Fluid/Electrolytes (Part 1)

What percentage of the human body is fluid?

60%

What are two major fluid compartments?

Intracellular fluid and extracellular fluid

What portion of body water is intracellular

2/3

Where is intracellular fluid located

Inside the cells (2/3 of water in skeletal muscle is intracellular)

What portion of body water is extracellular

1/3

The 3 extracellular fluid compartments

• intravascular

• interstitial

• transcellular

How much fluid is in the intravascular compartment

6 Liters

What makes up the 6L of intravascular fluid

• 3L plasma

• 3L erythrocytes, leukocytes, and thrombocytes

How much fluid is in the interstitial compartment

11-12 L

What is interstitial fluid

Fluid that surrounds the cells

How much fluid is in the transcellular compartment

About 1 L

Examples of transcellular fluid

• CSF

• pericardial fluid

• synovial fluid

• pleural fluid

• digestive secretions

For major functions of water

• solvent

• transport

• thermoregulation

• lubricant

The two types of electrolytes

cations and anions

Major cations

• Sodium (Na+)

• Potassium (K+)

• Calcium (Ca2+)

• Magnesium (Mg2+)

• Hydrogen (H+)

Which major cation is primarily extracellular

Sodium (Na+)

Which major cation is primarily intracellular

Potassium (K+)

Major anions

• Chloride (Cl-)

• Phosphate (P)

• Sulfate (SO4)

• Bicarbonate (HCO3)

Which major anion is primarily extracellular

Chloride (Cl-)

Which major anion is primarily intracellular

Phosphate (P)

What can a high anion gap indicate

Metabolic acidosis

What four processes move fluid between compartments

• Diffusion

• Active transport

• Filtration

• Osmosis

DIffusion

Movements of particle from higher concentration —> lower concentration

Does diffusion require energy

No

What is active transport

Movement of particles from lower concentration —> concentration

Does active transport require energy

Yes- ATP

Filtration

Movement of water across a membrane due to pressure differences

Osmosis

Movement of water across a semipermeable membrane from an area of lower solute concentration —> higher solute concentration

Oncotic pressure

Pressure exerted by proteins (mostly albumin)

Fluid balance is maintained via…

Input and output

What regulates fluid intake

• Thirst

• Dietary intake

• Tube feeds

• Parenteral infusions

What regulates fluid output

• Kidneys

• Skin

• GI tract

• Lungs

How much fluid do the kidneys normally excrete per day

1-2 L/day (1.5 avg)

Insensible fluid losses

Fluid losses that occur through the skin, lungs and stool

How much fluid is lower through the skin as an insensible loss?

300mL

How much fluid is lost through the lungs

500mL

How much fluid is lost through sool

200mL

What hormones help the kidneys maintain fluid balance

Aldosterone and ADH (antidiuretic hormone)

What does antidiuretic hormone do

Promotes water retention

Where is antidiuretic hormone made

hypothalamus; stored in pituitary gland

What does aldosterone cause

• Na+ and H2O retention

• K+ excretion

What regulates fluid balance through pressure sensing

Baroreceptors & mechanical sensor proteins

What hormonal system regulates fluid balance and blood pressure

Renin-angiotensin-aldosterone system (RAAS)

What triggers the Renin-angiotensin-aldosterone system (RAAS)

• Drop in BP

• Low blood volume

• Low Na+ levels

What natriuretic peptides are involved in fluid regulation?

• Atrial natriuretic peptide (ANP)

• Brain natriuretic peptide (BNP)

What are natriuretic peptides

Hormone released by your heart / blood vessels when the heart muscle is stretched under stress

Hypovolemia

Extracellular fluid loss exceeds intake (decrease in the volume of blood or fluid circulating in the body)

Dehydration

Loss of body fluid

Causes of hypovolemia

• Vomiting/diarrhea

• GI suctioning

• Sweating

• Hemorrhaging

• Decreased intake

Risk factors for hypovolemia

• Osmotic diuresis

• Adrenal insufficiency

• Coma

• Hemorrhage

• DKA/DI

• Hyperventilation

S/s of hypovolemia

• Hypotension

• Tachycardia

• Tachypnea

• Oliguria

• Flattened jugular veins

• Weak rapid thready pulse

• Decreased capillary refill

Common lab findings with hypovolemia

• increased blood and urine osmolality

• increased urine specific gravity

• increased HCT

• decreased BUN/Cr

• decreased GFR (Glomerular Filtration Rate)

How is hypovolemia treated

Fluids (PO or IV), specifically isotonic solutions

Hypervolemia

Too much fluid

Causes of hypervolemia

• Poor fluid excretion

• Heart failure

• Renal failure

• Cirrhosis

• Burns

• Corticosteroids

S/s of hypervolemia

• Crackles

• Edema

• JVD

• Tachycardia

• Hypertension

• Dyspnea

Common lab findings with hypervolemia

• decreased blood and urine osmolality

• decreased urine specific gravity

• decreased H/H (hematocrit + hemoglobin)

How is hypervolemia treated

• Treat the initial cause

• Diuretics

• Fluid restriction

What position is used for orthopnea with fluid overload

Semi-fowlers

What amount of weight gain should be reported in a hypervolemic patient

1-2lbs in 24 hr OR 3lbs in 1 week

Hyponatremia

Low sodium (Na+ < 135 mEq/L)

Causes of hyponatremia

• SIADH

• Kidney failure

• Diaphoresis

• Diuretics

• Hyperglycemia

• Heart failures

• Tap-water enemas

S/s of hyponatremia

• Nausea/vomiting

• Headache

• Fatigue

• Confusion

Serum osmolality with hyponatremia

<270

How is hyponatremia treated

• Water restriction

• 3% Na+ replacement (IV)

• PO sodium

Hypernatremia

High sodium levels (Na+ >145 mEq/L)

What causes hypernatremia

• Too much sodium intake

• Kidney failure

• Fever

• Heatstroke

• Cushing’s syndrome

S/s of hypernatremia

• Thirst

• Hyperthermia

• Tachycardia

• Orthostatic BP

• Sticky/dry mucous membranes

• Restlessness

• Flushed skin

• Seizures

Serum osmolality with hypernatremia

>300

How is hypernatremia treated

• PO tap water/encourage fluids

• D5W/hypotonic IV solution

• Free water in tube feed (bolus)

Hypokalemia

Low potassium (<3.5 mEq/L)

What acid-base disorder may occur with hypokalemia?

Metabolic alkalosis

Causes of hypokalemia

• GI loss

• Medications

• Poor diet

• Hyperaldosteronism

S/s of hypokalemia

• Fatigue

• Anorexia

• Nausea/vomiting

• Arrhythmias

• Cramps

• Muscle weakness

• High blood sugar

• Polyuria

ECG changes seen in hypokalemia

• Shallow T wave/PVCs

• Inverted T waves

• ST depression

hypokalemia treatment

• Potassium replacement / foods

• ECG monitering

why do potassium levels affect the heart

it controls the electrical signals that tell your heart muscle when to contract and relax

Hyperkalemia

High potassium levels (>5.0 mEq/L)

Causes of hyperkalemia

• Acidosis

• Poor renal function

• Hypoaldosteronism

• Burns

• Tissue damage

S/s of hyperkalemia

• Arrhythmias

• Bradycardia

• Cramps

• Muscle weakness

• Anxiety

• Nausea/vomiting

• Respiratory impairment

ECG changes seen with hyperkalemia

Peaked T waves

What ABG finding may occur with hyperkalemia

Metabolic acidosis

Hyperkalemia treatment

• IV calcium gluconate

• Limit dietary potassium

• Sodium bicarbonate

• D50 with insulin

• Loop diuretics

• Kayexalate

Where is >99% of calcium located

Bones/teeth

What vitamin is needed for calcium absorption

Vitamin D

What regulates calcium levels

• The thyroid

• Parathyroid hormone

Calcitonin

Hormone from thyroid that inhibits calcium breakdown from bone to lower calcium levels

Hypocalcemia

Low calcium levels (<8.6mg/dL)

Causes of hypocalcemia

• Hypothyroidism

• Malabsorption

• Renal failure

• Pancreatitis

• Alkalosis

• Lactose intolerance

• Vitamin D deficiency

S/s of hypocalcemia

• Trousseau’s

• Chvostek’s

• Laryngospasm

• Bradycardia

• Muscle spasm

• Anxiety

• Finger paresthesia

Hypocalcemia treatment

• IV calcium gluconate

• Vitamin D

• Diet changes

Important considerations for hypocalcemia

• Perform frequent airway assessment

• Administer calcium

• Practice weight bearing exercises

• Have emergency equipment on standby

Hypercalcemia

High calcium levels (>10.2 mg/dL)

S/s of hypercalcemia

• Muscle weakness

• Constipation

• Anorexia

• Nausea/vomiting

• Polyuria

• Arrhythmias

• Abdominal + bone pain

hypercalcemia treatment

• Address the cause

• Phosphate

• Lasix/furosemide

• Fluids

Nursing interventions for hypercalcemia

• Fiber for constipation

• Ambulate + assess

• Push fluids

Hypomagnesemia

Low magnesium levels (<1.8 mg/dL)

What electrolyte is hypomagnesemia associated with

Low calcium

Whaat does magnesium help metabolize

• Carbohydrates

• Protein

• Vitamin D

Causes of hypomangesemia

• Alcoholism

• Malnutrition