Quantitative impact analysis of remote ischemic conditioning and capsaicin application on human skin microcirculation.

BACKGROUND: Improvement of skin microcirculation would be beneficial in transplanted tissues and thus, there is a demand for effective, reliable and harmless angiogenic treatments. The aim of this study was to assess the effect of capsaicin application (CA), the remote effect of capsaicin application (REC), the impact of remote ischemic conditioning (RIC), and the impact of combined remote ischemic conditioning with capsaicin application (Comb) on human skin microcirculation. METHODS: Perfusion changes were assessed using a laser Doppler device (easyLDI, Aimago Lausanne). 30 healthy volunteers were enrolled and divided into two groups: 1) CA and REC: perfusion was assessed on both forearms after application of capsaicin cream on one forearm with an exposure time of 40 minutes. 2) RIC and Comb: perfusion of one forearm was assessed after four cycles of 5 min blood occlusion and 5 min reperfusion using a tourniquet on the contralateral upper arm and application of capsaicin on the ipsilateral forearm. Baseline skin perfusion measurements of both forearms were carried out initially and were used as intra-individual reference. RESULTS: 1) Skin perfusion significantly increased after capsaicin application (CA = +328.3% , p > 0.05). There was no remote skin perfusion change due to capsaicin (REC). 2) RIC significantly improves skin perfusion (RIC = +20.0% , p < 0.05). The combination of RIC and CA does not improve skin perfusion compared to CA alone (Comb). CONCLUSIONS: The conditioning techniques RIC and CA showed a significant increase in human skin perfusion, CA being superior to RIC. However, the combination of CA and RIC showed no additional improvement potential as compared to CA alone. Furthermore, a remote effect of capsaicin application could not be demonstrated. These results encourage to analyze if the conditioning treatments are also beneficial for transplanted tissue survival.

The Effect of Polyhexanide, Octenidine Dihydrochloride, and Tea Tree Oil as Topical Antiseptic Agents on In Vivo Microcirculation of the Human Skin: A Noninvasive Quantitative Analysis.

BACKGROUND: Antiseptics are indispensable for wound management and should focus not only on the efficacy in reducing the bacterial burden but also on how much they interfere in wound healing. In this study, the authors analyzed the direct effect of topical antiseptic agents on the microcirculation of intact human skin. METHODS: The perfusion dynamics were assessed before, and 10 minutes after, the volunteers' fingers of the right hand (n = 20) were immersed in the following solutions - octenidine dihydrochloride, polyhexanide, tea tree oil, and saline solution. The authors used the Oxygen to See (LEA Medizintechnik GmbH, Giessen, Germany) diagnostic device for noninvasive determination of oxygen supply in microcirculation of blood perfused tissues, which combines a laser light to determine blood flow, as well as white light to determine hemoglobin oxygenation and the relative amount of hemoglobin. RESULTS: Tea tree oil (÷19.0%) (B. Braun Melsungen AG, Melsungen, Germany) and polyhexanide (÷12.4%) (Lavanid, Serag Wiessner GmbH, Naila, Germany) caused a significant increase in blood flow compared to the negative control (-25.6%). Octenidine (Octenisept, Schülke & Mayr GmbH, Norderstedt, Germany) showed a nonsignificant trend towards an increase in blood flow (÷7.2%). There were alterations in the values of hemoglobin oxygenation and the relative amount of hemoglobin, but these were not significant. CONCLUSION: Perfusion is an important factor for wound healing. Therefore, it might be advantageous if antiseptic agents would increase blood flow. Tea tree oil and polyhexanide have a positive effect on skin blood flow and can therefore be used especially in critically perfused wounds, provided the adverse reactions and the antimicrobial efficacy are comparable.

Use of a Polylactide-based Copolymer as a Temporary Skin Substitute for a Patient With Moist Desquamation Due to Radiation.

Skin reactions are known adverse effects of radiation therapy. Despite advances in skin care products, there is still a demand for optimal skin care products to improve the therapy of these lesions. The authors report the use of a polylactide-based copolymer (Suprathel, PolyMedics Innovations GmbH, Denkendorf, Germany) as a temporary skin substitute for covering the skin defects of a patient with moist desquamation due to radiation.

Assessment of sural flap microcirculation: Which position maintains the optimal perfusion?

BACKGROUND: Limb elevation is a commonly used approach for reducing edema and increasing venous drainage. Considering the anatomy of the sural flap with retrograde perfusion and hence potentially difficult blood outflow, the best angle for positioning the leg following operation is not yet known. METHODS: A total of 14 patients undergoing sural flap lower limb reconstruction were enrolled in the study. We assessed the perfusion dynamics of the flaps using the oxygen-to-see (O2C) device that combines laser light, to determine blood flow, and white light to determine the relative amount of hemoglobin and oxygen saturation. Three different positions were evaluated: 45° angle downward, the horizontal position, and 45° angle upward. RESULTS: The blood flow was significantly higher in the 45° upward position compared to the 45° downward position. The relative amount of hemoglobin was significantly lower in the 45° upward position compared to the 45° downward position. No significant differences with regard to oxygen saturation were observed. CONCLUSION: The results of this study show a more precise pattern of perfusion due to different positioning. The 45° upward position of the leg generally maintains the best blood flow and venous drainage. However, compared to horizontal positioning, these differences were not statistically significant. As an elevation of 45° can be uncomfortable for patients, we recommend an elevation of the leg which approximates the 45° upward position but is still comfortable.

Post-operative monitoring of free muscle transfers by Laser Doppler Imaging: A prospective study.

PURPOSE: Despite different existing methods, monitoring of free muscle transfer is still challenging. In the current study we evaluated our clinical setting regarding monitoring of such tissues, using a recent microcirculation-imaging camera (EasyLDI) as an additional tool for detection of perfusion incompetency. PATIENTS AND METHODS: This study was performed on seven patients with soft tissue defect, who underwent reconstruction with free gracilis muscle. Beside standard monitoring protocol (clinical assessment, temperature strips, and surface Doppler), hourly EasyLDI monitoring was performed for 48 hours. Thereby a baseline value (raised flap but connected to its vascular bundle) and an ischaemia perfusion value (completely resected flap) were measured at the same point. RESULTS: The mean age of the patients, mean baseline value, ischaemia value perfusion were 48.00 ± 13.42 years, 49.31 ± 17.33 arbitrary perfusion units (APU), 9.87 ± 4.22 APU, respectively. The LDI measured values in six free muscle transfers were compatible with hourly standard monitoring protocol, and normalized LDI values significantly increased during time (P < 0.001, r = 0.412). One of the flaps required a return to theatre 17 hours after the operation, where an unsalvageable flap loss was detected. All normalized LDI values of this flap were under the ischaemia perfusion level and the trend was significantly descending during time (P < 0.001, r = -0.870). CONCLUSION: Due to the capability of early detection of perfusion incompetency, LDI may be recommended as an additional post-operative monitoring device for free muscle flaps, for early detection of suspected failing flaps and for validation of other methods.

Evaluation of Medical Students' Attitudes and Performance of Basic Surgery Skills in a Training Program Using Fresh Human skin, Excised During Body Contouring Surgeries.

BACKGROUND: Learning surgical skills in the operating room may be a challenge for medical students. Therefore, more approaches using simulation to enable students to develop their practical skills are required. OBJECTIVES: We hypothesized that (1) there would be a need for additional surgical training for medical students in the pre-final year, and (2) our basic surgery skills training program using fresh human skin would improve medical students' surgical skills. DESIGN: We conducted a preliminary survey of medical students to clarify the need for further training in basic surgery procedures. A new approach using simulation to teach surgical skills on human skin was set up. The procedural skills of 15 randomly selected students were assessed in the operating room before and after participation in the simulation, using Objective Structured Assessment of Technical Skills. Furthermore, subjective assessment was performed based on students' self-evaluation. The data were analyzed using SPSS, version 21 (SPSS, Inc., Chicago, IL). SETTING: The study took place at the Inselspital, Bern University Hospital. PARTICIPANTS: A total of 186 pre-final-year medical students were enrolled into the preliminary survey; 15 randomly selected medical students participated in the basic surgical skills training course on the fresh human skin operating room. RESULTS: The preliminary survey revealed the need for a surgical skills curriculum. The simulation approach we developed showed significant (p < 0.001) improvement for all 12 surgical skills, with mean cumulative precourse and postcourse values of 31.25 ± 5.013 and 45.38 ± 3.557, respectively. The self-evaluation contained positive feedback as well. CONCLUSION: Simulation of surgery using human tissue samples could help medical students become more proficient in handling surgical instruments before stepping into a real surgical situation. We suggest further studies evaluating our proposed teaching method and the possibility of integrating this simulation approach into the medical school curriculum.