Kidney Mega

What are the most common causes of AKI in dogs?

toxic, infectious

What are the most common causes of AKI in cats?

Obstruction, unknown

What usually causes AKI in the hospital?

Use of nephrotoxic drugs

Hemodynamic instability left untreated

Volume overload

What are causes of hemodynamic / volume responsive AKI?

Hypovolemia

Decreased CO

Systemic vasodilation

Renal vasoconstriction

What are the characteristics of hemodynamic AKI?

Rapidly reversible once inciting cause is eliminated

How do you treat hemodynamic AKI?

Restoration of perfusion

What are causes of renal AKI?

Prolonged ischemia, infectious disease, toxins, systemic disease

What are the phases of renal AKI?

1. Initiation/induction

2. Extension

3. Maintenance

4. Recovery

During what phase of renal AKI are clinical and laboratory findings visible?

Maintenance

How do you treat renal AKI?

Remove inciting cause

What are causes of obstructive AKI?

Any cause of urinary tract obstruction

What are the characteristics of obstructive AKI?

Rapidly reversible with restoration of urine flow, repair, and removal of urine that accumulated outside of urinary system

What grade of AKI is non-azotemic?

Grade 1

What are C/S of AKI?

Non-specific but over a short period of time

What is on physical exam of AKI?

Dehydration, oral ulceration, tongue tip necrosis, renomegaly and renal pain

What is the USG of a intrinsic AKI?

Isosthenuric

What is the USG of a hemodynamic AKI?

Adequately concentrated

What on a dipstick indicate PCT damage?

Glucosuria, proteinuria, ketonuria

What is the urine pH on AKI?

Acidic usually

What can WBCs with AKI inidcate?

Acute tubular necrosis, glomerulonephritis, pyelonephritis, nephrotic syndrome

What can RBCs with AKI indicate?

Vasculitis, glomerulonephritis

What can epithelial casts with AKI indicate?

Tubular damage like acute necrosis or glomerulonephritis

What are the most common changes on biochem with AKI?

Azotemia, hyperphosphatemia, hyperkalemia, metabolic acidosis

If BUN is disproportionately increased compared to creatinine what should you look for?

GI bleeding

If a cat has severe azotemia but is still eating and has mild C/S what should you look for?

Lily intoxication or nephron-ureteral obstruction

If there is hyponatremia, hyperkalemia, metabolic acidosis, hyperphosphatemia what should you look for?

Uroabdomen

If you have hyperproteinemia, hypercalcemia, hyperphosphatemia, and azotemia what should you look for?

Cholecalciferol or grape intoxication

If you have thrombocytopenia, elevated liver enzymes, hypokalemia what do you need to think?

Leptospirosis

If you have a high anion gap metabolic acidosis and hypocalcemia what do you need to think?

Ethylene glycol toxicityq

What are causes of renal hyperechogenicity on US?

Ethylene glycol, grapes, lilies

What are causes of subcapsular fluid?

Leptospirosis, lymphoma

What are IV positive contrast studies not useful for AKI?

Low GFR

What is the first step of when you have a patient with AKI?

Rule out things that are not directly related to the kidney like obstruction

What are the steps if you have a patient with AKI?

1. Rule out things not directly related to kidney like obstruction or rupture

2. Determine if it is pre-renal

3. Start specific testing for renal AKI causes

How can you detect is a patient has a pre-renal AKI?

Check BP

Test response to fluids and if no improvement in 8-12 hrs then it is intrinsic

If you have an AKI, where should samples come from to do a culture?

Renal pelvis is pyelectasia is present and urinary bladder

How do you test for ethylene glycol toxicity?

Commercially available in house kits, but only accurate in the first few hours

What is a FNA useful for diagnosing a specific cause of AKI?

Lymphoma

Why are patients with AKI so sensitive to fluid therapy?

The kidneys may not be able to increase urine output to get rid of excessive volume

What is the impact of volume overload on the kidneys?

Interstitial edema causing impaired oxygenation

Renal edema caused decreased GFR

Elevated BP

Increased mortality

What is required to remove excess fluid during volume overload?

Hemodialysis

What fluids do you give during AKI?

Buffered like Ringer’s Lactate

Why do you give buffered fluids during AKI?

Unbuffered solutions can cause metabolic acidosis and worsen GFR

What is the ROSE model?

Fluid therapy model used during AKI

What do you do during the Rescue phase of ROSE?

Replace fluid deficit swithin 4-6 hours to restore normal perfusion

How do you calculate fluid deficit?

Body weight X estimated % dehydration X 1000

What happens during the optimize phase of ROSE?

Balance the Ins and Outs to maintain a neutral fluid balance

Manage electrolytes (hypo or hyperkalemia)

Bicarbonate therapy if metabolic acidosis is present

Manage blood pressure

How do you calculate the outs of fluid loss?

Urine output in mL/kg/hr and 22 mL/kd/day for insensible losses

How can you treat hypertension during the Optimize phase of ROSE?

Amlodipine

What do you do during the Stabilize phase of ROSE?

Use enteral routes to provide nutrition and fluids

Manage GI signs with antiemetics and PPIs

When can you begin the de-Escalate phase of ROSE?

If azotemia and weight are stable on fixed IV and enteral fluids

How do you know you can continue to taper fluids during the ROSE model?

If urine output decreases in line with the decrease in fluid while maintaining a stable weight and perfusion markers

What can you give to patients with oliguria or anuria to manage fluid overload?

Furosemide

How do you test to see if furosemide will be useful to prevent fluid overload?

Give a single test does to see if kidneys will respond (will need to be a higher dose due to lower GFR)

If there is a refractory oliguria/anuria then giving more diuretics will not help and dialysis should be considered

When is renal replacement therapy useful?

Only in first 48 hours of presentation if there is

• Fluid overload

• Severe progressive intrinsic renal azotemia

• Refractory hyperkalemia

• Persistent oliguria

• Severe persistent acid-base disturbances

What is the mortality rate of AKI?

50%ish with most getting CKD after

Does AKI with polyuria have a better or worse prognosis than oliguria?

Better

T/F pre or post-renal azotemia is common to be present concurrently with CKD?

True

What are the risk factors for CKD?

Prior AKI

Familial or breed predisposition

Glomerular disease

Amyloidosis

Tubulointerstitial nephritis

What is CKD staging based on?

Creatinine and SDMA

A patient with CKD is non-azotemic with maybe a change in USG what stage is it?

Stage 1

A patient with CKD has mild azotemia but no systemic signs, what stage is it?

Stage 2

A patient with CKD has moderate azotemia and systemic signs, what stage is it?

Stage 3

A patient with CKD has severe azotemia and systemic signs. There might be uremia, what stage is it?

Stage 4

What are the substage of CKD based on?

Proteinuria based on UPC taken twice over 2 weeks

Blood pressure measured multiple times over 1-2 weeks

If you treat the a patient with CKD and hypertension how does it change the classification?

You keep it the same, but say treating hypertension at the end

What are the goals of CKD treatment?

Slow progression and preserve remaining kidney function

Maintain quality of life

What is the NEPHRONS acronym for CKD treatment?

Nutrition

Electrolytes

Phosphate, proteinuria, pressure, pH

Hydration status

Retention of wastes

Other renal insults to avoid

Neuroendocrine changes

Serial monitoring

When do you start to recommend a renal diet for CKD?

If there is Stage II CKD or stage I with proteinuria or hyperphosphatemia

Why do you not start a patient on a renal diet in the hospital?

They will associate that diet with the hospital and will not eat it at home

What are the key characteristics of a renal diet?

High palatability and caloric density

Modified amounts of high quality and digestible protein

Low phosphorus content

Increased fat

Fermentable fiber

Alkalinizing

Higher potassium and lower sodium

What is really important in the diet of CKD patients?

That they eat enough food to not lose any weight

Hypokalemia with CKD can cause what?

Weakness, lethargy, inappetence, constipation, reduced renal blood flow and GFR

What supplements can be used to treat hypokalemia with CKD?

Potassium citrate or potassium gluconate

What is a good potassium level?

> 4 mmol/L

Why do dogs not get hypokalemia with CKD?

They are on ACEi or ARBs which cause potassium retention

In what stage of CKD can HYPERkalemia develope?

Stage IV

What is associated with progression of CKD?

Hyperphosphatemia

How long does it take for phosphate levels to go to normal after starting renal diet?

1-2 months, so check phosphate levels 4-6 weeks after starting therapy and recheck every 3-4 months

At what stage of CKD is a renal diet not enough to control hyperphosphatemia?

Stage IV

What phosphate binders can be used to control hyperphosphatemia?

Aluminum hydroxide, lanthanum carbonate, chitosan, calcium carbonate

Why do you get proteinuria with CKD?

Increased protein in diet puts a strain on the PCT

When do you begin treating proteinuria during CKD with ACEi or ARBs?

UPC > 0.5 in dogs or 0.4 in cats

How do you treat proteinuria during CKD?

ACEi or ARB

What is the goal of proteinuria treatment with CKD?

Decrease UPC by 50% of baseline

At what BP do you begin treating hypertension with CKD?

> 160 mmHg

What is the first line of hypertension therapy in dogs?

ACEi or ARB

What is the first line of hypertension therapy in cats?

Calcium channel blocker

What is the second line of hypertension therapy in cats?

ACEi or ARB with a calcium channel blockers

What is the second line of hypertension therapy in dogs?

Calcium channel blocker

If a dog with CKD has severe hypertension what can you give?

ACEi or ARB with a calcium channel blockers

What stage of CKD gets metabolic acidosis?

Stage III and stage IV

Why is dehydration common in CKD patients?

Inability to match water intake with loss or when vomiting increases loss

What are mechanisms to improve hydration with CKD?

Have fresh water in different forms

Feed wet food

SQ fluid in cats

Via feeding tube

How do you prevent accumulation of uremic toxins during CKD?

Using a renal diet with fermentable fibers that trap nitrogen in the gut

What antiemetics can be used with CKD?

Maropitant or ondansetron

What appetite stimulants can be used with CKD?

Mirtazapine

Capromorelin

What are some other renal insults to avoid with CKD?

Nephrotoxic drugs

Pre-renal insults

Post-renal insults

Infections

What are some underlying causes of anemia with CKD?

GI bleeding

Underlying infections

Nutritional deficiencies

What is darbepoetin?

EPO analogue