Arterial Blood Gases (ABGs) and Acid-Base Balance Vocabulary

Vocabulary practice flashcards covering arterial blood gas analysis, physiological buffer systems, acid-base imbalances, clinical manifestations, and the ROME interpretation system.

Pulse Oximetry ($SpO_2$)

A noninvasive diagnostic measurement of arterial oxygen saturation, with normal values ranging from $94BA1$ to $99\%$ ($SpO_2 = 94\%$ to $99\%$).

Arterial Blood Gases (ABG)

Diagnostic blood tests used to evaluate oxygenation and acid-base balance by measuring parameters including $PaO_2$, $PaCO_2$, $pH$, $HCO_3^-$, and $SaO_2$.

Acid-Base Homeostasis Ratio

The steady body proportion of $1$ part carbonic acid ($H_2CO_3$) to $20$ parts base bicarbonate ($HCO_3^-$) required to maintain a normal blood $pH$ between $7.35$ and $7.45$.

Acidosis

An acid-base imbalance defined by a blood $pH < 7.35$, causing central nervous system (CNS) depression, sluggishness, hyperkalemia, and Kussmaul respirations.

Alkalosis

An acid-base imbalance defined by a blood $pH > 7.45$, causing central nervous system (CNS) irritability, twitchiness, hypocalcemia, and hypokalemia.

Chemical Buffer Systems

Regulators that act chemically to change strong acids to weak acids or bind acids, consisting of carbonic acid-bicarbonate, phosphate, protein, and hemoglobin buffers.

Medulla Respiratory Center

The brainstem structure controlling respiratory rate; increased respirations lead to $CO_2$ elimination, while decreased respirations lead to $CO_2$ retention.

Renal Acid Elimination Mechanisms

The three kidney pathways for maintaining acid-base balance: secreting free hydrogen ($H^+$), combining $H^+$ with ammonia ($NH_3$), and excreting weak acids.

Respiratory Acidosis

An acid-base imbalance caused by carbonic acid excess (increased $CO_2$), commonly resulting from COPD, pneumonia, or respiratory failure.

Respiratory Alkalosis

An acid-base imbalance caused by carbonic acid deficit (decreased $CO_2$), commonly resulting from hyperventilation, anxiety, or pain.

Metabolic Acidosis

An acid-base imbalance caused by base bicarbonate deficit (decreased $HCO_3^-$), commonly resulting from diabetic ketoacidosis (DKA), renal failure, or diarrhea.

Metabolic Alkalosis

An acid-base imbalance caused by base bicarbonate excess (increased $HCO_3^-$), commonly resulting from vomiting, nasogastric (NG) suction, or diuretics.

Causes of Acidosis vs. Alkalosis

A visual classification chart mapping etiologies to respiratory or metabolic disorders based on changes in carbonic acid or bicarbonate.

Kussmaul Respirations

A fast, deep breathing pattern that serves as a clinical manifestation and respiratory compensation strategy during acidosis.

ROME Mnemonic

An acid-base diagnostic mnemonic standing for Respiratory Opposite ($\uparrow pH$ $\downarrow PaCO_2$ is alkalosis; $\downarrow pH$ $\uparrow PaCO_2$ is acidosis) and Metabolic Equal ($\downarrow pH$ $\downarrow HCO_3^-$ is acidosis; $\uparrow pH$ $\uparrow HCO_3^-$ is alkalosis).

Normal ABG Reference Values

Standard arterial blood gas normal parameters: $pH = 7.35 - 7.45$, $PaCO_2 = 35 - 45\,\text{mmHg}$, and $HCO_3^- = 22 - 26\,\text{mEq/L}$.

Partial Compensation

An ABG interpretation state where the compensating parameter ($PaCO_2$ or $HCO_3^-$) is moving in the opposite direction to compensate, but the $pH$ has not yet normalized.

Full Compensation

An ABG interpretation state achieved when body buffer or organ adjustments successfully return the blood $pH$ to the normal range ($7.35 - 7.45$).