Role of plasma refill rate, its determinants and some other variables in pathogenesis of intradialytic hypotension

Abstract EN

Background : Despite technological advances, intradialytic hypotension (IDH) remains a relatively common acute complication of haemodialysis (HD) associated with significant morbidity and distress for both patients and medical staff.

Plasma refill is the main physiologic phenomenon that guards against hypovolaemia and hypotension during dialytic ultra filtration.

This work explores the role of plasma refill rate (PRR) and its determinants like plasma albumin level in causation of IDH.

The role of myocardial dysfunction, anemia and other factors will be addressed.

Subjects and Methods: Forty patients with end- stage renal disease (ESRD) treated with regular HD were enrolled, excluding patients with autonomic dysfunction, or vacuities.

Echocardiographic assessment of left ventricular systolic and diastolic function was done.

Blood pressure was recorded every 30 minutes during an HD session that met specific study requirements.

Plasma sodium, creatinine, total proteins and prealbumin were measured in pre- dialysis sample.

Blood urea, serum albumin and haematocrit value (HCT) were measured in paired samples (pre- and post dialysis) Urea reduction ratio (URR) and Kt/V were calculated.

Changes in plasma volume, as indicated by changes in HCT, were used for calculation of PRR.

Results : Sixteen patients (40%) developed IDH.

Compared with the remaining stable patients, they had significantly longer duration of dialysis, lower Kt / V, lower pre- dialysis serum sodium, prealbumin, HCT, lower E /A ratio and longer deceleration and isovolumic relaxation times, denoting left ventricular diastolic dysfunction.

They had significantly lower PRR (P = 0.017) and higher actual plasma volume change (P = 0.000).

PRR had a significant positive correlation with mean plasma albumin (r = 0.33, P = 0.037).

Risk factors for IDH identified by ROC curve analysis were low PRR, prolonged deceleration time, low E /A ratio, low pre- dialysis serum sodium, low HCT and long duration of dialysis.

Conclusions : IDH is closely related to a rapid decline in actual plasma volume, which results from a relatively low PRR compared to the concurrent ultra filtration rate (UFR).

Other risk factors for IDH in order of significance are anaemia, diastolic dysfunction, hyponatraemia and previous long duration on dialysis.

A role for hypoalbuminaemia in reducing PRR is suspected, but needs confirmation in another study.