Intradialytic Hypotension

Etiology

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 (low NO, high endothelin-1 and angiotensin-2)
  • 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 possible1
  • Modeling fluid removal- sequential ultrafiltration and dialysis, blood volume controlled hemodialysis2
  • Cool dialysate- isothermic dialysis3 is well tolerated and clearly reduces the incidence of hypotension4
  • Reduction of the ultrafiltration rate with prolongation of treatment time
  • Accurate estimation of dry weight (segmental bioimpedance, and others5)
  • Judiciously increasing dialysate calcium while avoiding hypercalcemia6
  • Medications7–
    • 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, Polacchini M. Blood volume controlled hemodialysis in hypotension-prone patients: a randomized, multicenter controlled trial. Kidney Int 62:1034-1045, 2002
  3. Rosales LM, Schneditz D, Morris AT, Rahmati S, Levin NW. Isothermic hemodialysis and ultrafiltration. Am J Kidney Dis 36:353-61, 2000
  4. Maggiore Q, Pizzarelli F, Santoro A, Panzetta G, Bonforte G, Hannedouche T, Alvarez de Lara MA, Tsouras I, Loureiro A, Ponce P, Sulkova S, Van Roost G, Brink H, Kwan JT. The effects of control of thermal balance on vascular stability in hemodialysis patients: Results of the European randomized clinical trial. Am J Kidney Dis 40:280-290, 2002
  5. Levin NW, Zhu F, Keen M. Interdialytic weight gain and dry weight. Blood Purif  19:217-221, 2001
  6. Kyriazis J, Glotsos J, Bilirakis L, Smirnioudis N, Tripolitou M, Georgiakodis F, Grimani I. Dialysate calcium profiling during hemodialysis: Use and clinical implications. Kidney Int 6:276-287, 2002
  7. Perazella MA. Pharmacologic options available to treat symptomatic intradialytic hypotension. Am J Kidney Dis. 38:S26-S36, 2001