Fluid, Electrolyte, and Acid-Base Regulation

What are electrolytes and where are they found?

Electrolytes are minerals found in urine, blood, tissues, and other bodily fluids. They also come from food, drinks, and supplements.

What are the major electrolytes?

Potassium, Sodium, Calcium, Magnesium

What are the functions of electrolytes

• Balance the amount of water in the body

• Balance body pH (acid-base)

• Move waste out of cells (vomiting, bowel movements)

• Move nutrients into cells

• Allow muscles, heart, nerves, and brain to function properly

• Conduct electrical charges

What factors contribute to electrolyte imbalance?

• Dehydration

• Overhydration

• Medications

• Heart, kidney, liver disorders

• IV fluids

• Tube feedings/TPN

• Poor diet

What is the normal potassium range and its major role?

• 3.5–5 mEq/L

• Powers heart rhythm and muscle function

Causes of hypokalemia (<3.5)?

• Loop diuretics

• Penicillin, Amphotericin B

• Prolonged vomiting/diarrhea

• Chronic laxative use

Signs and symptoms of hypokalemia

• Muscle weakness (very common)

• Cardiac arrhythmias

• Constipation

• Fatigue

• Paralytic ileus

• Rhabdomyolysis

• Hypotension

Causes of hyperkalemia?

• Renal failure (very common)

• Dehydration

• Trauma

• Diabetes mellitus

• Sepsis/acidosis

• Excess potassium intake

• PRBC transfusion

Signs and symptoms of hyperkalemia

• Nausea/vomiting

• Cardiac arrhythmias

• Heart failure

• Paralysis

• Muscle weakness/myalgias

Key nursing considerations for IV potassium

• Must be diluted in ≥100 mL

• NEVER IV push

• Rate ≤10–20 mEq/hr

• Max ~40 mEq per dose

• Cardiac monitoring required

• Recheck potassium level

Normal sodium range and major role

• 135–145 mEq/L

• Maintains water balance and brain function

Causes of hyponatremia

• Thiazide diuretics

• Severe vomiting/diarrhea

• Water intoxication

• Alcohol use

• Heart, kidney, liver disease

• Burns

Causes of hypernatremia

• Excess sweating

• Severe vomiting/diarrhea (water loss)

• Prolonged suction

• Burns

• Impaired thirst

• Medications/IV fluids

Signs and symptoms of sodium imbalance

• Muscle twitching

• Restlessness

• Irritability

• Confusion

• Headache

• Seizures

• Coma

• Death

Key rule for correcting sodium imbalance

Correct slowly and treat the underlying cause.

Normal calcium range and major role

• 9–10.5 mg/dL

• Supports bones, muscles, and nerve signaling

Causes of hypocalcemia

• Medications

• Low vitamin D

• Menopause

• Hypoparathyroidism

• Kidney disease

• Sepsis

Signs and symptoms of hypocalcemia

• Cardiac dysrhythmias, chest pain

• Laryngeal spasms

• Muscle cramps/spasms

• Confusion, seizures

• Skin/hair changes

• Dental issues

• Positive Chvostek’s & Trousseau’s signs

Causes of hypercalcemia

• Cancer

• Prolonged bed rest

• Hyperparathyroidism

• Kidney failure

• Medications

Signs and symptoms of hypercalcemia

• Constipation, nausea/vomiting

• Bone pain

• Kidney stones

• Lethargy

• Confusion, coma

Normal magnesium range and major role

• 1.3–2.1 mEq/L

• Calms muscles and nerves

Causes of hypomagnesemia

• Medications

• Poor intake

• GI disorders (Crohn’s, celiac)

• Diabetes

• Burns

• Alcohol use

Signs and symptoms of hypomagnesemia

• Nausea/vomiting

• Weakness

• Muscle cramps/tetany

• Increased reflexes

• Dysrhythmias

• Seizures

• Numbness/tingling

Causes of hypermagnesemia

• Kidney disease

• Magnesium-containing meds (laxatives)

• Trauma

• Hypothyroidism

Signs and symptoms of hypermagnesemia

• Confusion

• Muscle weakness

• Flaccid paralysis

• Flushing

• Hypotension

• Bradycardia

• Decreased reflexes

What is hypovolemia?

Decreased blood volume due to fluid or blood loss.

Causes of hypovolemia

• Sweating

• Burns

• Poor intake

• Excess urination

• Trauma/blood loss

• Fever

• Vomiting/diarrhea

Early signs of hypovolemia

• Thirst

• Dry mucous membranes

• Poor skin turgor

• Decreased urine output

Late signs of hypovolemia

• Confusion

• Chest pain

• Hypotension

• Tachycardia

  • Weak pulses

Severe complications of untreated hypovolemia

• Cyanosis

• Altered LOC

• Chest pain

• Oliguria

• Hypotension

• Weak pulse

• Hypovolemic shock

What is hypovolemic shock?

Loss of ≥20% of circulating blood/fluid volume.

Treatment goals for hypovolemic shock

• Stop fluid/blood loss

• Replace volume

• Restore circulation and organ perfusion

What is hypervolemia?

Excess fluid and sodium in extracellular space.

Causes of hypervolemia

• Heart failure

• Kidney failure

• Liver failure

• Pregnancy

• Excess IV fluids

• Sodium/water-retaining medications

Signs of hypervolemia

• Edema

• Hypertension

• JVD

• Bounding pulses

• Crackles

• Shortness of breath

• Weight gain

Treatment of hypervolemia

• Diuretics

• Low sodium diet

• Fluid restriction

• Treat underlying cause

What do hypotonic fluids do?

Move fluid INTO cells → cells swell
Examples: 0.45% NS

What do isotonic fluids do?

No fluid shift → stays balanced
Examples: 0.9% NS, Lactated Ringer’s

What do hypertonic fluids do?

Move fluid OUT of cells → cells shrink
Examples: 3% NS

Uses of IV fluids

• Hypotonic: DKA, hypernatremia

• Isotonic: shock, fluid loss

• Hypertonic: cerebral edema, severe hyponatremia

What are colloids and their purpose?

• Albumin → volume expansion, shock

• Dextran → volume expansion

• Hetastarch → hypovolemia

Purpose of blood transfusions

Replace blood volume and components.

What do PRBCs do?

Restore RBC levels without greatly increasing volume

What is whole blood used for

Trauma/surgery with major blood loss

What is plasma

Liquid portion of blood carrying cells

What are platelets used for

Prevent/stop bleeding

Types of transfusion reactions

• Circulatory overload

• Hemolytic reaction

• Febrile reaction

• Allergic reaction

• Anaphylaxis

• TRALI

• Delayed reactions

Signs of transfusion reaction

• Fever, chills

• BP changes

• Dyspnea/wheezing

• Chest/back pain

• Nausea/vomiting

• Rash, itching

• Jaundice

• Oliguria (low urine input)/hematuria (blood cells in urine)

Nursing action for transfusion reaction

• STOP transfusion

• Switch to normal saline

• Stay with patient

• Notify provider/RRT

• Send blood/tubing to lab

Nursing responsibilities for fluid/electrolyte balance

• Monitor labs (BMP)

• Monitor intake/output

• Daily weights

• Assess for signs of imbalance

• Administer IV fluids safely

• Monitor IV site complications

• Know dietary sources

• Cardiac monitoring when needed

What’s I&O

• Intake = fluids taken in

• Output = fluids lost

• Net = intake – output

Complications of IV therapy

• Infiltration

• Extravasation (can cause necrosis)

• Phlebitis

• Infection

• Air embolism

• Bleeding

Normal ABG values

• pH: 7.35–7.45

• CO₂: 35–45

• HCO₃⁻: 22–26

• O₂: 90–100

• SaO₂: 95–100

How does the body regulate acid-base balance

• Respiratory system compensates for metabolic problems

• Renal system compensates for respiratory problems

• Cells function best at neutral pH

What is acidosis

pH < 7.35

What is alkalosis

pH > 7.45

Metabolic acidosis causes

• Renal disease

• Diarrhea

• DKA

• Lactic acidosis

• Severe dehydration

Metabolic acidosis labs

• Low pH

• Normal CO₂

• Low HCO₃⁻

Metabolic alkalosis causes

• Vomiting

• NG suction

• Diuretics/laxatives

• Bicarbonate ingestion

Metabolic alkalosis labs

• High pH

• Normal CO₂

• High HCO₃⁻

Respiratory acidosis causes

• Opioids/sedation

• COPD

• Pneumonia

• Spinal cord injury

• Chest wall issues

Respiratory acidosis labs

• Low pH

• High CO₂

• Normal HCO₃⁻

Respiratory alkalosis causes

• Anxiety/panic

• Pain

• Pregnancy

• Fever

• Sepsis

Respiratory alkalosis labs

• High pH

• Low CO₂

• Normal HCO₃⁻

Nursing responsibilites for acid-base imbalance

• Monitor ABGs

• Identify cause (respiratory vs metabolic)

• Monitor respiratory status

• Monitor electrolytes

• Support ventilation if needed

• Administer ordered treatments

• Watch for complications