When intradialytic complications occur they are a consequence of an interaction between the patient’s physiology and dialysis-induced processes.
Intradialytic hypotension (IDH) is considered to be one of the most frequent complications of hemodialysis (HD).
Etiology of Intradialytic Hypotension
Patient related factors -
Impaired plasma volume refilling (too high ultrafiltration, autonomic dysfunction)
Decreased cardiac reserve (diastolic or systolic dysfunction)
Impaired venous compliance
Autonomic dysfunction (diabetes, uremia)
Arrhythmias
Anemia
Drug therapy (vasodilators, ß blockers, calcium channel blockers)
Alteration of vasoactive substances in blood
Eating during treatment (increased splanchnic blood flow)
Too low target weight estimation
Procedure related factors -
Rapid decrease in plasma osmolality (relatively large surface area membrane, high starting BUN)
Excess absolute volume and rate of fluid removal (for fluid overload)
Change in serum electrolytes (hypocalcemia, hypokalemia)
Dialysate – acetate, warm dialysate
Membrane blood interaction
Hypoxia (partially patient related)
Other less common causes -
Pericardial tamponade
Myocardial infarction
Aortic dissection
Internal or external hemorrhage
Septicemia
Air embolism
Pneumothorax
Hemolysis
Pathogenesis
Vascular instability during dialysis is a multifactorial process in which procedure and patient related factors may influence the decrease in plasma volume and induce an impairment of cardiovascular regulatory mechanisms. An awareness of the risk factors and by identifying those patients who are most susceptible may significantly improve cardiovascular stability during dialysis. Among high-risk patients, monitoring and biofeedback of the various hemodynamic variables, together with an extensive use of convection, can prevent the appearance of symptomatic hypotension and help in averting its onset.
Treatment
Stop or reduce ultrafiltration
Place patient in Trendelenburg position
Administration of saline and hypertonic agents. However, excess fluid replacement should be avoided to prevent sodium overload.
Continuous infusion of pressor agents (meteraminol, norepinephrine) are very rarely needed
Prevention
Patient end strategy
Reduce intradialytic weight gain (dietary and treatment compliance)
Avoid anti-hypertensive medication on the morning of the dialysis day
Avoid missing dialysis and stay the entire dialysis time for treatment
Avoid eating during dialysis
Procedure related strategy
Dialysate sodium- sodium profiling and sodium gradient protocol but maintaining zero sodium balance to the extent possible
Modeling fluid removal- sequential ultrafiltration and dialysis, blood volume controlled hemodialysis
Cool dialysate- isothermic dialysis is well tolerated and clearly reduces the incidence of hypotension
Reduction of the ultrafiltration rate with prolongation of treatment time
Accurate estimation of dry weight (segmental bioimpedance, and others)
Judiciously increasing dialysate calcium while avoiding hypercalcemia
Medications-
Midodrine given approximately 30 min before dialysis significantly reduces the incidence of hypotension. It has been considered safe and well tolerated.
Carnitine has been recommended in-patients with frequent hypotensive episodes.
References:
1. Straver B, De Vries PM, Donker AJ, ter Wee PM. The effect of profiled hemodialysis on intradialytic hemodynamics when a proper sodium balance is applied. Blood Purif 20:364-369, 2002
2. Santoro A, Mancini E, Basile C, Amoroso L, Di Giulio S, Usberti M, Colasanti G, Verzetti G, Rocco A, Imbasciati E, Panzetta G, Bolzani R, Grandi F, Pola…
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