Abstract
Foot baths and showering are two widely used methods to cleanse limb ulcers. However, some clinicians warn that foot baths may contribute to the spread of infection at the ulcer site. This study aimed to retrospectively investigate the relationship between cleansing methods and the limb prognoses of 236 patients with chronic limb ulcers. These patients were divided into two groups according to the method used to cleanse their ulcers, foot bath and showering. Limb prognosis, including loss of all toes and major amputation, was retrospectively analysed. The rates of loss of all toes and major amputation were 53·0% and 30% in the foot bath group, and 35·3% and 18·4% in the showering group, respectively. The rates of loss of all toes (adjusted odds ratios = 2·07; P = 0·0066; 95% confidence intervals, 1·22–3·50) and major amputation (adjusted odds ratio = 1·90; P = 0·037; 95% confidence intervals, 1·03–3·50) were significantly higher in the foot bath group than those in the showering group. Our results demonstrate that showering is preferable to foot baths for the cleansing of chronic limb ulcers. Clinicians should be cautious that inappropriate cleansing may cause ulcer infections to spread.
Keywords: Chronic ulcer, Infection, Irrigation, Limb prognosis, Limb salvage
Introduction
Chronic ulcers are a major health care problem. Diabetic foot ulcers caused by neuropathy and/or peripheral arterial disease (PAD) frequently lead to bacterial infection of pedal tissues. The deleterious effect of hyperglycaemia on neutrophils 1 causes immunopathy, and this can influence the severity of infections. Infection often impairs wound healing, leading to prolonged stays in hospital and more instances of major amputation among diabetic patients 2. Therefore, it is important that clinicians are vigilant and ensure that ulcer infections are properly controlled.
In general, wound cleansing is an integral part of the management of ulcers. Wound cleansing loosens and removes surface debris, bacteria, necrotic tissue and wound exudate, and thereby creates the optimal conditions for wound healing 3. Foot bath and irrigation with a shower (showering) are the most common wound cleansing techniques, and they are widely used to cleanse limb ulcers.
Foot bath is a traditional cleansing method 4 in Japan, which induces vasodilation 5, 6, improves vascular endothelial function 7, reduces bacterial colonisation 8 and relieves mental and physical fatigue 9. Moreover, antimicrobial liquids 4, oxygen 10 and carbon dioxide 11 are often added to the water with the aim of disinfecting wounds, improvingmicrocirculation and improving tissue oxygenation. We have previously treated patients with foot baths at our hospital, Saitama Medical University Hospital, in order to elicit such effects.
However, some clinicians warn that foot baths may promote the spread of infection at the ulcer site 12, 13. Infections, especially those of diabetic ulcers, often spread through the foot along tendons and tendon sheaths 14, 15, 16. Foot baths may promote the spread of bacteria and infectious materials along tendons. These concerns appeared plausible and consequently, from April 2009, it was decided to use showering rather than foot baths to cleanse the chronic limb ulcers of patients in our hospital. Since switching cleansing methods, the number of patients with uncontrollable infections and those who generally require major amputation has decreased, and limb salvage rate has improved. Although wound cleansing is a critical part of wound management, a lack of clinical studies means that a standardised wound cleansing method has not been established. Thus, this study aimed to retrospectively investigate the relationship between wound cleansing methods and limb prognosis in patients with chronic limb ulcers.
Material and methods
A case–control trial was designed to study the relationship between cleansing methods and limb prognosis of patients with chronic limb ulcers. The institutional review board of Saitama Medical University Hospital approved access to patient medical records so that they could be retrospectively reviewed. This study involved 236 patients (179 males and 57 females) with chronic limb ulcers together with diabetes mellitus (DM) and/or PAD (DM with PAD: 43·7%, without PAD: 41·9% and PAD only: 14·4%), who had been treated at the hospital's Wound Healing Center between January 2006 and December 2011. The ages of the patients ranged from 32 to 92 years (median, 65·0 years). The patient data are summarised in Table 1. Patients receiving corticosteroids, immunosuppressive agents, radiation therapy or chemotherapy, or those who had malignant tumour tissue at the ulcer site were excluded. The participants were classified into two groups according to the method used to cleanse their ulcers: foot bath (n = 100) and showering (n = 136).
Table 1.
Summary of patient data
| Overall | Foot bath group | Showering group | P value | |
|---|---|---|---|---|
| Systemic parameters | ||||
| Age (year) (median [range]) | 65·5 [32–97] | 66·0 [34–97] | 64·5 [32–90] | 0·86 |
| Male gender (%) [number] | 75·8 [179/236] | 70·0 [70/100] | 80·1 [109/136] | 0·07 |
| Body mass index (kg/m2) (median [range]) | 22·3 [10·8–50·6] | 23·5 [10·8–50·6] | 21·9 [11·9–46·1] | 0·06 |
| Risk factors (%) [number] | ||||
| Diabetes mellitus | 85·6 [202/236] | 86·0 [86/100] | 85·3 [116/136] | 0·88 |
| Chronic renal failure | 44·5 [105/236] | 49·0 [49/100] | 41·1 [56/136] | 0·23 |
| Peripheral artery disease | 58·1 [137/236] | 60·0 [60/100] | 56·6 [77/136] | 0·60 |
| Preoperative laboratory results (median [range]) | ||||
| Haemoglobin (mg/dl) | 9·8 [6·3–14·4] | 9·5 [6·3–14·1] | 10·0 [6·7–14·4] | 0·31 |
| Albumin (g/dl) | 2·9 [1·6–4·4] | 3·0 [1·6–4·3] | 2·9 [1·6–4·4] | 0·09 |
| C‐reactive protein (mg/dl) | 2·99 [0·1–39·4] | 2·58 [0·1–39·4] | 3·16 [0·1–34·8] | 0·50 |
| Limb prognosis (%) [number] | ||||
| Total toe loss | 42·8 [101/236] | 53·0 [53/100] | 35·3 [48/136] | 0·0066a |
| Major amputation | 23·3 [55/236] | 30·0 [30/100] | 18·4 [25/136] | 0·037a |
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a
P < 0·05 (P values compare the foot bath and showering groups).
Surgical treatment of chronic limb ulcers
First, patients who required arterial reconstruction underwent revascularisation. Then, all areas of necrotic and devitalised tissues were surgically removed until bleeding was macroscopically recognised. The wound was covered with dressings or negative pressure therapy was applied to the wound until spontaneous wound closure or surgical wound closure, such as skin grafts or flap reconstruction. Patients who had limb ulcers with progressive necrosis, uncontrollable infection and/or intolerable pain underwent major or minor amputation depending on their severity.
Cleansing methods and wound dressing changes
The frequency at which wound dressings were changed depended on the characteristics of the wound (minimum of three dressing changes per week). Wound care was standardised throughout the study as different types of wounds (e.g. dry, wet and intermediate) were treated with different types of dressings. The dressings of wet and intermediate wounds were changed daily as required by standards of care. For wounds treated with negative pressure therapy, dressings and sponges were changed thrice a week. Wounds were cleansed during each dressing change. In the foot bath group, ulcers were soaked in 0·01% chlorhexidine gluconate solution (Hibitane; Dainippon Sumitomo Pharma, Tokyo, Japan) at 40°C for 15 minutes in a bucket covered with a disposable plastic bag (Figure 1A). In the showering group, ulcers were gently cleansed with soap and then rinsed with tap water at 40°C using a shower (Figure 1B). Patients continued to receive these cleansing treatments and dressing changes until reconstructive surgery or spontaneous wound closure.
Figure 1.
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Assessment of limb prognosis
Limb prognosis, including total toe loss and major amputation, was retrospectively analysed. Total toe loss was defined as the loss of all toes (e.g. transmetatarsal, Chopart, Lisfranc and major amputation). Amputation above the ankle was classified as major amputation. Patient prognosis was judged based on the condition of the patient at the time of discharge. The influence of other factors on patient prognosis was also assessed, including systemic parameters [age, gender and body mass index, which is defined as body weight divided by body height 2], risk factors (DM, chronic renal failure and PAD) and preoperative laboratory results (levels of haemoglobin, serum albumin and C‐reactive protein).
Statistical analysis
Statistical analysis was performed using Microsoft Excel 97‐2003 (Microsoft, Tokyo, Japan) and SPSS statistical software (SPSS, Chicago, IL). Continuous data are expressed as medians and ranges, and were compared using the Mann–Whitney U‐test. Categorical data were compared using the χ2 test. P < 0·05 was considered to be statistically significant. Odds ratios were calculated to measure the effect sizes of the two cleansing methods on limb prognosis.
Results
There were no significant differences between the foot bath and showering groups in any systemic parameters, risk factors or preoperative laboratory results. The rates of total toe loss and major amputation were 53·0% (53/100) and 30·0% (30/100) in the foot bath group, and 35·3% (48/136) and 18·4% (25/136) in the showering group, respectively. The χ2 test showed that the rates of total toe loss (adjusted odds ratios = 2·07; P = 0·0066; 95% confidence intervals, 1·22–3·50) and major amputation (adjusted odds ratio = 1·90; P = 0·037; 95% confidence intervals, 1·03–3·50) were significantly higher in the foot bath group than those in the showering group.
Discussion
The relationship between cleansing methods and limb prognosis in patients with chronic limb ulcers together with DM and/or PAD was retrospectively investigated. The rates of major amputation and total toe loss were significantly higher in patients whose ulcers were cleansed by foot bath than those in patients whose ulcers were cleansed by showering. Uncontrollable infection is one of the major causes of amputation in patients with limb ulcers.
The most important aspect of chronic wound management and infection control is the removal of all devitalised tissues and inflammatory agents. This is commonly achieved by wound irrigation where an abundant amount of fluid is applied to the wound at an appropriate pressure 17. This can be achieved more effectively by showering than by foot baths 15, 16, 17.
We speculate that capillarity is linked to the spread of bacterial infections. Capillarity is associated with surface tension and results in the rise or depression of liquids in capillaries. This phenomenon plays an important role in the movement of body fluids, such as the drainage of constantly produced tear fluid from the eye towards the tear sac 18. This effect can be seen when liquids are drawn up by a narrow tube or into porous materials. The height of a liquid column (h) is calculated by the following equation: h = 2Tcosθ/ρgr, where T is the liquid–air surface tension (force/unit length), θ is the contact angle, ρ is the density of liquid (mass/volume), g is the local gravitational field strength (force/unit mass) and r is the radius of the tube (length) 19. For a water‐filled glass tube with a 0·1 mm diameter in air and at standard laboratory conditions, T = 0·0728 N/m at 20°C, θ = 20°, ρ = 1000 kg/m3 and g = 9·81 m/second2, indicating that the water would rise approximately 30 cm up the tube.
Limb ulcer infections usually spread along the tendons 20. Capillarity is observed in lentic water (soaking) but not in flowing water (showering). Therefore, in the foot bath group, infection may spread through narrow spaces along structures such as tendons, vessels and/or nerves and the sheaths of these structures, because of the uptake of liquid from the wound surface by capillarity (Figure 2). Furthermore, the foot is moved back‐and‐forth during the foot bath. This motion might exacerbate the spread of infection along the exposed tendons by promoting the uptake of contaminated water. Our results demonstrate that showering is preferable to foot baths for the cleansing of chronic limb ulcers.
Figure 2.
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The limitation of this study is that it is not a direct comparison between lentic and flowing water. The effects of adding various solutions to the foot bath water and the cytotoxicity of antimicrobial liquids 21, 22 were not verified. Nevertheless, foot baths and showering are widely used in clinical treatments. Therefore, our results may help to draw the attention of clinicians to wound cleansing methods, an area that has received little focus. Clinicians should be cautious that inappropriate cleansing may cause ulcer infections to spread.
In summary, there is little evidence verifying the relationship between wound cleansing methods and the limb prognosis of patients with chronic ulcers. In this study of 236 patients with chronic limb ulcers, patients in the foot bath group had higher rates of major amputation and total toe loss than those in the showering group. Foot baths might lead to the spread of infections along tendons, and clinicians should avoid using foot baths to cleanse chronic limb ulcers.
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