HAN477 Renal & Acid Base Emergencies

Renal anatomy

In retroperitoneal space at level of costovertebral angle (T12-L3)

Perfusion

Renal arteries

Receives about 25% of cardiac output

- 1,200 mL of blood/min

What is a nephron?

Functional unit of the kidney

- responsible for filtrating, reabsorbing and secreting fluids, electrolytes and waste products by forming urine

Each nephron contains?

- Bowman's capsule

- Glomerulus

- Proximal tube

- Loop of Henle

- Distal tubule

- Collecting duct

Filtrate that is not reabsorbed by the nephron travels to?

Distal collecting tubule

- secreted as urine

- normal urine is 95% water & 5% solute

- kidney can concentrate urine based on physiologic requirements

What is the normal urine output?

>500 mL/day

<500 mL/day is oliguria

What is renal failure?

Inability of kidneys to cleanse blood

- Resultant buildup of waste products

Classifications of acute renal failure

Prerenal

Intrarenal

Postrenal

Emergencies of renal failure: Prerenal

Sudden and severe drop in blood pressure (shock) or interruption of blood flow to the kidneys from severe injury or illness

Emergencies of Renal Failure: Intrarenal

Direct damage to the kidneys by inflammation, toxins, drugs, infection or reduced blood supply

Emergencies of Renal Failure: Postrenal

Sudden obstruction of urine flow due to enlarged prostate, kidney stones, bladder tumor to injury

Prerenal Renal Failure

There is a DECREASED glomerular filtration rate (GFR) and urine output.

Secondary to:

- Hypovolemia

- Cardiac Failure

- Decreased CO

- Accumulation of metabolic waste products in blood

- Increased blood urea nitrate (BUN), creatinine

Treatment for Prerenal Renal Failure

Correction of underlying cause of hypoperfusion

- hypovolemia

- control active hemorrhaging

- IV crystalloids, blood and blood products

- Cardiac failure

- Diuretics

- Nitrates

- Inotropic agents

- Vasopressures

Intrarenal Renal Failure

results from direct damage to kidney parenchyma

- secondary to trauma, infection or disease

Postrenal Renal Failure

- renal failure secondary to obstruction of urine flow

- urine backs up into kidney, filtration cannot occur

Causes of obstruction:

- prostatic hypertrophy

- renal calculi

- neoplasms

Postrenal Renal Failure Treatment

-Correction of obstruction

-Urine clearance

-Foley catheter

-Suprapubic urinary catheter

Acute Emergencies in chronic renal failure (CRF)

Regular dialysis needed for CRF patients

What is dialysis?

Method of removing toxins from blood when the kidneys cannot:

- pts w kidney failure

- pts w acute poisoning

Blood is circulated through filters

Complications of dialysis

hypotension, muscle cramps, loss of blood, hepatitis

Diagnostic findings of acute renal failure: BUN

Urea formed by liver, excreted by kidneys

Urea accumulated in blood if renal dysfunction occurs

Normal value: 5-20 mg/dl

Increases with renal failure

Can be affected by hydration statutes

Diagnostic findings of acute renal failure: Creatinine

Waste product of creatine phosphate, a high-energy molecule found in skeletal muscle tissue, released into blood

Normal value: 0.5-1.2 mg/dl

Best indicator of renal failure

Creatinine of 3-4 mg/dl indicates decrease of GFR by 50%

What are other lab values to evaluate renal failure?

- Urinalysis

- Proteinuria indicates Intrarenal or Postrenal renal failure

- Ketoneuria, glycosuria, elevated specific gravity indicates Prerenal origin of renal failure

- Serum protein

- Serum albumin

- Complete blood count

Chronic renal failure is the

Permanent loss of renal function

- 80% of nephrons in the kidneys destroyed

S/S include changes in the urinary habits, nausea, vomiting, dyspnea or acute coronary syndrome

Treatment of chronic renal failure

Fluid administration

Administration of diuretics (long-term solution)

Pain medication

Dialysis

Kidney Transplant

Renal Failure: Hyperkalemia

Serum potassium greater than 5.5 mEq/L

Electrolyte disorder caused ingestion of potassium supplements, acute or chronic renal failure, blood transfusions, sepsis, Addison's disease, acidosis, and crush syndrome

S/S include weakness, muscle cramps, tetany, paralysis, palpitations or arrhythmias

Diagnosed by ECG (Peaked T waves) and lab values

Acid-Base Physiology

Buffering systems used for short-term pH control

- Ties up H+

Respiratory and renal systems used for long term acid-base balance

- Removes H+ from body

- Manipulate pH with CO2, HCO3, & H+ secretion/retention

Combination of buffer, respiratory and renal systems maintain pH within normal 7.35-7.45 range

What is the slowest of the three systems (buffers and respiratory)

Renal system

- May take 24-48 hours to react to pH changes

Imbalances categorized to origin: Metabolic alkalosis

- pH > 7.45

Result of:

- Increased HCO3 intake

- Increased H+ loss

Can occur secondary to:

- excessive bicarbonate ingestion

- blood transfusion

- vomiting

- nasogastric suctioning

- drug therapy/abuse

Imbalances categorized to origin: Metabolic acidosis

- pH <7.35

Result of:

- Increased H+ reabsorption

- Decreased HCO3 production

- Decreased HCO3 intake

- Impaired HCO3 reabsorption

Can occur secondary to:

- Hypermetabolic state

- Anaerobic metabolism

- Ketoacidosis

- Acute or chronic renal, hepatic, and pancreatic failure

- Diarrhea

Kidney Stones

Aka renal lithiasis, nephrolithiasis

Small mineral deposits that form inside kidneys (mineral and acid salts)

How do kidney stones form?

Form when urine becomes concentrated and minerals crystallize and stick together

What are kidney stones?

- Calcium, oxalate and urine acid

Risk factors for Kidney Stones

Family history/ personal history

Dehydration

Certain diets: high in protein, sodium and sugar

Being obese: High bMI

Digestive diseases and surgery: gastric bypass surgery, inflammatory bowel disease or chronic diarrhea

Other medical conditions: renal tubular acidosis, cystinuria, hyperparathyroidism, certain medications and some urinary tract infections

Symptoms of Kidney Stones

Severe pain in the side and back, painful urination, pink/red/brown urine, cloudy or foul smelling urine, persistent need to urinate

Tests/Diagnosis for Kidney Stones

Blood Testing: too much calcium or urine acid in your blood

Urine Testing: the 24hour urine collection test may show that you're excreting too many stone-forming minerals or too few stone-preventing substances

Imaging: Imaging tests may show kidney stones in your urinary tract (X-rays or CT)

Analysis of passed stones: urinate through a strainer to catch stones and lab analysis will reveal the makeup of stones

Treatment for kidney stones

Smaller stones/minor symptoms: Drinking water 2-3 quarts/day, Pain relievers: ibuprofen, acetaminophen, Medical therapy: alpha blockers to relax muscles in ureter

Larger stones: Lithotripsy: sound waves to break up stones, surgery, scope through urethra, bladder, ureters, parathyroid gland removal

Kidney stones treatment

lithotripsy

Pyelonephritis

Can be life threatening if sepsis or complications develop

May present with few symptoms to severe symptoms (may/ may not have associated dysuria)

May have no fever to a fever greater than 103F

Costovertebral tenderness is a common presentation over the affected kidney

Ongoing Management for Pyelonephritis

- IV Access: NS bonus 250 ml

- Cardiac monitoring

- Antipyretics

- Pain medications as needed

- Antibiotic: readily responds to antibiotic therapy

- Sepsis protocol if needed