2 Acid–Base Disorders and Compensation Free Online FlashCards

What are common adult ABG reference ranges?

Common adult ranges are pH $7.35$–$7.45$, $\mathrm{PaCO_2}$ $35$–$45$ mm Hg, and $\mathrm{HCO_3^-}$ $22$–$26$ mEq/L; laboratory ranges may vary.

How do acidemia and acidosis differ?

Acidemia means blood pH is below $7.35$; alkalemia means it is above $7.45$. Acidosis and alkalosis are processes that tend to lower or raise pH, and multiple processes can coexist.

How do primary respiratory and metabolic patterns differ?

In a primary respiratory disorder, pH and $\mathrm{PaCO_2}$ move in opposite directions. In a primary metabolic disorder, pH and $\mathrm{HCO_3^-}$ move in the same direction.

What pattern identifies primary respiratory acidosis?

Respiratory acidosis has low pH and high $\mathrm{PaCO_2}$; $\mathrm{HCO_3^-}$ rises with compensation. Hypoventilation, including from lung disease or CNS-depressing drugs, is a common cause.

What pattern identifies respiratory alkalosis, and what must be assessed?

Respiratory alkalosis has high pH and low $\mathrm{PaCO_2}$; $\mathrm{HCO_3^-}$ falls with compensation. Assess for causes such as hypoxemia, sepsis, or pulmonary embolism rather than assuming anxiety.

What pattern and causes characterize metabolic acidosis?

Metabolic acidosis has low pH and low $\mathrm{HCO_3^-}$, with a compensatory fall in $\mathrm{PaCO_2}$. Causes include acid accumulation, reduced renal acid excretion, toxins, or bicarbonate loss.

What pattern and causes characterize metabolic alkalosis?

Metabolic alkalosis has high pH and high $\mathrm{HCO_3^-}$, with a compensatory rise in $\mathrm{PaCO_2}$. Vomiting, gastric suction, diuretics, or volume and chloride depletion are common causes.

How is the anion gap calculated in metabolic acidosis?

Calculate $\mathrm{AG}=\mathrm{Na^+}-(\mathrm{Cl^-}+\mathrm{HCO_3^-})$. A high gap may indicate unmeasured acids; consider albumin when interpreting it.

How do you estimate compensation in metabolic acidosis?

Winter’s formula is expected $\mathrm{PaCO_2}=(1.5\times\mathrm{HCO_3^-})+8\pm2$ mm Hg. A value above the range suggests additional respiratory acidosis; below it suggests respiratory alkalosis.

What respiratory compensation is expected in metabolic alkalosis?

For each $1$ mEq/L rise in $\mathrm{HCO_3^-}$ above $24$, $\mathrm{PaCO_2}$ rises about $0.6$–$0.75$ mm Hg. Compensation usually does not raise $\mathrm{PaCO_2}$ above about $55$ mm Hg.

How does bicarbonate compensation differ in acute and chronic respiratory acidosis?

In acute respiratory acidosis, $\mathrm{HCO_3^-}$ rises about $1$–$2$ mEq/L per $10$-mm Hg rise in $\mathrm{PaCO_2}$ above $40$. In chronic cases, it rises about $3$–$4$; renal compensation develops over days.

How does bicarbonate compensation differ in acute and chronic respiratory alkalosis?

In acute respiratory alkalosis, $\mathrm{HCO_3^-}$ falls about $1$–$2$ mEq/L per $10$-mm Hg fall in $\mathrm{PaCO_2}$ below $40$. In chronic cases, it falls about $4$–$5$; renal compensation develops over days.