Development of predictive nomograms for clinical use to quantify the risk of isolating resistance prone organisms in patients with infected foot ulcers.

Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) have been considered prevalent pathogens in foot infections. However, whether empiric therapy directed against these organisms is necessary, and in whom to consider treatment, is rather unclear. The aim of this study was to develop predictive algorithms for forecasting the probability of isolating these organisms in the infected wounds of patients in a population where the prevalence of resistant pathogens is low. This was a retrospective study of regression model-based risk factor analysis that included 140 patients who presented with infected, culture positive foot ulcers to two urban hospitals. A total of 307 bacteria were identified, most frequently MRSA (11.1%). P. aeruginosa prevalence was 6.5%. In the multivariable analysis, amputation (odds ratio (OR) 5.75, 95% confidence interval (CI) 1.48-27.63), renal disease (OR 5.46, 95% CI 1.43-25.16) and gangrene (OR 2.78, 95% CI 0.82-9.59) were identified as risk factors associated with higher while diabetes (OR 0.07, 95% CI 0.01-0.34) and Infectious Diseases Society of America infection severity >3 (OR 0.18, 95% CI 0.03-0.65) were associated with lower odds of P. aeruginosa isolation (C statistic 0.81). Similar analysis for MRSA showed that amputation was associated with significantly lower (OR 0.29, 95% CI 0.09-0.79) risk, while history of MRSA infection (OR 5.63, 95% CI 1.56-20.63) and osteomyelitis (OR 2.523, 95% CI 1.00-6.79) was associated with higher odds of isolation (C statistic 0.69). We developed two predictive nomograms with reasonable to strong ability to discriminate between patients who were likely of being infected with P. aeruginosa or MRSA and those who were not. These analyses confirm the association of some, but also question the significance of other frequently described risk factors in predicting the isolation of these organisms.

Managing real world venous leg ulcers with fetal bovine acellular dermal matrix: a single centre retrospective study.

OBJECTIVE: As compression treatment offers moderate improvement, especially to recurrent venous leg ulcers (VLUs), several alternative therapies using cellular based and/or tissue-derived products (CTPs) have emerged from bovine, porcine, and equine sources. Our aim was to look at the effect of a CTP in 'real-life' VLUs. METHODS: This study looked at complex patients with chronic, large wounds in a single-centre retrospective review. All patients were treated with fetal bovine acellular dermal matrix (FBADM) for VLUs at our outpatient urban wound care programme. RESULTS: A total of 40 wounds in 33 patients were analysed. At week four, 6% of wounds were closed; at week eight, 9% were closed; at week 12, 25% were closed; and at week 16, 38% of wounds were closed. The median time to wound closure was 67 days (range: 23-100 days) and the median percent wound closure through re-epithelialisation was 11% per week (range: 7-30% per week). At 4 weeks the median area reduction of all wounds was 23.5%, with 40% of VLUs having a ≥40% area reduction at the same point in time. CONCLUSION: There are limitations to any retrospective review; however; patients deemed to have a limited chance of closure at 4 months did better than expected, either healing or having a wound area reduction at 16 weeks, making their wound care much easier. Prospective studies should be conducted to optimise the treatment algorithm to determine if better clinical outcomes can be obtained for the 'real-life' VLU population.

Use of NPWT with and without Soft Port technology in infected foot wounds undergoing partial diabetic foot amputation.

OBJECTIVE: Negative pressure wound therapy (NPWT) has previously been shown to be effective in closing diabetic foot wounds that have undergone amputation over a 16-week period. For patients with plantar foot wounds, NPWT is a key therapy. An alternative NPWT with and without a novel soft, flexible port system needs to be evaluated for its comparable efficacy. Our objective was to show the non-inferiority of an alternative negative pressure system, and in a small subset, a novel foam dressing system. METHOD: We performed a single centre prospective study of patients with diabetes undergoing open bone resection in the foot for acutely infected wounds. Wounds were treated with NPWT/soft port technology (SPT), for 112 days or until primary closure or the wound was deemed ready for delayed primary closure. Rate of closure and quality of life were analysed. A previously published cohort was used as a control. RESULTS: Of the 30 patients initially recruited, 29 met eligibility requirements and had NPWT applied a median of 2 days postoperatively. There were seven patients (24%) who had delayed primary closure (mean=58 days) and 52% had sufficient progress to change in treatment (15/29; mean=62 days). Only one patient reached the 112-day mark without sufficient progress to be closed. The primary method of delayed primary closure was split-thickness skin graft. There was a reduction in wound area 56.3% (initial mean area=17.4cm(2) to final mean area=7.6 cm(2); p=0.001) at the end of treatment (mean=58.7 days) reduced to 4.3cm(2) a 67.2% reduction (p=0.004) at the end of study (112 days). CONCLUSION: The alternative NPWT and the soft port technology was well tolerated and effective in the population in aggregate. There was no inferiority between the two technologies. The aggregate closure or progression to be ready for closure rate of 75% at 69 days compares very favourably with previously published data for NPWT in this population of 56% at 56 days (range: 26-92 days). Both cohorts did significantly better than previously published standard of care closure rates of 39% at 77 days. DECLARATION OF INTEREST: J.C. Lantis is a paid consultant for Smith & Nephew, Acelity, Macrocure and Manukamed. This trial as supported by an institutional grant to St Luke's and Roosevelt Hospital sponsored by Smith & Nephew. The outcome of the trial had no bearing on the condition of the grant. No investigator holds an equity position in Smith & Nephew. C. Gendics is a paid consultant of Acelity.

Single-use negative pressure wound therapy for the treatment of chronic lower leg wounds.

OBJECTIVE: Lower extremity ulcers are caused by multiple disease processes and contribute to a high level of patient morbidity and health-care spending in the US. Negative pressure wound therapy (NPWT) has been used extensively for wound bed preparation. Our aim is to assess the efficacy of an affordable, low-profile single-use NPWT (single-use NPWT) on chronic lower extremity wounds that would usually be deemed too small or superficial for traditional NPWT. METHOD: A prospective pilot study was undertaken in which chronic lower extremity wounds were treated with single-use NPWT. Study visits were biweekly for primary contact dressing change, with the negative pressure unit being changed weekly. Biweekly assessments were made of wound appearance, surface area, depth, exudate amount, peri-wound skin integrity, and signs of clinical infection. Digital photography was performed at each visit. Patients with venous leg ulcers (VLUs) were treated with a 3-layer wrap. Diabetic foot ulcers (DFUs) were treated with off-loading shoes. RESULTS: The study recruited 12 patients. There were 13 wounds in total; two DFUs, two traumatic/postoperative/pressure ulcers, and nine VLUs. DFUs decreased in size on average 62%, VLUs by 32%, and traumatic/postoperative/pressure wounds by 74%. The wound appearance became more favourable and the wound depth decreased with the use of single-use NPWT. CONCLUSION: Single-use NPWT is a suitable therapy for chronic lower extremity wounds. Single-use NPWT led to a decrease in wound size and depth, an increased amount of granulation tissue, and a high level of patient satisfaction, with a low complication rate. DECLARATION OF INTEREST: This study was funded by Smith & Nephew, Hull, UK. JC Lantis is a paid consultant for KCI, Smith & Nephew, Healthpoint and Macrocure. C Gendics is a paid consultant for Macrocure and ManukaMed.

Surgical debridement alone does not adequately reduce planktonic bioburden in chronic lower extremity wounds.

OBJECTIVE: It is commonly believed that sharp surgical debridement provides adequate bacteria control for local wound beds, despite limited supporting scientific evidence. We undertook a prospective study to evaluate the reduction in planktonic bacteria pre- and post-operative debridement in critically colonised wounds. METHOD: Twelve patients, corresponding to 14 wounds, underwent debridement with either hydrodebridement or sharp steel debridement with pulse irrigation. Wound quantitative tissue cultures were taken pre- and post-debridement. There was no significant difference in wound aetiology or surface area between the two groups. RESULTS: TThe bacterial counts before debridement were 1×107 colony-forming units per gram (CFU/g) in the hydrodebridement group vs 1.4×107 CFU/g in the sharp debridement group; and 2.5×106 CFU/g (hydrodebridement) vs 7.5×105 CFU/g (sharp) after debridement (p=0.41). The total bacteria reduction was 7.5×106 CFU/g after hydrodebridement vs 1.3×107 CFU/g after sharp steel debridement (p=0.37). The mean percentage of bacteria killed from baseline was 75% by hydrodebridement and 93% killed by sharp debridement (p<0.05). CONCLUSION: Extensive operative debridement using either modality does not provide adequate immediate reduction in wound planktonic bioburden. However, all wounds appeared clinically appropriate for closure after debridement and postoperative antibacterial therapy. Postoperative antibacterial therapy may be imperative in cases of critically colonised wounds to achieve good outcomes. DECLARATION OF INTEREST: The senior author receives research grant support from Healthpoint Biotherapeutics; KCI; Manuka Honey; Smith & Nephew; Medline Ind., Macrocure; CODA. In addition the senior author is a consultant for: Smith & Nephew and KCI and medical consultant and reviewer for Macrocure. While the study as presented evaluates in part the efficacy of a commercial product from Smith & Nephew, no industry support for this study was sought or provided.

Negative Pressure Wound Therapy With Instillation (NPWTi) Better Reduces Post-debridement Bioburden in Chronically Infected Lower Extremity Wounds Than NPWT Alone.

OBJECTIVE: An overabundance of bacteria in the chronic wound plays a significant role in the decreased ability for primary closure. One means of decreasing the bioburden in a wound is to operatively debride the wound for wound bed optimization prior to application of other therapy, such as Negative Pressure Wound Therapy (NPWT). We undertook a prospective pilot study to assess the efficacy of wound bed preparation for a standard algorithm (sharp surgical debridement followed by NPWT) versus one employing sharp surgical debridement followed by Negative Pressure Wound Therapy with Instillation (NPWTi). METHODS: Thirteen patients, corresponding to 16 chronic lower leg and foot wounds were taken to the operating room for debridement. The patients were sequentially enrolled in 2 treatment groups: the first receiving treatment with operative debridement followed by 1 week of NPWT with the instillation of quarter strength bleach solution; the other receiving a standard algorithm consisting of operative debridement and 1 week of NPWT. Quantitative cultures were taken pre-operatively after sterile preparation and draping of the wound site (POD # 0, pre-op), post-operatively once debridement was completed (POD # 0, post-op), and on post-operative day 7 after operative debridement (POD # 7, post-op). RESULTS: After operative debridement (post-operative day 0) there was a mean of 3 (±1) types of bacteria per wound. The mean CFU/gram tissue culture was statistically greater - 3.7 × 10(6) (±4 × 10(6)) in the NPWTi group, while in the standard group (NPWT) the mean was 1.8 × 10(6) (±2.36 × 10(6)) CFU/gram tissue culture (p = 0.016); at the end of therapy there was no statistical difference between the two groups (p = 0.44). Wounds treated with NPWTi had a mean of 2.6 × 10(5) (±3 × 10(5)) CFU/gram of tissue culture while wounds treated with NPWT had a mean of 2.79 × 10(6) (±3.18 × 10(6)) CFU/gram of tissue culture (p = 0.43). The mean absolute reduction in bacteria for the NPWTi group was 10.6 × 10(6) bacteria per gram of tissue while there was a mean absolute increase in bacteria for the NPWT group of 28.7 × 10(6) bacteria per gram of tissue, therefore there was a statistically significant reduction in the absolute bioburden in those wounds treated with NPWTi (p = 0.016). CONCLUSION: It has long been realized that NPWT does not make its greatest impact by bioburden reduction. Other work has demonstrated that debridement alone does not reduce wound bioburden by more than 1 Log. Wounds treated with NPWTi (in this case with quarter strength bleach instillation solution) had a statistically significant reduction in bioburden, while wounds treated with NPWT had an increase in bioburden over the 7 days.

In vivo effect of sustained-release silver sulphadiazine foam on bioburden and wound closure in infected venous leg ulcers.

OBJECTIVE: To determine the in vivo effect of a sustained-release silver sulphadiazine powder foam dressing on the bacterial burden of venous leg ulcers (VLUs), with a view to correlating the wound closure rate with the degree of bioburden and to assess other markers of its progression towards healing. METHOD: Patients attending a tertiary care wound practice were screened for a VLU bacterial count of >105 colony forming units (cfu/g) per gram of tissue. Patients were treated with the above topical dressing plus multilayer compression bandaging for 12 weeks. Quantitative cultures were taken at weeks 0, 2, 4 and 8. Wounds were assessed at each weekly visit using photography and planimetry. RESULTS: Twenty-four of the 33 screened patients met the inclusion criteria. The average baseline wound size was 12.3 cm². At week 8, the bioburden had reduced to < 105 cfu/g in 54.2% of patients, with 41.7% achieving this reduction by week 2. At week 8, the median reduction was 0.7 log¹° (p < 0.001). The median percentage reductions in bioburden were 50.5%, 56.8% and 80.4% at weeks 2, 4 and 8 respectively. Over the study period, 79.2% of the patients had > 75% wound area reduction and 45.8% achieved ulcer closure in a median of 80.5 days. CONCLUSION: Although the wound size and bacterial counts reduced significantly, there was no statistical correlation between the two. Nevertheless, the in vivo data show that this active antimicrobial dressing was associated with a very high healing rate in these hard-to-heal wounds.

Infrainguinal bypass grafting in patients with end-stage renal disease: improving outcomes?

OBJECTIVE: This study was undertaken to examine recent trends in the outcomes of patients with end-stage renal disease (ESRD) undergoing infrainguinal bypass grafting (IBG) with autogenous vein. METHODS: A retrospective analysis of all IBGs performed on patients with ESRD at a single tertiary care institution during the interval 1993 to 1999 was undertaken. The comparison groups consisted of concurrent series of patients with elevated creatinine (creatinine level > 1.2 mg/dL) and patients with normal renal function undergoing IBG. Procedural variables, angiographic runoff scores, and extent of tissue necrosis at presentation were correlated with outcome. Categoric parameters were compared with chi(2) analysis; rates were computed with life-table analysis. RESULTS: Of an overall cohort of 622 IBGs performed during this interval, 78 IBGs (12.5%) were performed on 60 patients with ESRD, with a perioperative mortality rate of 1.3% that was comparable to controls. All reconstructions in the ESRD cohort were for limb salvage indications. Four-year survival, primary, assisted primary, and secondary patency rates for the ESRD group were 51% +/- 9%, 60% +/- 11%, 86% +/- 5%, and 86% +/- 5%, respectively; these were not statistically different from the control groups. Limb salvage in the ESRD group was 77% +/- 6% at 4 years and was significantly less then either the elevated creatinine (92% +/- 4%; P <.02) or the normal renal function group (90% +/- 2%: P <.02). Of 16 amputations in the ESRD group, nine were performed in limbs with patent grafts. The only absolute predictor of limb loss despite a patent graft was the presence of a heel ulcer more than 4 cm in diameter. Age, runoff score of the International Society for Cardiovascular Surgery/Society for Vascular Surgery, isolated tibial bypass graft, and location of distal anastomosis were not predictive of hemodynamic failure. CONCLUSIONS: Patients with ESRD constitute an increasing proportion of patients undergoing IBG in a tertiary care setting. Four-year survival, perioperative mortality, and graft patency rates are similar to patients with normal renal function and support an aggressive approach to this population. Major limb amputation despite a patent graft remains a problem of unique frequency in patients with ESRD. Adequate predictors of hemodynamic failure of IBG in this group do not exist, although a heel ulcer more than 4 cm may indicate an unsalvageable foot.

A comparison of collagen and PTFE patch repair in a rabbit model of congenital diaphragmatic hernia.

The use of prosthetic material in severe cases of congenital diaphragmatic hernia is complicated by infection, bowel adhesion, and patch dehiscence. We hypothesized that a bioprosthetic collagen patch would reduce these complications and be remodeled into autogenous tissue over a short period of time. Thirty-two New Zealand White rabbits had two 2 x 2-cm left diaphragmatic defects created. One of these defects was repaired with a collagen bioprosthetic patch (n = 20) and the other with a polytetrafluoroethylene (PTFE) patch (n = 20). Members of a control group (n = 12) had their defects closed primarily. The animals were then placed in either a 6- or 12-week survival cohort. At necrosectomy the repairs were assessed histologically, graded for adhesion formation, and tensiometrically tested. The PTFE patch was noted to have a significantly higher average adhesion grade than the collagen patch. The tensile strength of the two repair methods was statistically equivalent at both time intervals. On histologic examination the collagen patches were surrounded by an increased number of macrophages and fibroblasts. The PTFE patch exhibited no neovascularization or fibroblast deposition at the periphery, but had a much greater surrounding inflammatory response. Thus, there was evidence of early remodeling of the collagen with no increase in the amount of adhesions or loss of strength when compared to the PTFE, while the PTFE patches exhibited a more severe grade of adhesions.

The 3-D monitor and head-mounted display. A quantitative evaluation of advanced laparoscopic viewing technologies.

BACKGROUND: Stereoscopic (3-D) monitors and head-mounted displays have promised to facilitate laparoscopic surgery by increasing positional accuracy and decreasing operative time. To test this hypothesis, we evaluated the performance of subjects using these displays to perform standardized laparoscopic dexterity drills. METHODS: Fifty laparoscopic novices worked within an abdominal cavity simulator using four videoscopic display configurations: (1) standard (2-D) monitor; (2) 3-D monitor; (3) 2-D head-mounted display; and (4) 3-D head-mounted display. Subjects repeated 3 standardized training exercises 2 times. We measured time to complete each drill and number of errors committed. RESULTS: Mean total times to complete all 3 drills were 455, 459, 485, and 449 sec for configurations 1-4, respectively. Mean total errors committed numbered 11.3, 10.4, 12.3, and 10.8, respectively. Neither comparison reached statistical significance (p < 0.05). When 3-D configurations were compared to 2-D configurations overall, a small but statistically significant reduction in errors was noted for 1 drill only (4.3 vs 5.0, p = 0.018). CONCLUSIONS: Three-dimensional imaging slightly reduced the number of errors committed by laparoscopic novices during one test drill; this improvement, however, was not clinically significant. Neither the 3-D monitor nor the head-mounted display decreased task performance time. Widespread adoption of this technology awaits future improvement in display resolution and ease of use.

Tack entrapment of the ilioinguinal nerve during laparoscopic hernia repair.

Nerve injury has a reported incidence of 2% during laparoscopic hernia repair. These injuries usually involve the femoral branch of the genitofemoral nerve and the lateral cutaneous nerve of the thigh. Recently, in an effort to decrease the size of the port sites, surgeons have been using 5-mm tacking devices. These devices penetrate tissue more deeply and in so doing may injure nerves not classically at risk, such as the ilioinguinal and the iliohypogastric. We report the first documented injury to the ilioinguinal nerve during laparoscopic hernia repair. In addition, we review the anatomy and technique in an effort to help avoid this complication in the future.

Microwave applications in clinical medicine.

Over the last fifty years, energy has been applied to various human tissues for both the diagnosis and therapy of numerous diseases. However, in general, the medical community remains uninformed about the many potential applications of this energy source. We review the many areas in which microwave energy has shown clinical utility.