Changes in skeletal muscle microcirculation after a hemodialysis session correlates with adequacy of dialysis

Chrysoula Pipili,1 Eirini Grapsa,1 Elli-Sophia Tripodaki,1 Sophia Ioannidou,2 Christos Manetos,1 Maria Parisi,1 Serafim Nanas1 1First Critical Care Department, 2Laboratory of Biochemistry, Evangelismos General Hospital, National and Kapodistrian University of Athens, Athens, Greece 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. Keywords: hemodiafiltration, near infrared spectroscopy, end stage renal disease, single-pool Kt/V&nbsp

Attenuated microcirculatory response to maximal exercise in patients with chronic heart failure

PURPOSE: Exercise training programs improve microcirculatory alternations in patients with chronic heart failure (CHF). However less is known about the acute effect of maximum exercise on the skeletal muscle microcirculation. We aimed to assess the effect of acute exercise on peripheral microcirculation of patients with CHF, as assessed by near-infrared spectroscopy with vascular occlusion technique. METHODS: Tissue oxygenation was evaluated in 8 stable patients with CHF (7 males; mean age, 60) 9 years; body mass index, 26.3) 3.8 kg/m2 ) and 8 healthy subjects (matched for age, sex, and body mass index) before and after cardiopulmonary exercise testing. Tissue oxygen saturation (StO 2 ), StO 2peak , oxygen consumption rate, and endothelial function (reperfusion rate), before and after maximum exercise, were assessed. RESULTS: Patients with CHF had lower StO 2 and reperfusion rate compared with healthy subjects (71.4%) 9.8% vs 81.0%) 5.4% and 9) 1 %/min vs 13.9) 5.8%/min, respectively; P < .05) at rest. Oxygen consumption rate increased after exercise in patients with CHF and healthy subjects (from - 31.7) 8.2 to - 43.7) 12.7 and from - 35.7) 6.7 to - 42.4) 6.4, respectively; P < .05). StO2decreased significantly after maximal exercise in patients with CHF (from 71.4) 9.8 to 65.2) 12.7; P < .05), whereas it returned to the preexercise values in healthy subjects (from 81.0) 5.4 to 80.3) 7.0). There was a significant between-group difference ( P < .05). CONCLUSIONS: Patients with CHF present microcirculatory alternations. Acute exercise exerts an effect on microcirculation in peripheral, nonexercising muscles, with altered response in patients with CHF compared with healthy subjects. Copyright © 2016 Wolters Kluwer Health, Inc

Muscle microcirculation alterations and relation to dipping status in newly diagnosed untreated patients with arterial hypertension—A pilot study

Objective: The importance of abnormalities observed in the microcirculation of patients with arterial hypertension (AH) is being increasingly recognized. The authors aimed to evaluate skeletal muscle microcirculation in untreated, newly diagnosed hypertensive patients with NIRS, a noninvasive method that evaluates microcirculation. Methods: We evaluated 34 subjects, 17 patients with AH (13 males, 49±13 years, BMI: 26±2 kg/m2) and 17 healthy controls (12 males, 49±15 years, BMI: 25±3 kg/m2). The thenar muscle StO2 (%) was measured by NIRS before, during and after 3-minutes vascular occlusion to calculate OCR (%/min), EF (%/min), and RHT (minute). The dipping status of hypertensive patients was assessed. Results: The RHT differed between AH patients and healthy subjects (2.6±0.3 vs 2.1±0.3 minutes, P<.001). Dippers had higher EF than nondippers (939±280 vs 710±164%/min, P=.05). Conclusions: The study suggests an impaired muscle microcirculation in newly diagnosed, untreated AH patients. © 2017 John Wiley & Sons Lt

Hormonal imbalance in relation to exercise intolerance and ventilatory inefficiency in chronic heart failure

Background: Skeletal muscle wasting is associated with altered catabolic/anabolic balance and poor prognosis in patients with chronic heart failure (CHF). This study evaluated catabolic and anabolic abnormalities in relation to disease severity in CHF patients. Methods: Forty-two stable CHF patients (34 men; aged 56±12 years, body mass index, 27±5 kg/m2) receiving optimal medical treatment underwent incremental symptom-limited cardiopulmonary exercise testing on a cycle ergometer. Blood samples were drawn within 10 days to determine serum cortisol, plasma adrenocorticotropin (ACTH), and serum dehydroepiandrosterone sulfate, insulin-like growth factor 1, growth hormone, and total testosterone in men. Results: Patients with higher cortisol levels presented with impaired peak oxygen uptake (Vo2 peak: 18.3±3.9 vs 14.2±3.7 ml/kg/min, p<0.01), ventilatory (Ve) response to exercise (Ve/carbon dioxide output [Vco2] slope: 36±6 vs 30±5, p<0.01), and chronotropic reserve ([peak heart rate [HR] - resting HR/220 - age - resting HR]×100%: 40±19 vs 58±18, p=0.01) compared with those with lower serum cortisol. Cortisol was inversely correlated with Vo 2 peak, (r = -0.57; p<0.01) and was correlated with Ve/Vco 2 slope (r = 0.47; p<0.01) and chronotropic reserve (r = 0.44; p = 0.017). In multivariate regression analysis, cortisol was an independent predictor of Vo2peak (R2 = 0.365, F = 12.5, SE = 3.4; p≤0.001) and Ve/Vco2 slope (R2 = 0.154; F = 8.5; SE = 5.96; p = 0.006), after accounting for age, body mass index, sex, CHF etiology, creatinine, left ventricular ejection fraction, and ACTH in all patients. In men, cortisol and dehydroepiandrosterone levels were both independent predictors of Vo2peak (R2 = 0.595, F = 24.53, SE = 2.76; p<0.001) after accounting also for all measured hormones, whereas cortisol remained the only independent predictor of Ve/Vco2 slope (R2 = 0.133; F = 6.1; SE = 6.2; p = 0.02). Conclusions: Enhanced catabolic status is significantly associated with exercise intolerance, ventilatory inefficiency, and chronotropic incompetence in CHF patients, suggesting a significant contributing mechanism to their limited functional status. © 2013 International Society for Heart and Lung Transplantation

Skeletal muscle microcirculatory abnormalities are associated with exercise intolerance, ventilatory inefficiency, and impaired autonomic control in heart failure

Background: Several skeletal muscle abnormalities have been identified in patients with chronic heart failure (CHF), including endothelial dysfunction. We hypothesized that skeletal muscle microcirculation, assessed by near-infrared spectroscopy (NIRS), is impaired in CHF patients and is associated with disease severity. Methods: Eighty-three stable patients with mildmoderate CHF (72 males, mean age 54 ± 14 years, body mass index 26.7 ± 3.4 kg/m 2) and 8 healthy subjects, matched for age, gender and body mass index, underwent NIRS with the vascular occlusion technique and cardiopulmonary exercise testing (CPET) evaluation on the same day. Tissue oxygen saturation (StO 2, %), defined as the percentage of hemoglobin saturation in the microvasculature compartments, was measured in the thenar muscle by NIRS before, during and after 3-minute occlusion of the brachial artery. Measurements included StO 2, oxygen consumption rate (OCR, %/min) and reperfusion rate (RR, %/min). All subjects underwent a symptom-limited CPET on a cycle ergometer. Measurements included VO 2 at peak exercise (VO 2peak, ml/kg/min) and anaerobic threshold (VO 2AT, ml/kg/min), VE/VCO 2 slope, chronotropic reserve (CR, %) and heart rate recovery (HRR 1, bpm). Results: CHF patients had significantly lower StO 2 (75 ± 8.2 vs 80.3 ± 6, p < 0.05), lower OCR (32.3 ± 10.4 vs 37.7 ± 5.5, p < 0.05) and lower RR (10 ± 2.8 vs 15.7 ± 6.3, p < 0.05) compared with healthy controls. CHF patients with RR <9.5 had a significantly greater VO 2peak (p < 0.001), VO 2AT (p < 0.01), CR (p = 0.01) and HRR 1 (p = 0.01), and lower VE/VCO 2 slope (p = 0.001), compared to those with RR <9.5. In a multivariate analysis, RR was identified as an independent predictor of VO 2peak, VE/VCO 2 slope and HRR 1. Conclusions: Peripheral muscle microcirculation, as assessed by NIRS, is significantly impaired in CHF patients and is associated with disease severity. © 2011 International Society for Heart and Lung Transplantation. All rights reserved

Respiratory drive and breathing pattern abnormalities are related to exercise intolerance in chronic heart failure patients

Background: Patients with chronic heart failure (CHF) are characterized by exercise intolerance and ventilatory abnormalities that are related to poor prognosis. We hypothesized that CHF patients have increased respiratory drive and abnormal breathing pattern during exercise in relation to disease severity. Materials and methods: The study population consisted of 219 stable CHF patients and 30 healthy control subjects. All subjects underwent a symptom-limited cardiopulmonary exercise testing (CPET), pulmonary function tests, measurement of the maximal inspiratory pressure (PImax) and respiratory drive (P0.1).Measurements included peak oxygen uptake (VO2 peak, ml/kg/min). Respiratory drive was measured by mouth occlusion pressure P0.1 and P0.1/PImax ratio at rest, and by mean inspiratory flow (VT/TI) at rest and during exercise. CHF patients were divided into 3 groups according to VO2 peak (Group A: >20, Group B: 20-16 and Group C: <16ml/kg/min). Results: CHF patients presented higher P0.1/PImax (4.1±3.6 vs 3.0±1.5, p=0.007) and VT/TI at rest (0.48±0.14 vs 0.41±0.10, L/s respectively, p=0.004) and lower VT/TI at peak exercise (2.17±0.66 vs 2.56±0.73, L/s, p=0.009) compared to controls. P0.1/PImax was higher in CHF Group C vs B vs A (4.9±2.9 vs 3.6±1.8 vs 3.1±1.8, respectively, p<0.001), while VT/TI at peak exercise was lower (1.71±0.43 vs 2.15±0.52 vs 2.65±0.64, L/s, respectively, p<0.001). Conclusions: CHF patients present increased respiratory drive at rest and abnormal breathing pattern during exercise in relation to CHF severity. © 2013 Elsevier B.V

Chronotropic incompetence and abnormal heart rate recovery early after left ventricular assist device implantation

Background: Chronotropic response to exercise and heart rate recovery immediately after exercise (HRR1) are valid prognostic markers in patients with chronic heart failure (CHF). The aim of this study was to evaluate heart rate profile during and after exercise in CHF patients early after left ventricular assist device (LVAD) implantation. Methods: We enrolled seven stable consecutive CHF patients (five males, mean age: 45 ± 16 years) after 1 month of LVAD (HeartMate II; Thoratec Corp, Pleasanton, CA, USA) implantation, seven healthy subjects, and 14 patients with advanced HF (HF control group) who performed an incremental symptom-limited cardiopulmonary exercise testing (CPET). CHF patients performed CPET at 1 and 3 months after LVAD. HRR1 was defined as the HR difference from peak to 1 minute after exercise and chronotropic response to exercise as the chronotropic reserve ([CR, %]=[peak HR-resting HR/220-age-resting HR]à - 100). Results: LVAD patients 3 months after implantation had a significantly different HR profile during exercise compared to healthy controls, with significantly lower CR (57 ± 31 vs 90 ± 14, %, P < 0.001) and HRR 1 (14 ± 6 vs 28 ± 8, bpm, P < 0.01). HR profile during exercise did not significantly change 1 and 3 months after LVAD implantation. There was no statistical difference compared to HF control group and LVAD group regarding cardiopulmonary parameters. Conclusions: LVAD patients present an impaired CR and an abnormal HRR1 after implantation, indicating significant cardiac autonomic abnormalities. These alterations seem to remain unaltered 3 months after LVAD implantation. © 2011, The Authors. Journal compilation

Peripheral muscle microcirculatory alterations in patients with pulmonary arterial hypertension: A pilot study

Background: Pulmonary microcirculation abnormalities are the main determinants of pulmonary arterial hypertension (PAH) pathophysiology. We hypothesized that PAH patients have peripheral tissue microcirculation alterations that might benefit from hyperoxic breathing. We evaluated peripheral muscle microcirculation with near-infrared spectroscopy, before and after hyperoxic breathing. Methods: Eight PAH subjects, 8 healthy subjects (controls) matched for age, sex, and body mass index, and 16 subjects with chronic heart failure and matched for functional capacity with the PAH subjects underwent near-infrared spectroscopy. Tissue O2 saturation, defined as the hemoglobin saturation (%) in the microvasculature compartments, was measured on the thenar muscle. Then the 3-min brachial artery occlusion technique was applied before, during, and after 15 min of breathing 100% O2. We calculated the oxygen consumption rate (%/min), the reactive hyperemia time, and the time needed for tissue O2 saturation to reach its baseline value after the release of the occlusion. Results: Compared to the controls, the PAH subjects had a significantly lower resting tissue O2 saturation (65.8 ± 14.9% vs 82.1 ± 4.0%, P = .005), a trend toward a lower oxygen consumption rate (35.3 ± 9.1%/min vs 43.4 ± 19.7%/min, P = .60), and a significantly higher reactive hyperemia time (3.0 ± 0.6 min vs 2.0 ± 0.3 min, P <.001). The PAH subjects also had lower tissue O2 saturation (P =.08), lower peripheral arterial oxygen saturation (P = .01), and higher reactive hyperemia time (P = .02) than the chronic heart failure subjects. After hyperoxic breathing, the PAH subjects had increased tissue O2 saturation (65.8 ± 14.9% to 71.4 ± 14.5%, P =.01), decreased oxygen consumption rate (35.3 ± 9.1%/min to 25.1 ± 6.6%/min, P = .01), and further increased reactive hyperemia time (3.0 ± 0.6 min to 4.2 ± 0.7 min, P = .007). Conclusions: The PAH subjects had substantial impairments of peripheral muscle microcirculation, decreased tissue O2 saturation (possibly due to hypoxemia), slower reactive hyperemia time, (possibly due to endothelium dysfunction), and peripheral systemic vasoconstriction. Acute hyperoxic breathing improved resting tissue O2 saturation (an expression of higher oxygen delivery) and decreased the oxygen consumption rate and reactive hyperemia time during reperfusion, possibly due to increased oxidative stress and evoked vasoconstriction. © 2013 Daedalus Enterprises