2 ABG Interpretation Free Online FlashCards

What do arterial blood gases help assess?

ABGs help assess acid–base status, ventilation, and oxygenation.

What adult reference ranges are given for pH, PaCO₂, and HCO₃⁻?

A useful adult reference is pH $7.35–7.45$, PaCO₂ $35–45$ mm Hg, and HCO₃⁻ $22–26$ mEq/L; laboratory ranges can vary.

What do low and high ABG pH values indicate?

A pH below $7.35$ indicates acidemia; a pH above $7.45$ indicates alkalemia.

What PaCO₂ pattern suggests a primary respiratory process?

A PaCO₂ moving opposite to the pH suggests a primary respiratory process.

What HCO₃⁻ pattern suggests a primary metabolic process?

HCO₃⁻ moving in the same direction as the pH suggests a primary metabolic process.

What does compensation do, and what may an unexpected response indicate?

Compensation moves pH toward normal. If the measured response differs substantially from the expected response, consider a mixed disorder.

Which ABG measures inform oxygenation?

Assess oxygenation separately: PaO₂ and oxygen saturation inform it; pH, PaCO₂, and HCO₃⁻ alone do not establish whether oxygenation is adequate.

What is Winter’s formula for expected PaCO₂ in metabolic acidosis?

For metabolic acidosis, expected PaCO₂ = $(1.5 × \text{HCO₃⁻}) + 8$, with a range of $±2$ mm Hg.

What do PaCO₂ values outside Winter’s formula range suggest?

With metabolic acidosis, PaCO₂ above the Winter’s formula range suggests an additional respiratory acidosis; a value below it suggests an additional respiratory alkalosis.

What does elevated PaCO₂ with elevated HCO₃⁻ suggest in chronic obstructive lung disease?

Elevated PaCO₂ indicates respiratory acidosis; elevated HCO₃⁻ is consistent with renal compensation over time. The pattern can occur with chronic CO₂ retention.

How can repeated vomiting contribute to metabolic alkalosis?

Repeated vomiting can contribute to metabolic alkalosis through loss of gastric acid; assess volume status and relevant electrolyte results.

What disorder is suggested by high pH, low PaCO₂, and near-normal HCO₃⁻?

High pH with low PaCO₂ and HCO₃⁻ near the usual range indicates acute respiratory alkalosis. Rapid breathing can have serious causes, so assess the patient and oxygenation.