ABGs Acid Base and Compensation Vocabulary

Vocabulary flashcards covering arterial blood gas (ABG) normal reference values, diagnostic patterns, compensation mechanisms, and clinical manifestations.

Normal pH

$$7.35\text{--}7.45$$

Normal $\text{PaCO}_2$

$$35\text{--}45\,\text{mmHg}$$

Normal $\text{PaO}_2$

$$80\text{--}100\,\text{mmHg}$$

Normal $\text{HCO}_3^-$

$$22\text{--}26\,\text{mEq/L}$$

Normal Base Excess

$$-3\text{ to }+3$$

Acidosis / Acidemia

Condition indicated by a pH $< 7.35$.

Alkalosis / Alkalemia

Condition indicated by a pH $> 7.45$.

Respiratory Component

Represented by $\text{PaCO}_2$ in ABGs; $\text{CO}_2$ behaves like an acid.

Metabolic Component

Represented by $\text{HCO}_3^-$ in ABGs; bicarbonate behaves like a base.

Complete Compensation

Occurs when secondary physiological responses return the pH to the normal range ($7.35\text{--}7.45$) despite an underlying acid/base disorder.

Metabolic Acidosis Pattern

$$\downarrow \text{pH} + \downarrow \text{HCO}_3^-$$

Metabolic Acidosis Causes

Bicarbonate loss, renal disease, lactic acidosis, DKA, toxins, hypoxia.

Metabolic Acidosis Respiratory Compensation

Increase rate and depth of respiration to lower $\text{PaCO}_2$.

Metabolic Acidosis Manifestations

Kussmaul respirations, $\downarrow \text{BP}$, hyperkalemia, warm skin, N/V, neuromuscular changes.

Metabolic Alkalosis Pattern

$$\uparrow \text{pH} + \uparrow \text{HCO}_3^-$$

Metabolic Alkalosis Causes

Vomiting/NG suction, excess bicarbonate, diuretics, hyperaldosteronism.

Metabolic Alkalosis Respiratory Compensation

Hypoventilation/decreased respiratory rate and depth.

Metabolic Alkalosis Manifestations

Confusion, weakness/paresthesia, cramps/tremors, dysrhythmias, hypoventilation.

Respiratory Acidosis Pattern

$$\downarrow \text{pH} + \uparrow \text{PaCO}_2$$

Respiratory Acidosis Mechanism

$\text{CO}_2$ retention from hypoventilation or increased dead space.

Acute Respiratory Acidosis Causes

Drugs, neurologic disorders, pneumonia, asthma, stroke, surgery.

Chronic Respiratory Acidosis Causes

COPD and heart failure.

Respiratory Acidosis Manifestations

Sleep difficulty, anxiety, SOB, cyanosis, and increased ICP depending on cause.

Respiratory Alkalosis Pattern

$$\uparrow \text{pH} + \downarrow \text{PaCO}_2$$

Respiratory Alkalosis Mechanism

Hyperventilation causes excessive $\text{CO}_2$ loss.

Respiratory Alkalosis Causes

Hypoxemia, CNS stimulation, respiratory disease, sepsis/liver failure, meds, ventilation.

Respiratory Alkalosis Manifestations

Dyspnea, dizziness, confusion/anxiety, weakness, numbness/paresthesia.

Renal Compensation for Acidosis

Kidneys regenerate/retain $\text{HCO}_3^-$ and remove $\text{H}^+$.

Renal Compensation for Alkalosis

Kidneys retain $\text{H}^+$ and remove $\text{HCO}_3^-$.

Speed of Renal Compensation

Takes hours to days.

ROME Memory Aid

Stands for Respiratory Opposite, Metabolic Equal.