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Evidence In Practice |
Stephanie B Grim, Jordan M Duffy, and Peter N Theodosopoulos, MSc, are physical therapist students in the Department of Rehabilitation Science, University at Buffalo, The State University of New York, Buffalo, NY
Dale R Fish, PT, PhD, is Associate Professor and Associate Dean, School of Public Health and Health Professions, University at Buffalo, The State University of New York
Patricia J Ohtake, PT, PhD, is Associate Professor, Department of Rehabilitation Science, University at Buffalo, The State University of New York
| The purpose of "Evidence in Practice" is to illustrate the literature search process to obtain evidence that can guide clinical decision making. This article is not a case report. The examination, evaluation, and intervention sections are purposely abbreviated.
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A 68-year-old man was referred to our facility by his family doctor for treatment of a diabetic ulcer on his left heel that had been present for 6 weeks. He had been diagnosed with type 1 diabetes mellitus at 8 years of age. Five years ago, he underwent a transtibial amputation of his right leg because of an infected diabetic ulcer on his right heel. He now uses a transtibial prosthesis and a cane for ambulation. He stated that, since his amputation, he has been diligent with his foot care, which consists of daily visual inspection (for redness, inflammation, and wounds), moisturizing following showering, and callus and nail trimming. Despite his rigorous attention to his foot, he developed an ulcer on his left heel, which has been resistant to standard wound treatment (debridement, dressing changes, and off-loading).1 He was using Lantus* (daily) and Humalog
(with meals) to control his diabetes, Accupril
for his hypertension, and the antibiotics Cipro
and Amoxicillin.||
The patient reported decreased "feeling" in his left lower extremity and was concerned about the prospect of having another amputation. He did not appear to have an active systemic infection: when asked, he said that he had no recent nausea, fever, vomiting, or fatigue. His vital signs were all within normal ranges: body temperature of 37.1°C, heart rate of 72 beats per minute, respiratory rate of 14 breaths per minute, and blood pressure of 128/78 mm Hg. The patient's body mass index was 31 kg/m2, indicating that he was overweight. Examination of the foot and lower leg revealed no problems with skin coloration and skin integrity, a cool foot skin temperature (29°C; normal foot skin temperature is approximately 34°C), and a weak dorsal pedal pulse on palpation. There were no signs of lower-extremity edema. These findings are consistent with reduced perfusion of the lower extremity.
Lower-leg and foot sensation was assessed using Semmes-Weinstein monofilaments. Sensation in the foot was altered as follows: plantar and dorsal foot sensation was absent when the 10-g monofilament was used and present when the 75-g monofilament was used, and lower-leg sensation was absent when the 1-g monofilament was used and present when the 10-g monofilament was used. Patients who can detect the pressure associated with the 10-g monofilament have intact protective sensation, which is the ability to detect forces that often result in tissue injury.2 An inability to perceive the 10-g monofilament indicates a loss of protective sensation and is associated with an increased risk of ulceration.2
The ulcer was located on the lateral plantar surface of the left heel and was circular, measuring 1.5-cm wide and 0.4-cm deep. The base of the wound consisted of granulation tissue, and no deeper structures were exposed. The wound had a slow serosanguineous drainage; however, no other drainage or odor was observed.
The patient's home had one set of stairs with 2 railings, and he required his wife's assistance when ascending the stairs because he was unstable. Otherwise, he was independent in the home. The patient indicated that, outside the home, he felt "off balance" when ambulating on uneven surfaces such as the lawn. His inability to drive limited his community independence.
We believed the heel wound was caused by prolonged loading of the posterior heel that went unnoticed because of the patient's decreased sensation to pain and pressure. Furthermore, we thought that decreased perfusion, as evidenced by his diminished dorsal pedal pulse, contributed to the delayed healing. Because of the patient's previous amputation, we were very concerned about healing this ulcer. Our goal was to provide an effective treatment to heal the wound and prevent the patient from undergoing another amputation. We decided to look for and analyze the evidence related to electrical stimulation (ES) as an adjuvant therapy because our clinical experience suggested that the addition of this modality to the standard wound treatment of debridement, dressing changes, and off-loading may enhance healing rates of diabetic ulcers.
 | Databases used for search: CINAHL, EBM Reviews-Cochrane Central Register of Controlled Trials, EBM Reviews-Cochrane Database of Systematic Reviews, and MEDLINE (1966-December Week 3 2002) |
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CINAHL (www.cinahl.com) is a database that covers the literature related to nursing and the allied health professions, including physical therapy. Because over 1,200 journals are indexed and updated weekly in CINAHL, using this database broadened our search. Furthermore, nurses are often involved in wound treatment; therefore, we felt that there might be some information that is geared toward nursing but that might be relevant to our topic. CINAHL is available through many academic institutions and health care facilities, but it requires a subscription.
OVID lists several reputable evidence-based medicine (EBM) databases, under the heading "EBM Reviews," that include only peer-reviewed articles. One of these databases is the Cochrane Central Register of Controlled Trials. We decided to include this database in our search because it contains over 300,000 bibliographic references to controlled trials published in health care journals, including international sources. These trials are peer-reviewed by contributors to the Cochrane Collaboration to ensure that only reports of randomized controlled trials or controlled clinical trials are included. The Cochrane Central Register of Controlled Trials is part of the Cochrane Library.
The other EBM Reviews database that we searched was the Cochrane Database of Systematic Reviews. This database contains the full text of the regularly updated systematic reviews on the effects of health care prepared by the Cochrane Collaboration. The abstracts of Cochrane Systematic Reviews are available without charge at www.cochrane.org. Individuals or organizations that want to subscribe to the Cochrane Library and obtain the full text of the articles and reviews can find the subscription information at that Web site.
The last database that we included in our search was MEDLINE (1966–December Week 3 2002). MEDLINE is produced by the National Library of Medicine. It contains citations and abstracts from journal articles related to many medical fields, including nursing, physical therapy, and dentistry and covers over 4,600 biomedical journals published in the United States and many other countries. MEDLINE can be accessed for free through PubMed at www.PubMed.gov. Our search was performed on January 7, 2003.
Using the OVID search engine, we clicked on the OVID change database button and then selected the Select more than one database to search tab. We then chose our 4 databases—CINAHL, EBM Reviews–Cochrane Central Register of Controlled Trials, EBM Reviews–Cochrane Database of Systematic Reviews, and MEDLINE (1966–December Week 3 2002)—by clicking the check box next to each database title. We then clicked the Click to Begin Search bar on the left side of the screen. (See Fig. 1.) This brought us to the main search page.
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| Initial keywords: diabet$, ulcer$, electric$ stimulation, heal$ |
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 TopDatabases used for search:... Initial keywords: diabet$,... Limits: human, randomized...Selection of articles for...Clinical decision:References |
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We searched each keyword individually and then combined the 4 searches by typing in 1 and 2 and 3 and 4 in the keyword or phrase box. Each number corresponded to the line numbers for each term in our search history. Our rationale for combining the keywords was to ensure that the articles that we retrieved contained the information necessary to answer our clinical question. This initial search yielded 25 citations. We then decided to limit our search.
| Limits: human, randomized controlled trial |
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TopDatabases used for search:...Initial keywords: diabet$,...Limits: human, randomized...Selection of articles for...Clinical decision:References |
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| Selection of articles for review: |
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TopDatabases used for search:...Initial keywords: diabet$,...Limits: human, randomized...Selection of articles for...Clinical decision:References |
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Peters EJ, Lavery LA, Armstrong DG & Fleischli JG (2001). Electric stimulation as an adjunct to heal diabetic foot ulcers: a randomized clinical trial. Archives of Physical Medicine & Rehabilitation, 82, 6, 721-5, Jun.OBJECTIVE: To evaluate high-voltage, pulse-galvanic electric stimulation as an adjunct to healing diabetic foot ulcers. DESIGN: Randomized, double-blind, placebo-controlled pilot trial. SETTING: University medical center. PATIENTS: Forty patients with diabetic foot ulcers, consecutively sampled. Twenty patients each assigned to treatment and placebo groups. Five patients (2 treated, 3 placebo) withdrew because of severe infection. INTERVENTIONS: Electric stimulation through a microcomputer every night for 8 hours. The placebo group used identical functioning units that delivered no current. Additional wound care consisted of weekly debridements, topical hydrogel, and off-loading with removable cast walkers. Patients were followed for 12 weeks or until healing, whichever occurred first. MAIN OUTCOME MEASURES: Proportion of wounds that healed during the study period. Compliance with use of device (in hr/wk), rate of wound healing, and time until healing. RESULTS: Sixty-five percent of the patients healed in the group treated with stimulation, whereas 35% healed with placebo (p = .058). After stratification by compliance, a significant difference was identified among compliant patients in the treatment group (71% healed), noncompliant patients in the treatment group (50% healed), compliant patients in the placebo group (39% healed), and noncompliant patients in the placebo group (29% healed, linear-by-linear association = 4.32, p = .038). There was no significant difference in compliance between the 2 groups. CONCLUSION: Electric simulation enhances wound healing when used in conjunction with appropriate off-loading and local wound care.
[© 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation. Abstract reprinted with permission from Elsevier Science.]
This randomized, double-blind, placebo-controlled pilot trial demonstrated that ES delivered 8 hours per night resulted in wound healing in 71% of the patients in the treatment group who adhered to the protocol as compared with 39% of the patients in the placebo group who adhered to the protocol. Because our patient was very motivated to heal his wound and because the nighttime treatment would interfere minimally with his daily life, we decided to obtain a copy of the full article from our health science library to examine it further.
Exclusion criteria for the subjects with diabetes in this pilot study included soft tissue or bone infection, malignancy, or any cardiac conductivity disorder. Our patient was similar to the patients in the study, and he fit the criteria for inclusion in this study. The protective sensation threshold and vibratory perception threshold of each subject were tested to determine the presence of a neuropathy. Plantar pressures and initial glycosylated hemoglobin blood levels also were measured. There were no significant differences in demographic characteristics between the treatment and the placebo groups. The subjects in the treatment group wore a Dacron-mesh silver nylon stocking** through which they received nocturnal ES using a Micro-Z device.** Each hour over an 8-hour period, a subsensory 10-minute dosage of 50 V, with 80 twin-peak, monophasic pulses per second (pps), was delivered, followed by 10 minutes of stimulation at 8 pps, and then a 40-minute rest period. The placebo group wore a similar stocking connected to a similar device, but no electrical current was delivered. No adverse effects were noted.
Based on their findings, the authors concluded that high voltage pulsed current, delivered more than 20 hours per week, may enhance wound healing when used in combination with traditional wound care (debridement, NU-GEL collagen wound gel), pressure reduction at the site of ulceration, and daily dressing changes. The authors indicated that, although the Micro-Z ES units were donated by the manufacturer, there was no conflict of interest involved in the conduct of this investigation. The article included the following statement: "No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization(s) with which the author(s) is/are associated."
Although this was a pilot study and the number of subjects was small, we considered the results to be favorable. Electrical stimulation performed as described would be convenient for our patient because the ES would be delivered at night, avoiding disruption of his daily activities.
Baker LL, Chambers R, DeMuth SK, Villar F. Effects of electrical stimulation on wound healing in patients with diabetic ulcers. Diabetes Care. 20(3):405-12, 1997 Mar.OBJECTIVE: To evaluate the effects of two stimulation waveforms on healing rates in patients with diabetes and open ulcers. The hypothesis was that stimulus waveforms with minimal polar characteristics would provide significant healing for this patient sample.
RESEARCH DESIGN AND METHODS: This was a prospective study that enrolled 80 patients with open ulcers. Patients received stimulation with either an asymmetric biphasic (A) or symmetric biphasic (B) square-wave pulse. Amplitudes were set to activate intact peripheral nerves in the skin. Two other groups received either very low levels of stimulation current (MC), or no electrical stimulation (C). When combined these groups were referred to as the control group. Treatment was carried out daily until the wound healed, the patient withdrew from the study, or the physician changed the overall wound management program. Average healing rates were calculated from weekly measures of the wound perimeter and were used for statistical comparison through a one-way analysis of variance. RESULTS: Stimulation with the A protocol significantly increased the healing rate, enhancing healing by nearly 60% over the control rate of healing. Stimulation with the B protocol did not increase the healing rate when compared with control subjects. CONCLUSIONS: Electrical stimulation, given daily with a short pulsed, asymmetric biphasic waveform, was effective for enhancement of healing rates for patients with diabetes and open ulcers.
[© 1997 American Diabetes Association. Abstract reprinted with permission from the American Diabetes Association.]
The abstract suggested that including ES with an asymmetric, biphasic, square-wave pulse with standard wound treatment results in significantly increased healing rates in people with diabetic ulcers compared with standard wound treatment alone. We decided to read the full text of this article in order to more closely review the results of the different ES waveforms used in this study. We obtained a copy of the full-text article from our health sciences library.
All patients in the study had diabetes and were randomized to 1 of 4 groups: group A received stimulation with an asymmetric (n=21), biphasic, square-wave pulse; group B received stimulation with a symmetric, biphasic, square-wave pulse (n=20); group MC received a low level of stimulation current (n=19); and group C received no ES (n=20). The subjects were treated as inpatients (seen 5 days per week by the therapist) or as outpatients (seen weekly in clinic). Patients received ES in addition to their standard wound treatment of dressing changes. Control patients were reassigned to the A or B treatment protocols after 1 month, and their stimulation-treated wounds were counted as new wounds. Thus, a total of 114 wounds were treated, with 17 patients managed for more than one wound, and 5 patients were changed from the control group to a treatment protocol. Patients were followed until: their ulcers healed (45 wounds), the physician decided on another form of treatment (24 wounds), or the patient did not adhere to the protocol (17 wounds) or withdrew from the study (28 wounds). Initial analysis demonstrated no significant difference in mean healing rates among the 4 groups. In addition, as many wounds healed in group A (45%) as in the control group C (48%).
Because there was no difference between the 4 groups and because group MC was designed to be a control group (although the authors stated that the microstimulation that group MC received appeared to have a beneficial effect on wound healing), the authors felt justified in combining groups C and MC into a single control group (CONTROL). They then reanalyzed the data. With this regrouping of patients, a greater healing rate of 10% per week was identified in group A compared with the CONTROL group (27.0±4.0 vs 17.3±2.7% per week); however, healing rates in group B (16.4±6.1% per week) were not different from either group A or the CONTROL group.
Although the patients were unaware of the type of treatment they were receiving, the therapist performing the daily stimulation treatment and weekly wound tracings knew the assignment of each patient, which thus introduced a potential for bias in the data. Although the groups were similar demographically, group A contained patients with wounds of a longer duration (A: 109±24 days; B: 74±21 days; MC: 54±10 days; C: 59±10 days).
The results reported in this article suffer from reduced validity because the patients were not all analyzed in the original groups to which they were assigned, an intention-to-treat analysis was not carried out despite the high dropout rates, the primary person collecting the data was aware of the patient assignment (ie, was not "blinded" to group assignment), and the wounds in one group had been present for a longer duration at the start of the study. In addition, some patients in groups A and B used the ES device longer than the 3 periods of 30 minutes per day. As a result, the duration of stimulation ranged from 0.9 to 4.6 hours per day. This range of treatment length makes it impossible to determine an effective treatment duration. We therefore decided not to use this study when making our clinical decision.
Lundeberg TC, Eriksson SV & Malm M. (1992). Electrical nerve stimulation improves healing of diabetic ulcers. Annals of Plastic Surgery. 29, 4,328-31,Oct.A controlled study of the effects of electrical nerve stimulation (ENS) was performed in conjunction with a standard treatment for healing chronic diabetic ulcers on 64 patients divided randomly into two groups. All patients received standard treatment (paste-impregnated bandage and a self-adhesive elastic bandage) plus placebo ENS or ENS (alternating constant current; frequency, 80 Hz; pulse width, 1 msec; intensity-evoking strong paresthesias) for 20 minutes twice daily for 12 weeks. Comparison of percentages of healed ulcer area and the number of healed ulcers was made after 2, 4, 6, 8, and 12 weeks. There were significant differences (p < 0.05) in both ulcer area and healed ulcers in the ENS group compared with the placebo group after 12 weeks of treatment. The results of the present study support the use of ENS in diabetic ulcers. ENS is easy to apply and can be used by the patient at home following instructions from a medical doctor or a therapist experienced in electrical stimulation and the treatment of ulcers. Additional studies are needed to identify the mechanisms involved in the promotion of ulcer healing with electrical stimulation and to determine the stimulus variables that most efficaciously accelerate tissue repair.
[© 1992 Lippincott Williams & Wilkins. Abstract reprinted with permission from Lippincott Williams & Wilkins.]
According to the abstract, electrical nerve stimulation (ENS) demonstrated beneficial effects. The protocol differed from the study by Peters et al in the magnitude and duration of ES. Most notably, this intervention evoked strong paresthesias compared with the subsensory stimulation used by Peters et al, and it was applied only 40 minutes per day compared with 8 hours per day by Peters et al. In an effort to further our investigation of different protocols, we decided to obtain the full-text article from our health science library.
In this study, the authors compared the effects of standard wound treatment (a paste-impregnated bandage and a self-adhesive elastic bandage) plus ENS with the effects of standard wound treatment and placebo ENS on the healing of diabetic foot ulcers. The placebo group was treated with the same protocol as the treatment group but without electrical output from the ENS units. The patients were told that "they might experience light sensation, strong sensation, or no sensation at all" and that sensation (or lack of sensation) was not "related to the effects of therapy."
At the beginning of the study, each group contained 32 participants; however, 13 participants (5 from the control group and 8 from the treatment group) withdrew from the study because of allergy, pain, or unspecified reasons (the reasons for withdrawal from the study were not different between groups). The ulcers of 10 of the participants in the treatment group and of 4 of the participants in the control group were healed within 12 weeks. We were surprised by the authors' general description of patients as having "diabetic leg ulcers due to venous stasis" because diabetic foot ulcers are most commonly associated with arterial disease and peripheral neuropathy. We decided that the results of this study might not apply to our patient because his foot ulcer was attributed to a combination of reduced perfusion and neuropathy, not venous stasis.
| Clinical decision: |
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TopDatabases used for search:...Initial keywords: diabet$,...Limits: human, randomized...Selection of articles for...Clinical decision:References |
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In conclusion, developing a clinical question, utilizing the question to develop search terms, and searching several databases simultaneously permitted us to efficiently identify 3 useful abstracts. Review of the full-text articles allowed us to identify one small, well-conducted (and thus valid) investigation that used ES as an adjunct to standard wound treatment to aid the healing of wounds in patients with diabetes who were similar to our patient. Although we were able to identify only one study, it was of sufficient quality in our opinion to consider a trial of ES. This evidence, coupled with our patient's desire to utilize all resources available to him to prevent his wound from resulting in an amputation, led us to recommend a trial of ES in combination with standard wound treatment.
| Footnotes |
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Eli Lilly & Co, Lilly Corporate Center, Indianapolis, IN 46285.
Pfizer Inc, 235 E 42nd St, New York, NY 10017-5703.
Bayer Corp, Pharmaceutical Division, 400 Morgan Ln, West Haven, CT 06516.
|| GlaxoSmithKline, 5 Moore Dr, PO Box 13398, Research Triangle Park, NC 27709.
# Ovid Technologies, 333 Seventh Ave, 4th Fl, New York, NY 10001.
** Prizm Medical Inc, 3400 Corporate Way, Ste I, Duluth, GA 30096.
Ethicon Inc, a Johnson & Johnson Company, Rte 22 West, Somerville, NJ 08876.
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