Blood Gasses 1+2

What is the normal pH range of extracellular fluid (ECF)?

7.35 - 7.46 (35-45 nmol/L).

What organs are primarily responsible for acid-base balance?

The lungs and the kidneys.

Equation relating CO2 and H+ concentration?

CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-.

What is the anion gap formula?

Anion gap = (Na+ + K+) – (Cl- + HCO3-), normal 10-18 mmol/L.

Define acidosis.

High [H+] and therefore low pH.

Define alkalosis.

Low [H+] and therefore high pH.

Causes of non-respiratory acidosis?

Increased [H+] (ketoacidosis, lactic acidosis), decreased excretion (renal failure), decreased bicarbonate (diarrhoea).

How does the body compensate for non-respiratory acidosis?

Hyperventilation to remove CO2 (compensatory respiratory alkalosis).

Treatment for non-respiratory acidosis?

Treat the underlying cause; bicarbonate cautiously if pH <7.0.

Causes of respiratory acidosis?

Airway obstruction, depression of respiratory center, neuromuscular disease, pulmonary disease.

Primary treatment of respiratory acidosis?

Oxygen therapy and ventilation if needed.

Causes of non-respiratory alkalosis?

Excess alkali administration, diuretics, potassium depletion, G/I loss.

What is the main treatment for non-respiratory alkalosis?

Correction of volume depletion with saline and potassium supplements.

Causes of respiratory alkalosis?

Hypoxia, altitude, anemia, pulmonary disease, hyperventilation.

Management of respiratory alkalosis?

Remove underlying cause; rebreathing CO2 in cases of hyperventilation.

What is a ventilation/perfusion (V/Q) mismatch?

An imbalance between air reaching alveoli (ventilation) and blood reaching alveoli (perfusion), leading to impaired gas exchange.

What is the major buffer system for H+ in blood?

Bicarbonate buffering system.

What happens to PCO2 and HCO3- in respiratory acidosis?

Both PCO2 and HCO3- are elevated.

What happens to PCO2 and HCO3- in respiratory alkalosis?

Both PCO2 and HCO3- are decreased.

Why is bicarbonate important in acid-base homeostasis?

It buffers H+ ions to maintain pH stability.