Vitamin K is essential for the activity of γ-carboxyglutamate (Gla)-proteins including matrix Gla28 protein and osteocalcin; an inhibitor of vascular calcification and a bone matrix protein, respectively. Insufficient vitamin K intake leads to the production of non-carboxylated, inactive proteins and this could contribute to the high risk of vascular calcification in hemodialysis patients. To help resolve this, we measured vitamin K(1) and K(2) intake (4-day food record), and the vitamin K status in 40 hemodialysis patients. The intake was low in these patients (median 140 μg/day), especially on days of dialysis and the weekend as compared to intakes reported in a reference population of healthy adults (mean K(1) and K(2) intake 200 μg/day and 31 μg/day, respectively). Non-carboxylated bone and coagulation proteins were found to be elevated in 33 hemodialysis patients, indicating subclinical hepatic vitamin K deficiency. Additionally, very high non-carboxylated matrix Gla28 protein levels, endemic to all patients, suggest vascular vitamin K deficiency. Thus, compared to healthy individuals, hemodialysis patients have a poor overall vitamin K status due to low intake. A randomized controlled trial is needed to test whether vitamin K supplementation reduces the risk of arterial calcification and mortality in hemodialysis patients.

The initiation of hemodialysis is associated with an accelerated decline of cognitive function and an increased incidence of cerebrovascular accidents and white matter lesions. Investigators have hypothesized that the repetitive circulatory stress of hemodialysis induces ischemic cerebral injury, but the mechanism is unclear. We studied the acute effect of conventional hemodialysis on cerebral blood flow (CBF), measured by [O]HO positron emission tomography-computed tomography (PET-CT). During a single hemodialysis session, three [O]HO PET-CT scans were performed: before, early after the start of, and at the end of hemodialysis. We used linear mixed models to study global and regional CBF change during hemodialysis. Twelve patients aged ≥65 years (five women, seven men), with a median dialysis vintage of 46 months, completed the study. Mean (±SD) arterial BP declined from 101±11 mm Hg before hemodialysis to 93±17 mm Hg at the end of hemodialysis. From before the start to the end of hemodialysis, global CBF declined significantly by 10%±15%, from a mean of 34.5 to 30.5 ml/100g per minute (difference, -4.1 ml/100 g per minute; 95% confidence interval, -7.3 to -0.9 ml/100 g per minute; =0.03). CBF decline (20%) was symptomatic in one patient. Regional CBF declined in all volumes of interest, including the frontal, parietal, temporal, and occipital lobes; cerebellum; and thalamus. Higher tympanic temperature, ultrafiltration volume, ultrafiltration rate, and pH significantly associated with lower CBF. Thus, conventional hemodialysis induces a significant reduction in global and regional CBF in elderly patients. Repetitive intradialytic decreases in CBF may be one mechanism by which hemodialysis induces cerebral ischemic injury.

Summary Background and objectives The hemodialysis procedure may acutely induce regional left ventricular systolic dysfunction. This study evaluated the prevalence, time course, and associated patient- and dialysis-related factors of this entity and its association with outcome. Design, setting, participants, & measurements Hemodialysis patients (105) on a three times per week dialysis schedule were studied between March of 2009 and March of 2010. Echocardiography was performed before dialysis, at 60 and 180 minutes intradialysis, and at 30 minutes postdialysis. Hemodialysis-induced regional left ventricular systolic dysfunction was defined as an increase in wall motion score in more than or equal to two segments. Results Hemodialysis-induced regional left ventricular systolic dysfunction occurred in 29 (27%) patients; 17 patients developed regional left ventricular systolic dysfunction 60 minutes after onset of dialysis. Patients with hemodialysis-induced left ventricular systolic dysfunction were more often male, had higher left ventricular mass index, and had worse predialysis left ventricular systolic function (left ventricular ejection fraction). The course of blood volume, BP, heart rate, electrolytes, and acid–base parameters during dialysis did not differ significantly between the two groups. Patients with hemodialysis-induced regional left ventricular systolic dysfunction had a significantly higher mortality after correction for age, sex, dialysis vintage, diabetes, cardiovascular history, ultrafiltration volume, left ventricular mass index, and predialysis wall motion score index. Conclusions Hemodialysis induces regional wall motion abnormalities in a significant proportion of patients, and these changes are independently associated with increased mortality. Hemodialysis-induced regional left ventricular systolic dysfunction occurs early during hemodialysis and is not related to changes in blood volume, electrolytes, and acid–base parameters.

Background: Intradialytic hypotension (IDH) is considered to be a frequent complication of hemodialysis (HD) and is associated with symptom burden, increased incidence of access failure, cardiovascular events, and higher mortality. This systematic literature review aims to analyse studies that investigated the prevalence of IDH. A complicating factor herein is that many different definitions of IDH are used in literature. Methods: A systematic literature search from databases, Medline, Cinahl, EMBASE, and the Cochrane library to identify studies reporting on the actual prevalence of IDH was conducted. Studies were categorized by the type of definition used for the prevalence of IDH. A meta-analysis of the prevalence of IDH was performed. Results: In a meta-analysis comprising 4 studies including 1,694 patients and 4 studies including 13,189 patients, the prevalence of HD sessions complicated by IDH was 10.1 and 11.6% for the European Best Practice Guideline (EBPG) definition and the Nadir <90 definition, respectively. The proportion of patients with frequent IDH could not reliably be established because of the wide range in cutoff values that were used to identify patients with frequent IDH. There was a large variety in the prevalence of symptoms and interventions. Major risk factors associated with IDH across studies were diabetes, a higher interdialytic weight gain, female gender, and lower body weight. Conclusion: Our meta-analysis suggests that the prevalence of IDH is lower than 12% for both the EBPG and the Nadir <90 definition which is much lower than stated in most reviews.

Near-infrared spectroscopy (NIRS) is used to monitor cerebral tissue oxygenation (rSO 2 ) depending on cerebral blood flow (CBF), cerebral blood volume and blood oxygen content. We explored whether NIRS might be a more easy applicable proxy to [ 15 O]H 2 O positron emission tomography (PET) for detecting CBF changes during hemodialysis. Furthermore, we compared potential determinants of rSO 2 and CBF. In 12 patients aged ! 65 years, NIRS and PET were performed simultaneously: before (T1), early after start (T2), and at the end of hemodialysis (T3). Between T1 and T3, the relative change in frontal rSO 2 (DrSO 2 ) was À8 AE 9% (P ¼ 0.001) and À5 AE 11% (P ¼ 0.08), whereas the relative change in frontal gray matter CBF (DCBF) was À11 AE 18% (P ¼ 0.009) and À12 AE 16% (P ¼ 0.007) for the left and right hemisphere, respectively. DrSO 2 and DCBF were weakly correlated for the left (r 0.31, P ¼ 0.4), and moderately correlated for the right (r 0.69, P ¼ 0.03) hemisphere. The Bland-Altman plot suggested underestimation of DCBF by NIRS. Divergent associations of pH, pCO 2 and arterial oxygen content with rSO 2 were found compared to corresponding associations with CBF. In conclusion, NIRS could be a proxy to PET to detect intradialytic CBF changes, although NIRS and PET capture different physiological parameters of the brain.