Effective compression therapy
Complex wounds, How to guides, Leg Ulcers, Skin integrity | K Vowden, P Vowden
Venous disease is common and most healthcare professionals will encounter patients who need or are receiving compression therapy, either with hosiery or bandages. Compression is the mainstay of treatment or prevention for venous ulcers and the aim must always be to ensure safe application and effective therapy. This ‘how to’ guide is intended to help practitioners understand the rationale for applying compression therapy and aid them in managing patients with lower limb venous ulceration.
Management of venous leg ulcers
Chronic venous insufficiency affects up to 50% of the adult population (Venous Forum, 2011) and it is estimated that 1% of the UK population will suffer from leg ulceration during their lifetime (Callam, 1992). The majority of these ulcers are caused by vascular disease (venous, arterial and lymphatic), with venous disease accounting for between 60-80% of leg ulceration (Callam, 1992).
Correctly applied compression therapy is now recognised as the mainstay of treatment for both the preventative and therapeutic care of venous disease, with high compression bandaging now established as the treatment of choice for venous leg ulceration (O'Meara et al, 2009). Studies would suggest that healing rates above 50% after 12 weeks of care should be achievable (Vowden et al, 1997; Barwell et al, 2004) and guidelines indicate that patients failing to respond to care within this time frame should be referred for vascular and specialist wound care assessment (Marston and Vowden, 2003).
Understanding venous disease
In a healthy individual, venous pressure at the ankle falls during exercise due to the action of the calf muscles and the presence of functional venous valves that prevent venous reflux. Figure 1 illustrates normal venous physiology and how valvular disease affects venous return. Calf muscle pump failure due to inactivity or paralysis, failure of the venous valves due to varicose veins, or damage to the deep veins secondary to venous thrombosis, trauma or venous obstruction, decrease the efficiency of this system. This results in a higher venous pressure, a condition known as chronic venous hypertension. Chronic venous hypertension has a number of consequences and changes occur in the microcirculation. This is associated with lower limb discomfort, swelling and skin changes and ultimately may lead to venous ulceration. The progression of venous disease is classified using the CEAP grading system (Eklof et al, 2004) (see Table 1).
In a normal limb a balance exists between the pressure in the capillary bed, tissue pressure and oncotic pressure. As venous pressure rises this balance is disturbed. Blood moves more slowly through the capillaries and veins increasing the risk of thrombosis and activation of white blood cells. The raised pressure also leads to increased vessel permeability with the leaking of fluid and protein into the tissues (Partsch, 2003).
Treatment of venous disease is aimed at correcting, as far as possible, the effects of valvular incompetence and reducing the damaging effects of venous hypertension. This is achieved by applying compression therapy in the form of hosiery or bandages and undertaking corrective venous surgery, endo-venous ablation therapy or sclerotherapy where investigations have demonstrated superficial venous reflux (varicose veins) to be present (Venous Forum, 2011). Treating venous disease has been demonstrated to:
- Significantly improve a patient's quality of life
- Relieve lower limb symptoms
- Delay or prevent the long-term complications of chronic venous insufficiency
- Be a cost-effective use of resources.
- Understanding compression
- Compression therapy aims to reverse the effects of venous hypertension by:
- Decreasing the capacity of and pressure within the superficial veins. This aids venous return by increasing the blood flow velocity in the deep veins
- Reducing oedema by decreasing the pressure difference between capillaries and the surrounding tissue and transferring tissue fluid back into the vascular space. This can reduce exudate
- Minimising or reversing skin changes, to aid the healing of venous ulceration.
For compression to work it must be graduated, generating a pressure that is highest at the ankle. This must be sufficient to overcome the pressure in the lower limb veins when the patient is standing and sustained in order to deliver the necessary benefits over time. In addition, it must be tolerable to the patient.
Elastic and inelastic bandage systems
The level of compression produced by any bandage system is established by a series of complex interactions, including the size, shape and the physical structure of the limb, the type of bandage used, the layers incorporated in the bandage system, the overlap of the bandage, and the skill and technique of the bandager (Clark, 2003). Compression may contain elastic or inelastic materials or a combination of both:
- Elastic (also referred to as long-stretch) contains elastomeric fibres that are capable of stretching and returning almost to their original size.
- Inelastic (also referred to as short-stretch) contains few or no elastomeric fibres and have minimal extensibility.
Bandages are classified according to their ability to apply and maintain a safe, predetermined level of compression (Hopkins and Worboys, 2005). When applying a bandage system to a limb the aim is to provide a 'stiff', but shaped container against which muscles in the calf can contract. This generates a high 'working' pressure, which in a graduated system, aids venous return to the heart while maintaining a lower 'resting' pressure during inactivity (Fig 2).
Stiff bandaging may be achieved by using either inelastic bandages or elastic bandages in a multi-layer system such as the 4-layer bandage (Partsch, 2005). Elastic bandages are rarely used in isolation in current practice, as they provide little or no stiffness. For a table showing the classifications for the different compression bandages see Beldon, 2009.
One of the beneficial effects of compression with a high static stiffness index (SSI) (Fig 3) is a rapid initial change in limb size as oedema is reduced. One consequence of this is that the bandage system will need to be re-applied more frequently due to the rapid reduction of oedema. This is particularly relevant when using inelastic materials as, without elastomeric fibres, their effectiveness will decrease and bandage slippage is more likely to occur as these systems fail to accommodate for the change in limb circumference. The importance of SSI in restoring venous function is shown in Figure 4.