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Welcome to the Deep Dive.
Today, we're tackling a really big topic from medical surgical nursing,
kidney failure.
Our goal is to break down a dense chapter on acute kidney injury and chronic kidney disease into the essentials you need to grasp quickly.
And it's so important because when we talk about impaired urinary elimination, that's really the heart of it.
It impacts almost everything else.
Why so?
Well, the kidneys handle waste, fluids, electrolytes, acid -base balance, even hormones.
So when they falter, you see ripple effects across basically every organ system.
It's systemic.
Okay, let's get some key terms straight first.
We've got two main conditions here.
Right, first there's acute kidney injury, AKA think rapid, like hours or days.
And crucially, it's often temporary, reversible if caught early.
Okay, rapid onset, potentially temporary.
And the other?
That's chronic kidney disease, or CKD.
This is the opposite slow, progressive, irreversible, usually defined as lasting longer than three months.
It's a path toward end -stage kidney disease.
And as things worsen, we see waste building up.
Exactly, that's azotemia.
Too much nitrogen waste, urea, in the blood.
You see it on the labs.
But labs are one thing.
When does it become a clinical problem for the patient?
That's uremia.
Uremia is azotemia plus symptoms.
So nausea, vomiting, maybe confusion, fatigue.
Yeah.
That's when the waste buildup is actually making the patient sick.
It's a toxic state.
Got it.
And one more key sign we track,
urine output.
Definitely.
Oliguria, that's specifically defined as a urine output, less than 400 millilail over a full 24 hours.
A really critical sign, especially in AKI.
All right, let's focus on AKI first.
That sudden problem.
What's the clinical definition we use now?
Seems like it's evolved.
It has.
We rely on the KDI GO criteria.
It gives us a few ways to define it.
Okay.
An increase in serum creatinine by 0 .3 mil GDL or more within just 48 hours.
That's pretty quick.
Right.
Or if creatinine jumps to one and a half times the patient's baseline level within seven days.
Okay, so a relative increase too.
Yes.
And the third one is that urine output measure we mentioned.
Urine volume less than 0 .5 millilimals per kilogram per hour for six straight hours.
Six hours.
But creatinine is slow, isn't it?
We often feel like we're behind the curve.
That's the classic problem.
Creatinine lags.
Damage is already happening by the time it rises significantly, but there's newer stuff.
Like what?
New biomarkers.
Think TMP2 and IGFBP7.
They function a bit like cardiac troponin does for the heart.
Ah, indicating actual cell damage earlier.
Precisely.
They can signal kidney stress or damage much sooner than creatinine changes, sometimes 12 to 24 hours earlier.
This gives us a chance to intervene before major function is lost.
It's a big step towards earlier detection.
Makes sense.
So to intervene effectively, we need to know why the AKI is happening.
The causes fall into categories, right?
There are three main types based on where the problem originates.
First is pre -renal.
This means the issue is before the kidney.
It's about perfusion.
Not enough blood flow getting to the kidneys.
So things like shock,
dehydration.
Exactly.
Shock, severe dehydration, sepsis, major burns.
Even common drugs like NSAIDs can cause it by reducing blood flow to the kidney.
Okay, pre -renal is perfusion.
What's next?
Intrinsic, sometimes called intra -renal.
This is direct damage to the kidney tissue itself.
Ah, so like toxins.
Yes, nephrotoxic agents are a big one.
Certain antibiotics, IV contrast dye used for scans, heavy metals.
Also things like glomerulonephritis.
Pre -renal, intrinsic.
And the third?
Post -renal.
This means that the problem is after the kidney.
There's an obstruction blocking urine from getting out.
Like kidney stones.
Kidney stones, tumors, and enlarged prostate in men.
Anything that physically blocks the outflow tract.
Understanding those causes really highlights the nursing priority, doesn't it?
Especially that pre -renal type.
Absolutely.
Since reduced perfusion is so common, preventing volume depletion is critical.
And this leads to a major safety point.
Which is?
Don't wait for that official six hours of oliguria defined by KDIGO.
That's too long.
Damage is progressing.
The action alert is clear.
Report urine output less than 30 milliliter per hour for two consecutive hours.
Report it immediately.
Two hours, not six.
Got it.
And for intrinsic risk, like with contrast dye.
Hydration is key.
Dilution and flushing it out.
The goal is adequate IV fluids before and after contrast exposure.
Specifically aiming for a good urine output.
Like 150 milliliter per hour for those first six hours after the contrast.
Okay, let's talk management for AKI.
What are the immediate goals?
First off, maintain normal fluid balance.
We call it uvolemia.
And critically, avoid hypotension.
Keep that blood pressure up to perfuse the kidneys.
Is there a specific target MAP?
It's individualized, of course.
But for patients who already have hypertension, aiming for a mean arterial pressure around 80 to 85 millimetre G might reduce AKI rates.
But you have to balance that against other risks.
Like possibly triggering atrial fibrillation.
If we suspect low volume, we might give a fluid challenge.
Maybe 500 to 1000 millimetres of saline fast.
Yes, but only if the patient isn't already fluid overloaded.
You have to assess their fluid responsiveness first.
Maybe use a passive leg raise test or other measures.
Just pouring in fluid without checking can be dangerous, especially in critical illness.
Fluid overload kills.
Right, and what about diuretics?
Like furosemide, we use them a lot.
We do, but it's crucial to understand their role.
Diuretics help manage fluid overload symptoms.
Like pulmonary edema.
They get rid of excess fluid.
They do not fix the underlying kidney injury or preserve kidney function itself.
That's a key distinction.
Okay, fluids are immediate.
What about nutrition?
You mentioned AKI is stressful.
Extremely.
It triggers a high catabolic state.
The body breaks down protein rapidly.
This increases waste products.
So nutrition needs careful calculation by a dietician.
And the protein amount depends on dialysis.
Yes, if the patient is not on dialysis, protein is usually restricted.
Maybe around 0 .6 grams per kilogram of body weight.
But if they're on dialysis, they lose protein during the treatment.
So they actually need more, maybe one to 1 .5 grams per kilogram.
Are there special formulas?
Often, yes.
Things like NEPRO or SUPLINA.
They're designed for kidney patients lower in sodium, potassium, phosphorus, the electrolytes that build up.
When does AKI get severe enough that we need kidney replacement therapy, KRT?
KRT, or dialysis, becomes necessary when conservative management isn't enough and life -threatening problems arise.
Like what specifically?
Emergent indications include symptomatic uremia, things like pericarditis or neurological changes,
persistently high potassium, usually 6 .5 millipule or higher,
severe metabolic acidosis, like a pH below 7 .1, or fluid overload that's so bad it's compromising breathing or circulation.
And if they need KRT urgently, they get a temporary catheter.
Correct.
Usually a central venous catheter, often in the internal jugular.
And the safety rule here is absolute.
The catheter is only for dialysis.
No blood draws, no IV fluids, no medications through that line, ever.
It risks infection and damage to the access.
Super important.
And there are different types of KRT for AKI.
Right, two main kinds.
There's intermittent KRT, which is standard hemodialysis, maybe three to six hours, three times a week.
That works for more stable patients.
And for unstable patients.
For them, we use continuous KRT, often called CKRT or CRRT.
This runs much slower, over about 24 hours.
It's gentler, better tolerated by patients in the ICU, whose blood pressure can't handle the rapid fluid shifts of intermittent dialysis.
Okay, that covers AKI.
Let's shift gears to chronic kidney disease, CKD.
The slow, irreversible one.
Main causes.
The two big ones, far and away, are hypertension and diabetes mellitus.
They account for most cases.
And CKD progresses in stages.
Yes, stage based on the glomerular siltration rate, the GFR, which measures how well the kidneys are filtering.
Stage one is actually GFR over 90, so technically normal filtration.
But there's evidence of kidney damage, like protein leaking into the urine albuminuria.
And as it gets worse.
Stage three is a GFR between 30 and 59.
By this point, esatemia is usually present, and patients need restrictions on fluids, protein, electrolytes.
Stage five is end stage kidney disease, ESKD, with the GFR below 15.
At that point, KRT dialysis or transplant is needed to live.
CKD affects the whole body, doesn't it?
Let's talk about bones.
How does kidney failure weaken the skeleton?
Seems counterintuitive.
It's a complex chain reaction leading to renal osteodystrophy.
So the failing kidney can't activate vitamin D properly.
Without active vitamin D, your gut can't absorb calcium well.
At the same time, the kidneys aren't excreting phosphate, so phosphate levels rise.
Low calcium and high phosphate trigger the parathyroid gland to release more parathyroid hormone, or PTH.
And PTH pulls calcium from bone.
Exactly.
PTH tells the bones to release calcium to try and normalize blood levels.
Over time, this constant pulling weakens the bones, causing density loss, pain, and fractures.
We also have to watch the calcium phosphate product.
If it gets too high, crystals can form in soft tissues.
Very dangerous.
Wow, and the heart is deeply involved, too.
Absolutely.
It's called cardiorenal syndrome.
The heart and kidneys are intimately linked.
CKD makes hypertension worse because of fluid overload and problems with the renin -angiotensin system.
Which leads to heart failure.
Very commonly.
Heart failure happens because of the volume overload, the chronic anemia that comes with CKD, and the high blood pressure.
Sometimes the uremic toxins themselves can damage the heart muscle, uremic cardiomyopathy, or cause inflammation around the heart sac pericarditis.
An acid -based balance gets thrown off.
Yes, kidneys are crucial for excreting acid.
When they fail, hydrogen ions build up, causing metabolic acidosis.
The body tries to compensate by breathing faster and deeper, trying to blow off carbon dioxide, which is an acid.
This specific pattern is called Kussmaul respirations.
It's a sign of severe acidosis.
You mentioned uremic toxins earlier.
What are some other signs that uremia is really taking hold systemically, like in the blood or GI system?
Well, anemia is almost universal because the kidneys stop making enough erythropoietin, the hormone that signals bone marrow, to make red blood cells.
Okay.
In the GI tract, uremia changes the bacteria in the mouth.
Urea gets broken down into ammonia, causing that characteristic bad breath, uremic fetter.
And the whole GI system is more fragile, higher risk of ulcers, inflammation, and bleeding.
Seen black, Terry Stuhl's Molina is a serious warning sign.
So, managing CKD involves tackling all these systemic issues.
What are the priorities?
Fluid control is huge.
Daily weights are essential.
Remember, a one kilogram gain usually means about one liter of fluid retained.
Fluid restrictions are tailored, often based on the previous day's urine output, plus about 500 bill of ales for insensible losses.
And blood pressure control remains vital.
Absolutely critical to slow progression.
The target is generally 130 over 80 or lower.
ACE inhibitors are often preferred drugs because they offer cardiovascular protection too.
Nutrition gets complex.
You mentioned phosphate binders earlier.
What's the key teaching point there?
Timing.
They must be taken with meals.
They work by binding phosphorus in the food right there on the gut, preventing absorption.
If taken between meals, they don't do much good.
Anything else patients need to strictly avoid?
Yes.
Salt substitutes are usually potassium chloride and potassium is dangerous in CKD.
Also, many over -the -counter antacids contain magnesium, which the kidneys can no longer excrete effectively.
So, avoid those too.
When CKD reaches end stage, KRT is needed long -term.
Hemodialysis requires reliable access.
Right, the AV fistula or AV graft.
The fistula where they surgically connect
is preferred, but needs months to mature, maybe up to four months.
The graft is an option if veins aren't suitable.
And this access site is precious.
The safety alert.
It's non -negotiable.
Never use the arm with the fistula or graft for blood pressure measurements, IV starts, or blood draws.
Ever.
It can damage the access or cause clotting.
And how do we check if it's working?
Frequent checks.
Every four hours or so, you need to feel for the thrill that's a vibration and listen with a stethoscope for the brute,
a whooshing sound.
Thrill and brute mean blood is flowing through.
What about after dialysis?
Any specific monitoring?
Yes, monitor closely for four to six hours post dialysis.
Hypotension is common because of the fluid removal.
Also, avoid invasive procedures if possible because patients get heparin during dialysis to prevent clotting, and it takes a while to wear off.
Okay, that's hemodialysis.
What about the other main option, peritoneal dialysis?
PD uses the patient's own peritoneal membrane in the abdomen as the filter.
It involves cycles of filling the abdomen with dialysate fluid, letting it dwell for a set time, and then draining it out.
What's the biggest risk with PD?
Peritonitis infection of the peritoneal cavity, the major complication.
The absolute key sign that everyone, patient, family, nurse, needs to recognize immediately is cloudy or opaque effluent, the fluid that drains out.
That signals infection and needs urgent treatment.
And the third option, besides lifelong dialysis?
Kidney transplantation.
This offers the best chance at a more normal life, but it requires finding a compatible donor based on blood type and tissue matching, HLA.
Biggest hurdle after transplant?
Rejection.
The body's immune system recognizing the new kidney is foreign and attacking it.
Acute rejection is the most common type.
So preventing rejection is paramount.
Absolutely.
The number one most critical factor for long -term transplant success is lifelong strict adherence to the prescribed immunosuppressive medications.
Skipping doses can lead to rejection and loss of the kidney.
It's a lifetime commitment.
It's clear that managing both AKI and CKD is incredibly complex involving so many body systems.
It really is.
From the rapid crisis of AKI to the slow deterioration of CKD, the impact is profound.
Remembering those core safety cues, like immediate reporting of oliguria and AKI, checking that thrill and brute for HD access, watching the calcium phosphate balance in CKD is vital.
We've covered the pathophysiology, the management, but there's a human side too.
Our sources mention the psychosocial burden.
Oh, immensely.
Think about this.
The average dialysis patient, according to the data, spends around 173 days.
That's almost half the year, either in the hospital or actually undergoing dialysis treatments.
173 days, that's staggering.
It really puts it in perspective.
It highlights that managing kidney failure isn't just about labs and procedures.
It's fundamentally about supporting patients' quality of life, helping them navigate denial or depression, and empowering self -management against, frankly, overwhelming challenges.
That's something to really carry with you.