Improvement of local microcirculation through intermittent Negative Pressure Wound Therapy (NPWT).

BACKGROUND: Negative Pressure Wound Therapy (NPWT) is widely used across different kinds of surgical disciplines. A controversial debate was raised by diverging results from studies that were conducted to examine the impact of NPWT on local perfusion. Thus, there is a lack of evidence for one important underlying factors that influences the physiology of wound healing under an applied NPWT-dressing. OBJECTIVE: To investigate the immediate local perfusion changes due to an applied intermittent NPWT protocol. MATERIAL AND METHODS: A NPWT dressing was applied to the antero-lateral thigh of seven healthy volunteers with two probes of both pressure and microcirculatory measuring devices. One of each probe was placed under the NPWT dressing, the other one in close proximity next to it. A protocol consisting of two cycles of 10 min of -125 mmHg pressure, followed by 10 min of 0 mmHg pressure was applied. Measurements of local pressure to the underlying tissue, as well as microcirculatory changes were performed continuously. RESULTS: Applied vacuum caused compressional forces (27.33 mmHg, p < 0.05) towards the underlying tissue. Blood Flow was increased after both suction periods (+52.5%, +108.7%; p < 0.05) and continued increasing until the end of measurements (+145.3%). This was accompanied by significant increase in Oxygen Saturation (+21.6%; p < 0.05) and Relative Hemoglobin Content (+16.7%). Red Blood Cell Velocity was found to be increased without statistical significance. Next to the dressing, changes were also significant but less pronounced. CONCLUSION: Intermittent NPWT improves local microcirculation with consecutive enhancement of oxygen supply.

[Remote Ischemic Conditioning - Endogenous Tissue Protection and its Possible Applications in Surgery]. / Remote ischemic Conditioning ­ endogene Gewebeprotektion und ihre Einsatzmöglichkeiten in der Chirurgie.

Tissue perfusion is pivotal to wound healing and tissue regeneration after surgery. Ischemia and reperfusion lead to inflammatory reactions with consecutive tissue damage and necrosis. Multiple conditioning techniques have been described to protect tissue from those damaging mechanisms in the perioperative period. However, most of these fail to meet the requirements of a good therapeutic effect, time and cost efficiency, non-invasiveness and applicability without the need for additional devices or drugs. Remote ischemic conditioning (RIC) is a technique to provide endogenous tissue protection, which fully meets those requirements. Repeated, short cycles of ischemia/reperfusion applied to a circumscribed vascular territory lead to the activation of endogenous signal pathways resulting in increased tolerance to hypoperfusion and limiting the damage caused by reperfusion, even in tissues located far away from the conditioned area. The non-invasive application of the conditioning stimulus requires no more than a pressure cuff, which is placed on the upper arm and is repeatedly inflated to suprasystolic pressures. Different concepts of remote ischemic pre-, peri- and postconditioning enable the usage in both elective and emergency surgical interventions. Based on encouraging experimental studies, the application of RIC has increased in the clinical setting. In addition to studies addressing cardio-, nephro- or neuroprotection there are some initial findings supporting a potential beneficial application in reconstructive microsurgery. This article aims to give an overview of the development, concepts and mechanisms of RIC with a focus on its clinical application in the field of surgery.

Albumin reduces the antibacterial efficacy of wound antiseptics against Staphylococcus aureus.

OBJECTIVE: The influence of proteins on the efficacy of antiseptic solutions has been rarely investigated even though exudate can contain high levels of protien. The aim of this study was to analyse the antibacterial efficacy of commonly used solutions in the presence of albumin protein. METHOD: Using Staphylococcus aureus in a standardised quantitative suspension assay, the antibacterial effects of poly (1-(2-oxo-1-pyrrolidinyl) ethylene)-iodine (PVP-I) and octenidin-dihydrochloride/phenoxyethanol (OCT/PE) were analysed in the presence of 0-3% bovine serum albumin (BSA). These were compared with previous results obtained with polyhexamethylene biguanide hydrochloride (PHMB). RESULTS: Presence of albumin caused a significant (p<0.001) decrease in antibacterial effect in the analysed solutions. The concentrations of albumin that provoked highly significant decreases in the bacterial reduction factors of the study agents were: 0.01875 % for PVP-I, followed by 0.75 % for OCT/PE. After addition of 3 % albumin, adequate antimicrobial effects were ensured for titrations to 5 % PVP-I and 8 % OCT/PE. As we could show before, it is not possible to titrate PHMB in order to assure adequate potency. CONCLUSION: This study demonstrates that albumin induces a significant decrease of the antibacterial potency of the analysed solutions.

[Therapy of burns]. / Therapie von Brandverletzungen.

Burns are classified according to the depth of the burn wound and extent of affected burned body surface area. In deep second degree and higher grade burns the epidermis and skin appendages are destroyed so that healing can only take place with severe scarring. In these cases necrectomy and skin grafting are recommended. Extensive and deep burns should be treated at specialized centers and more precise criteria for this are laid down in the guidelines. Emergency room treatment protocols have improved the quality of admission and treatment. Concomitant injuries need to be diagnosed and treated early. In addition to the damage to the skin the subsequent burn disease with massive accumulation of interstitial fluid determines the prognosis. The circulation is stabilized and the risk of infection is controlled by intensive fluid management, early necrectomy and split thickness skin grafting. Modern sedation and ventilation management allows a more rapid convalescence.

Upper extremity ischemia is superior to lower extremity ischemia for remote ischemic conditioning of antero-lateral thigh cutaneous blood flow.

Remote ischemic conditioning (RIC) is known to improve microcirculation in various settings, but little is known about the impact of the amount of ischemic tissue mass or the limb itself. Since ischemia and subsequent necrosis of flaps is one of the most dreaded complications in reconstructive surgery, adjuvant methods to improve microcirculation are desirable. We therefore performed a randomized trial to compare the effect of arm versus leg ischemia for RIC of the cutaneous microcirculation of the antero-lateral thigh. Forty healthy volunteers were randomized to undergo 5 min of ischemia of either the upper or lower extremity, followed by 10 min of reperfusion.Ischemia was induced by a surgical tourniquet applied to the proximal limb, which was inflated to 250 mmHg for the upper and 300 mgHg for the lower extremity. This cycle was repeated a total of three times. Cutaneous microcirculation was assessed by combined laser doppler spectrophotometry on the antero-lateral aspect of the thigh to measure cutaneous blood flow (BF), relative hemoglobin content (rHb), and oxygen saturation (StO2). Baseline measurements were performed for 10 min, after which the ischemia/reperfusion cycles were begun. Measurements were performed continuously and were afterwards pooled to obtain a mean value per minute. Both groups showed significant increases in all three measured parameters of cutaneous microcirculation after three cycles of ischemia/reperfusion when compared to baseline (BF: 95.1% (P < 0.001) and 27.9% (P = 0.002); rHb: 9.4% (P < 0.001) and 5.9% (P < 0.001), StO2: 8.4% (P = 0.045) and 9.4% (P < 0.001). When comparing both groups, BF was significantly higher in the arm group (P = 0.019 after 11 min., P = 0.009 after 45 min). In conclusions, both ischemic conditioning of the upper and lower extremity is able to improve cutaneous BF on the ALT donor site. However, RIC of the upper extremity seems to be a superior trigger for improvement of cutaneous BF.

Albumin reduces the antibacterial activity of polyhexanide-biguanide-based antiseptics against Staphylococcus aureus and MRSA.

BACKGROUND: Wound infection is one of the major complications in acute and chronic wound healing. Antiseptic solutions and wound irrigating agents are routinely used for therapy and prevention in healthcare today. Even if wound exudate contains total protein concentrations up to 9.3% and albumin concentrations up to 2.7% its influence to the antibacterial efficacy of these agents is barely investigated. MATERIALS AND METHODS: This study analyzed the antibacterial effect of polyhexanide biguanide (PHMB) agents (PHMB-concentration 0.005-0.1%) against Staphylococcus aureus and methicillin-resistant-S. aureus (MRSA) after 2min incubation in presents of albumin in different concentrations (0-3%) in a standardized quantitative suspension assay. RESULTS: A significant decrease of the antibacterial activity against S. aureus was shown for a PHMB-concentration of 0.005% from 0.3% albumin (p<0.05), respectively highly significant from 0.75% (p<0.01) on. Thereby the loss of antimicrobial effect was presented as a linear correlation to the rising concentration of albumin. Furthermore a reduction of the antibacterial activity against MRSA in comparison to S. aureus was presented, for albumin concentrations from 3% on highly significant (p<0.01). CONCLUSION: The study showed that albumin causes a significant decrease of the antibacterial potency of PHMB-based antiseptics. Furthermore a diminished potency of the investigated substances for MRSA-contaminated wounds must be taken in consideration. If in vitro experiments show a significant decrease of antibacterial efficacy in the presence of albumin a sufficient activity of PHMB-based agents in clinical practice, especially in cases of exuding wounds or dried-up exudates, cannot be expected.

[Wound healing complications in smokers, non-smokers and after abstinence from smoking]. / Wundheilungsstörungen bei Rauchern, Nichtrauchern und nach Rauchstopp.

BACKGROUND: The pulmonary and cardiovascular ramifications of smoking are well documented and this also applies to increased wound healing complications in smokers. The aim of this study was to ascertain whether preoperatively refraining from smoking would affect the incidence of wound healing disorders. MATERIAL AND METHODS: Between 2006 and 2008 a total of 295 patients underwent aesthetic (n = 167) or reconstructive surgery (n = 128). They were divided into three groups: A (n = 98) non-smokers for at least 2 years, B (n = 99) patients who refrained from smoking 6 weeks prior to surgery and C (n = 98) smokers. Smoking abstinence was verified by cotinine tests. Wound healing complications were defined as dehiscent wounds, wound infections, atypical scar formation and adiponecrosis. RESULTS: Smokers developed wound healing complications in 48.2% of cases, non-smokers in 21.0% and patients who had stopped smoking for 6 weeks in 30.8% of cases (p = 0.006). CONCLUSION: Elective surgery should only be performed on non-smokers and smokers who had refrained from smoking for at least 6 weeks to reduce wound healing complications as far as possible.

[Three case reports of frostbite. Management and literature]. / Drei Fallberichte über Erfrierungen. Management und Literatur.

Due to social and demographic changes as well as new leisure activities, the number of frostbite injuries in the general population is on the increase. Because the injuries are primarily located on the hands and feet the consequences for those concerned are devastating. We provide help in grading and introduce concrete therapeutic regimes for frostbite which are illustrated by three case reports from our clinical experience with varying risk profiles.

[Aneurysm of the radial artery in a patient with marfan syndrome]. / Aneurysma der Arteria radialis bei Marfan-Syndrom.

We present a 52-year-old male patient suffering from Marfan syndrome who developed an aneurysm of the distal radial artery. The histology showed the typical marfanoid structure of a thrombosed aneurysm. As far as we know, this is the first description of a hand aneurysm in a patient with Marfan syndrome.