Maggots are an effective, low-cost salvage option to debride poorly vascularized, infected wounds in patients with diabetes, especially when vascular remediation is not possible....
Lawrence Eron, MD, infectious disease consultant at Kaiser Moanalua Medical Center and associate professor of medicine at the John A. Burns School of Medicine of the University of Hawaii in Honolulu, stated that, in addition to debriding nonviable tissue, maggots secrete bacteriostatic substances that help eradicate infections in conjunction with antibiotics. He said his talk involved a medical device, "and the device is the maggot."
Dr. Eron said that diabetic limb infections are difficult to treat with antibiotics in part because of vascular insufficiency. Maggot debridement therapy (MDT), using the larvae of the green blowfly (Lucilia sericata), not only removes necrotic tissue without affecting viable tissue but also stimulates the formation of granulation tissue.
Dr. Eron and colleagues used MDT to treat 37 patients with diabetes with complex wounds complicated by diabetic comorbidities. "In some cases, these wounds had been present for as long as 5 years and had failed multiple attempts at treatment," he said. The original wounds were abscesses, infected ulcers, and osteomyelitis with very narrow fistula tracts.
MDT consisted of applying 50 to 100 maggots to a wound, which were covered with nylon mesh fabric (similar to pantyhose) and then removed after 2 days. Clinicians then reapplied more maggots, and the cycles were repeated as necessary (median, 5 cycles; range, 1 - 30 cycles). Maggots were commercially obtained from Monarch Labs at a cost of just under $100 per treatment with 200 maggots.
The researchers defined a successful outcome as elimination of the infection, complete debridement of devitalized tissue, formation of robust granulation tissue, and greater than 50% closure of the wound. "The maggots will not totally heal the wound," Dr. Eron said. "We need other, further methods to heal the wound."
Of the 37 patients, "three quarters, roughly, achieved successful outcomes. The majority had Gram-positive infections. The Gram-positive infections seemed to do better than the Gram-negative anaerobic infections," Dr. Eron reported. The numbers were quite small, however, and a few wounds were culture-negative.
Representative Gram-positive organisms were methicillin-resistant Staphylococcus aureus, methicillin-sensitive S aureus, and group B streptococci. Patients were treated with appropriate, commonly used antibiotics, depending on the infecting organisms.
Failures occurred in patients with severe peripheral vascular disease with narrow fistulae that were not mechanically accessible after they healed after a single treatment in 3 patients with osteomyelitis, with bleeding from wounds (n = 2), or with excessive inflammation around the wound (n = 1). Pain limited treatment for 1 patient, but Dr. Eron said 5 or 6 patients responded well to acetaminophen for discomfort.
"The rest of the patients seemed to acquire, even with their peripheral neuropathy and numbness, some degree of sensation and would feel a creepy, crawly sensation, which they didn't object to," he said. "In fact, they appreciated [it] when they were dealing with anesthetic feet prior to [MDT]. It's an interesting phenomenon, and probably is worthy of investigation."
He warned that MDT is contraindicated in patients with coagulopathies and in patients with large blood vessels near their wounds.
Diabetic wound healing is hampered by a number of factors, not the least of which is vascular disease. Dr. Eron told the audience that MDT "allowed many of these patients -- three quarters of them -- to be ready for a second phase" of wound treatment, "and in many cases it averts amputation." He compared the median cost of about $500 for MDT to the cost of an amputation, which can be $65,000.
He noted that patients with peripheral vascular disease also have generalized vascular disease, so averting an amputation may allow a patient to live out his or her life with limbs intact. In the study, 5 patients died, usually from heart disease, during follow-up after successful MDT.
These investigators saw, as have others, an apparent antimicrobial effect from the maggot therapy. "It may stimulate defensins, which are part of our innate immune system," Dr. Eron said. "There seems also to be an angiogenesis type of effect because in many cases it converted dry wounds into moist, healthy wounds ... and finally it seemed to stimulate granulation tissue."
51st Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract L-967. Presented on September 18, 2011
Showing posts with label diabetes and foot ulcers. Show all posts
Showing posts with label diabetes and foot ulcers. Show all posts
Tuesday, October 11, 2011
Thursday, June 16, 2011
A1c Predicts Diabetic Wound Healing
Worse glycemic control correlated with slower wound healing in patients with diabetes. Every 1% increase in HbA1c was associated with -0.028 cm2decrement in the daily change in wound area....
Every 1% increase in hemoglobin A1c was associated with almost a 0.03 cm2reduction in daily rate of wound resolution. Diabetic patients with peripheral neuropathy or peripheral arterial disease (PAD) were especially susceptible to the impact of glycemic control on wound healing.
In a multivariate analysis, hemoglobin A1c, used as a surrogate for glycemic control, was the only independent predictor of change in wound area, according to a report.
Anna L. Christman, BA, of Johns Hopkins University in Baltimore, stated that, "Our results suggest that better glycemic control could help wound healing in diabetic patients, but that would have to be confirmed in a prospective clinical study."
"It would seem logical that glycemic control would affect wound healing, but to our knowledge, this is the first time the association has been clearly demonstrated," she added.
"Previous studies had evaluated the effect of glucose levels on the risk of amputation, and the results were inconsistent. Ours is the first study to use digital imaging of wounds to examine the association."
Diabetes continues to be a major contributor to lower-leg amputations, ranking second only to trauma as a cause. The necessity of amputation in diabetic patients arises from disease-related neuropathy and vasculopathy.
Identification of modifiable factors that influence wound healing could help reduce the need for amputation, Christman and colleagues noted in a poster presentation. To that end, they performed a retrospective cohort study to identify clinical variables associated with wound healing.
Investigators hypothesized that elevated A1c levels would be the strongest predictor of poor wound healing among common laboratory and clinical measures.
The study involved 183 diabetic patients with an average of 310 wounds and a total wound area that averaged 7.2 cm2. Clinical evaluation of the patients included blood pressure, pulse, temperature, and assessment of peripheral neuropathy status. Laboratory values of interest included HbA1c, total cholesterol, LDL, HDL, triglycerides, and white blood-cell count, as well as body mass index (BMI), smoking status, and presence of PAD.
The primary outcome was the change in the size of the wound area as determined by calibrated tracings of digital images. The impact of clinical variables on wound healing was assessed by multiple linear regression and investigators stratified the results by peripheral neuropathy status and PAD status.
The patients had a mean age of 61, with men and whites each accounting for 55% of the study population. The BMI averaged 35. The mean HbA1c was 8.0%, including 71 patients with values more than 7%, 42 patients with levels of 7.0 to 8.0%, and 70 with HbA1c values >8%.
A majority of the study group (60%) had peripheral neuropathy and 29% had PAD. The patients had an average of 2.3 wounds with a total wound area of 7.2 cm2.
In the overall analysis, HbA1c remained the only significant predictor of the change in wound area per day. Every 1% increase in HbA1c was associated with -0.028 cm2 decrement in the daily change in wound area (P=0.03).
The association remained significant in the stratified analyses. Among patients with peripheral neuropathy, each 1.0% increase in HbA1c was associated with a 0.022 cm2 decrease in the daily wound-healing rate (P=0.043).
Patients with PAD had a decrease in healing rate of 0.030 cm2 for every 1% increase in HbA1c (P=0.046).
Practice Pearls
Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Explain that a retrospective cohort study found diabetics with higher HbA1c had a significantly slower rate of wound healing than those with lower HbA1c.
Note that wound healing rates were calculated from calibrated tracings of digital wound images
Christman AL, et al "Hemoglobin A1ac predicts healing rate in diabetic wounds" SID 2011; Abstract 204
Every 1% increase in hemoglobin A1c was associated with almost a 0.03 cm2reduction in daily rate of wound resolution. Diabetic patients with peripheral neuropathy or peripheral arterial disease (PAD) were especially susceptible to the impact of glycemic control on wound healing.
In a multivariate analysis, hemoglobin A1c, used as a surrogate for glycemic control, was the only independent predictor of change in wound area, according to a report.
Anna L. Christman, BA, of Johns Hopkins University in Baltimore, stated that, "Our results suggest that better glycemic control could help wound healing in diabetic patients, but that would have to be confirmed in a prospective clinical study."
"It would seem logical that glycemic control would affect wound healing, but to our knowledge, this is the first time the association has been clearly demonstrated," she added.
"Previous studies had evaluated the effect of glucose levels on the risk of amputation, and the results were inconsistent. Ours is the first study to use digital imaging of wounds to examine the association."
Diabetes continues to be a major contributor to lower-leg amputations, ranking second only to trauma as a cause. The necessity of amputation in diabetic patients arises from disease-related neuropathy and vasculopathy.
Identification of modifiable factors that influence wound healing could help reduce the need for amputation, Christman and colleagues noted in a poster presentation. To that end, they performed a retrospective cohort study to identify clinical variables associated with wound healing.
Investigators hypothesized that elevated A1c levels would be the strongest predictor of poor wound healing among common laboratory and clinical measures.
The study involved 183 diabetic patients with an average of 310 wounds and a total wound area that averaged 7.2 cm2. Clinical evaluation of the patients included blood pressure, pulse, temperature, and assessment of peripheral neuropathy status. Laboratory values of interest included HbA1c, total cholesterol, LDL, HDL, triglycerides, and white blood-cell count, as well as body mass index (BMI), smoking status, and presence of PAD.
The primary outcome was the change in the size of the wound area as determined by calibrated tracings of digital images. The impact of clinical variables on wound healing was assessed by multiple linear regression and investigators stratified the results by peripheral neuropathy status and PAD status.
The patients had a mean age of 61, with men and whites each accounting for 55% of the study population. The BMI averaged 35. The mean HbA1c was 8.0%, including 71 patients with values more than 7%, 42 patients with levels of 7.0 to 8.0%, and 70 with HbA1c values >8%.
A majority of the study group (60%) had peripheral neuropathy and 29% had PAD. The patients had an average of 2.3 wounds with a total wound area of 7.2 cm2.
In the overall analysis, HbA1c remained the only significant predictor of the change in wound area per day. Every 1% increase in HbA1c was associated with -0.028 cm2 decrement in the daily change in wound area (P=0.03).
The association remained significant in the stratified analyses. Among patients with peripheral neuropathy, each 1.0% increase in HbA1c was associated with a 0.022 cm2 decrease in the daily wound-healing rate (P=0.043).
Patients with PAD had a decrease in healing rate of 0.030 cm2 for every 1% increase in HbA1c (P=0.046).
Practice Pearls
Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Explain that a retrospective cohort study found diabetics with higher HbA1c had a significantly slower rate of wound healing than those with lower HbA1c.
Note that wound healing rates were calculated from calibrated tracings of digital wound images
Christman AL, et al "Hemoglobin A1ac predicts healing rate in diabetic wounds" SID 2011; Abstract 204
Tuesday, April 26, 2011
Understanding the 2010 Consensus Recommendations for Diabetic Foot Ulcer Care
Note to the Reader: These articles summarize the "Consensus Recommendations on Advancing the Standard of Care for Treating Neuropathic Foot Ulcers in Patients with Diabetes," authored by Robert J. Snyder et al., published as a supplement to Ostomy Wound Management in April 2010.
Published as a supplement to the April 2010 issue of Ostomy Wound Management was a pivotal reference paper titled, "Consensus Recommendations on Advancing the Standard of Care for Treating Neuropathic Foot Ulcers in Patients with Diabetes."1 The authors are a recognized group of leading experts in the field who convened the consensus panel.
The world's population with diabetes will increase from 171 million to 366 million by 2025.2 In the U.S., there are an estimated 24 million people with diabetes. Up to 25% of those with diabetes will develop a foot ulcer in their lifetimes.3 That translates roughly to 1-2% of the diabetic patients per year.
Diabetic foot ulcers (DFU) and lower extremity amputations (LEA) are a costly problem. In 2007, it was estimated that $30 billion was spent for the care of those two conditions.4
The recommendations from the consensus panel are important because they help to update the standard of care based on a review of 111 studies. The recommendations are divided into three categories: Assessment, Treatment, Advanced Therapies.
In this issue we will look at recommendations on assessment of the diabetic foot ulcer.
Recommendations on Assessment of the Diabetic Foot Ulcer
The team approach to assessment and management of the DFU is recognized as the standard of care. No physician "is an island", and the co-morbidities within the diabetic foot cross multiple physician disciplines. A thorough history should be performed. Since wound healing delays can occur with anemia, renal insufficiency, and uncontrolled blood sugar, a CBC and HbA1c should be performed at baseline. If osteomyelitis is suspected, erythrocyte sedimentation rate (ESR) and (CRP) should be ordered.
The patient's nutritional status should be assessed by history and serum pre-albumin. Historical concerns are unintentional weight loss, chronic alcohol use, and problems chewing or swallowing. Smoking is a risk factor for peripheral arterial disease (PAD) and delays wound healing. One should remember the four A's of smoking cessation: Ask about smoking, Advise to quit, offer Assistance, Arrange follow-up.
Neurologic screening should consist of 10 gram monofilament and 128-Hz tuning fork tests. Vascular evaluation is more complicated. There is no single test that can completely evaluate vascular health. Palpation of pulses or ante brachial index (ABI) cannot be relied upon in this population. The absence of pulses is a good indicator of poor flow, but the presence of pulses cannot rule out arterial insufficiency. The toe brachial index (TBI) is less susceptible to false readings due to diabetic arterial calcification. Skin perfusion pressure (SPP) measures capillary pressure in the skin and is very sensitive at uncovering vascular disease in diabetics as well as predicting wound healing. Transcutaneous oximetry (TCPO2) can validate referral for hyperbaric oxygen. Vascular imaging tests should be performed by an appropriate specialist if there is reasonable suspicion of underlying vascular disease.
The foot examination should include assessment of dermatologic changes, musculoskeletal deformities, and ulcer evaluation. Dermatologic changes can show inflammation by thermometry or thermography. Also, it can reveal ischemia by the presence of purpura, fat atrophy, loss of hair growth, or taut skin. The podiatrist is a key member of the team for understanding the biomechanical abnormalities that lead to ulceration. Range of motion of the ankle and first metatarsophalangeal joints should be assessed for restriction in dorsi-flexion. Inspect for deformities associated with Charcot joint disease.
Radiography is useful to help uncover osteomyelitis or deformities. The foot should be x-rayed at baseline and it is appropriate to perform bilateral x-rays for comparison.
The wound assessment and documentation includes size, depth, shape, probing, undermining, condition of the wound bed, and condition of the periwound area. One should use a standard wound classification scheme. The consensus panel recommends use of the University of Texas Classification.5
Infection is devastating to the diabetic foot and its evaluation is primarily clinical. Heat, redness, pain, and swelling are the classic symptoms. The diabetic neuropathic patient does not always exhibit all those signs, so one should be aware of secondary signs like exudate, delayed healing, discolored granulation tissue, and malodor. Culture should only be taken if the clinician suspects infection.
Published as a supplement to the April 2010 issue of Ostomy Wound Management was a pivotal reference paper titled, "Consensus Recommendations on Advancing the Standard of Care for Treating Neuropathic Foot Ulcers in Patients with Diabetes."1 The authors are a recognized group of leading experts in the field who convened the consensus panel.
The world's population with diabetes will increase from 171 million to 366 million by 2025.2 In the U.S., there are an estimated 24 million people with diabetes. Up to 25% of those with diabetes will develop a foot ulcer in their lifetimes.3 That translates roughly to 1-2% of the diabetic patients per year.
Diabetic foot ulcers (DFU) and lower extremity amputations (LEA) are a costly problem. In 2007, it was estimated that $30 billion was spent for the care of those two conditions.4
The recommendations from the consensus panel are important because they help to update the standard of care based on a review of 111 studies. The recommendations are divided into three categories: Assessment, Treatment, Advanced Therapies.
In this issue we will look at recommendations on assessment of the diabetic foot ulcer.
Recommendations on Assessment of the Diabetic Foot Ulcer
The team approach to assessment and management of the DFU is recognized as the standard of care. No physician "is an island", and the co-morbidities within the diabetic foot cross multiple physician disciplines. A thorough history should be performed. Since wound healing delays can occur with anemia, renal insufficiency, and uncontrolled blood sugar, a CBC and HbA1c should be performed at baseline. If osteomyelitis is suspected, erythrocyte sedimentation rate (ESR) and (CRP) should be ordered.
The patient's nutritional status should be assessed by history and serum pre-albumin. Historical concerns are unintentional weight loss, chronic alcohol use, and problems chewing or swallowing. Smoking is a risk factor for peripheral arterial disease (PAD) and delays wound healing. One should remember the four A's of smoking cessation: Ask about smoking, Advise to quit, offer Assistance, Arrange follow-up.
Neurologic screening should consist of 10 gram monofilament and 128-Hz tuning fork tests. Vascular evaluation is more complicated. There is no single test that can completely evaluate vascular health. Palpation of pulses or ante brachial index (ABI) cannot be relied upon in this population. The absence of pulses is a good indicator of poor flow, but the presence of pulses cannot rule out arterial insufficiency. The toe brachial index (TBI) is less susceptible to false readings due to diabetic arterial calcification. Skin perfusion pressure (SPP) measures capillary pressure in the skin and is very sensitive at uncovering vascular disease in diabetics as well as predicting wound healing. Transcutaneous oximetry (TCPO2) can validate referral for hyperbaric oxygen. Vascular imaging tests should be performed by an appropriate specialist if there is reasonable suspicion of underlying vascular disease.
The foot examination should include assessment of dermatologic changes, musculoskeletal deformities, and ulcer evaluation. Dermatologic changes can show inflammation by thermometry or thermography. Also, it can reveal ischemia by the presence of purpura, fat atrophy, loss of hair growth, or taut skin. The podiatrist is a key member of the team for understanding the biomechanical abnormalities that lead to ulceration. Range of motion of the ankle and first metatarsophalangeal joints should be assessed for restriction in dorsi-flexion. Inspect for deformities associated with Charcot joint disease.
Radiography is useful to help uncover osteomyelitis or deformities. The foot should be x-rayed at baseline and it is appropriate to perform bilateral x-rays for comparison.
The wound assessment and documentation includes size, depth, shape, probing, undermining, condition of the wound bed, and condition of the periwound area. One should use a standard wound classification scheme. The consensus panel recommends use of the University of Texas Classification.5
Infection is devastating to the diabetic foot and its evaluation is primarily clinical. Heat, redness, pain, and swelling are the classic symptoms. The diabetic neuropathic patient does not always exhibit all those signs, so one should be aware of secondary signs like exudate, delayed healing, discolored granulation tissue, and malodor. Culture should only be taken if the clinician suspects infection.
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