What's the pathophysiology of AKI? If you are super confused about it and wondering how to pass your renal exam in nursing school, stick around because I'm going to give you a really easy breakdown of acute kidney injury pathophysiology. And before we dive in, I just want to make sure that you download the nursing school study checklist that I have for you that walks you through how to study for your med-surg nursing exams step-by-step. The link is in the description below for you to download it. Hey there, friend!
Christina here, and welcome to The Nursing School Show. I am here to help you pass nursing school and become an amazing nurse. So, if you want to rock nursing school without completely losing your mind, hit that subscribe button and click the notification bell, and let's dive in.
Now, AKI is also called acute kidney injury or acute renal failure. You'll hear all of those terms, but they all mean one thing. The kidneys are injured and we need to fix it.
Acute kidney injury happens when the kidneys are suddenly damaged by things like certain medications, sepsis, or lack of blood flow. Now, this damage can be reversible as long as it's treated promptly. The causes of acute kidney injury are divided up into three main categories, pre-renal, intrarenal, and post-renal. Now, pre-renal refers to things that happen before the blood gets into the kidneys or things that happen generally throughout the body, things like sepsis, heart failure, infection, or an obstruction that blocks blood flow to the kidneys.
Now, sepsis is a big deal and nursing instructors love to test you on it. So check out this video before you take your next exam. And if you are a nursing SOS member, head on over to your dashboard and check out the whole sepsis video series that we have for you.
Now, intrarenal refers to things that happen within the kidneys, like a medication that damaged the nephrons themselves, kidney infection, or an obstruction with within the kidney itself. Then post-renal means the causes after the kidneys and the ureters, the bladder, or the urethra. Now, these could be things like kidney stones or renal calculi, benign prostatic hypertrophy or BPH, or a bladder infection.
Now, if you're a Nursing SOS member, you will also want to check out the Renal GU course that we have for you that includes the video series. on benign prosthetic hypertrophy. Now that will help you learn it faster for your exam. So really what it comes down to is if the cause is generalized throughout the body or if it's something having to do with something outside of the renal system, then it's most likely considered pre-renal.
If it's inside the kidney, it's intrarenal, and if the cause comes after the kidney is in the urinary system, it is post-renal. Now let's walk through the phases or stages of acute kidney injury and the pathophysiology of what happens during AKI. Now, these are actual stages that have been defined for AKI, and you absolutely need to know these for nursing school.
You will most likely be tested on this. So here we go. The first phase or the first stage of AKI is onset or initiation.
It's the onset phase. Blood flow to the kidney is decreased and the urine output starts to decline. The kidneys need blood flow to function properly, so when they don't get enough blood, they aren't able to do their job as well, right? So urine output will start to decrease.
Now, this phase can last anywhere from a couple hours to days. Now, the second phase of acute kidney injury is the oligarch phase, where the patient's urine output is less than 400 milliliters per day because there isn't enough blood flow going to the kidneys. they stop functioning properly and they can't produce as much urine or get rid of as much waste as they should.
So this will cause oliguria, which is a decrease in urine production and an increase then in waste products such as creatinine and urea. Now this phase often lasts between one to two weeks. And if you want a super easy breakdown of renal labs like creatinine and blood urea nitrogen, click on this video right here. Now, the third phase of AKI is the diuretic phase, and this will happen only if the kidneys get more blood flow and the damage has stopped. So, if the cause of the AKI was fixed, the kidneys will slowly start recovering and working again.
Now, during this diuretic phase, it's just what it sounds like, a lot of diuresis. The kidneys are coming back swinging, and they are getting rid of a lot of urine. So, you might see the patient urinate between four and five liters per day, and this can last between one to two weeks.
Now the final phase is the recovery phase of AKI, which can take months to years for full recovery. Now as the kidneys heal over time, urine output starts to normalize again. It's important to note, however, that if AKI isn't fixed and if the damage of the kidneys still progresses, it can lead to chronic kidney disease and ultimately renal failure.
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