Discussion Board

I believe what you are referring to is the entity in which a dialysis patient (specifically a hemodialysis patient) develops bradycardia while receiving dialysis. This is a complication of late dialysis (usually near the end of the dialysis session) and occurs because of significant hypovolemia, causing the cardiodepressor reflex (aka - Bezold-Jarisch reflex) to activate). It is a paradoxical bradycardia, but is often symptomatic. [learn more about this paradoxical bradycardia]

PD would be an excellent choice because, as you alluded in your question, it is a modality in which the rate of ultrafiltration (= amount of fluid removed from the patient per unit time) is lower than in HD. The lower ultrafiltration rate would give the body time to equilibrate and thereby lessen the chances of bradycardia.

However, there are some maneuvers that can be done on hemodialysis to lessen the risk of bradycardia. If possible (based on the kT/V), a lower blood flow can be used. Typical blood flows are 300-450 ml/min; lower blood flows would keep more blood in the patient, thereby decreasing preload to a lesser degree. A second option would be to decrease the ultrafiltration rate. This can be accomplished by either:

• decreasing the amount of ultrafiltration (water) to be removed from the patient, or
• increasing the amount of time in which the desired ultrafiltration should be achieved

FInally, one can increase the number of dialysis sessions per week (from the typical 3x/week to 4 or even 5x/week) to achieve the desired ultrafiltration.

When intradialytic hypotension first develops, the normal reaction is to increase one's heart rate. Indeed this is what we see in most dialysis patients. As hypovolemia persists, there should be a movement of salt and water from the interstitial space and into the intravascular space. This movement ought to restore euvolemia and cause the heart rate to return to the resting rate.

When this movement does not occur, or occurs at a slow rate, the cardiodepressor reflex becomes activated. It is believed that this reflex (aka Bezold-Jarisch reflex) is cardioprotective in that the lowered heart rate creates a lowered oxygen demand. Given the persistent hypovolemia, the reflex recognizes the decrease in oxygen supply and lowers oxygen demand by causing bradycardia.

Renal Faculty