Progression of coronary artery calcification in renal transplantation and the role of secondary hyperparathyroidism and inflammation

BACKGROUND AND OBJECTIVES

Transplantation should favorably affect coronary calcification (CAC) progression in dialysis; however, changes in CAC score in the individual patient are not reliably evaluated.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

The authors used special tables of reproducibility limits for each score level to study, by multislice computed tomography and biochemistries, the 2-year changes in CAC in 41 transplant patients (age 48 +/- 13 yr, 25 men, dialysis vintage 4.8 +/- 4.3 yr, underwent transplant 6.2 +/- 5.5 yr prior). Thirty balanced dialysis patients served as controls.

RESULTS

In the study group, Agatston score was stable, and C-reactive protein decreased, whereas fetuin and osteoprotegerin increased. In the control group, Agatston score increased, parathyroid hormone and phosphate decreased, and inflammation markers were persistently twice as high as in the study group. With regard to individual changes, 12.2% transplant patients worsened, compared with 56.6% of patients in dialysis (P < 0.0001). Patients without calcification at entry showed slower progression in transplantation (8.3%) than in dialysis (44.4%; P < 0.034), and the difference was similar to that observed in cases with CAC (17.6% versus 61.9%; P < 0.007). Discriminant analysis indicated parathyroid hormone, the modality of therapy (dialysis or transplantation), and erythrocyte sedimentation rate as the variables most associated with worsening.

CONCLUSIONS

Renal transplantation lowers but does not halt CAC progression. Inflammation and hyperparathyroidism are associated with progression in the populations studied.

Soluble α -Klotho Serum Levels in Chronic Kidney Disease

Transmembrane α-Klotho (TM-Klotho), expressed in renal tubules, is a cofactor for FGF23-receptor. Circulating soluble-α-Klotho (s-Klotho) results from TM-Klotho shedding and acts on Phosphate (P) and Calcium (Ca) tubular transport. Decreased TM-Klotho, described in experimental chronic kidney disease (CKD), prevents actions of FGF23 and lessens circulating s-Klotho. Thus, levels of s-Klotho could represent a marker of CKD-MBD. To evaluate the clinical significance of s-Klotho in CKD we assayed serum s-Klotho and serum FGF23 in 68 patients (age 58 ± 15; eGFR 45 ± 21 mL/min). s-Klotho was lower than normal (519 ± 183 versus 845 ± 330 pg/mL, P < .0001) in renal patients and its reduction was detectable since CKD stage 2 (P < .01). s-Klotho correlated positively with eGFR and serum calcium (Cas) and negatively with serum phosphate (Ps), PTH and FGF23. FGF23 was higher than normal (73 ± 51 versus 36 ± 11, P < .0002) with significantly increased levels since CKD stage 2 (P < .001). Our data indicate a negative effect of renal disease on circulating s-Klotho starting very early in CKD. Assuming that s-Klotho mirrors TM-Klotho synthesis, low circulating s-Klotho seems to reflect the ensuing of tubular resistance to FGF23, which, accordingly, is increased. We endorse s-Klotho as an early marker of CKD-MBD.

Calcitriol/calcifediol ratio: An indicator of vitamin D hydroxylation efficiency?

Background

Calcifediol (25D) availability is crucial for calcitriol (1,25D) synthesis, but regulation of vitamin D hydroxylases is majorly responsible for 1,25D synthesis. The net efficiency of vitamin D hydroxylases might be informative. We assume that the ratio between calcitriol and calcifediol (25D/1,25D) serum concentrations could suggest the vitamin D hydroxylation efficiency.

Methods

We evaluated 25D/1,25D in different patient populations: hemodialysis (HD, n = 76), CKD stage 2–5 (n = 111), renal transplant (TX, n = 135), patients with no renal disease (No-CKD, n = 290), and primary hyperparathyroidism (PHP, n = 20).

Results

The geometric mean of 1,25D/25D (pg/ng) averaged 1.11 (HD), 1.36 (CKD), 1.77 (TX), 2.22 (No-CKD), and 4.11 (PHP), with a progressive increment from HD to PHP (p-value for the trend <0.001). Each clinical condition elicited a significant effect on 25D/1,25D (p < 0.0001) and adjusted multivariate analysis indicated levels of Cas, Ps, PTH, and 25D as predictors of 25D/1,25D. Both in vitamin D deficient and replete subjects (25D< or ≥20 ng/ml) 25D/1,25D associated with each clinical condition (p < 0.0001) and mean values increased progressively from HD to PHP (p-values for the trend <0.0001). Regression analysis between 25D (substrate) and 25D/1,25D (efficiency) revealed an exponential negative correlation in No-CKD (r²Exp = 0.53, p < 0.001) with sharp increments of 25D/1,25D when 25D values are <20 ng/ml. At variance, in CKD (r²lin = 0.19) and in TX (r²lin = 0.32) the regression was linear as if, in case of deficit, some inhibition of the system were operating.

Conclusion and General significance

In conclusion 1,25D/25D can reflect the efficiency of vitamin D hydroxylases more than separate evaluation of 25D and 1,25D and can facilitate the therapeutic choices in different patient populations.

•

1,25D/25D ratio could represent an index of vitamin D hydroxylation efficiency.

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1,25D/25D ratio progressively increases from HD to CKD, TX, No-CKD and PHP.

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Each of these clinical conditions affected the value of the ratio.

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In selected populations 1,25D/25D ratio could guide substitutive therapeutic choices.

Copper and ceruloplasmin dyshomeostasis in serum and cerebrospinal fluid of multiple sclerosis subjects

Although many studies have been carried out in order to understand the implication of copper (Cu) in the pathogenesis of multiple sclerosis (MS), the exact role that this metal plays in the disease is not still clear. Because of the lack of information in this subject, the present study compared the serum and cerebrospinal (CSF) levels of copper in MS patients in respect to a control group, matched for age and sex, finding a significant increase of metal concentrations, in both biological fluids of MS subjects. To confirm the possible impairment of Cu metabolism, we analyzed ceruloplasmin (Cp) level and activity, seeing as this protein is an established peripheral marker in diseases associated with Cu imbalance. By comparing these two parameters between control and MS subjects, we found an increase of Cp levels, associated with a decrease in Cp activity, in the second group. By analysing these data, free copper levels were calculated, significantly increased in serum of MS subjects; the increase in free copper could be one of the predisposing factors responsible for the Cu altered levels in CSF of MS patients. At the same time, this alteration could be attributable to the inability to incorporate Cu by Cp, probably due to the high oxidative environment found in serum of MS patients. Overall, all these copper alterations may play a role in MS pathogenesis.

Interactions of sclerostin with FGF23, soluble klotho and vitamin D in renal transplantation

Relationships of Sclerostin, a bone anti-anabolic protein, with biomarkers of mineral bone disorders in chronic kidney disease are still unsettled, in particular in kidney transplant (KTR). In 80 KTR patients (31F/49M, 54.7±10.3 years) we studied the relationships of serum Sclerostin with eGFR, Calcium, Phosphate, Alkaline Phosphatase (AP), intact Parathyroid hormone (iPTH), soluble alpha-Klotho (sKlotho), intact Fibroblast Growth Factor 23 (iFGF23), 25-hydroxyvitamin D(25D) and 1,25-dihydroxyvitamin D (1,25D). Thirty healthy subjects (35.0±12.4 years, eGFR 109.1±14.1 ml /min/1,73m²) served as control for Sclerostin, iFGF23 and sKlotho. With a median eGFR of 46.3 mL/min/1.73m² (IQR, 36.2–58.3) our KTR had median Sclerostin levels of 23.7 pmol/L (IQR: 20.8–32.8), not different from controls (26.6 pmol/L, IQR: 22.0–32.2; p = n.s). Sclerostin correlated negatively with AP (r = -.251; p = 0.023) and positively with iFGF23 (r = .227; p = 0.017) and 25D (r = .214; p = 0.025). Age-adjusted multiple regression analysis identified AP and 1,25D as negative and 25D and sKlotho as positive best predictors of Sclerostin. No correlation was evident with eGFR. The negative correlation with AP confirms the direct anti-anabolic role of Sclerostin. The associations either negative or positive with iFGF23, sKlotho, and vitamin D metabolites suggest also a modulatory role in mineral homeostasis. In particular, the associations with iFGF23 (positive) and 1,25D (negative) underline the relevant inhibitory action of Sclerostin on vitamin D activation. In conclusion, Sclerostin levels in KTR are normal and influenced more by bone turnover than by eGFR. Its involvement with other hormones of mineral homeostasis (FGF23/Klotho and Vitamin D) is part of the sophisticated cross-talk between bone and the kidney.

Oxygen Extraction Ratio (OER) as a Measurement of Hemodialysis (HD) Induced Tissue Hypoxia: A Pilot Study

HD tissue hypoxia associates with organ dysfunctions. OER, the ratio between SaO₂ and central-venous-oxygen-saturation, could estimate oxygen requirements during sessions, but no data are available. We evaluated OER behavior in 20 HD patients with permanent central venous catheter (CVC) as vascular access. Pre-HD OER (33.6 ± 1.4%; M ± SE) was higher than normal (range 20–30%). HD sessions increased OER to 39.2 ± 1.5% (M ± SE; p < 0.05) by 30′ and to 47.4 ± 1.5% (M ± SE; p < 0.001) by end of treatment (delta 40%). During HD sessions of the long and short interdialytic intervals, OER values overlapped, suggesting no influence of patient’s hydration status shifts. OER increased (p < 0.05) after 30′ of isolated HD (zero ultrafiltration), but not during isolated ultrafiltration (zero dialysate flow), suggesting a role for blood-membrane-dialysate interaction, independent of volume reduction. In ten patients, individual variability of pre-HD OER was low and repeatable (maximum calculated difference over time 6.6%), and negatively correlated with HD-induced OER increments (r = 0.860; p < 0.005), suggesting a decline in the adaptive response along with resting OER increments. In 30 prevalent patients, adjusted multivariate analysis showed that pre-HD OER (HR = 0.88, CI 0.79–0.99, p = 0.028) and percent HD-induced OER (HR = 1.04, CI 1.01–1.08, p = 0.015) were both associated with mortality, with threshold values respectively <32% and >40%. In HD patients with CVC as vascular access, OER is a cheap, easily measurable and repeatable parameter useful to assess intradialytic hypoxia, and a potential biomarker of HD related stress and morbidity, helpful to recognize patients at increased risk of mortality.

Positioning novel biologicals in CKD-mineral and bone disorders

Renal osteodystrophy (ROD), the histologic bone lesions of chronic kidney disease (CKD), is now included in a wider syndrome with laboratory abnormalities of mineral metabolism and extra-skeletal calcifications or CKD-mineral and bone disorders (CKD-MBD), to highlight the increased burden of mortality. Aging people, frequently identified as early CKD, could suffer from either the classical age-related osteoporosis (OP) or ROD. Distinguishing between these two bone diseases may not be easy without bone biopsy. In any case, besides classical therapies for ROD, nephrologists are now challenged by the possibility of using new drugs developed for OP. Importantly, while therapies for ROD mostly aim at controlling parathyroid secretion with bone effects regarded as indirect, new drugs for OP directly modulate bone cells activity. Thus, their action could be useful in specific types of ROD. Parathyroid hormone therapy, which is anabolic in OP, could be useful in renal patients with low turnover bone disease. Denosumab, the monoclonal antibody against receptor activator of NF-κB ligand (RANK-L) that inhibits osteoclast activity and proliferation, could be beneficial in cases with high turnover bone. Use of romosozumab, the monoclonal antibody against sclerostin, which both stimulates osteoblasts and inhibits osteoclasts, could allow both anabolic and anti-resorptive effects. However, we should not forget the systemic role now attributed to CKD-MBD. In fact, therapies targeting bone cells activity could also result in unpredicted extra-bone effects and affect cardiovascular outcomes. In conclusion, the new biologicals established for OP could be useful in renal patients with either OP or ROD. In addition, their potential non-bone effects warrant investigation.

A new technique for measuring fistula flow using venous blood gas oxygen saturation in patients with a central venous catheter

Background

Doppler ultrasound (DU) monitoring early after arteriovenous fistula (AVF) creation allows the identification of low blood flow (Qa) requiring prompt revision, but it is costly (needs skilled operators and technical instruments) and is not available in all dialysis units. Therefore alternative first-line methods to measure Qa would be welcomed. We reasoned that once an AVF is created, an increment in central venous oxygen saturation (ScvO₂) is predictable and proportional to Qa.

Methods

Accordingly, in patients receiving dialysis through a central venous catheter (CVC) in whom an AVF was created, we measured, by means of blood gas analysis, the ScvO₂ increment before and after manual compression of the arteriovenous shunt and verified its correlation with DU-measured Qa.

Results

We sampled blood gas in 18 patients with CVC and AVF before and after 30 s manual compression of the AVF. ScvO₂ averaged 70.5 ± 3% before and 65.2 ± 3% after AVF closure, with an average drop of 5.1 ± 3% (range 1-12). AVF Qa, which was measured within 24 h by means of DU, averaged 635 ± 349 mL/min (range 50-1300) and was strictly and positively correlated with ΔScvO₂ (r = 0.954, P < 0.0001).

Conclusions

Therefore we suggest that in patients with CVC and a newly created AVF, it is possible to monitor AVF Qa without DU by simply measuring blood gas and ΔScvO₂. This technique is simple, cheap, repeatable, non-invasive and operator independent and represents a new useful screening test to detect delayed AVF access maturation deserving prompt DU measurement and surgical revision. It helps to quickly identify patients in urgent need of DU verification and possible surgical revision. Regrettably, it is applicable only in patients with CVC.

Association between Cognitive Impairment and Malnutrition in Hemodialysis Patients: Two Sides of the Same Coin

Cognitive impairment and malnutrition are prevalent in patients on hemodialysis (HD), and they negatively affect the outcomes of HD patients. Evidence suggests that cognitive impairment and malnutrition may be associated, but clinical studies to assess this association in HD patients are lacking. The aim of this study was to evaluate the association between cognitive impairment evaluated by the Montreal Cognitive Assessment (MoCA) score and nutritional status evaluated by the malnutrition inflammation score (MIS) in HD patients. We enrolled 84 HD patients (44 males and 40 females; age: 75.8 years (63.5-82.7); HD vintage: 46.0 months (22.1-66.9)). The MISs identified 34 patients (40%) as malnourished; the MoCa scores identified 67 patients (80%) with mild cognitive impairment (MCI). Malnourished patients had a higher prevalence of MCI compared to well-nourished patients (85% vs. 70%; p = 0.014). MoCa score and MIS were negatively correlated (rho:-0.317; p < 0.01). Our data showed a high prevalence of MCI and malnutrition in HD patients. Low MoCA scores characterized patients with high MISs, and malnutrition was a risk factor for MCI. In conclusion, it is plausible that MCI and malnutrition are linked by common sociodemographic, clinical, and biochemical risk factors rather than by a pathophysiological mechanism.

[Understanding the different functions of vitamin D]

Exposure of the skin to sunlight is now considered the most important source of vitamin D in Western countries. It is presumed to contribute approximately two thirds of the total requirement, leaving the remaining one third to the few foods naturally rich in this vitamin. In the skin, vitamin D is synthesized as a cholesterol chain which undergoes structural modifications following exposure to UVB rays. Once produced in the skin or absorbed in the gut as cholecalciferol, vitamin D enters the blood to be transported by a specific vitamin D binding protein, which is synthesized in the liver and has a powerful buffering capacity. The transport system carries the metabolites to the sites of further activation (25-hydroxylation in the liver and 1alpha-hydroxylation in the kidney), ultimately resulting in the production of calcitriol. This last compound, now regarded as a hormone, circulates freely in minimal amounts and, compared with the other metabolites, shows the highest affinity for the vitamin D receptor (VDR). The mechanism of VDR activation is rather complex, resulting in either stimulation or inhibition of protein synthesis. Importantly, besides its presence in parathyroid, bone, kidney and intestine, this receptor has been demonstrated in several tissues, where its stimulation results in a reduced proliferation rate and increased differentiation. Accordingly, vitamin D is now regarded as a complex hormonal system, involved not only in the regulation of divalent ions and bone, but also in the proliferation and differentiation of numerous cell types with potential involvement in several diseases like cancer, immune diseases, diabetes, hypertension and heart failure.

MO821OXYGEN EXTRACTION RATIO AND MORTALITY RISK IN HAEMODIALYSIS PATIENT: A MULTICENTRE STUDY

Background and Aims

Patients on haemodialysis (HD) suffer a very high rate of cardiovascular mortality with some evidence suggesting a possible association with decreasing blood oxygen saturation (SO2) during sessions. The ratio between arterial SO2 (SaO2) and central venous SO2 (ScvO2) or Oxygen Extraction Ratio (OER), which represents an estimate of the amount of oxygen claimed by peripheral tissues and of the haemodialysis related hypoxic stress, might represent a new prognostic factor.

Method

We evaluate the relationship between OER values and mortality risks in HD patients in a prospective multicentre observational study. We enrolled chronic HD patients with permanent central venous catheter (CVC) and no fistula, in whom ScvO2 measurement is at hand and SaO2 is available with a peripheral oxymeter. OER ([(SaO2−ScvO2)/SaO2]×100) was measured before and after HD at enrolment (HD OER sessions) in each patients, and a one-year follow-up was planned to record the number of deaths.

Results

In 101 patients (age 71.5 ± 14 years on dialysis for 47 ± 38 months), during 9 ± 6 months of follow up, we recorded 35 deaths. Patients were then divided into two groups, above or below the median value of pre-HD OER, which was 30%. In these groups, the average incidence of deaths was 12% (24 deaths) and 5,5% (11 deaths) respectively (p&lt;0.05), with significantly different survival curves (Kaplan-Meier log rank test = 0.04, fig). No difference in mortality was evident if we divided patients according to the median intradialytic change in OER value.

Conclusion

Patients with pre-HD OER &gt; 30% have a higher mortality risk, most probably secondary to reduced capability to respond to HD related oxygen requirements. OER is novel biomarker to identify patients at greatest clinical risk.

Oxygen extraction ratio to identify patients at increased risk of intradialytic hypotension

Intradialytic hypotension (IDH) is a hemodynamic phenomenon recently associated with decreased blood oxygen saturation (SO₂). The ratio between peripheral oxygen saturation (SpO₂) and central venous SO₂ (ScvO₂) or Oxygen Extraction Ratio (OER), which represents a roughly estimate of the amount of oxygen claimed by peripheral tissues, might be used to estimate haemodialysis (HD) related hypoxic stress. Aim of this pilot study was to evaluate the relationship between OER increments during dialysis sessions (ΔOER) and episodes of IDH. We enrolled chronic HD patients with permanent central venous catheter (CVC) and no fistula, in whom ScvO₂ measurement is at hand. OER ([(SpO₂ − ScvO₂)/SpO₂] × 100) was measured in three consecutive HD sessions (HD OER sessions) before HD, after 15′, 30′ and 60′ min and at the end of HD. Then, a one-year follow-up was planned to record the number of IDH episodes. In the 28 enrolled patients (age 74 ± 2.6 years), during 12 ± 1.2 months of follow up, incidence of IDH was 3.6%. We divided patients into two groups, above or below the median value of ΔOER at the end of HD, which was 36%. In these groups, the average incidence of IDH was 7% and 2% respectively (p < 0.01), while OER values before HD were not different. Notably, in the high ΔOER group the OER increment was evident since after 15′ and was significantly higher than in the low ∆OER group (∆OER-15′ = 19 ± 3.0% vs. 9.0 ± 3.0%; p < 0.05). By comparison, blood volume changes overlapped in the two groups (average change − 9 ± 0.8%). Values of ∆OER > 19% after only 15′ of HD treatment or > 36% at the end of the session characterize patients with higher rates of hypotension. Intradialytic ∆OER, a parameter of tissue hypoxic stress, identifies more fragile patients at greater risk of IDH.

[Update on the pathogenesis and possible therapeutic approach to vascular calcifications in patients with chronic renal failure]

Chronic renal failure is a well-known risk condition for cardiovascular disease and in particular vascular calcifications. In fact, with respect to the normal population, where only ''classic'' risk factors have been described, kidney patients also have non-classic risk conditions. Among these, alterations in divalent ions, parathyroid hormone and vitamin D are of utmost importance. Further, several substances are recognized to have inhibitory or inductive effects in the pathogenesis of vascular calcifications, affecting either the calcium salts precipitation phenomenon or the phenotypic transformation of vascular smooth muscle cells into osteoblast-like cells (the latter phenomenon being regarded as a determinant of calcification of the tunica media). Given that vascular calcifications are irreversible, therapeutic strategies are aimed at preventing their formation or at blunting their progression (which is especially accelerated in renal patients). For this purpose it is essential to pursue optimal biochemical control of secondary hyperparathyroidism, but we must consider that in the individual patient the choice of drugs and their dosage can be essential for the development of calcifications. Given the physiological importance of inhibitory substances, we can hypothesize their future use in this setting. Finally, we must consider that by administering drugs known to interfere with inhibitors (like warfarin) or with the normal process of mineralization (like bisphosphonates), we can hypothetically favor or respectively prevent vascular calcifications.

P1020ROLE OF CHRONIC KIDNEY DISEASE AND ASSOCIATED BIOCHEMICAL ALTERATION ON ARTERIAL STIFFNESS IN T2 DIABETIC PATIENTS WITHOUT CARDIOVASCULAR DISEASE

Background and Aims

DMT2 and its complications such as chronic kidney disease (CKD) lead to increase vascular stiffness, measurable with CAVI, and biochemical alterations in substances implicated in vascular damage like Klotho, FGF23, and Sclerostin. The aim of the study was to evaluate the role of CKD stage 1-2 and possible alterations of 25 (OH)Vitamin-D, FGF23, Klotho, and Sclerostin on early vascular damage in DMT2 patients

Method

Patients included: DMT2 from &lt;10 years, age &lt;60 years, no insulin therapy, eGFR≥60 ml/min/1.73m2, absence of vascular complications. We have evaluated CAVI, albumin-excretion-rate (ACR), 25(OH)Vitamin-D, Klotho, FGF23, and Sclerostin. 30 healthy subjects were the control for CAVI, Klotho, FGF23 and Sclerostin.

Results

We enrolled 40 women and 60 men, average age 56 years (IQR: 52-59), 5-year DMT2 (IQR: 2.7-7), HbA1c 6.3% (5.8-6.7), eGFR of 95 ml/min/1.73m2. FGF23 (42±10 vs controls 29.8±11 pmol/l, p&lt;.05) and Sclerostin (36.2±7 vs 26.6±1 pmol/l, p&lt;.05) were increased and Klotho reduced (673±300 vs 845±330 pg/ml, p&lt;.05). CKD (ACR≥30mg/gr; eGFR between 60-90 ml/min /1.73m2) was present in 12.6%. The mean CAVI value was normal. Patients with borderline (≥8, 33%) and pathological (≥9, 13%) CAVI were older (p.001), with longer duration of DMT2 (p.022) and lower 25(OH)Vitamin-D (p.041). CAVI correlated positively with age (p.001), Hb1Ac (p.036), systolic blood pressure (SBP) (p.012) and diastolic blood pressure (DBP) (p.001) and correlated negatively with 25(OH)Vitamin-D (p.046). The multivariate analysis showed positive predictors of CAVI age (p.001), DBP (p.0001), ACR (p.008) and Klotho (p.017).

Conclusion

In our DMT2 population, borderline and pathological CAVI is associated with increased ACR, elevated DBP and reduced 25(OH)Vitamin-D. Furthermore the alterations of FGF23, Sclerostin and Klotho, secondary to CKD, are an early sign of possible vascular damage. ACR, 25(OH)Vitamin-D and DBP can be modifiable risk factors for early vascular damage in DMT2

P1435RELATIONSHIP BETWEEN INTRA-DIALYTIC OXYGEN EXTRACTION RATIO (OER) CHANGE AND IDH

Background and Aims

Intradialytic hypotension (IDH) involves a reduced tolerance to hemodialysis (HD), a poor quality of life and is associated with mortality. Intradialytic monitoring systems (blood pressure, heart rate, volemia) are not able to identify patients at greater risk of IDH. IDH is a hemodynamic phenomenon and attention has recently been given to the evaluation of oxygen saturation to evaluate its role in IDH. Oxygen Extraction Ratio (OER), the ratio between SaO2 and ScvO2, is a parameter used to monitor parenchyma oxygen consumption and stress. Recent evidence showed that HD patients with a greater delta OER (ΔOER) during HD (threshold 40%)had higher mortality risk. OER could be a new monitoring instrument to measure hemodialysis induced sub-clinical parenchyma hypoxia and stress, two elements included in the pathogenesis of IDH. The aim of the study was to evaluate the relationship between OER and IDH incidence.

Method

Inclusion criteria: age ≥18 years, chronic HD treatment by means of permanent jugular CVC, no evidence of acute underlying illness. We evaluated OER ([(SaO2 − ScvO2)/SaO2] × 100) before HD and at 15’, 30’, 60’ and post HD in three HD sessions (HD OER sessions). For the statistic analysis we considered for each patient the median OER value obtained from the three HD OER sessions. Then we started the follow-up study with a minimum follow-up of three months and end follow-up of two years, to record IDH (defined according to K/DOQI guidelines) for each patient. We divided the population in two groups using as a threshold the median percentage number of IDH in our population and evaluate the differences between the obtained two groups in pre HD OER, Delta OER and intradialytic OER trends.

Results

During the follow-up period (mean 12 ± 1.2 months), we enrolled 28 patients with permanent jugular CVC: 13 males and 15 females, aged 74±2.6 years, HD vintage 46 ± 6.5 months. The HD OER sessions for each patient were asymptomatic. Pre HD OER was 34 ± 1.4, post HD OER 46 ± 1.8, with a Delta OER of 39 ± 5 %. OER change during HD was evident since after 15 minutes (OER% 15’: 40 ± 1.2 p&lt;.001) and continued to increase progressively (OER% end HD 46 ± 1.8; p&lt;.0001). During the follow up period we monitored 4342 HD sessions of which 186 with IDH, the median incidence of IDH was 3.6% of all HD sessions. We divided patients into two groups based on the median value of IDH incidence: (IDH % ≤ 3.6 and IDH % &gt; 3.6). The two groups were not different for age (76 ± 2.4 vs 73 ± 3.0 years; p &lt;ns), HD vintage (52 ± 8.6 vs 40 ± 4.0 months; p &lt;ns), systolic (125 ± 3.2 vs 129 ± 4.0 mmHg; p &lt;ns) and diastolic blood pressure (67 ± 2.2 vs 70 ± 2.2 mmHg; p &lt;ns) and heart rate (70 ± 2.2 vs. 76 ± 2.3 bpm; p &lt;ns) (Tab. 2). The IDH % &gt;3.6 group had 159 IDH out of a total of 1911 sessions (9%), while IDH % ≤ 3.6 group had 27 IDH out of 2431 sessions (0.9%). Pre HD OER values were not different between the groups while the IDH % &gt;3.6 group had greater delta OER% than the IDH % ≤ 3.6 group (43 ± 4.8 vs. 35 ± 3.0 %; p &lt;.05) (Figure). Evaluating the OER trend during HD session a higher ΔOER% was found at 15 minutes of HD treatment in the IDH % &gt; 3.6 group (ΔOER 20± 3.0 % vs. 8.0 ± 3.0 %; IDH % &gt; 3.6 group vs. IDH % ≤ 3.6 group, p &lt;.05), data confirmed at 30' (24 ± 3.0 % vs. 13 ± 5.0 %; p &lt;.05), and post HD (43 ± 5.0 % vs 35 ± 3.0 %; p &lt;.05), but not at 60 minutes of HD treatment (19 ± 4.0 % vs. 17 ± 4.6 %; p &lt;ns).

Conclusion

Our data show that intradialytic ΔOER, representative of the extent of tissue hypoxic stress, identifies patients at greater risk of IDH. In particular, a ΔOER of 20% after the first 15 minutes of HD and of 43% at the end of the HD session characterizes the more hemodynamically fragile patients. The measurement of the OER can be a new and easy monitoring instrument to identify the most hemodynamically fragile patients already after the first 15 minutes of HD treatment.

Diastolic Pressure and ACR Are Modifiable Risk Factors of Arterial Stiffness in T2DM Without Cardiovascular Disease

AIM

To evaluate early, before the onset of cardiovascular events and of chronic renal insufficiency, the association between chronic kidney disease (CKD)-mineral bone disorder (MBD) biomarkers and vascular stiffness [Cardio Ankle Vascular Index (CAVI)] in the course of type 2 diabetes (T2DM).

METHOD

We evaluated 174 T2DM patients [median age 56 years; male/female (M/F) 100/74] with diabetes duration < 10 years and without decreased estimated glomerular filtration rate (eGFR; ≥60 mL/min/1.73 m2) or macrovascular complications. Thirty-four age-matched healthy subjects [M/F 13/21; age 53.5 (50.0-57.7) years; eGFR 107.5 (97.0-119.7) mL/ min1.73 m2] served as local reference control for CAVI (pathological: ≥8) and the novel CKD-MBD biomarkers.

RESULTS

Albumin-to-creatinine ratio (ACR) averaged 8.5 mg/g (5.6-17.2) with 12.6% of the patients showing pathologic values, indicative of incipient diabetic nephropathy. Serum parathyroid hormone, fibroblast growth factor 23, and sclerostin were higher while 1,25-dihydroxyvitamin D and Klotho were lower than a control group. CAVI was normal (<8) in only 54% and correlated positively with age (P < 0.001), hemoglobin 1A1c (P = 0.036), and systolic (P = 0.021) and diastolic blood pressure (DBP) (P = 0.001) and negatively correlated with 25-hydroxyvitamin D (P = 0.046). In multivariate analysis, age, DBP, ACR, and serum Klotho were independent positive predictors of CAVI.

CONCLUSION

In the absence of overt cardiovascular disease and of chronic renal insufficiency, CAVI is frequently pathologic in T2DM. DBP and ACR are modifiable risk factors of vascular stiffness in T2DM, thus warranting optimal assessment.