Questions about hemodialysis rinseback and post-rinseback hypertension

[cloudtalk]

So, I've noticed that many patients have a higher blood pressure after their dialysis treatment is completed than they did before it began. Do any of you know why this happens? I know that sometimes blood pressure medications can be dialyzed off, but I don't think that is always the cause.

One thought I had was that if their blood pressure is pretty stable throughout the treatment, it is because fluid is being gradually pulled from their tissues into the blood vessels to compensate for the fluid we are pulling out. So when I rinse them back, the ~250 ml of fluid that is returned to their blood vessels is the cause of the increase in blood pressure, as it isn't immediately reabsorbed into the tissues. But I don't know, would that be enough to cause a significant increase in blood pressure?

Another thing I'm feeling confused about along with this is whether I am actually rinsing back 250 mL of blood, or 250 mL blood plus 250 mL saline. I was taught to document and add to the UF goal that we are giving them 250 mL saline with the prime, and 250 mL saline with rinse back, because that is the volume of the tubing. But aren't we actually giving them 250 mL of saline with the prime, and 250 mL blood with the rinseback? Because most of the saline emptied from the bag during rinseback remains in the tubing?

I'm pretty new to dialysis, so I would really appreciate if any of you could share your understanding of these issues. Thanks!

[Chisca, RN]

Renal Fellow Network: Hypertensive emergency during dialysis

Renal Fellow Network: Intradialytic hypertension

[cloudtalk]

Thank you, those are helpful links. So, I take it that it's a phenomenon that's not very well understood, but likely a result of a a variety of factors? However, I'm still concerned about the post-rinseback blood pressure being significantly higher than the pre-rinseback blood pressure. For example, the SBP might be increased by 15 mmHg over a period of a few minutes. Is that normally a part of what occurs with intradialytic hypertension? Will it normally stabilize over the next few hours post-treatment? Thanks again.

[Chisca, RN]

The rinseback provides a slight increase in fluid volume in the circulatory system. Increases in volume without a decrease in vascular resistance causes a rise in pressure. This is very temporary as saline is not going to stay in the blood stream but will move out into the tissue. Rapidly. You probably don't have the time but if you could measure the BP 15 minutes or 30 minutes after you could see the pressure increase doesn't last very long. NS is referred to as a crystaloid, something thicker like albumin or blood is a colloid. The rinseback increase in BP is not part of the intradyalitic rise but rather a transient increase in preload volume which also affects blood pressure.