1 Acid–Base Balance and ABG Interpretation Free Online FlashCards

How do the lungs and kidneys regulate acid–base balance?

The lungs regulate carbon dioxide through ventilation; the kidneys regulate bicarbonate and acid excretion.

How do acidemia and alkalemia differ from acidosis and alkalosis?

Acidemia and alkalemia describe measured blood pH below or above its reference range. Acidosis and alkalosis are processes that tend to lower or raise pH.

What are typical adult ABG reference ranges?

Typical adult ranges are pH $7.35\text{–}7.45$, PaCO₂ $35\text{–}45$ mm Hg, HCO₃⁻ $22\text{–}26$ mEq/L, and PaO₂ about $80\text{–}100$ mm Hg.

What does ROME indicate when identifying an ABG disorder?

ROME means Respiratory Opposite: pH and PaCO₂ move in opposite directions. Metabolic Equal: pH and HCO₃⁻ move in the same direction.

What primary change characterizes respiratory acidosis?

Respiratory acidosis is an acidifying process with elevated PaCO₂, often associated with hypoventilation or impaired ventilation.

What primary change characterizes respiratory alkalosis?

Respiratory alkalosis is an alkalinizing process with decreased PaCO₂. Hyperventilation associated with pain, anxiety, hypoxemia, or fever can contribute.

What primary change characterizes metabolic acidosis?

Metabolic acidosis involves decreased HCO₃⁻. Examples of causes include diarrhea, ketoacidosis, lactic acidosis, renal dysfunction, and some toxins.

What primary change characterizes metabolic alkalosis?

Metabolic alkalosis involves increased HCO₃⁻. Vomiting, gastric suction, diuretics, and other causes of acid or chloride loss can contribute.

Which systems compensate for metabolic versus respiratory disorders?

The lungs compensate for metabolic disorders by changing ventilation; the kidneys compensate for respiratory disorders by adjusting bicarbonate and acid handling. Respiratory responses are quicker than renal compensation.

How is expected PaCO₂ estimated in metabolic acidosis?

For metabolic acidosis, expected PaCO₂ = $(1.5 \times \text{HCO₃⁻}) + 8$, with a margin of $\pm 2$ mm Hg. A value outside the expected range suggests an additional respiratory disorder.

How does renal compensation differ in acute and chronic respiratory disorders?

For each $10$ mm Hg PaCO₂ rise above $40$, HCO₃⁻ rises about $1\text{–}2$ mEq/L acutely and $3\text{–}4$ chronically. For each $10$ mm Hg fall below $40$, it falls about $1\text{–}2$ acutely and $4\text{–}5$ chronically.

How does PaCO₂ typically compensate for metabolic alkalosis?

In metabolic alkalosis, PaCO₂ usually rises about $0.6\text{–}0.75$ mm Hg for each $1$ mEq/L increase in HCO₃⁻ above $24$. Compensation is limited.