Association of intradialysis blood sodium level, blood pressure variability, and hydration status with hemodialysis-related headache: a prospective cohort study

Objective To identify primary factors contributing to hemodialysis-related headache (HRH) in maintenance hemodialysis (MHD) patients. Methods Adult outpatients receiving MHD were prospectively enrolled from a hemodialysis (HD) center of a tertiary hospital in China. Twelve dialysis sessions were successively monitored for each patient. HRH is defined as having at least three headache episodes that begin during HD and resolve within 72 h of HD session completion. Blood gas analysis during headache episodes and body composition analysis after dialysis were conducted. Hour-to-hour vital sign variability during dialysis was assessed using the metric of average real variability (ARV). Multivariable logistic regression analysis was conducted to explore the factors triggering HRH. Results A total of 95 Chinese MHD patients were enrolled, with 92 patients (60.9% were males) included in the final analysis. The mean age of the 92 patients was 59.3 ± 17.5 years, and the median dialysis vintage was 27.1 (12–46.2) months. Among them, 12 patients (13%) complained of 42 headache attacks, and eight (8.7%) were diagnosed with HRH. For eight patients with HRH, headache occurred 100.3 ± 69.5 min after the start of dialysis, with a mean VAS score of 4.3 ± 1 points. The quality of headaches was dull (six patients), pulsating (one patient), or stabbing pain (one patient); all the headaches were bilateral, with one having concomitant vomiting. The intradialysis headache duration and the whole headache duration were 98.8 ± 68.1 and 120 (65–217.5) minutes, respectively. Younger age (OR = 0.844, 95% CI 0.719–0.991, p = 0.039), decreased blood sodium level (OR = 0.309 in the range of 133–142 mmol/L, 95% CI 0.111–0.856, p = 0.024), increased ARV of intradialysis systolic blood pressure (OR = 3.067, 95% CI 1.006–9.348, p = 0.049) and ratio of overhydration to dry weight (OR = 1.990, 95% CI 1.033–3.832, p = 0.040) were found to be independent risk factors for HRH. Conclusions This study suggested a significant attribution of blood sodium, hydration status and blood pressure variability to HRH.