electrolyte imbalance and ABG

Hyponatremia

Na⁺ <135 mEq/L

Common causes of hyponatremia

Excess fluid intake, diuretics, vomiting/diarrhea, heart failure, kidney problems

Signs & symptoms of hyponatremia

Headache, confusion, fatigue, nausea/vomiting, muscle cramps, seizures

Nursing interventions for hyponatremia

Monitor neurological status, seizure precautions, monitor fluid balance

Hypernatremia

Na⁺ >145 mEq/L

Common causes of hypernatremia

Dehydration, excess sodium intake, water loss, fever, diabetes insipidus

Signs & symptoms of hypernatremia

Extreme thirst, dry mucous membranes, restlessness, confusion, muscle twitching, seizures

Nursing interventions for hypernatremia

Monitor hydration status, encourage fluids if appropriate, monitor sodium levels

Normal potassium level

3.5–5.0 mEq/L

Functions of potassium

Cardiac conduction, muscle contraction, nerve transmission

Hypokalemia

K⁺ <3.5 mEq/L

Common causes of hypokalemia

Diuretics, vomiting, diarrhea, poor nutrition

Signs & symptoms of hypokalemia

Muscle weakness, fatigue, leg cramps, constipation, irregular heart rhythms

ECG changes in hypokalemia

Flattened T waves, U waves

Nursing interventions for hypokalemia

Monitor ECG, replace potassium, assess muscle strength

Hyperkalemia

K⁺ >5.0 mEq/L

Common causes of hyperkalemia

Kidney failure, tissue injury, excess potassium intake, potassium-sparing medications

Signs & symptoms of hyperkalemia

Muscle weakness, numbness/tingling, abdominal cramping, dangerous heart rhythms

ECG changes in hyperkalemia

Tall peaked T waves, wide QRS, cardiac arrest risk

Nursing interventions for hyperkalemia

Cardiac monitoring, check kidney function, administer medications as ordered

Normal calcium level

8.5–10.5 mg/dL

Functions of calcium

Bone strength, muscle contraction, blood clotting, nerve function

Common causes of hypocalcemia

Vitamin D deficiency, thyroid problems, kidney disease

Signs & symptoms of hypocalcemia

Tingling around mouth/fingers, muscle cramps, twitching, seizures, weakness

Nursing interventions for hypocalcemia

Monitor for spasms, calcium replacement, safety precautions

Common causes of hypercalcemia

Cancer, hyperparathyroidism, excess calcium supplements

Memory aid for hypercalcemia

"Stones, Bones, Groans, Moans"

Signs & symptoms of hypercalcemia

Kidney stones, bone pain, abdominal discomfort/constipation, confusion

Nursing interventions for hypercalcemia

Encourage fluids if appropriate, monitor cardiac rhythm, assess mental status

Normal magnesium level

1.7–2.2 mg/dL

Functions of magnesium

Muscle relaxation, nerve function, heart rhythm

Common causes of hypomagnesemia

Alcohol use, malnutrition, diarrhea, diuretics

Signs & symptoms of hypomagnesemia

Tremors, muscle cramps, hyperactive reflexes, seizures, irregular heartbeat

Common causes of hypermagnesemia

Kidney failure, excess magnesium medications

Signs & symptoms of hypermagnesemia

Low blood pressure, weakness, decreased reflexes, slow breathing, cardiac arrest

Normal chloride level

98–106 mEq/L

Common causes of hypochloremia

Vomiting, excessive sweating

Signs & symptoms of hypochloremia

Weakness, muscle cramps, metabolic alkalosis

Common causes of hyperchloremia

Dehydration, kidney disease

Signs & symptoms of hyperchloremia

Weakness, metabolic acidosis

Common causes of hypophosphatemia

Malnutrition, alcohol use, vitamin D deficiency

Signs & symptoms of hypophosphatemia

Muscle weakness, confusion, respiratory problems

Common causes of hyperphosphatemia

Kidney failure

Signs & symptoms of hyperphosphatemia

Muscle cramps, calcium imbalance, bone problems

Normal pH

7.35–7.45

Normal PaCO₂

35–45 mmHg

Normal HCO₃⁻

22–26 mEq/L

Normal PaO₂

80–100 mmHg

ABG stands for

Arterial Blood Gas

ABGs evaluate

Oxygenation, ventilation, acid-base balance

Step 1 of ABG interpretation

Check pH

pH <7.35 indicates

Acidosis

pH >7.45 indicates

Alkalosis

Step 2 of ABG interpretation

Check PaCO₂

Normal PaCO₂

35–45 mmHg

High PaCO₂ indicates

Respiratory acidosis

Low PaCO₂ indicates

Respiratory alkalosis

Step 3 of ABG interpretation

Check HCO₃⁻

Normal HCO₃⁻

22–26 mEq/L

Low HCO₃⁻ indicates

Metabolic acidosis

High HCO₃⁻ indicates

Metabolic alkalosis

ABG Example: pH 7.30, PaCO₂ 50, HCO₃⁻ 24

Respiratory acidosis

Common causes of respiratory acidosis

COPD, hypoventilation, respiratory depression

ABG Example: pH 7.50, PaCO₂ 30, HCO₃⁻ 24

Respiratory alkalosis

Common causes of respiratory alkalosis

Hyperventilation, anxiety, pain

ABG Example: pH 7.25, PaCO₂ 40, HCO₃⁻ 18

Metabolic acidosis

Common causes of metabolic acidosis

Diarrhea, kidney disease, diabetic ketoacidosis (DKA)

ABG Example: pH 7.50, PaCO₂ 40, HCO₃⁻ 32

Metabolic alkalosis

Common causes of metabolic alkalosis

Prolonged vomiting, excessive gastric suctioning, excess bicarbonate intake, diuretic use

Signs & symptoms of metabolic alkalosis

Confusion, muscle weakness, tingling/numbness, lightheadedness, irregular heart rhythms

Hypovolemic hypotonic hyponatremia

Low fluid volume and low osmolality

Common causes of hypovolemic hypotonic hyponatremia

Dehydration, diuretic use, Addison's disease with dehydration, third spacing (burns, pancreatitis)