Išeminių audinių perfuzijos pokyčiai atkuriant kraujotaką tiesiogiai pagal angiosomą ir netiesiogiai

Background. Blood flow restore in critical limb ischemia according to angiosomes is becoming very popular. This method allows to restore blood flow precisely to the artery supplying the ischemic zone, based on the angiosome concept. However, angiosome revascularization is not a gold standard because of the lack of evidence supporting this approach. The aim of this study was to compare tissue oxygenation changes in ischemic zone during endovascular revascularization procedure either following angiosome concept or performing indirect revascularization. Methods. A prospective observational study was performed. Patients with critical limb ischemia and tissue loss due to chronic total occlusion of below the knee arteries were included. Endovascular revascularization was performed in all cases. Tissue oxygen saturation was observed intraoperatively using near-infrared spectroscopy. Tissue oxygenation changes near the ischemic wound were compared between direct and indirect revascularization groups. Results. This clinical trial included 30 patients with critical limb ischemia (Rutherford 5) and occluded below the knee arteries intended to treat. In 15 patients the procedure was performed according to angiosome, while the other half underwent indirect revascularization. Tissue oxygenation near the wound was monitored during the intervention. Greater oxygen saturation increase was observed in the group with direct revascularization (29% and 23% accordingly), however the difference between groups was not statistically significant (t-test for independent group, p = 0,544). Conclusions. The increase in tissue oxygen saturation differed very slightly in direct and indirect revascularization groups and the difference was statistically insignificant. Įvadas. Vis populiarėja galūnės kraujotakos atkūrimas pagal angiosomas, esant kritinei galūnės išemijai, t. y. revaskuliarizuojama būtent ta kraujagyslė, kuri maitina pažeistą plotą. Tačiau revaskuliarizacija atsižvelgiant į angiosomas nėra laikoma kritinės galūnių išemijos gydymo standartu, nes mokslinėje literatūroje trūksta įrodymų, pagrindžiančių šio gydymo metodo pranašumus. Pristatomo tyrimo tikslas – palyginti audinių oksigenacijos pokyčius išeminėje zonoje, endovaskuliniu būdu atkūrus kraujotaką tiesiogiai pagal angiosomą ir netiesiogiai. Metodai. Tai perspektyvusis stebimasis tyrimas. Į tyrimą įtraukti pacientai, kuriems diagnozuota kritinė galūnės išemija, esant gangrenai dėl užakusių blauzdos arterijų. Pacientams taikyta endovaskulinė revaskuliarizacija. Procedūros metu oksigenacijos pokyčiai stebėti naudojant artimųjų infraraudonųjų spindulių spektroskopiją. Gauti rezultatai lyginti pacientų, kuriems taikyta tiesioginė ir netiesioginė revaskuliarizacija, grupėse. Rezultatai. Tiriamąją imtį sudarė 30 pacientų, sergančių kritine galūnių išemija (5 Rutherfordo kategorija). Visiems pacientams nustatyta blauzdos arterijų okliuzija, kai reikia atkurti kraujotaką. Tyrimo metu 15 pacientų (50 %) kraujotaka buvo atkurta pagal angiosomą, tokiai pat daliai pacientų (50 %) – ne pagal angiosomą. Visiems tiriamiesiems procedūros metu matuoti oksigenacijos pokyčiai išeminėje zonoje. Didesnis oksigenacijos pokytis pastebėtas pacientų, kuriems atlikta revaskuliarizacija pagal angiosomą, grupėje (atitinkamai 29 proc. ir 23 proc.), bet statistiškai reikšmingo oksigenacijos skirtumo tarp grupių nenustatyta (nepriklausomos grupės t testas, p = 0,544). Išvados. Klinikinio tyrimo metu audinių oksigenacijos pokytis atkuriant kraujotaką pagal angiosomą mažai skyrėsi nuo audinių oksigenacijos pokyčio atkuriant kraujotaką ne pagal angiosomą. Skirtumas nebuvo statistiškai reikšmingas

Analysis of revisions operations performed due to dislocation after total hip arthroplasty. Results from Lithuanian arthroplasty register

The aim of the thesis: To analyse revisions operations performed due to dislocation after total hip arthroplasty in Lithuania. Objectives: 1. Estimate risk factor for dislocation. 2. Investigate the causes of re-revisions operations. 3. Compare re-revision rate between dual-mobility cups and other surgical options after total hip revision performed due to dislocation. Methods: Data were derived from the Lithuanian Arthroplasty Register, we estimated risk factor for revision and calculated the cumulative re-revision rates after surgery. For survival analysis, we used re-revision for all reasons and for dislocations as an end-point. Cox proportional hazards models were used to analyze the influence of various covariates (age, gender, diagnosis of primary operation and implant concept). Results: The biger relative risk (RR) due to dislocation has 70 years and older patients RR 1,7 (95% confidence intervals (CI): 1,2-2,3; p=0,002), posterior aproach RR 4,6 (95% CI: 2,5-8,8; p=0,001) primary diagnosis of femural neck fracture RR 4,7 (95% CI: 3,4-6,5; p=0,001) compared with younger that 70 years old patients, lateral aproach and primary diagnosis of primary arthrosis. A total of 1,388 revisions were recorded from 2011 to 2016, of which 362 were performed due to recurrent dislocation. Out of 362 revisions, 247 were performed using dual-mobility cups, while others were operated using a variety of other surgical options including conventional cup, stem, femoral head exchange or anti-luxation ring. 27 patients had been re-revised for the following reasons: dislocations - 15, infections - 7, periprosthetic fractures - 3, and cup loosening - 2. Cox regression adjusting for age, gender and diagnosis of primary operation showed that the use of dual-mobility cup had 7 times (95% CI: 1.8-27.5, p=0.005) lower risk of revision due to dislocation and 3 times lower risk of revision for all reasons (95% CI 1.3-7.3, p=0.011) as compared with other surgical options. Interpretation: 1. 70 years and older, posterior aproach and primary diagnosis of femoral neck fracture are the risk factors for dislocation after total hip arthroplasty. 2. The comon cause of re-revision operation after revision operation performed due to dislocation is recurent dislocation. 3. Significantly lower re-revision rate was observed for patients revised due to recurrent dislocation when dual-mobility cups were used. Recomendations: At the time of revision hip replacement operations performed by recurrent dislocations, in order to avoid the repetition of dislocations, it is appropriate to use dual mobility implants

Comparison of dual mobility cup and other surgical construts used for three hundred and sixty two first time hip revisions due to recurrent dislocations : five year results from Lithuanian arthroplasty register

Purpose: Recently, there has been increasing interest in the use of dual mobility systems in the treatment of hip instability. The aim of this study was to investigate the re-revision rate of dual mobility cup compared to different surgical concepts when used for first-time hip revisions due to recurrent dislocations. Methods: The data were derived from the Lithuanian Arthroplasty Register. For survival analysis, we used both re-revision for all reasons and for dislocations as an end-point. Cox proportional hazards models were used to analyze the influence of various covariates (age, gender, and implant concept). Results: A total of 1388 revisions were recorded from 2011 to 2015, of which 362 were performed due to recurrent dislocation. Of the revisions, 247 were performed using dual mobility cups, while 115 were performed using a variety of other surgical constructs including constrained acetabular cups, conventional cups, femoral head exchanges, stem exchanges or anti-luxation rings. There were 27 re-revisions of which 15 were for additional dislocations. There were only 2% re-revisions due to dislocation with dual mobility vs 9% when using other surgical constructs. Cox regression adjusting for age and gender showed that in the short-term, dual mobility cup had a lower risk of revision due to dislocation as well as for all reasons compared to the other surgical constructs. Conclusion: In revision of total hip arthroplasties for dislocation, significantly lower short-term re-revision rate was observed for patients revised with dual mobility cup

Methodology for asynchronous motor impedance measurement by using higher order harmonics

The control methods of asynchronous motors have changed during past decades. In the past, asynchronous motors were connected to grid directly. Later, thyristors as switching element-based frequency converters for asynchronous motors have appeared. Today, asynchronous motors are controlled with variable speed drives that are frequency converters consisting of IGBT power modules as switching elements that form the output voltage for asynchronous motors. Because of IGBT’s high switching speed of around few kilohertz, higher order harmonics appear in the output voltage. Their influence was not analyzed in the past as the methodology of asynchronous motor winding resistance measurement was under development. In this article, a new methodology of motor resistance measurement for mass production is introduced. The resistance—compared to higher order harmonics values between the windings of benchmark and tested motors—gives an ability to faster and more accurately determine a motor’s characteristics and losses induced by higher order harmonics that appear when a motor is powered by a variable speed drive. Motor winding’s inductance dependency on the current of magnetic biasing and the higher frequency of voltage is analyzed in this article. In addition, the simulation model of resistance to higher order harmonics of motor measurement is introduced and analyzed in this article

Oxygen Saturation Increase in Ischemic Wound Tissues after Direct and Indirect Revascularization

Background: The primary approach for treating ischemic wounds is restoring oxygen supply to the ischemic region. While direct angiosomal revascularization is often associated with better post-operative wound healing and limb salvage, its superiority over non-angiosomal revascularization remains controversial. This study aimed to compare intraoperative tissue oxygen saturation changes in ischemic zones following either direct or indirect revascularization in below-the-knee arteries. Methods: This prospective observational study included patients undergoing direct and indirect below-the-knee endovascular revascularizations. Assignment to the groups was not randomized. Near-infrared spectroscopy was used to monitor rSO2 changes near the ischemic wounds intraoperatively. The changes were compared between the groups. Results: 15 patients (50%) underwent direct angiosomal revascularization, while an equal number of patients underwent indirect revascularization. Overall, a statistically significant increase in regional oxygen saturation was observed after revascularization (p = 0.001). No statistically significant difference was found between the direct and indirect revascularization groups (p = 0.619). Conclusions: This study revealed a minor difference in the oxygen saturation increase between the angiosomal and non-angiosomal revascularization groups. Such a finding indicates that the clinical significance of angiosomal revascularization is negligible and might be concealed by confounding factors, such as the vessel diameter and outflow impact on the restenosis rate