Dialysis & Other Renal Points

In this lesson we’re going to cover in a little bit more detail some important points about the renal and GU system that we haven’t explored in other lessons. Mainly we’re going to talk about Dialysis. Now, as a new graduate nurse, you will not be performing dialysis – this is a specialty that requires extra training. However, you will potentially have a patient who receives dialysis during your shift, so you need to know the most important things to look for in these patients.

When we talk about dialysis, we are essentially talking about the process of taking over the functions of a nonfunctioning kidney. This might be temporary, for example in a patient with AKI, or long-term in a patient with CKD. In hemodialysis, we pull their blood from their body, run it through this machine to clear waste and toxins, remove urea, creatinine, uric acid, and regulate electrolytes and acid-base balance – most of the basic functions of the kidney – then we return their cleaned blood back to them. All of this happens by diffusion across a semipermeable membrane. Essentially we run their blood through a filter. The way it works is their blood is on this side of the semipermeable membrane, and on the other side is a solution called dialysate. In that dialysate we have a specific concentration of certain substances. For example, the potassium concentration might be 2.5. So if their potassium is 6.5, that extra potassium in their blood will automatically move from an area of high concentration to low concentration – so it pulls out of their blood and across this membrane. So that’s how we are able to regulate the different substances in their blood.

In order to do hemodialysis, we have to have some sort of access into their vascular system. There are a lot of options. One of which is a permacath or an external catheter placed usually in the subclavian vein. This may be temporary while we wait for a more permanent access solution – we treat it like a picc line or central line in terms of dressing changes and preventing infection. The other two are permanent solutions. The first is a graft – a surgeon will place an artificial vessel between the artery and vein in the arm. This creates an area of high velocity flow that allows for the high pressures of dialysis. Or they can do what’s called a fistula, which is what you see here. They will create a connection between the artery and vein that will again increase the pressures and flow in that area. Then we pull from the high flow area and put it back into the vein once we’ve cleaned it. Here’s the thing with these access devices – this is the patient’s LIFELINE. If they lose this access, they can’t get dialysis, and they can die. SO we need to protect it! We’re going to assess this with every head to toe assessment. We want to listen over it to hear a bruit, which is a swooshing sound, and we want to feel for a thrill. I remember this because “thrilled” is a feeling – it should be vibrating when you touch it. We also want to assess distal circulation like pulses and cap refill – if any of this is absent, it might be clotted off so you need to notify the provider. We’ll also put a Limb Alert on this side – that means NO blood pressure, NO IV sticks or injections on that arm. We need to protect this access! Also, for the same reason, we never use a hemodialysis catheter for ANYTHING but dialysis.

The other option we have is peritoneal dialysis. In PD, instead of having a machine with a filter, the peritoneum itself acts as the semipermeable membrane. We instill that dialysate fluid I talked about and let the diffusion happen, then we remove the fluid from the abdominal cavity. This could be continuous or intermittent, and it can be done at home by the patient or their family. I’ve actually had patients who will instill the fluid in the morning, then go to work, and they empty and replace the fluid when they get home! This is more convenient for patients who can’t make it to a hemodialysis center 3 days a week. However, it comes with a high risk of peritonitis. So it’s imperative that we teach and maintain strict sterile technique and always assess the fluid flowing out for any signs of infection, like if it’s cloudy.

Now, there are a few nursing priorities for any patient receiving dialysis, but especially hemodialysis. We’re literally pulling off up to 4 liters of fluid in 2-4 hours, so there’s a high risk for hypotension, even hypovolemic shock. We’re messing with their electrolytes so there’s a risk for EKG changes or seizures. So it’s really important that we monitor their vitals throughout. We keep careful I&O measurements and we weigh the patient before and after to determine how much fluid we were able to get off. Remember that 1 kg body weight equals 1 L of fluids. We also want to be careful with medications that we give them before dialysis for two reasons. One, like we said, is that dialysis can drop their blood pressure. So we want to hold any antihypertensives before dialysis so we make sure their BP doesn’t drop too low. The other is that many medications will actually be removed with dialysis, so we need to give those AFTER dialysis, not before, otherwise the patient won’t actually get the effects of the drug. For both of these things you need to verify with your pharmacist and your provider to confirm. And again, protect that vascular access, it’s their lifeline – literally.

Now, we’ve mentioned a cystoscopy a few times, like in the renal calculi lesson, so we just wanted to review what that is. Any time you see cysto, think bladder. So this is when we insert a camera (that’s the scope part) through the urethra, into the bladder to examine it. We can look at the urethra, bladder, and the ureters. We can even remove stones and take biopsies with a cystoscopy. Now, when it comes to biopsies, we can take it internally or externally for a renal biopsy. Either way you always want to assess coagulation studies before to see if there’s a risk for bleeding, we assess for signs of bleeding post-op, and if it is an external renal biopsy, we want to apply pressure afterwards.

Lastly I want to talk about contrast dye as it relates to the kidneys. We mentioned this in the AKI lesson, but we want to clarify it here. Contrast dye that is used in imaging like CT scans, urographies, angiographies, etc., can be damaging to the kidneys, or it’s nephrotoxic. So we want to assess patients for an allergy to the dye, or iodine, or shellfish, or even a previous reaction or bad outcome from contrast dye. Many times we will avoid contrast altogether with these patients, sometimes we can give benadryl and extra fluids and protect their kidneys. With ANY kidney patient we will make sure they are hydrated going into the scan and then we’ll increase their fluids after as well in order to flush the dye out of the kidneys. The longer it stays in there, the more damage it can do. Lastly, it’s important that you know what to do if your patient is taking metformin. Studies have shown that in the presence of renal insufficiency, patients who take metformin after receiving contrast dye can develop a life threatening lactic acidosis. SO – if your patient has not-so-great kidneys (remember you can check their GFR!), and they’re taking metformin, we ALWAYS want to hold Metformin for 48 hours after the scan. Now, remember, to hold any medication you need a provider order, so make sure you call them and advocate for this to be held.

So, let’s recap. Hemodialysis is the process of cleaning the blood in an artificial kidney by diffusion across a semipermeable membrane. It’s pretty cool how big of a machine is required in order to replace a tiny kidney. In peritoneal dialysis, the peritoneum itself acts as the semipermeable membrane and patients can do this at home. We want to prevent complications like hypovolemia, shock, or infection, and we want to protect that access at all times. Remember that a cystoscopy is a camera inserted to examine the bladder, remove stones, or take biopsies. And finally that contrast dye can be damaging to the kidneys so we always want to assess for that risk and give fluids to protect the kidneys. And, of course, hold metformin afterwards if applicable.

Okay guys, that’s it for the Renal and GU section, let us know if you have any questions. Make sure you check out the resources attached to this lesson to learn more. Now, go out and be your best selves today. And, as always, happy nursing!