Alteration in Renal Function: Acute and Chronic Kidney Injury

Renal Function

• Primary function is to Filter blood and maintain body’s homeostasis

• Reabsorption of 80% of electrolytes, water, glucose, amino acids, HCO3 (bicarb) to regulate volume, composition of extra-cellular fluid, and acid-base balance 

• Excrete waste products (urea, creatinine, ammonia, uric acid)

Renal Function: secretion

• Secretes renin for blood pressure control via renin-angiotensin-aldosterone system

• Secretes erythropoietin to stimulate RBC production

• Secretes calcitriol a form of Vitamin D that helps body absorb calcium and phosphorus

Renal Failure

• Inability to excrete waste products & H2O

• To prevent acute renal failure, ensure the patient stays hydrated with an adequate fluid volume

• Types: Acute and Chronic

AKI

• Onset: sudden 

• Most common causes: acute tubular necrosis 

• Diagnostics criteria:  acute reduction in urine output and/ or elevation in serum creatinine 

• Reversibility: potentially 

• Cause of death: infection 

CKD

• Onset: gradual, over yrs 

• Most common causes: diabetic nephropathy 

• Diagnostics criteria: GFR <60 mL/ min/ 1.73m2 for 3 months and/or kidney damage > 3 months 

• Reversibility: progressive and irreversible 

• Cause of death: cardiovascular disease 

Acute Kidney Injury (AKI)

• Usually follows severe prolonged hypotension, hypovolemia, or exposure to nephrotoxic agent

Acute Kidney Injury (AKI) results in

• Azotemia: nitrogen-containing waste products in the blood

• Uremia: uremic toxins (one type of toxin-urea) build up in the blood

AKI Causes…Prerenal

• (usually reverses quickly)

  • Due to factors external to kidney that reduces systemic circulation (cardiogenic shock, HF, MI)

  • Oliguria and Decreased GFR. Tx: ie. NSS IV if reduced fluid volume or fluid removal if HF

AKI Causes… Intrarenal

• (55% mortality)

  • Caused by direct damage and impairing nephrons (ischemia, nephrotoxins-aminoglycosides, contrast dye, increased hemoglobin, increased myoglobin for damaged muscles, Acute tubular necrosis from major surgery, shock or blood transfusion reaction). Tx: underlying cause, ie. Administer IV fluids

AKI Causes… Post renal

• (can resolve quickly if initial problem fixed)

  • Caused by mechanical obstruction of urinary outflow. Urine refluxes into renal pelvis

  • Caused by cancer, stones, trauma. Tx: underlying cause, ie. Remove obstruction

  • Prolonged obstruction can lead to atrophy and irreversible kidney fibrosis

AKI Phases in all causes…oliguric

• Low urine output or continues to make urine without filtering waste

  • Urinary output less than 400 mL/day (norm 0.5mL/kg/hr or 30mL/hr). 

  • Volume overload (edema), Pulmonary edema

  • Metabolic Acidosis. Rapid, deep respirations, lethargy, confusion, n, v, weakness

  • Hemodilution effects: Decrease in sodium (diluted sodium) and calcium (poor absorption), increase in potassium (decrease excretion)

  • Increase in BUN, creatinine (waste)

AKI oliguric urinalysis

• Urinalysis: casts, RBCs, WBCs, protein

AKI Phases in all causes…diuretic

• Kidney begins to excrete urine (1 to 3 L/day), but not to concentrate urine

• Check for hyponatremia, hypokalemia, dehydration

AKI Phases in all causes…recovery

• GFR increases to norm, BUN & Creatinine decrease to normal

AKI Diagnostics

• BUN (urea), Creatinine, Serum electrolytes

• Renal Ultra-sound

• Renal Scan of blood flow and tubular function

• CT Scan

• Renal Bx

• U/A, C & S

• Creatinine Clearance

• Osmolality

Osmolality

• concentration of particles in urine (norm 50-1200 mOsm/kg)

AKI osmolarity

• If renal perfusion diminishes, urine osmolality elevates more than blood osmolality

• Less blood running through kidney means less urine being made, with the result of urine being more concentrated. Urine specific gravity (norm 1.005-1.030) increases.

• The retention of fluid in the blood means blood is more dilute.

AKI Collaborative Care

• Eliminate precipitating cause

• Fluid Restriction (avg 600mL/day)

• Treat elevated K+ levels. Telemetry monitoring.

• Monitor BUN and Creatinine levels. Provide for safety if urea levels are elevated.

• Manage Ca/Phos inverse ratio

• Loop diuretics, if early in treatment

• Hemodialysis, if needed

• Continuous Renal Replacement Therapy (CRRT), if needed

AKI dietiary adjustments

• Dietary Adjustments

  • Adequate protein-AKI needs it for tissue repair due to catabolism

  • Decreased protein for CKD because can’t excrete urea

  • Diet restrictions: potassium, phosphate, sodium

AKI Collaborative Care Treatments For Elevated Potassium (Hyperkalemia) Levels

• IV Insulin to move K in cells and Glucose to prevent hypoglycemia

• IV Sodium Bicarbonate (NaHCO3) to correct acidosis and move K into cells

• IV Calcium Gluconate, mostly for cardiac issues 

• Sodium Polystyrene Sulfonate (Kayexalate)

  • PO or enema

  • Diarrhea

• Hemodialysis

• Potassium Dietary Restriction to 40 mEq/day

Chronic Kidney Disease (CKD)

• GFR less than 60mL/min for longer than 3 months

• Progressive, irreversible destruction of nephrons

• Necessitates dialysis and/or transplantation eventually

• Results in systemic disease effecting every body organ

• Progressive stages that lead to the last stage of “End Stage Renal Disease”, kidney failure

CKD…Glomerular Filtration Rate

• Kidneys receive 1–1.5 L of blood per minute (20–25 percent of cardiac output)

• This maintains the glomerular filtration rate (GFR) at about 125 mL per minute.

• Levels below 60 mL/min for 3 or more months are a sign of chronic kidney disease.

CKD…Stage 1

•  Kidney damage with normal or >/= 90mL/min GFR

CKD… Stage 2

• Kidney damage with mild decrease in GFR  60-89mL/min 

CKD… Stage 3

• Moderate decrease in GFR, 30-59mL/min GFR, anemia, polyuria

CKD… Stage 4

• Severe decrease in GFR. 15-29mL/min GFR, Renal Failure, onset of symptoms, prep for dialysis

CKD… Stage 5

End-stage Renal Disease. Renal Failure. <15mL/min GFR, worsening of symptoms, requires dialysis

CKD Clinical Manifestations

• Varying degrees of Uremia

• Polyuria, followed by oliguria, followed by anuria

• Increase in Creatinine & BUN. Decrease in GFR.

• Chronic Meta Acidosis. Kussmauls breathing

• Edema, HTN, HF

• Anemia, Bleeding tendencies

• CVD

• Dysrhythmias (hyperkalemia, hypocalcemia)

• CNS depression, mental changes, weakness

• Pruritis from calcium-phosphorus deposits on skin (hyperphosphatemia)

• Uremic toxins/frost if BUN >200mg/dL. Check pt for safety issues.

Varying degrees of Uremia

• buildup of toxins like urea and creatinine

• Nausea, vomiting, weight loss, fatigue, difficulty concentrating, mental confusion, abnormal bleeding, heart problems, swelling in the feet

CKD Diagnostics

• BUN, Creatinine, Serum electrolytes, Lipid profile

• Renal Ultra-sound

• Renal Scan of blood flow and tubular function

• CT Scan

• Renal Bx

• U/A, check protein in the urine

• Serum Creatinine Clearance. Most accurate because kidney excrete creatinine

CKD Collaborative Care

• Cardiac monitor for changing electrolytes

• Monitor K+, Treat hyperkalemia. Monitor NA, Treat hypernatremia

• Control HTN and dyslipidemia

• Manage Renal Osteodystrophy (abnormal bone development) by balancing calcium and phosphorus. Restrict Phosphate intake, Give Ca supplements, if needed

• Parathyroidectomy, if needed, to control hyperparathyroidism

  • Tx for low blood calcium levels

• Dialysis/CRRT: Sterile technique

CKD nutrition

• Nutrition, Electrolytes: No House diets, Restrict Protein, Sodium, Potassium, Phosphate

CKD fluid intake

• Fluid: Restrict fluid intake of >300 mL with each meal and at bedtime, Restrict IV fluid infusing at 100 mL/hr or more, Take daily weights 

CKD Collaborative Care…Medications

• Phosphate binders. calcium carbonate, sevelamer 

• Ca+ supplements. Calcium citrate, calcium gluconate

• Antihypertensives. amlodipine

• ACE inhibitors. captopril, enalapril, lisinopril

• ARBS. losartan, valsartan

• Erythropoietin. To manage anemia 

• Lipid lowering. atorvastatin, pravastatin, simvastatin

• Adjust drug dose to degree of renal function

Dialysis

• Movement of fluid and molecules across a semi-permeable membrane from one compartment to another

• Corrects fluid and electrolyte imbalances by Ultrafiltration

  • PD—glucose in dialysate

  • HD—pressure gradient

• Removes waste products

• Used when uremia necessitates it. Ie. Encephalopathy, uncontrolled hyperkalemia

• Sterile technique needs to be done with dialysis

Continuous Automated/Ambulatory Peritoneal Dialysis (CAPD)

• Catheter via abdominal wall

• Contraindicated with abdominal or thoracic surgery, COPD, Crohns

• Fills, dwells, empties at night and then a few times during the day

• Outflow is clear and yellowish or amber

Complications of CAPD

• Exit site infection

• Peritonitis: cloudy peritoneal effluent (fluid) that has a WBC count of over 250 cells per microliter

• Abdominal pain: abdomen usually feels distended when dwelling, but not really pain

• Lower back pain

• Bleeding

Complications of CAPD (2)

• Blockage

• Pulmonary edema, atelectasis, pneumonia

• CHO and lipid abnormalities: glucose is absorbed which increases insulin secretion which stimulates liver production of triglycerides

blockage

• dialysate from the peritoneal catheter has stopped before the infused volume amount is drained. Educate pt to turn from side to side to break any internal suction on the catheter, reposition self, or have a BM.

Hemodialysis

• Rapid exchanges

• Requires vascular access. Two needles inserted 

• Blood is filtered against a pressure gradient

• Treatments last 3-5 hrs, 3 times weekly

• Pre & Post assessment to evaluate weight and fluid status/removal

Hemodialysis monitoring

• VS monitored closely during Rx. Can cause HTN during tx or hypotension after tx. BP meds usually held during Rx. 

Vascular Access for Hemodialysis Arteriovenous (AV) Fistula

• Bruit

• Thrill

• Limb Alert

• Monitor for Complications (infection, bleeding, obstruction)

• No heavy lifting

• Mild soap

Components of Hemodialysis System

Hemodialysis Complications

• Hypotension

• Muscle cramps: Pain med if needed

• Blood loss: Monitor I/O

• Hepatitis B & C: Monitor labs

• Sepsis, Infection: Monitor for local and systemic symptoms

• Clotting of vascular access/AV fistula

• Disequilibrium Syndrome

• Irritation of fistula arm: Mild soap and water for baths 

Clotting of vascular access/AV fistula:

• Never take BP, insert IV, or draw blood in extremity with AV access-sign needed.  Avoid carrying heavy objects in arm with fistula.

Disequilibrium Syndrome

• Monitor LOC

  • Solutes removed more rapidly from blood than CSF causes cerebral edema

Continuous Renal Replacement Therapy (CRRT)

• Similar to Hemodialysis but preferred for hemodynamically unstable patient

• Requires 12-24 hrs to do what hemodialysis can do in 3-4 hrs

• Lower risk of hypotension 

• Slow continuous removal of fluids & waste via arterial access

• Can remove large volumes over days

• Operated by trained ICU RN

CRRT Types

• Continuous venovenous hemofiltration (CVVH)

• Slow continuous ultrafiltration (SCUF)

• Continuous venovenous hemodialysis (CVVHD)

• Continuous venovenous hemodiafiltration (CVVHDF)

AKI and CKD Collaborative Care

• Monitor VS (including pre and post dialysis treatment)

• I & O

• Weigh pt daily and pre and post dialysis treatment

• Assess breathing pre & post treatment

• Urine examination

• Dialysis site assessment

• Restriction sign for site use

• Evaluate Neuro status frequently

• Evaluate for fluid overload

• Monitor Labs pre and post treatments

• Clear explanations for patient and family

• Meticulous sterile technique for all procedures and dialysis treatments

• Medication dosage adjustments

• Cough, deep breathe, turn q2h, ambulation

• Skin care

• Mouth care

Dialysis Nutritional Adjustments:

• high-quality protein, strictly limiting sodium, potassium, phosphorus, and fluid intake

CKD Kidney Transplantation

• Reverses physiologic changes of renal failure

• Less expensive than dialysis after 1 year

• Recipient selection

Recipient selection

• Based on need; scored as points by the national organ procurement system

• Candidates meet physical requirements as well as psychological requirements

• Must be able to withstand surgery and be compliant with post-op regimen for remainder of the life of the organ

Donors for Kidney Transplantation: live donors

• Blood relatives or emotionally related 

• Must be free of disease

• Better patient & graft survival rates because of minimal cold time and organ in best medical condition

• Must be emotionally stable

• Must be informed of risks and benefits

• Done as open nephrectomy or laparoscopic procedure

Donors for Kidney Transplantation: cadaver donors

• Healthy people who have suffered irreversible brain damage. Brain dead patient kept on life support until organs can be removed

• Free of disease

• Requires permission of next-of-kin even if donor card signed

• Cold time should not exceed 24 hours or ATN may occur but can go up to 72 hours

• Kidney matched to recipient

Collaborative Care…Kidney Transplantation Recipient (KTR)

• First 12-24 hours in ICU

• Monitor I & O. Large UO (1L/hr) may be noted after kidney initially placed. A sudden decrease in urinary output after surgery is cause for concern. 

• Careful Fluid replacement: Intake mL should = Output mL

• Central Venous Pressure readings to monitor fluid status in heart

• May require dialysis due to Acute Tubular Necrosis (ATN) of transplanted kidney 

• Monitor & replace electrolytes

• Monitor for urinary catheter blockage, check patency   

Collaborative Care for KTR: Immunosuppressive Therapy

• Suppresses immune response to prevent rejection of transplanted kidney

• Started immediately post-op. Taken for the life of the transplanted organ

• High risk of infection-fungal, viral, bacterial

• High risk of malignancy due to immunosuppression

Collaborative Care for KTR: Assess for Recipient Rejection 

• Increased Creatinine & BUN 

• Fever, Increased BP

• Weight gain, edema, decreased U.O. (oliguria) 

• Tenderness over graft site, apprehension

• Frequently reversible by increasing immunosuppressive agents and corticosteroids

Collaborative Care for KTR: assess for infection

• Recipient is immunosuppressed and therefore at greater risk for infection. Monitor for local or systemic infections (temp, redness, warmth)

• Frequent hand-washing

• Separate from infected population

Collaborative Care for KTR: assess for CVD

• Increased incidence of atherosclerotic vascular disease due to HTN, DM, rejection, hyperlipidemia

• Immunosuppressants can worsen HTN & hyperlipidemia

• Monitor weight gain

• Monitor blood glucose

• Manage HTN

Collaborative Care for Live Donor

• Usual post-op care for nephrectomy patient

• Observe for retro-bleed

• Cough & deep breathe,  IS

• Pain management

• Acknowledge gift of organ donation

• Support if donation fails

• Turn q 2 hr

• OOB to chair

A patient is admitted to the unit and the lab results are returned. Which lab results will make the nurse suspect acute kidney injury?

A. blood urea nitrogen level 20 mg/dL

B. serum creatinine level 1.8mg/dL

C. low-density lipoprotein (LDL) level 146mg/dL

D. serum potassium level 4.9 mEq/L

The nurse teaches a patient with chronic kidney disease about prevention of complications.  Which intervention should the nurse include in the teaching plan?

A. Monitor for proteinuria daily with a urine dipstick.

B. Perform self-catheterization every 4 hours to measure urine. 

C. Take calcium-based phosphate binders on an empty stomach.

D. Check weight daily and report a gain of greater than 4 pounds.

A patient diagnosed with chronic kidney disease undergoes dialysis exchanges several times each day. Which foods should the nurse teach the patient to include in their daily dietary intake? 

A. canned goods, salty snacks

B. bananas, oranges, tomatoes

C. dairy products, processed foods

D. apples, berries, broccoli

A patient with chronic kidney disease is scheduled for hemodialysis. During the pre-dialysis assessment, the nurse notes the patient has shortness of breath and a blood pressure of 180/95 mmHg. Based on this assessment, which nursing action is most appropriate?

Administer the patient’s antihypertensive medication immediately.

Restrict the patient’s fluid intake to 500 mL/day.

Notify the dialysis team and prepare the patient for treatment.

Cancel the dialysis session until the blood pressure stabilizes.