5 Blood Gases, Cardiac Markers, and Clinical Practice Free Online FlashCards

What pH range is commonly expected in adult ABGs?

A common adult reference range is $7.35\text{–}7.45$. Below $7.35$ is acidemia; above $7.45$ is alkalemia.

What does PaCO₂ reflect in an ABG?

PaCO₂ reflects the respiratory component of acid–base balance; CO₂ acts as an acid. A common adult range is $35\text{–}45\ \mathrm{mmHg}$.

What does HCO₃⁻ reflect in an ABG?

HCO₃⁻ reflects the metabolic, primarily renal, component of acid–base balance and acts as a base. A common adult range is $22\text{–}26\ \mathrm{mEq/L}$.

What ABG pattern suggests respiratory acidosis?

Low pH with high PaCO₂ suggests respiratory acidosis: the pH and PaCO₂ move in opposite directions.

What ABG pattern suggests metabolic acidosis?

Low pH with low HCO₃⁻ suggests metabolic acidosis: the pH and HCO₃⁻ move in the same direction.

What can an unexpected ABG compensation response suggest?

The other system may shift to reduce the pH change, but compensation does not necessarily normalize pH. An unexpected response may indicate a mixed disorder.

Why assess oxygenation separately from pH?

Assess oxygenation separately: a near-normal pH does not rule out dangerous hypoxemia. Interpret PaO₂ alongside oxygen delivery, SpO₂, and the clinical picture.

What does an elevated cardiac troponin establish by itself?

A value above the assay-specific 99th-percentile upper reference limit indicates myocardial injury, but one elevated value alone does not establish its cause or prove a heart attack.

When may troponin testing need to be repeated?

An early nondiagnostic result may need repeat testing: the cited guideline recommends sampling at $1\text{–}2$ hours for high-sensitivity assays or $3\text{–}6$ hours for conventional assays.

Should troponin results delay reperfusion for ECG-confirmed STEMI?

With ECG evidence of STEMI, reperfusion treatment should not be delayed while waiting for troponin results.

What do BNP and NT-proBNP help assess?

BNP and NT-proBNP are released in response to cardiac wall stress and can support heart-failure assessment, but an elevated result is not diagnostic by itself.

How should CK-MB be interpreted when troponin testing is available?

CK-MB is a less commonly used cardiac marker when troponin testing is available. Interpret it with local guidance and the full clinical picture, not as a substitute for troponin.