Arterial Blood Gas Interpretation and Acid-Base Balance

Vocabulary flashcards covering arterial blood gas (ABG) values, acid-base regulation mechanisms, and primary acid-base imbalances from lecture notes.

Normal Blood pH Range

The normal physiological range for arterial blood pH, defined as $7.35 - 7.45$.

Normal $pCO_2$ Range

The normal arterial partial pressure of carbon dioxide, which ranges from $35 - 45$.

Normal $HCO_3^-$ Range

The normal arterial bicarbonate ion concentration range, defined as $22 - 26$.

Normal $PaO_2$ Range

The normal arterial partial pressure of oxygen, defined as $80 - 100$.

Acidosis

A clinical state characterized by an arterial blood pH below $7.35$, resulting from an increase in $CO_2$ or a decrease in $HCO_3^-$.

Alkalosis

A clinical state characterized by an arterial blood pH above $7.45$, resulting from a decrease in $CO_2$ or an increase in $HCO_3^-$.

Hydrogen Ion ($H^+$)

The primary acidic ion in acid-base balance whose increased concentration causes blood pH to drop.

Bicarbonate Ion ($HCO_3^-$)

The primary basic ion in blood acid-base regulation, primarily excreted or reabsorbed by the kidneys.

Buffer System

The fastest-acting primary acid-base regulator (acting in seconds) that changes strong acids into weak acids, neutralizes acids, or swaps cations.

Cellular Cation Exchange

A buffer mechanism where $H^+$ enters cells and $K^+$ moves into extracellular fluid during acidosis (causing hyperkalemia), or $K^+$ enters cells and $H^+$ moves out during alkalosis (causing hypokalemia).

Respiratory System (Acid-Base Regulation)

The second fastest mechanism of acid-base regulation (acting in minutes) that hyperventilates to excrete excess $CO_2$ or hypoventilates to retain $CO_2$.

Renal System (Acid-Base Regulation)

The slowest acid-base regulator (taking days) that maintains balance by reabsorbing and conserving filtered $HCO_3^-$ and excreting acid.

Respiratory Acidosis

An acid-base imbalance caused by hypoventilation and $CO_2$ retention, characterized by blood pH $< 7.35$ and $pCO_2 > 45$.

Respiratory Alkalosis

An acid-base imbalance caused by hyperventilation and excessive $CO_2$ excretion, characterized by blood pH $> 7.45$ and $pCO_2 < 35$.

Metabolic Acidosis

An acid-base imbalance caused by acid accumulation or $HCO_3^-$ loss (e.g., DKA, shock, renal failure, diarrhea), characterized by blood pH $< 7.35$ and $HCO_3^- < 22$.

Metabolic Alkalosis

An acid-base imbalance caused by loss of acid or excess $HCO_3^-$ gain (e.g., NG suction, vomiting, antacids, diuretics), characterized by blood pH $> 7.45$ and $HCO_3^- > 26$.

Kussmaul Respirations

A deep and rapid breathing pattern with prolonged expiratory effort that occurs as a compensatory mechanism to increase $CO_2$ loss during metabolic acidosis.

Partial Compensation

An acid-base state where the compensating system has begun responding, but the arterial blood pH has not yet returned to the normal range ($7.35 - 7.45$).

Full Compensation

An acid-base state where compensatory mechanisms have successfully restored arterial blood pH to within the normal range ($7.35 - 7.45$) while $pCO_2$ and $HCO_3^-$ remain abnormal.