgical procedures for treating deep venous insufciency are more complex and are not as common as supercial vein surgery; we will not present these here.
Vein Stripping
This was the most common procedure worldwide to treat supercial venous insufciency until about the turn of the century. It has largely been abandoned in the past decade due to more advanced, minimally invasive methods. It is now seen as an outdated procedure and should only be used when endovascular procedures are not feasible or not available. Vein stripping may be the only option in low-resource countries, as endovascular procedures are far more costly.
Endovascular Procedures
Today most surgical procedures for supercial venous insufficiency are performed by minimal-invasive, endovascular techniques. Often only local anesthesia is used to do this procedure in an outpatient setting. The incompetent veins are occluded by medicinal glue, sclerotizing foam, using heat from a laser, or radio-frequency
16 B. E. Günther and R. Mani
source. A Cochrane review from 2021 concluded that heat-based treatment had better technical success than chemical-based endovenous treatment (Hopf et al.
2008). The same review concluded that radio wave endovenous treatment had the
least recurrence rates compared to the other methods. However, the authors stated that the condence in the evidence ranged from moderate to very low du e to the poor designs of many studies. A recent development in endovascular procedures is using the microwave catheter. This has similarities to the radio-frequency device with the advantage that the heating coils do not need to be in contact with the vein wall to achieve thermal destruction (Rogers et al. 2011). Another relatively new technique involves transcutaneous high-intensity focused ultrasound (HIFU). By this non-invasive method, an ultrasound beam is precisely directed to the vein level, heating the tissue (Gerhard-Herman et al. 2017).
Surgical Treatment of Incompetent Perforator Veins
An incompetent perforator vein close to a venous leg ulcer should be addressed in slow-healing or non-healing ulcers. Open surgery for treating incompetent perfo­rating veins like the Cockett or Lynton procedures are outdated and should not be used anymore as they are associated with a high risk of surgical site complications. In 1985, endoscopic techniques (SEPSsubfascial endoscopic perforating vein surgery) for occluding perforating veins were introduced (Aboyans et al. 2018). In the past decade, this has mainly been replaced by the minimal invasive transluminal occlusion of perforators (TRLOP) performed in local anesthesia using ultrasound guidance. In this technique, the perforator veins are occluded using radio frequency or laser as a heat source. Treating incompetent perforator veins by this method is also effective for recalcitrant venous ulcers. Some studies showed healing rates of 90% when at least one perforating vein was closed (Jensen et al. 1991). In the same study, no ulcer healed without at least one perforator being closed. The study also highlighted that repeat ablation may be necessary. Post procedure duplex ultrasound revealed that the initial success of the rst ablation was 58%, while repeat ablation was 90% successful.
For smaller perforating veins injecting sclerotizing foam under ultrasound guidance can be an alternative to TRLOP (Armstrong et al. 2011; Parisi et al. 2016).
Surgical Treatment of the Wound Bed
Shaving of the Wound Bed (Debridement)
Besides routine debridement of the wound bed, extensive resection of the inam­matory base in the hypodermis can be done, particularly in large, slow–healing venous ulcers (Parisi et al. 2016; Felipe and Plata-Que 2021; Marco et al. 2020). This technique is called shave therapy (or dermatolipectomy) and is often per­formed using a dermatome. This is the same instrument used for harvesting split-thickness skin grafts (STGS). A dermatome can be adjusted to allow the precise shaving of the wound bed down to a millimeter at each instrument pass.
The Role of Technology in Managing Vascular Wounds 17
Shave therapy with simultaneous split-thickness skin grafting shows promising results in several studies (Parisi et al. 2016; Marco et al. 2020).
Negative Pressure Wound Therapy (NPWT)
While this is not a surgical procedure, it is often combined with split-thickness skin grafting. A Cochrane review from 2015 concluded that there was no RCT evidence on the effectiveness of NPWT as a primary treatment for leg ulcers (Mohammedi et al. 2016). This review, however, looked at leg ulcers in general, not only venous leg ulcers. There is general expert consensus that there is a place for NPWT in treating venous ulcers, especially for extensive and recalcitrant venous ulcers (Eder et al. 2020; Federman et al. 2016; McDermott et al. 1994; Pednekar et al. 2016). The negative pressure provides excellent exudate management and signicantly promotes the development of granulation tissue. Note that NPWT does not enhance epithelialization at the end phase of wound healing. Once the wound bed is suf­ciently granulated, NPWT is discontinued and is left to heal by itself or is covered with a skin graft. NPWT provides adequate wound-bed preparation and facilitates split-thickness graft take (Weaver et al. 2017).
Split-Thickness Skin Grafts (STGS)
When the woun d bed is adequately prepared and well granulated, STGS usually take well in venous ulcers and can shorten the healing time considerably (Mills et al. 2014; Chong et al. 2002; Kechagias et al. 2008) Many authors recommend NPWT to prepare the wound bed before a skin graft. Alternatively, shave therapy can be used before doing an STSG (Parisi et al. 2016; Marco et al. 2020; Taylor et al. 2003).
Ischemic Leg Ulcers
Arterial Ulcers
A meta-analysis reported a conservative estimate of more than 202 million indi­viduals worldwide diagnosed with peripheral arterial disease (PAD), and a 23.5% global increase in PAD prevalence during the new millenniums rst decade (Fowkes et al. 2017). This signicant increase in prevalence and the impact of associated comorbidities demands a responsive approach to ensure the early detection and treatment of PADparticularly since arterial insufciency is identi­ed as the primary causative factor for arterial ulcers (Fowkes et al. 2017).
Although PAD is a chronic disease that can impact both the upper and lower extremities, it is more common in the lower limbs. Our focus in this chapter is primarily below the knee where most arterial ulcerations occur. In recent years the term lower extremity arterial disease (LEAD) is commonly used to distinguish it from disease in the abdominal aorta and iliac arteries. PAD/LEAD often results in tissue ischemia and ulceration and is a signicant barrier to the wound healing process (Hopf et al. 2006; Williams et al. 2005). 4,8 (Norgren et al. 2007; Hopf
18 B. E. Günther and R. Mani
et al. 2008) Patients with LEAD may develop spontaneous ulcerations that fail to heal or that progress to gangrene and/or critical limb ischemia (CLI) (Hopf et al.
2008). CLI is now more accurately being referred to as critical limb-threatening
ischemia (CLTI), and will be referred to as such throughout this chapter.
Arterial insufficiency inhibits the wound healing process as tissues are poorly perfused and the delivery of systemic antimicrobials is compromised as a result of the lack of blood supply to the wound site (Rogers et al. 2011). Therefore, addressing the underlying PAD/ LEAD is essential when caring for patients who present with lower extremity ulcers (Norgren et al. 2007; Hopf et al. 2008).
PAD/LEAD and Smoking
Smoking is a major risk factor for patients with PAD/LEAD, and it contributes to amputation risk, post-operative complications and death (Norgren et al. 2007; Hopf et al. 2008; Gerhard-Herman et al. 2017; Aboyans et al. 2018). The relationship between smoking and PAD has been recognized since 1911, when Erb reported that intermittent claudication (IC) was three times more common among smok ers than among non-smokers (Norgren et al. 2007). PAD is most often diagnosed one decade earlier in smokers than in non-smokers (Norgren et al. 2007). Heavy smoking decreases tissue perfusion by causing peripheral vasoconstriction (Norgren et al. 2007). Smoking a cigarette decreases arterial blood supply by more than 30% in 45 min in specic areas of the body, especially in distal areas (Jensen et al.
1991).
PAD/LEAD and Diabetes Mellitus
Diabetes mellitus (DM) is the second most signicant risk factor for developing LEAD and lower extremity ulcers. PAD frequently co-exists with peripheral neu­ropathy (Norgren et al. 2007; Armstrong et al. 2011). Neuropathy impairs sensory function, increasing the risk of developing a lower extremity ulcer (Parisi et al.
2016; Felipe and Plata-Que 2021). LEAD is more aggressive with DM-due to the
peripheral neuropathy LEAD may go undetected or is masked. Masked or unde­tected LEAD increases the risk for ulceration, infection and limb loss (Parisi et al.
2016). Patients diagnosed with both PAD and DM have been shown to be seven to
15 times more likely to experience major amputation following the development of an ulcer, as compared with those without DM (Marco et al. 2020; Mohammedi et al.
2016).
Critical Limb Threatening Ischemia (CLTI)
PAD/LEAD may progress to CLTI, a condition characterized by chronic ischemic rest pain presenting for >2 weeks, non-healing ulcers and/or gangrene in one or both lower extremities in conjunction with a clear diagnosis of PAD/LEAD (Hopf et al. 2008). The diagnosis of CLTI is based on clinical signs that include loss of hair on the dorsum of the feet and toes; cool, shiny or dry skin; thickening of toenails; devitalized soft tissue with a dry or wet crust; atrophy of the skin; and mummied or dry black toe(s) (Hopf et al. 2008). Another clinical sign, revealed by performing the Buergers test, is when an elevation of the lower extremity results in
The Role of Technology in Managing Vascular Wounds 19
pallor, but when the extremity returns to a lowered position the foot becomes ruborous (often called dependent rubor) (Eder et al. 2020) This rapid return of colour is called reactive hyperemia and is considered a sign of advanced PAD/LEAD.
Pain in advanced PAD/LEAD is usually localized in the toes or the distal foot and rarely in the calf when the patient is supine. Relief will occur upon sitting or standing (Hopf et al. 2008).
Capillary rell is not a reliable indicator of tissue perfusion; (Federman et al.
2016) and the diagnosis of CLTI should be conrmed by other diagnostic vascular
studies (Hopf et al. 2008). Furthermore, persons with CLTI should always be assessed for the level of risk for amputation. A low ankle-brachial pressure index (ABPI < 0.9) is one of the strongest indicators of PAD/LEAD, cardiovascular (CV) risk and associated mortality (McDermott et al. 1994; Pednekar et al. 2016). Fontaine, Rutherford and WIfI are classication systems used by clinicians to grade the level of disease, and consequently the risk of an eventual amputation. In addition to tissue ischemia, the presence of a wound and infection should be considered when determining amputation risk, as presented in the WIfI classica­tion system (Weaver et al. 2017).
Assessment Tools
The Fontaine classication was the rst assessment tool for PAD/LEAD and is still in use today. It is a very simple tool, which is helpful to stage the severity of peripheral ischemic disease in general. However, with concern to ischemic leg ulcers it is too vague as it does not include any tests of the arterial circulation, nor does it address infection. The more recent Wi(Wound, Ischemia and Foot infection) was developed by the Society for Vascular Surgery in 2014, for use during the initial patient assessment, targeting those who present with ischemic rest pain, diabetic foot ulcers, non-healing lower limb wounds and/or gangrene (Weaver et al. 2017; Mills et al. 2014). As opposed to the Fontaine classication, the WIFI score also adds a score for the presence and severity of infection (Mills et al. 2014). Although tissue perfusion is considered to be a primary determinant of patient outcomes, the presence and severity of infection can also increase the risk to the limb in regard to potential amputation (Mills et al. 2014).
Other existing tools are available but require conrmed validation: Physical Examination and Chronic Lower-Extremity Ischemia, Intermittent Claudication Questionnaire (ICQ), San Diego Questionnaire, LEGS score based on TASC, Finnvasc and PAD nomogram (Mills et al. 2014; Chong et al. 2002; Kechagias et al. 2008; Taylor et al. 2003).
Physical Examination
Physical examination of a patient with LEAD can conrm the clinical impression and can help determine the severity and extent of the disease. The asses sment should include a comprehensive examination of the pulses of the lower extremities, along with an inspection of both feet (Gerhard-Herman et al. 2017; Anderson et al.
2013). When a wound is present, the physical examination should focus on the
20 B. E. Günther and R. Mani
evaluation of arterial blood ow to determine the degree of healing potential of the arterial wound site (Norgren et al. 2007; Hopf et al. 2008, 2006).
Simple digital palpation of the main arteries of the foot, particularly the dorsalis pedis and tibialis posterior are still considered a mandatory part of the physical examination, despite other more advanced vascular assessments available (Mills et al. 2014) In some literature we nd references to grading the intensity of the pulse. However, studies have shown signicant inter-observer disagreement with the conclusion that grading pulses is not helpful (Williams et al. 2005). While the absence of a palpable pulse correlates highly with PAD(LEAD, a palpable pulse does not necessarily rule out severe arterial insufciency. This is an important principle to remember because failure to realize this has led to delayed treatment for many patients (Khan et al. 2006).
Diagnostic Studies
Currently, the diagnostic tests used to screen for and conrm PAD/LEAD include: ankle-brachial pressure index (ABPI), toe brachial pressure index (TBPI), duplex ultrasound (DUS), pulse volume recording (PVR), transcutaneous oxygen tension (TcPO
), continuous-wave and leg segmental pressure measurements, computed
2
tomography angiography (CTA), magnetic resonance angiography (MRA) and conventional angiography (Anderson et al. 2013).
Ankle-Brachial Pressure Index (ABPI)
Measuring the ABPI is generally accepted as the main diagnostic test for deter­mining the arterial blood circulation at ankle level. It can be carried out manually using a hand-held doppler probe or with automated multiple cuff systems. It has some pitfalls; especially in diabetic patients the results may be unreliable due to intima c alcications that lead to stiff, incompressible arterial walls. (Donohue et al.
2020; Caruana et al. 2005; Weatherley et al. 2006) Previously the ABPI was
calculated using the highest reading from either the dorsalis pedis artery or the tibialis posterior artery. Recent studies, however, show the importance of calcu­lating the ABPI using measures taken from two arteries of each foot (Carabott et al.
2021). The arterial ow in the foot can be divided into six individual regions called
angiosomes (Clemens and Attinger 2010). Accordingly, recent literature provides some evidence that the specic location of a foot ulcer should be taken into con­sideration when deciding which reading from which artery to use for the ABPI measurement (Carabott et al. 2021). If the patient for example has an arterial ulcer on the fourt h toe, the reading from the dorsalis pedis artery is most relevant as this artery supplies most of the blood to that region.
Toe-Brachial Pressure Index (TBPI)
A TBPI measure can be obtained similarly to an ABPI. A small, toe-sized cuff is applied, usually to the great toe, instead of the ankle. In the case of incompressible arteries, often the result of vessel calcication secondary to DM, a TBPI is a more reliable measurement. Arteries in the rst digit are narrower and therefore less
The Role of Technology in Managing Vascular Wounds 21
prone to the calcication that may result in false-positive (falsely elevated) mea­sures when using ABPI (Tehan et al. 2016).
Transcutaneous Oxygen Tension (TcPO
TcPO
measures are obtained using a transcutaneous oximetry device. This is
2
)
2
usually only available at larger vascular centers. The diagnostic test provides information about the supply and delivery of oxygen to the underlying microvas­cular circulatory system by recording the partial pressure of oxygen at the skin surface (Leenstra et al. 2020). A TcPO
value < 40 mmHg suggests hypoxia suf-
2
cient to impair or prevent wound healing (Leenstra et al. 2020).
CTA and MRA
Computed tomographic angiography (CTA), magnetic resonance angiography (MRA) and contrast angiography are indicated to evaluate whether re-vascularization is a possibility. CTA is most commonly used as it is a fast and cost-effective method. Each method has its advantages and disadvantages. Magnetic resonance angiography (MRA) for example does not show calcications as well but gives better visualization of tibial vessels than CTA.
Pain Assessment
Managing pain is a priority for patients with LEAD who are experiencing inter­mittent claudication (IC) (IC), rest pain and/or local wound pain. Therefore, a patients pain experience should be thoroughly assessed as an essential aspect of the plan of care. Pain assessment requires the use of validated measurement tools, such as the FACES, visual analogue and numerical rating scales (Aboyans et al. 2018).
Feet and Footwear Assessment
A thorough assessment of the general condition of the skin and nails of the lower extremities can provide insight into the overall risk level of the patient. Clinicians should look for cool, shiny , dry skin; colour changes (pale, bluish or dark reddish); loss of hair on feet and legs; thickening and brittleness of the toenails; open sores; skin infections or ulcers that will not heal. Deformities of the foot and toes, for example, hammer toes increase the risk of footwear related skin damage. Because of poor tissue perfusion, pressure over boney prominences on the lower extremities signicantly increases the risk of pressure injury and trauma from external forces. In most cases arterial ulcers on the feet are due to inadequate footwear. Clinicians should assess the ability of the patient to purchase and wear appropriate footwear and receive regular foot care.
It is also important to carry out an assessment of the patients ability to perform self-care. Is the patient able to inspect the feet for any changes? Can the patient himself/herself trim toenails?
The presence of peripheral neuropathy, with associated loss of protective sen­sation and/or foot deformity, further increases the risk for pressure injury It is recommended that a person with LEAD be assessed for level of risk for pressure injury (Bonham et al. 2009). The Braden Scale for Predicting Pressure Ulcer Risk is
22 B. E. Günther and R. Mani
one example of a commonly used validated assessment tool for predicting the risk of pressure injury (Kring 2007).
Wound Assessment
As for all aspects of chronic wound care, making the correct diagnosis as to what type of ulcer the patient has is essential to provide the correct treatment. It is usually not difficult to diagnose arterial ulcerations. The diagnosis is made from a com- bination of the clinical vascular investigations and the appearance of the ulcer. When assessing a new patient with arterial ulceration it is important to use a standardized approach (objective structured clinical examination-OSCE) (Abdillah and Nurjannah 2016).
The assessment of an arterial ulcer should include the location, shape, size, depth, tissue type, presence and nature of wound exudate, presence of malodor, peri wound tissue characteristics and wound pain (Bonham et al. 2016). Validated assessment tools should be used to measure and describe the characteristics of the local wound environment and surrounding tissues and to deter mine whether wound healing is taking place. Characteristics of an arterial (ischemic) ulcer include the following: often located on the lower extremities; often over boney prominences or other areas traumatized by external mechanical forces. Arterial ulcers classically have a punched outappearance with well-dened borders. They are often asso­ciated with little or no exudate or peri-wound edema, may be supercial or deep with possible exposure to tendon and/or bone. Commonly there is yellow slough or black eschar, with minimal or no granulation. Arterial ulcerations are commonly associated with moderate to severe pain. Ischemic regions may appear as dry gangrene (dry eschar). Periwound tissues may be pale, shiny, dry, with loss of hair and dystrophic nails.
After completing a thorough assessment of the local wound site, clinicians should determine the risk of complications, including infection and amputation.
Treatment Modalities for PAD/LEAD
The primary treatment of arterial ulcerations should be aimed at re-establishing an adequate arterial circulation. Of all treatment modalities revascularization is the only treatment where there is signicant evidence for its effectiveness. The topical treatment of the ulcer itself (i.e. the choice of dressings is of lesser importance).
Conservative Treatment
In patients without severe ischemic pain or ulcerations a conservative approach can be tried. All types of conservative approaches have the aim to encourage the development of new collateral arteries to compensate for the decrease blood ow. The mainstay of conservative treatment is cessation of use of nicotine products (especially cigarette smoking) and exercises of the lower extremities. Motivating a patient to stop smoking can be difcult and best results are achieved when the help is provided in a structured manner. The 2018 American College of Cardiology decision pathway on tobacco cessation treatment is an excellent resource for clin­icians (Piñeiro et al. 2018).
The Role of Technology in Managing Vascular Wounds 23
It is important to explain to the patient that they will not feel any immediate differences when quitting smoking and that this may diminish their motivation. It usually takes many months before even subtle improvements of PAD/LEAD symptoms may be noticed after quitting smoking. The same principle applies to exercising. The evidence supporting the efcacy of exercise therapy for patients with PAD dates back to 1966 when 6 months of unsupervised intermittent walking exercise was demonstrated to improve time walked to onset of pain and peak walking time (PWT) (Treat-Jacobson et al. 2019). Over the 50 years since that rst report, numerous randomized clinical trials and meta-analyses have added to the body of evidence supporting the efficacy of exercise to improve functioning and quality of life in patients with PAD.
Supervised treadmill exercise therapy using intermittent bouts of walking exercise manage to moderately severe levels of claudication pain is the form of exercise that has been studied most for patients with PAD and claudication. However, more recent evidence shows that modalities other than supervised treadmill exercise, including home-based walking exercise, leg cycling, and per­haps resistance training, can also improve walking performance and health related quality of life (HRQOL) in patients with PAD. Future studies should focus on identifying optimal exercise programs for patients with PAD (Treat-Jacobs on et al.
2019).
Mechanical Stimulation of Arterial Circulation
There are several mechanical therapies to stimulate arterial blood. With the exception of compression bandages and medical grade stockings, mechanical therapies usually involve some sort of compression or suction pump. All these therapy modalities have in common that they need to be used over long periods of time before signicant clinical improvements can be seen. In many cases the patients will not feel any improvements before 12 weeks of treatment or longer. In cases with severe ischemia with imminent threat of gangrene or other complications invasive reperfusion techniques are indicated instead.
The following mechanical stimulation modalities are available:
(i) Compression therapy with compression bandages or medical grade stockings
It is a generally accepted theory that by compressing tissues below the knee, veins become emptied, and the increased arterial-venous pressure gradient enables greater arterial ow. There is some discussion about the safety of compression bandages/stockings in patients with severe PAD/LEAD. If the compression is applied too strongly the arterial blood ow may be impaired, potentially causing gangrene. The international consensus is that compression therapy should not be used below an ankle-brachial index (ABI) of <0.5. Even in patients with an ABI of between 0.5–0.8 compression should only be used by health care personnel with experience in compression therapy.
There is limited evidence to recommend the cautious use of compression therapy to benet the healing of ulcers that have been assessed to have mixed etiology
24 B. E. Günther and R. Mani
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(arterial and venous). In such cases, the presence of lower extremity edema is considered to be a barrier to wound healing (Hopf et al. 2006). When advanced LEAD is suspected, a decision to use compression is contraindicated until safe parameters can be determined for the patient, in collaboration with a vascular specialist. Accurate blood ow measures should be determined through appropriate investigations prior to applying compression. A lower level of compression may be appropriate for patients who have a documented ABPI >0.50–<0.80, but should be avoided for those with ABPI < 0.50 (Stansal et al. 2018; Zaleska et al. 2019). Compression at higher levels may be appropriately used to manage lower limb edema after a successful revascularization procedure has been performed to restore adequate blood ow to the affected extremity (Bonham et al. 2016). In addition, the prescribing of a lower level compression (18–30 mmHg) should be considered after lower extremity bypass surgery to manage edema (Bonham et al. 2016).
(ii) Arterial assisted intermittent pneumatic compression
Intermittent pneumatic compression is a treatment modality where inatable compression cuffs are attached to the extremity, and a mechanical pump inates and deates the cuffs with regular intervals. IPC is commonly used to treat lym­phoedema and severe venous insufciency, but it seems that it also has a benet for arterial circulation (Sultan et al. 2011). Again, the theory is that when the veins are emptied by the ination of the cuffs the increased arterial-venous pressure gradient enables greater arterial ow.
Some intermittent pneumatic devices utilize another approach whereby the intermittent pneumatic compression actually limits the limb venous outow by venous obstruction. In a long therapy period studies have shown an expansion of the perfusion vessels and brought about persistent reactive hyperemia (Zaleska et al.
2019).
(iii) Negative pressure chamber system (FlowOx)
The FlowOxboot is a novel negative pressure chamber system intended for home use to increase arterial blood ow, reduce pain, and improve wound healing for patients with peripheral artery disease and critical limb ischemia The device applies intermittent negative pressures to the lower leg in a closed chamber. In a qualitative study published in 2021 improvements in pain- free walking distances were observed after 12 weeks of use. In a follow -up study of 24 weeks of inter­mittent negative press ure-treatment, both pain-free and maximum walking distance increased (Hoel et al. 2021). Robust evidence incl uding its application to treat arterial ulcers is awaited to make nal conclusions about this device.
Invasive Techniques to Improve Arterial Blood Circulation
In cases of severe ischemic disease, surgical treatment by either endovascular or open technique, should be the primary treatment modality. The primary indications for surgical intervention are severe ischemic pain, signs of gangrene formation or