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    The effect of hemodilution during normothermic cardiac surgery on renal physiology and function: a review. Vermeer H,Teerenstra S,de Sévaux R G L,van Swieten H A,Weerwind P W Perfusion Although the definitions of renal dysfunction vary, loss of renal function is a common complication following cardiac surgery using cardiopulmonary bypass (CPB). When postoperative dialysis is required, mortality is approximately 50%. CPB-accompanied hemodilution is a major contributing factor to renal damage as it notably reduces oxygen delivery by reducing the oxygen transport capacity of the blood as well as disturbing the microcirculation. To minimize hypoxemic damage during CPB, lowering of body temperature is applied to reduce the patient's metabolic rate. At present, however, temperature management during elective adult cardiac surgery is shifting from moderate hypothermia to normothermia. To determine whether the currently accepted levels of hemodilution during CPB can suffice the normothermic patient's high oxygen demand, we focused this study on renal physiology and postoperative renal function. Hemodilution reduces the capillary density through a diminished capillary viscosity, thereby, redistributing blood from the renal medulla to the renal cortex. As the physiology of the renal medulla makes it a hypoxic environment, this part of the kidney appears to be especially at risk for hypoxic damage caused by a hemodilution-induced lowered oxygen transport and oxygen delivery. In addition, hemodilution is also likely to disturb the hormonal systems regulating renal blood distribution. Clinical studies, mostly of retrospective or observational nature, show that perioperative nadir hematocrit levels lower than approximately 24% are associated with an increased risk to develop postoperative renal failure. A better comprehension of the cause-and-effect relation between low perioperative hematocrits and loss of postoperative renal function may enable more effective renal protective strategies. 10.1177/0267659109105398
    Pathophysiology and clinical implications of microbubbles during hemodialysis. Barak Michal,Nakhoul Farid,Katz Yeshayahu Seminars in dialysis Microbubbles have been detected in the human circulation of end-stage renal disease patients who are treated by hemodialysis throughout the past decade as a result of advanced ultrasound and Doppler technology. These detection tools uncovered signals of microbubbles, which originate in extracorporeal lines and tubing of hemodialysis machine, circulate in the blood stream until lodging in the capillary bed of various organs, mainly the lungs. During its course within the capillary, a bubble abrades the glycocalyx layer lining the surface of the vessels and thereafter obstructs blood flow through the capillary. This causes tissue ischemia, inflammatory response, and complement activation. Aggregation of platelets and clot formation occurs as well, leading to further obstruction of the microcirculation and subsequent tissue damage. In this review, we describe the biological and clinical effects of microbubbles during hemodialysis and discuss management with regard to prevention and treatment. 10.1111/j.1525-139X.2008.00424.x
    Skin Blood Flow and Vascular Endothelium Function in Uremia. Smogorzewski Miroslaw J Journal of renal nutrition : the official journal of the Council on Renal Nutrition of the National Kidney Foundation Prevalence of dermatological disorder in patients with end-stage kidney disease is estimated as 50% to 100% in various studies. Some of the skin lesions are specific for the diseases causing chronic kidney disease (CKD), some are associated with CKD, and still others are the dermatological manifestation of uremia. Microangiopathy was also found in both arterioles and venule in the skin biopsy of "normal looking" skin in patients with end-stage kidney disease. In a cross-sectional study in patients on dialysis, we measured skin blood flow (SBF) using laser Doppler device in a standardized way at various areas of lower extremities at 2 different local skin temperatures: 35°C and 44°C. Local heating increases skin perfusion by mechanisms dependent on nitric oxide (NO). SBF was impaired in CKD patients Stage 5 on HD, particularly in those with diabetes mellitus as a cause of CKD. The reduced response in the SBF to the heat in our patients may be due to decreased generation of NO in uremia. Endothelium-dependent vasodilatation in patients on dialysis and the response of the skin microcirculation to acetylcholine was diminished in hypertensive patients on dialysis. Similarly, patients with diabetes mellitus had decreased SBF during intradermal microdialysis with a NO synthase inhibitor. Multiple uremic toxins have been studied in vitro and show to cause various degree of endothelial cell dysfunction. Unfortunately, no clear benefit has been described in CKD patients to different intervention aimed to reduce uremic toxin effect on endothelium. There are no long-term data on the factors which can modify endothelium function in uremia, but non pharmacologic interventions, diet, and several pharmacologic approaches could be beneficial. Measurement of SBF can be useful in evaluation of vasculopathy in CKD population and can potentially be used for assessment of vascular response during specific clinical intervention. 10.1053/j.jrn.2017.04.012
    Effects of hemodialysis on blood volume, macro- and microvascular function. Montero David,Haider Thomas,Nägele Matthias P,Barthelmes Jens,Cantatore Silviya,Sudano Isabella,Ruschitzka Frank,Bonani Marco,Flammer Andreas J Microvascular research BACKGROUND:Vascular dysfunction is considered to spur the progression of cardiovascular disease in hemodialysis (HD) patients. Whether the HD procedure itself contributes to vascular dysfunction remains incompletely investigated. The present study sought to comprehensively assess the effects of HD on arterial and venous function along with concomitant changes in blood volume (BV). METHODS AND RESULTS:We determined BV with high-precision, automated carbon monoxide-rebreathing, arterial stiffness using applanation tonometry and intrinsic microvascular function via retinal vessel analysis prior to and after conventional 4-hour HD in fasting-controlled conditions in 10 patients. All HD patients were non-smokers and non-obese (body mass index = 22.8 ± 2.8 m·kg). Hypertension (70%), coronary artery disease (40%) and diabetes mellitus (20%) were the most prevalent comorbidities. Prior to HD, all patients presented with hypervolemia (+2208 ± 1213 ml). HD decreased body weight (-1.72 ± 1.25 kg, P = 0.002) and plasma volume (-689 ± 566 ml, P = 0.004), while hematocrit (Hct) was concomitantly increased (+4.8 ± 4.5%, P = 0.009). HD did not affect large elastic artery stiffness, as determined by carotid-femoral pulse wave velocity (P = 0.448) and carotid distensibility (P = 0.562). In contrast, flicker light-induced retinal venular dilation was reduced by three-fourths after HD (-2.4 ± 1.7%, P = 0.039), in parallel to increased retinal venular diameter (+11.2 ± 4.9 μm, P = 0.002). In regression analyses, a negative association was observed between HD-induced changes in Hct and retinal venular dilation (r ≥ -0.89, P ≤ 0.045). CONCLUSION:Conventional HD resulting in substantial plasma volume removal do not alter large artery elastic properties, whereas intrinsic microvascular venular dilator function is markedly impaired, an effect directly associated with the increase in hemoconcentration. 10.1016/j.mvr.2019.103958
    Plasma albumin levels correlate with decreased microcirculation and the development of skin defects in hemodialyzed patients. Mistrík Erik,Dusilová-Sulková Sylvie,Bláha Vladimír,Sobotka Lubos Nutrition (Burbank, Los Angeles County, Calif.) OBJECTIVES:Difficulty healing wounds and skin defects is a frequent problem in patients on chronic hemodialysis (HD) because of malnutrition, inflammation, and atherosclerosis (MIA) syndrome. The aim of the present study was to estimate the influence of peripheral blood flow changes during HD on the development of foot defects and its relationship to plasma albumin levels. METHODS:Peripheral skin blood flow was measured using a laser Doppler line scanner in 10 different areas of the dorsal part of the instep and the toes of each foot before and during HD with ultrafiltration (897 +/- 465 mL/procedure) in 31 HD patients (10 female, 21 male; age 36-79 y, body mass index = 28 +/- 5.0). No skin defects or apparent acute disease or infection were detected in any patient at the time of laser Doppler line scanner measurement. The feet of the patients were clinically re-examined carefully over the next 18 mo. RESULTS:We found a significant and constant decrease of skin blood flow during the HD procedure (P < 0.001). Skin blood flow was significantly correlated with serum albumin level both before HD (r = 0.36, P = 0.05) and during HD (r = 0.47, P = 0.007). Skin defects developed in 11 patients, with significantly lower skin blood flow during the 18-mo follow-up period. A significantly larger number of patients who had normal perfusion remained defect-free in comparison to patients with critical perfusion (93% versus 38%, P = 0.002, Kaplan-Meier analysis). CONCLUSION:Skin blood flow may be impaired in HD patients. The apparent malnutrition and inflammation in HD patients are likely responsible for the decreased skin blood flow and the development of the difficulty to heal skin defects and wounds. 10.1016/j.nut.2010.05.007
    Effects of ultrapure hemodialysis and low molecular weight heparin on the endothelial surface layer. Cornelis Tom,Broers Natascha J H,Titulaer Denise C L M,Henskens Yvonne M,van Oerle Rene,van der Sande Frank M,Spronk Henri M,Vink Hans,Leunissen Karel M,ten Cate Hugo,Kooman Jeroen P Blood purification BACKGROUND:Chronic kidney disease patients show changes in the endothelial surface layer (ESL). Whether hemodialysis (HD) itself or low molecular weight heparins (LMWH) induce ESL alterations is unknown. METHODS:We studied the ESL in 20 HD patients with Sidestream Dark Field Imaging [measuring perfused boundary region (PBR)] and measurement of ESL constituents in plasma during HD in 2 studies. LMWH was administered at the start of HD in study A, and 120 min after the start of HD in study B. Mean platelet volume (MPV) and platelet large cell ratio (P-LCR) were also measured. RESULTS:Syndecan-1 increased significantly 30 min after LMWH administration. sP-Selectin increased 120 min after HD start, and MPV and P-LCR decreased significantly during HD. No significant changes of PBR, sE-Selectin, sICAM-1, or sVCAM-1 were perceived. CONCLUSIONS:HD caused a significant increase in Syndecan-1 without a change in PBR. The administration of LMWH appeared to precede the rise in Syndecan-1. 10.1159/000369055
    Harnessing the microcirculation to increase dialysis efficiency. Kong Chiew H,Farrington Ken Nephron 10.1159/000065577
    Detection of microcirculatory impairment by transcutaneous oxymetry monitoring during hemodialysis: an observational study. Benhamou Ygal,Begarin Loic,David Nathalie,Cailleux Nicole,Bessin Catherine,Lévesque Herve,Edet Stephane BMC nephrology BACKGROUND:Little is known about the effects of intermittent hemodialysis on microcirculatory perfusion. The aim of this study is to assess the effects of hemodialysis on microvascular perfusion using transcutaneous oxymetry (TCPO2). METHODS:In this observational study, hourly TCPO2 measurements were performed during hemodialysis sessions. Ankle brachial index (ABI) was carried out to classify patients according their vascular condition. RESULTS:50 patients (mean age 70 ± 8 years old) were enrolled. Mean TCPO2 decreased significantly on average 23.9% between start and finish of hemodialysis. Severe ischemia (TCPO2 < 30 mmHg) and critical ischemia (TCPO2 < 10 mmHg) occurred during dialysis in 47.1% and 15.5% respectively. Critical ischemia occurred only in limbs with ABI < 0.9 (8.3%) or > 1.3 (28%). Patients with critical ischemia experienced a significantly larger decline in mean blood pressure (32.4 ± 26.1 mmHg vs 12.7 ± 10.7 mmHg; P = 0.007) and a more pronounced ultrafiltration (45.55 ± 16.9 ml/kg vs 35.17 ± 18.2 ml/kg; P = 0.04) compared to patients without ischemia. Clinical outcomes (death or vascular procedures) were five times more frequent in patients who had developed critical ischemia (55.7% vs 10.1% P = 0.01). The elevated age of patients, the low basal value of TCPO2, and the occurrence of critical ischemia were more frequently associated with clinical outcome (P = 0.03, P = 0.048, P = 0.01 respectively). CONCLUSIONS:This study demonstrates that hemodialysis induces microcirculatory injury, dependent on blood pressure reduction, peripheral vascular state and ultrafiltration. The occurrence of critical ischemia is associated to pejorative patient outcome and therefore, TCPO2 seems to be useful to avoid potential distal tissue damage during hemodialysis. 10.1186/1471-2369-15-4
    Haemodialysis is associated with changes in cutaneous microcirculation in diabetes mellitus. Beckert S,Sundermann K,Wolf S,Königsrainer A,Coerper S Diabetic medicine : a journal of the British Diabetic Association AIMS:To examine the cutaneous microcirculation on the dorsum of the foot before, during and after haemodialysis in diabetic and non-diabetic patients. METHODS:Fourteen age-matched patients (seven diabetic, seven non-diabetic) without active foot ulceration were studied. Cutaneous microcirculation was assessed using a micro-lightguide spectrophotometer to measure venous oxygen saturation and relative blood flow determined at two tissue depths: 2 and 6 mm. Cumulative relative changes of each parameter during haemodialysis were calculated as area under the curve. Differences between and within the groups were calculated by Mann-Whitney U-test and anova following post hoc testing, respectively. RESULTS:At baseline, relative blood flow at 6 mm tissue depth was significantly greater in diabetic patients (P = 0.048). Thirty minutes after the end of dialysis, relative blood flow at 2 and 6 mm tissue depth was significantly higher in non-diabetic patients (P = 0.048 and P = 0.001). Mean cumulative relative changes in venous oxygen saturation and relative blood flow at 2 mm as well as 6 mm tissue depth were positive for non-diabetic subjects and negative for diabetic patients. CONCLUSIONS:Haemodialysis is associated with changes in cutaneous microcirculation, which differ between people with and without diabetes. In those without diabetes, we found an increase in blood flow during haemodialysis, whereas blood flow was reduced in diabetic patients. This may be the result of abnormal vasomotor regulation due to distal neuropathy. 10.1111/j.1464-5491.2008.02610.x
    Cardiovascular death in dialysis patients: lessons we can learn from AURORA. Sniderman Allan D,Solhpour Amirreza,Alam Ahsan,Williams Ken,Sloand James A Clinical journal of the American Society of Nephrology : CJASN Cardiovascular events are the dominant cause of death in patients with ESRD. Until recently, plaque rupture due to atherogenic dyslipoproteinemias was presumed to be a major mechanism of cardiovascular events in dialysis patients. But how reasonable was that hypothesis and was it entirely discredited by the results of 4D and AURORA? This article places the conventional lipids-cholesterol and triglyceride-within the more physiologic framework of the apoB lipoproteins. Viewed from the perspective of atherogenic particle number, the failure of statins to lower cardiovascular mortality in hemodialysis patients versus the continuing potential for success in peritoneal dialysis patients becomes comprehensible. In the former, apoB is characteristically not elevated and therefore apoB-lowering therapy can have only limited effect; in the latter, apoB is characteristically high and therefore apoB-lowering therapy might have considerable clinical benefit. Nevertheless, plaque rupture is only one mechanism leading to cardiac death. In addition to those previously noted, a new mechanism is suggested for consideration-recurrent reperfusion injury. The coronaries of dialysis patients are often narrowed, the microcirculation underdeveloped, and the left ventricle hypertrophied-all of these plus transient hypotension could produce severe ischemia followed by reperfusion necrosis. The minor but common elevations of troponin that are so well known yet widely disregarded may be markers of an adverse sequence of events that could each trigger a fatal arrhythmia and tend to reduce left ventricular function. Thus sudden death due to arrhythmia and slow progressive death due to heart failure could be manifestations of reperfusion injury. 10.2215/CJN.06300909
    Comparison of myocardial perfusion during hemodialysis and hemodiafiltration. De Andrade Roger,Kotze Tessa,Lesosky Maia,Swanepoel Charles Nephron. Clinical practice BACKGROUND:We compared myocardial perfusion in patients first on conventional hemodialysis (HD) and then on hemodiafiltration (HDF). METHODS:Myocardial perfusion scintigraphy was performed in 25 patients pre- and post-HD. Patients were then converted to HDF for 3 months prior to repeating the scintigraphy. (99m)Tc-methoxyisobutylisonitrile was administered intravenously pre-dialysis and then within the last hour of dialysis. Up to 90 min after injection, tomographic images were obtained. Clinical and laboratory data were collected pre- and post-dialysis. RESULTS:Five patients did not complete the study. Patients entering the study were on average 41.7 years old and on HD for 4 years (median). The mean standard Kt/V for the two procedures was not statistically different (1.55 for HD and 1.48 for HDF). The mean substitution volume for HDF was 18.48 liters. There were no significant differences in changes in blood pressures between HD and HDF (p = 0.22). There were no significant differences in myocardial perfusion defects in patients on HD compared with those on HDF. During dialysis in both studies, the data showed a general trend to worsening of perfusion defects. CONCLUSIONS:There was no advantage of HDF over HD with no statistical difference in perfusion defects between HD and HDF. There was a trend to worsening of perfusion defects during dialysis in the majority on HD and HDF. Midweek dialysis perfusion scores appeared to be consistently lower than early-week dialysis, but this was not statistically significant. The pathogenesis of the defects may lie at a microcirculatory level. 10.1159/000360907
    Evaluation of skin microcirculation during hemodialysis. Mistrík Erik,Dusilová Sulková Sylvie,Bláha Vladimír,Kalousová Marta,Knízek Jirí,Moucka Petr,Herout Vladimír,Kadlec Mirko,Stilec Roman,Sobotka Lubos Renal failure BACKGROUND:Cardiovascular mortality in hemodialysis (HD) patients remains high despite improvements in HD technique such as dialysis adequacy, dialysis fluid purity, and membrane biocompatibility. Optimal fluid balance to maintain optimal hemodynamic stability during hemodialysis (HD) procedure is essential. At the present time, hemodynamic stability is conventionally assessed as stability of macrocirculation, especially as maintenance of systemic blood pressure with no attention paid to peripheral perfusion. Peripheral ischemic vascular disease represents a serious problem with high mortality and morbidity. We estimated skin microcirculation changes during HD using new device, Laser Doppler Line Scanner (Moor Instruments, Devon, UK). AIMS:The aims were to introduce the novel method of detection of skin perfusion changes during hemodialysis and to evaluate possible relationship of these to ultrafiltration as well as to selected biochemical characteristics. METHODS:In 36 hemodynamically stable patients, we performed paired measurements of skin blood flow in both hands before and during HD with registering the time of dialysis and the total ultrafiltration achieved. RESULTS:We found a significant decrease in a majority of the evaluated areas. However, the skin blood flow change was not homogenous as it decreased more on the fingers. CONCLUSION:To our knowledge, this is the first study when the microcirculatory changes during hemodialysis are demonstrated and evaluated in large skin surface area, and showing not only a decrease in a majority of areas but also the heterogeneity of the changes. 10.3109/08860220903375286
    Haemodialysis Impairs the Human Microcirculation Independent from Macrohemodynamic Parameters. Meinders Arend-Jan,Nieuwenhuis Laurens,Ince Can,Bos Willem-Jan,Elbers Paul W G Blood purification Hemodynamic changes during haemodialysis are common. Often these changes are associated with symptoms that are thought to be the result of reduced microcirculatory blood flow and oxygen delivery. The microcirculatory effect of hemodialysis is scarcely researched, though of possible influence on patient outcome. New techniques have become available to visualise and analyse microvascular blood flow. We performed an observational study using Sidestream Dark Field imaging, a microscopic technique using polarised light to visualise erythrocytes passing through sublingual capillaries, to analyse the effect of haemodyalisis on central microvascular blood flow. We showed that there is a substantial impairment of microvascular blood flow and a discrepancy between micro- and macro-vascular parameters. 10.1159/000380902
    ENDOTHELIAL DYSFUNCTION ASSESSED BY LASER DOPPLER POST-OCCLUSIVE HYPEREMIA IN CHRONIC KIDNEY DISEASE PATIENTS. Busila Irina,Onofriescu Mihai,Gramaticu Angelica,Hogas Simona,Covic Adrian,Florea Laura Revista medico-chirurgicala a Societatii de Medici si Naturalisti din Iasi UNLABELLED:This study was intended to investigate the microcirculation endothelial dysfunction through a laser Doppler method (PORH post-occlusive reactive hyperemia) in patients with chronic kidney disease. MATERIALS AND METHODS:The study included 299 patients diagnosed with chronic kidney disease, which were divided into three groups: hemodialysis patients, peritoneal dialysis patients and patients with chronic kidney disease stages 3-4. Endotelial dysfunction was assesed with the Laser Doppler Perfusion Monitor type device (Periflux System Monitor 5001). RESULTS:The values of the parameters we evaluated with postocclusive reactive hyperemia were altered in all patients with chronic kidney disease. In the dialysis groups there was no statistically significant correlation between parameters we tested by measuring PORH and the method of renal replacement therapy or dialysis duration. The same was observed in patients with pre-dialysis chronic kidney disease. CONCLUSIONS:Post-occlusive reactive hyperemia, a novel method for assessing endothelial dysfunction on the microcirculatory system and early marker of cardiovascular damage requires more studies to validate in patients advanced renal disfunction.
    Ultrafiltration rate is an important determinant of microcirculatory alterations during chronic renal replacement therapy. Veenstra Gerke,Pranskunas Andrius,Skarupskiene Inga,Pilvinis Vidas,Hemmelder Marc H,Ince Can,Boerma E Christiaan BMC nephrology BACKGROUND:Hemodialysis (HD) with ultrafiltration (UF) in chronic renal replacement therapy is associated with hemodynamic instability, morbidity and mortality. Sublingual Sidestream Dark Field (SDF) imaging during HD revealed reductions in microcirculatory blood flow (MFI). This study aims to determine underlying mechanisms. METHODS:The study was performed in the Medical Centre Leeuwarden and the Lithuanian University of Health Sciences. Patients underwent 4-h HD session with linear UF. Nine patients were subject to combinations of HD and UF: 4 h of HD followed by 1 h isolated UF and 4 h HD with blood-volume-monitoring based UF. Primary endpoint: difference in MFI before and after intervention. During all sessions monitoring included blood pressure, heartrate and SDF-imaging. TRIAL REGISTRATION NUMBER:NCT01396980. RESULTS:Baseline characteristics were not different between the two centres as within the HD/UF modalities. MFI was not different before and after HD with UF. Total UF did not differ between modalities. Median MFI decreased significantly during isolated UF [2.8 (2.5-2.9) to 2.5 (2.2-2.8), p = 0.03]. Baseline MFI of each UF session was correlated with MFI after the intervention (r  = 0.52, p = 0.006). CONCLUSION:During HD with UF or isolated HD we observed no changes in MFI. This indicates that non-flow mediated mechanisms are of unimportance. During isolated UF we observed a reduction in MFI in conjunction with a negative intravascular fluid balance. The correlation between MFI before and after intervention suggests that volume status at baseline is a factor in microvascular alterations. In conclusion we observed a significant decrease of sublingual MFI, related to UF rate during chronic renal replacement therapy. 10.1186/s12882-017-0483-z
    Prognostic Value of Coronary Flow Reserve in Patients with Dialysis-Dependent ESRD. Shah Nishant R,Charytan David M,Murthy Venkatesh L,Skali Lami Hicham,Veeranna Vikas,Cheezum Michael K,Taqueti Viviany R,Kato Takashi,Foster Courtney R,Hainer Jon,Gaber Mariya,Klein Josh,Dorbala Sharmila,Blankstein Ron,Di Carli Marcelo F Journal of the American Society of Nephrology : JASN Capillary rarefaction of the coronary microcirculation is a consistent phenotype in patients with dialysis-dependent ESRD (dd-ESRD) and may help explain their excess mortality. Global coronary flow reserve (CFR) assessed by positron emission tomography (PET) is a noninvasive, quantitative marker of myocardial perfusion and ischemia that integrates the hemodynamic effects of epicardial stenosis, diffuse atherosclerosis, and microvascular dysfunction. We tested whether global CFR provides risk stratification in patients with dd-ESRD. Consecutive patients with dd-ESRD clinically referred for myocardial perfusion PET imaging were retrospectively included, excluding patients with prior renal transplantation. Per-patient CFR was calculated as the ratio of stress to rest absolute myocardial blood flow. Multivariable Cox proportional hazards models, including age, overt cardiovascular disease, and myocardial scar/ischemia burden, were used to assess the independent association of global CFR with all-cause and cardiovascular mortality. The incremental value of global CFR was assessed with relative integrated discrimination index and net reclassification improvement. In 168 patients included, median global CFR was 1.4 (interquartile range, 1.2-1.8). During follow-up (median of 3 years), 36 patients died, including 21 cardiovascular deaths. Log-transformed global CFR independently associated with all-cause mortality (hazard ratio, 0.01 per 0.5-unit increase; 95% confidence interval, <0.01 to 0.14; P<0.001) and cardiovascular mortality (hazard ratio, 0.01 per 0.5-unit increase; 95% confidence interval, <0.01 to 0.15; P=0.002). For all-cause mortality, addition of global CFR resulted in risk reclassification in 27% of patients. Thus, global CFR may provide independent and incremental risk stratification for all-cause and cardiovascular mortality in patients with dd-ESRD. 10.1681/ASN.2015030301
    Microcirculatory alterations during continuous renal replacement therapy in ICU: A novel view on the 'dialysis trauma' concept. Pipili Chrysoula,Vasileiadis Ioannis,Grapsa Eirini,Tripodaki Elli-Sophia,Ioannidou Sophia,Papastylianou Adroula,Kokkoris Stelios,Routsi Christina,Politou Marianna,Nanas Serafeim Microvascular research OBJECTIVE:The purpose of this study was to evaluate microcirculation over 24 h renal replacement therapy (CRRT) in critically ill patients. METHODS:We conducted a single-center, prospective, observational study, measuring microcirculation parameters, monitored by near infrared spectroscopy (NIRS) before hemodiafiltration onset (H0), and at six (H6) and 24 h (H24) during CRRT in critically ill patients. Serum Cystatin C (sCysC) and soluble (s)E-selectin levels were measured at the same time points. Twenty-eight patients [19 men (68%)] were included in the study. RESULTS:Tissue oxygen saturation (StO2, %) [76.5 ± 12.5 (H0) vs 75 ± 11 (H6) vs 70 ± 16 (H24), p = 0.04], reperfusion rate, indicating endothelial function (EF, %/sec) [2.25 ± 1.44 (H0) vs 2.1 ± 1.8 (H6) vs 1.6 ± 1.4 (H24), p = 0.02] and sCysC (mg/L) [2.7 ± 0.8 (H0) vs 2.2 ± 0.6 (H6) vs 1.8 ± 0.8 (H24), p < 0.0001] significantly decreased within the 24 h CRRT. Change of EF positively correlated with changes of sCysC within 24 h CRRT (r = 0.464, p = 0.013) while in patients with diabetes the change of StO2 correlated with dose (r = − 0.8, p = 0.01). No correlation existed between hemoglobin and temperature changes with the deteriorated microcirculation indices. sE-Selectin levels in serum were elevated; no difference was established over the 24 h CRRT period. A strong correlation existed between the sE-Selectin concentration change at H6 and H24 and the mean arterial pressure change in the same period (r = 0.77, p < 0.001). CONCLUSIONS:During the first 24 h of CRRT implementation in critically ill patients, deterioration of microcirculation parameters was noted. Microcirculatory alterations correlated with sCysC changes and with dose in patients with diabetes. 10.1016/j.mvr.2015.09.004
    Changes in skeletal muscle microcirculation after a hemodialysis session correlates with adequacy of dialysis. Pipili Chrysoula,Grapsa Eirini,Tripodaki Elli-Sophia,Ioannidou Sophia,Manetos Christos,Parisi Maria,Nanas Serafim International journal of nephrology and renovascular disease BACKGROUND:Monitoring of the microcirculation may add additional information in terms of improving the adequacy of hemodialysis (HD) for patients. Withdrawal of liquid and complement activation during a HD session reduces the external pressure on the microcirculation and leads to an increased dilatation of the peripheral capillaries. The purposes of this study were to assess the effect of a single HD or hemodiafiltration session on the thenar microcirculation in patients with end-stage renal disease (ESRD) with or without diabetes, investigate the possible relationship between changes in the microcirculation and adequacy of dialysis (including Kt/V and parameters indicating secondary hyperparathyroidism), and compare microcirculation measurements obtained from patients with ESRD and those from healthy controls. METHODS:This pilot prospective observational study including eleven patients with ESRD on maintenance HD (nine men of mean age 73±10.5 years, ten [91%] with hypertension), nine patients with ESRD on maintenance hemodiafiltration (six men of mean age 65.5±13.2 years, five [55.5%] with diabetes and four [44.5%] with hypertension), and eight healthy volunteers. Two paired microcirculation assessments were recorded for each HD patient before and after a dialysis session. Near infrared spectroscopy and the vascular occlusion test were used to assess the microcirculation, and blood work samples were collected before and after dialysis when the pump slowed down. RESULTS:Patients with ESRD showed an increase in thenar cell metabolism at rest after a 4-hour HD session, and changes in cell metabolism correlated with the Kt/V of the session. Pre-dialysis tissue oxygen saturation over the 4-hour HD session correlated with pre-dialysis serum calcium and parathyroid hormones. Vascular reactivity was lower in ESRD patients receiving HD or hemodiafiltration than in healthy controls. CONCLUSION:Improvement in skeletal muscle microcirculation noted after a HD session was related to adequacy of dialysis. Evaluation of the microcirculation may provide additional information for management of patients on HD and identify novel targets for treatment. These preliminary findings need to be tested using a larger data set. 10.2147/IJNRD.S68639
    The systemic microcirculation in dialysis populations. Williams Jennifer,Gilchrist Mark,Strain David,Fraser Donald,Shore Angela Microcirculation (New York, N.Y. : 1994) In a rapidly expanding population of patients with chronic kidney disease, including 2 million people requiring renal replacement therapy, cardiovascular mortality is 15 times greater than the general population. In addition to traditional cardiovascular risk factors, more poorly defined risks related to uremia and its treatments appear to contribute to this exaggerated risk. In this context, the microcirculation may play an important early role in cardiovascular disease associated with chronic kidney disease. Experimentally, the uremic environment and dialysis have been linked to multiple pathways causing microvascular dysfunction. Coronary microvascular dysfunction is reflected in remote and more easily studied vascular beds such as the skin. There is increasing evidence for a correlation between systemic microvascular dysfunction and adverse cardiovascular outcomes. Systemic microcirculatory changes have not been extensively investigated across the spectrum of chronic kidney disease. Recent advances in non-invasive techniques studying the microcirculation in vivo in man are increasing the data available particularly in patients on hemodialysis. Here, we review current knowledge of the systemic microcirculation in dialysis populations, explore whether non-invasive techniques to study its function could be used to detect early stage cardiovascular disease, address challenges faced in studying this patient cohort and identify potential future avenues for research. 10.1111/micc.12613
    An observational study of microcirculation in dialysis patients and kidney transplant recipients. Yeh Yu Chang,Chao Anne,Lee Chih-Yuan,Lee Chen-Tse,Yeh Chi-Chuan,Liu Chih-Min,Tsai Meng-Kun European journal of clinical investigation BACKGROUND:Microcirculatory dysfunction contributes to acute and chronic kidney diseases. To the best of our knowledge, no study has compared differences in microcirculation among healthy volunteers, dialysis patients and kidney transplant recipients. MATERIALS AND METHODS:Sublingual microcirculation was examined using sidestream dark field imaging and was compared among 90 healthy volunteers, 40 dialysis patients and 40 kidney transplant recipients. The gender effect on microcirculation and the correlations among the microcirculation parameters, age, body mass index, heart rate and blood pressure were analysed. RESULTS:Total small vessel density, perfused small vessel density and the proportion of perfused small vessels were lower in the dialysis patients than in the healthy volunteers and kidney transplant recipients [total small vessel density; healthy volunteers vs. dialysis patients vs. kidney transplant recipients, 25·2 (2·3) vs. 22·8 (2·6) vs. 24·2 (2·9) mm/mm , P < 0·001]. Systolic blood pressure showed a weak negative correlation with the microvascular flow index scores in the healthy volunteers. By contrast, systolic blood pressure, diastolic blood pressure and mean arterial pressure showed weak positive correlations with proportion of perfused small vessels and the microvascular flow index scores in the dialysis patients. CONCLUSIONS:Microcirculatory dysfunction is noted in dialysis patients, and this alteration is ameliorated in KT recipients. The positive correlation between blood pressure and microcirculation in dialysis patients suggests that additional studies should investigate the optimal goal of blood pressure management for dialysis patients. 10.1111/eci.12784