Download Hello, welcome to the Stanford University video curriculum on

Hello, welcome to the Stanford University video curriculum on chronic kidney disease. My name is Rob Rope and I am one of the Stanford nephrology fellows presenting these slides on the behalf of the Nephrology faculty – Drs. Bhalla, Fatehi, and Pham. This is the final video of our four part series and we will discuss end‐stage renal disease in regards to uremia and basic renal replacement therapy. This current video will refer to content from the ESRD chapter in the Stanford HHD syllabus. 1
After watching this video you will hopefully be able to
2
There are numerous possible signs and symptoms of End‐
Stage Renal Disease, not of all of which are addressed by dialysis, which is the main replacement therapy for kidney failure. Those at lease partially addressed by dialysis include those listed. We have already discussed hypervolemia, acidosis, high phosphorus, and hypertension. We will discuss the uremic syndrome shortly. Those not addressed by dialysis are also listed –
supplementation for anemia and vitamin D deficiency is still required on dialysis. 3
The decision of when to do dialysis is often tricky. Patients rarely ask for it and there are multiple possible indications for dialysis. Patients often exhibit more than one of the signs or symptoms of kidney failure. Dialysis may be started for acute failure of kidney function during a single illness or progressive chronic renal failure which we call end‐stage renal disease or ESRD. A standard mnemonic you will see for indications of dialysis is AEIOU and it works reasonably well.
1) Acidosis – As GFR drops ammoniagenesis and bicarbonate regeneration drops resulting in acidosis. 2) Electrolytes – The principle concern being hyperkalemia, which can cause cardiac
arrhythmias and sudden cardiac death. 3) Intoxications – Which are relatively rare but dialysis can be life saving in certain ingestions such as ethylene glycol (in anti‐freeze), aspirin, or lithium overdoses. 4) Overload – which represents volume overload. In extreme renal failure the kidney cannot compensate and patients develop a positive sodium balance and therefore become fluid overloaded.
5) Uremia – which is the most common indication for dialysis in progressive chronic renal failure and represents the buildup of organic toxins that make people feel sick. 4
Uremia is the most common and hardest to define indication for dialysis. There is no level of BUN that defines uremia or necessitates dialysis though usually it presents in patients with a GFR < 10
ml/min.
Uremic patients look and feel unwell and often complain of nonspecific symptoms including n/v, anorexia, poor sleep, fatigue, confusion, and
itching
5
The table shows additional signs and symptoms of uremia. Its important to note how global the impacts of kidney failure are – with almost all organ systems involved and also how non‐specific most of the symptoms are. 6
Will switch gears now to dialysis—the main replacement therapy for renal failure. The goals of all forms of dialysis are to maintain normal intracellular and extracellular physiology. This is done by cleaning the blood to maintain the appropriate extracellular fluid composition and removing fluid which the failing kidneys can no longer do. Circuit of blood flow ‐‐ to do hemodialysis blood is removed from the patient, run through a pump, and cleaned in the dialyzer and returned to the patient. In the dialyzer a semi‐permeable membrane separates the blood from another fluid, dialysate that is free of toxins but otherwise osmotically similar to our plasma. This allows for diffusion of solutes like BUN, phosphorus, and potassium out of the patient, down a concentration gradient, into the dialysate. It also always for bicarbonate, our base, to diffuse into the patient to counteract the acidosis of renal failure. Finally, fluid is squeezed out via a hydrostatic pressure gradient created across the membrane to control the volume of the patient’s ECF. 7
Peritoneal dialysis is an another dialysis therapy that is home based and utilizes the potential space between the visceral and parietal peritoneal membranes. Patients infuse dialysate into this space, in this case manually. Toxic solutes then diffuse out of the patient across their own semipermeable peritoneal membrane into the fluid as seen in the lower picture. The toxins are then removed when the fluid is withdrawn. Contrary to hemodialysis, water is sucked out of the patient by an osmotic pressure generated by glucose in the dialysate to control hypertension and prevent edema. While the schematic of this patient is showing manual dialysis. There are machines, known as cyclers, which allow patients to do 8
dialysis in the night while they sleep.
8
This is a brief table comparing the two modalities. At this point there is no clear data to suggest that either modality is better in terms of morbidity or mortality. Decisions are made based on the patient’s personal goals, ability to care for themselves, and support system. 9
So if we have this great technology of dialysis which keeps people alive. What is missing? Why do some dialysis patients not feel as good as you or I? The diffusion removing toxins in dialysis is analogous to glomerular filtration. However the native kidney can also remove significantly more toxins through active transporter secretion in the proximal tubule. Dialysis cannot replace this function meaning there are loads of organic toxins that are not well removed by dialysis. In addition the intermittent nature of most dialysis regimens will likely never be able to adequately match up to a continuously functioning kidney. Currently as it stands the most effective way to replace the function of a dying kidney is to give patients a new one with transplantation. 10
Kidney transplants were the first solid organ transplants performed in the 1950s when the Herrick twins, underwent the first successful kidney transplant. This earned Joseph Murray (pictured on the left) the Nobel Prize in 1990. Once pts with CKD have a GFR < 20 ml/min they can be listed for a living or deceased donor transplant. Most living kidney transplants come from a family member or friend but it doesn’t have to.
Unfortunately in many areas of the country, like Northern California, it can take 5‐10 years to get a deceased donor transplant. This is why we need MORE DONORS!!!! So anybody who is willing 11
to donate a kidney will probably get an A.
11
Indeed patients who receive kidney transplants, seen in gray in this graph, are less likely to die than comparable patients who do not have a transplant. And they can stop doing dialysis which they like. Patients who receive a transplant then have a second job almost – in addition to recovering from major surgery, they must take immunosuppressive medications to prevent rejection and they face a higher risk of complications like infection or malignancy. However the majority of transplant patients do very well and protect their kidneys ferociously. 12
13
14
15
16