Alterations in Arterial Blood Gases

Flashcards on Arterial Blood Gases (ABGs)

What do Arterial Blood Gases (ABGs) measure?

Partial pressure of oxygen (O2), carbon dioxide (CO2), pH (acid/base), and bicarbonate (HCO3) in the bloodstream.

What pH level indicates acidosis?

pH is < 7.35

What pH level indicates alkalosis?

pH is > 7.45

What is the role of buffers in pH regulation?

Chemical substances that balance or “buffer” the pH by releasing or binding H+.

How do the lungs regulate pH?

By eliminating CO2 when exhaling; may speed up respiratory rate or slow down, depending on pH level.

How do the kidneys regulate pH?

Responsible for producing, excreting, and retaining HCO3; excrete H+.

What are the normal ranges for pH?

7.35 – 7.45

What are the normal ranges for pCO2?

35 – 45 mmHg

What are the normal ranges for HCO3?

22 – 26 mEq/L

What are the normal ranges for pO2?

80 – 100 mmHg

If the pH is low, what condition is indicated?

Acidosis

If the pH is high, what condition is indicated?

Alkalosis

In respiratory acidosis, are the pH and pCO2 levels?

pH low, pCO2 high

In respiratory alkalosis, what are the pH and pCO2 levels?

pH high, pCO2 low

In metabolic acidosis, what are the pH and HCO3 levels?

pH low, HCO3 low

In metabolic alkalosis, what are the pH and HCO3 levels?

pH high, HCO3 high

Define uncompensated ABG.

pH and one other value (pCO2 or HCO3) are out of range

Define partially compensated ABG.

pH, pCO2, and HCO3 are all out of range

Define fully compensated ABG.

pH is normal, pCO2 and HCO3 are both out of range

What causes respiratory acidosis?

Inadequate ventilation due to CNS depression, impaired respiratory function, etc.

What are manifestations of respiratory acidosis?

Headache, behavioral changes/confusion, weakness, tremors, paralysis, stupor  coma, warm/flushed skin

What causes respiratory alkalosis?

Hyperventilation secondary to pain, anxiety, fear, fever, sepsis, CNS lesions

What are manifestations of respiratory alkalosis?

Constriction of cerebral vessels, dizziness/panic, light-headedness, tetany, numbness/tingling of digits, seizures, cardiac dysrhythmias

What causes metabolic acidosis?

Decreased HCO3 production, decreased acid excretion by kidneys, excess HCO3 loss, increased acid production or ingestion, increased plasma Cl concentration

What are manifestations of metabolic acidosis?

HYPERkalemia, anorexia, N/V, abdominal pain, weakness, confusion, stupor, or coma, peripheral vasodilation, dysrhythmias, warm/flushed skin, bone disease

What causes metabolic alkalosis?

Increased renal production of HCO3, excess ingestion of alkali substances, GI suctioning, vomiting, bulimia nervosa, diuretic therapy, excess adrenocorticosteroid hormones

What are manifestations of metabolic alkalosis?

HYPOkalemia, hyperactive reflexes, tetany, confusion, seizures, hypotension, dysrhythmias

How do the lungs compensate for Metabolic Acidosis

The lungs compensate by increasing the rate and depth of breathing (exhaling more CO2). Called “Kussmaul’s Respirations”

How do the lungs compensate for Metabolic Alkalosis

The lungs compensate by decreasing the respiratory rate (retaining CO2).