The study subjects included 50 end-stage renal disease (ESRD) patients on hemodialysis (HD) who were recruited from HD units in Ain Shams University Hospitals, Cairo, Egypt.
This is a cross-sectional study.
Inclusion criteria and subject selection
Age ≥ 18 and ≤ 60 years and clinically stable chronic HD patients on thrice-weekly 4-h sessions on HD for at least 6 months before the study were included.
Diabetic patients; chronic liver disease patient’s Child-Pugh class B or C; smokers; history of evident cardiac, peripheral, vascular, or cerebrovascular insult as transient ischemic attacks or strokes; uncontrolled hypertension; severe anemia (HB < 8 g/dl); collagen disease; and active infection were excluded from the study.
Patients on HD for at least 6 months before the study, using a standard bicarbonate-containing dialysate and using biocompatible HD membrane (Polysulphone, F6 series, Fresenius, Germany) low-flux dialyzer and heparin as an anticoagulant. Blood flow rates ranged from 250 to 300 mL/min, while dialysate flow rate was kept constant at 500 mL/min. All HD patients were maintained at their target dry body weight. A review of medical records
included demographic data such as age, sex, smoking habits, body mass index (BMI) (kilograms/square meter), etiology of renal failure, duration of HD, vascular access, dry weight (kilograms), ultrafiltration (UF) volume (liters) on the session, the average of pre-HD systolic and diastolic BP (mmHg) per week, mean arterial BP (MAP; mmHg), concomitant medication, and biochemical test results were undertaken. Full general and neurological examination was done.
Biochemical blood samples were collected before the midweek HD session and before heparin administration. Laboratory tests done for all patients included hemoglobin (Hgb), hematocrit, serum iron profile, creatinine, sodium (Na), potassium (k), blood urea nitrogen (BUN), calcium (Ca), phosphate (P), intact PTH (iPTH), albumin, lipid profile (total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG), fasting blood sugar (FBS), and high-sensitivity CRP (hsCRP).
Urea reduction ratio (URR) was calculated using pre-dialysis urea (Upre) and post-dialysis urea (Upost). URR = Upre – Upost × 100/Upre.
All blood samples were collected pre-dialysis with the exception of the post-dialysis serum urea nitrogen to calculate urea kinetics. The HCV antibody status was examined using the third generation of HCV enzyme immunoassay
Transcranial Doppler sonography parameters
An assessment of cerebral circulation hemodynamics (for both sides) by transcranial Doppler sonography and transcranial color-coded duplex (DWL multidop x2, USA; esaote Mylab 5, Italy) using 2 MHz phased array probe insonating axial planes through temporal window while the patients are in the supine position was done. Patients were assessed in non-dialysis day to examine mean flow velocity (MFV) in the middle cerebral artery (MCA) and posterior cerebral artery (PCA). The MFVs in the MCA and PCA in our study were compared to normal according to Kassab et al.  as shown below:
Extracranial carotid system (common carotid, internal and external carotid arteries) and vertebral artery (V0, V1, and V2 segments) for all subjects were assessed by carotid duplex using 5–12 MHz linear probe (esaote Mylab 5, Italy) to exclude extracranial stenosis, which may affect intracranial hemodynamics.
Ethics approval and consent to participate
This study was approved through the local ethics committee of Ain Shams University Hospital. The study has been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki. All the enrolled patients have informed written consent. All patients or relatives were informed about the study and its possible benefits
The analyses were performed with Stata® version 11 for Windows (Stata Corp, College Station, TX, USA). Data was presented and suitable analysis was done according to the type of data obtained for each parameter.
Mean, standard deviation, and range for parametric numerical data.
Frequency and percentage of non-numerical data.
Testing of normality of data was done using Shapiro-Wilk test, and suitable statistical test was used accordingly whether the data follow the parametric or non-parametric distribution.
Mann-Whitney test (U test) was used to assess the statistical significance of the difference of a non-parametric variable between two study groups.
Independent sample t test was used to assess the statistical significance of the difference of a parametric variable between two independent means of two study groups.
Chi-squared test was used to examine the relationship between two qualitative variables but when the expected count is less than 5 in more than 20% of the cells; Fisher’s exact test was used.
Spearman’s correlation coefficient (r) will be used as a measure of the strength of a linear association between two quantitative variables. The correlation coefficient, r, can take a range of values from + 1 to − 1.
Multiple Linear Regression analysis was used to find out significant predictors of MCA and PCA scores.