 Hello and welcome to Nursing School Explained. Today's topic is acute kidney injury. Whenever we talk about any kind of injury or physiological mechanism, it always helps to look at the physiology behind the causes. So for acute kidney injury, there are basically three types of causes which is pre-renal, intra- renal and post-renal. And to demonstrate this, I've drawn out a kidney here with the renal artery. So blood comes from the descending order and then branches off into the renal artery. Then it supplies the kidney. The kidney does its filtration, does all the beautiful functions that it does. The urine then goes through the ureter into the bladder, which serves as a reservoir. And then it gets excreted. And I've also drawn a prostate here for male patients. So in pre-renal kidney injury or causes of injury, just think about the damage occurs before the kidney, pre-renal. So the only thing that really comes before that is the renal artery. So now for causes, what can go wrong with in the pre-renal arena here that would cause the kidney to fail? So number one cause is decreased perfusion. So when the kidney, like any organ, doesn't get enough blood flow, it is unable to function properly. And therefore it can cause kidney injury and can lead to further damage. Another cause for low perfusion can be hyperbolemia. So that means low blood pressure due to whatever causes there might be. It might be dehydration, it might be heat exhaustion, it might be a traumatic injury with a lot of blood loss. So whenever there's hyperbolemia and therefore hypotension, the renal artery does not supply enough blood to the kidneys and therefore it causes renal failure. The other cause that we are looking at over here for pre-renal is renal artery stenosis. As you most likely know, stenosis means that there is a narrowing or a decrease in the opening of any kind of artery, any kind of opening, such a heart valve. So stenosis means that there's trouble with the opening. So when the renal artery is stenosed, there is something that doesn't allow it to open the way that it should. It's going to be decreased perfusion to the kidney as well, leading to intra-renal failure. Sorry, pre-renal failure. Now for intra-renal failure, there are causes that happen from within the kidney, so intra-renal. And those are basically three different things that can happen here. So one and most important is nephrotoxins. So anything that is toxic to the kidneys, as you know, when you look up medications, a lot of times nephrotoxicity is noticed. And we have to be very cautious about taking a good history of the patient to see what medications, and if any, that can be nephrotoxic that can lead to acute kidney injury. And the most prominent ones are aminoglycosides. That's a type of antibiotics that the patient might be on. They have a very high likelihood of causing some kidney problems. And then secondly noticed here is contrast. So that would be IV contrast. So for somebody who is not able to tolerate that, it can lead to intra-renal failure. And then hemolysis. So if for some reason there are blood cells that are lice that basically explode or burst, so that can lead to intra-renal failure because now they're clogging up the kidney. Severe crush injuries is basically the same kind of principle as well as myoglobin release as seen in rhabdomyolysis. And what that basically means, rhabdomyolysis is something that happens when there's an excessive breakdown of muscle tissue. Now all these proteins are being released and the kidney is unable to process those large molecules. They clog up the kidney's filtration system and therefore lead to intra-renal failure. Now number two here is interstitial nephritis, which are basically other medications such as other types of antibiotics. NSAIDs can be nephrotoxics as well as ACE inhibitors. You know that they work on the RAS system. They work specifically on the kidney, whether it's on the adrenal medulla or the cortex causing some problem there. And then for interstitial nephritis also infections can cause acute kidney injury, which would be acute palon nephritis, kidney infection, and viral or fungal infections such as glomerulonephritis, which I'll be discussing in more detail in a different video. Now other causes here prolonged pre-renal ischemia. So now if the renal artery is not delivering the blood supply that the kidney needs, eventually the pre-renal will lead to intra-renal failure because the kidney is just not able to function properly. Acute glomerulonephritis, like I just talked about, and then SLE, systemic lupus erythematis. So lupus is an autoimmune disease that also has adverse effects on the kidneys, which can lead to intra-renal failure as well as kidney stones. So think about if there's kidney stones clogging up the kidney's filtration system, they can lead to acute kidney injury and eventually kidney failure. Now then if we look at our post-renal causes here, so that's anything behind or after the kidney, which can be the ureter, the bladder or the prostate. So post-renal causes can be prostate disorders such as BPH, benign prostate hyperplasia, which is basically a benign enlarged prostate, which is very common in men as they age. It's a very common problem that they'll encounter and or cancer of the prostate. So now if the prostate here gets enlarged and is basically clamping down on the ureter that runs through it, it's not going to, the patient is not going to be able to excrete their urine, which then means if the urine can't flow out from the ureter, it's going to fill up the bladder and then it's going to back up into the kidney and the kidney is going to swell, causing hydronephrosis, and then it's going to impair its ability to filter properly. Now bladder cancer and stones as well can lead to post-renal causes. Just think about if there are stones that accumulate here or a tumor, that again can block the outlet here or any kind of outlet even anywhere here, again leading to back up into the kidney. And then we have neuromuscular disorders such as multiple sclerosis, where there's an issue with the communication from the brain to the neurological innovation of the bladder. So the communication is interrupted, therefore the patient does not notice when there's or doesn't receive the signal that urination should occur, therefore it can cause a distended bladder, again leading to that back up, as well as strictures. And strictures is basically just narrowing. So if any of these tubes here that drain the kidney, whether it's the ureter or the urethra down here, have strictures that usually occurs from any kind of other surgery that the patient had, that now there's scar tissue that's clamping down on the tubes that should be draining the kidney or the bladder, again causing that back up, and then spinal cord injury or disorder. So anything that happens in the spinal cord, again it has to do with the communication, with the nerve function between the brain and the bladder. So if there's miscommunication or no communication between the brain and the bladder saying or telling the bladder the signal or the bladder telling the brain the signal that it's time to empty the bladder, then again it can cause the back up here. Now signs and symptoms will be oliguria, which basically means decrease in urine output. And you know that in adults the urine output needs to be at least 30 milliliters per hour, so but make sure that you always calculate that because we don't usually urinate once an hour, we usually urinate maybe every three to four hours. So on average if you divide that the urine per hour should be about 30 milliliters, but if it's less than that it's oliguria. And that basically means if the kidney is not functioning it's not getting enough perfusion, there's something happening within the kidney or after the kidney the kidney is not going to be able to do its function, which is to create the urine and therefore the urine output will go down. Now it will also lead to metabolic acidosis. You probably recall that the kidney has a big, plays a big role in acid base and pH regulation of the body by absorbing and excreting bicarbonate and hydrogen ions. So if the kidney is not functioning well it's not going to be able to help with those mechanisms and then it'll lead to metabolic acidosis, which is a low pH level and also to coosemouth respirations and those are those kind of erratic breasts that the patient will have and that is in an effort to blow off the CO2, the acid that is accumulating in this metabolic acidosis and that has to do with the renal and respiratory system working in conjunction for pH balance. If you need a review of that please watch my other video on the different ABG interpretation and analysis of pH. Now also if the kidney is not functioning it's not going to be able to excrete the sodium and the potassium appropriately leading to hyperkalemia, increased potassium level, which will make the patient weak. Remember how potassium plays a role in muscle contraction and the biggest muscle that we always worry about is the heart so it can also lead to palpitations and dysrhythmias as well as fatigue and then signs and symptoms if there's post-renal causes as we just discussed with the prostate issues, bladder cancer, stones, any of those the patient will be unable to void or they will only be able to void a minor amount not really producing the urine output that we would like to see. Now for diagnostic tests whenever there's something going on with the kidney we want to collect the urine sample. Now a lot of times that will show red blood cells or white blood cells depending on what's going on and there can be casts in there which is basically slough so if there's damage to the filtration mechanism of the kidney it'll kind of slough off some cast and they can be visible as they're carried out in the urine. Now ABGs are going to be very important because we worry about this metabolic acidosis and we know acidosis is a low pH less than 7.35 and the bicarbonate will be less than 22 corresponding with metabolic acidosis and also as already discussed when the kidney is not able to regulate sodium on potassium, excretion and absorption the sodium level will usually be decreased and the potassium level will be increased causing hyperkalemia which can be very concerning and again because it can cause palpitations and dysrhythmias we want to check in EKG. BUN and creatinine will be elevated because kidney function those are the two golden measures of kidney function and then in addition if there is a concern for any of these intrarino mechanisms or causes for renal failure we would want to maybe do a renal ultrasound biopsy or CT scan that would be more for evaluation for lupus or kidney stones can be seen on ultrasound or CT scan. All right so now how do we treat patients with intrarino with acute kidney injury? So we need to treat the underlying cause so we need to do whatever we need to treat whatever caused the problem to begin with and again we distinguished the three different causes here pre intra and post renal so if we look at pre renal causes if there's low perfusion we're going to need to increase the perfusion to the kidney so if the patient is dehydrated severely dehydrated we're going to need to hydrate them but be careful because the kidney also plays a role in filtration whenever you give the patient high volumes of isotonic solution for hyperbolemia and hypotension you always have to observe for signs of fluid volume excess which would be crackles and peripheral edema and maybe confusion so so always keep that in mind and if the cause is renal artery stenosis then we're going to have to do surgery most likely to fix this narrowed artery that's causing the kidney not to be receiving the blood that it needs to be functioning properly. One more thing on perfusion so IV fluids or blood transfusions so if there's a trauma patient who had some major crush injury or maybe an artery was cut from a big laceration they lost a lot of blood we're going to have to replace that volume not only with IV fluids but also with blood. Now intra renal causes we need to discontinue the causative agent medication or stone so if the causative agent was an amino glycoside antibiotic the patient is on then he just needs to be switched to a different antibiotic if it's a kidney stone we need to get rid of it if the patient is taking too many NSAIDs for chronic back pain then we need to consider changing those and in saving the kidney. Post renal causes because we know most of the time it's caused by this prostate disorder the patient is going to need a catheter to just drain the bladder let all that urine that has now backed up let that drain out and let the kidney recover and then certainly we're going to need to treat the enlarged prostate or any kind of cancer or stone or stricture that would be the cause of that post renal failure. Now I've also written down here treatment for hyperkalemia so whenever you think kidney think about hyperkalemia and we know potassium imbalances can be fatal whether they're high or low now in acute kidney injury most likely the potassium will be high because again of that filtration impaired filtration of the kidney so how do we treat that of course we need to treat the underlying cause but if the potassium is really high to maybe now the patient has symptoms in addition they might need some other treatment and we can do that with certain medications so the first two they should really be listed together here is regular insulin IV as well as IV dextrose and what that does the insulin as we know helps to to drive the glucose into the cell and typically potassium is an intracellular electrolyte and but now when we can measure it in the bloodstream it's circulating outside the cell so the the the insulin helps to drive the potassium back into the cell where it belongs but whenever we administer insulin especially if this patient is not diabetic we have to worry about dropping their blood sugar which is why we have to give them some dextrose to kind of counterbalance that now if we know the patient has acidosis metabolic acidosis we've determined this through our pH and ABG analysis then they're going to need bicarbonate which corrects the acidosis remember how bicarbonate and hydrogen ion kind of balance each other out to achieve homeostasis and acid-base balance then the patient might also need calcium gluconate and what that does it stabilizes the cardiac cells because now they're more excitable or less excitable because of that high potassium that's causing maybe the thrithmias and palpitations and then K-exolate is a PO medication that comes in a liquid form just think about K-exolate K-potassium X get it out of the body excretes the potassium in the bowel so the patient will have diarrhea because it binds to the potassium and then it's excreted in the stool and generally one gram of K-exolate eliminates approximately one MEQ of potassium you might recall that potassium is measured in MEQs and then six is hemodialysis so if all these mechanisms fail the patient's kidney is still not working we're still dealing with elevated B-U-N creatinine hyperbolemia all these signs and symptoms then the patient is going to have to undergo hemodialysis because now the kidney the main filtration system of the body is not working and so hemodialysis might not be something that the patient is going to need forever such as in patients with end-stage renal disease which is chronic renal failure this is more acute but also an acute kidney failure the patient might need hemodialysis and that's usually accomplished by inserting a vascular catheter into one of their big veins usually in the subclavian vein in order to accomplish that exchange and then the dialysis machine will basically take over the filtration mechanism of the kidney externally briefly or for a short period of time until the underlying cause can be resolved maybe surgery can be accomplished and the kidney will be back functioning normally thank you for watching nursing school explain in this video an acute kidney injury i will also have videos on chlomerulonafritis and nephrodic syndrome coming up shortly please subscribe to my channel share with others and make any comments regarding any other topics you would like me to review good to see you thanks for watching nursing school explained