Hypoxemia: decrease in arterial PO₂

Hypoxia: more general term. decrease in O₂ delivery to or utilization by, the tissues. can be caused by hypoxemia.

• High alititude
• Hypoventilation
• Diffusion defect (e.g. fibrosis)
• V/Q defect
• Right to left shunt

Aveolar-arterial O₂ gradient

Physiological shunts:

1. Bronchial circulation

2. Thebesian vein(for coronary artery)

If the O₂ supplement does not cause A-a gradient to return to normal then there is a Shunt problem.

1. Extrinsic factors:

-lack of O₂ in atmosphere (high altitude)

-hypoventilation (neuromuscular disorders)

2. Lung diseases:

-hypoventilation (↑airway resistance or ↓compliance)

-abnormal V/Q ratio (↑physiological dead space or ↑physiological shunt)

3. Venous to arterial shunts: (R-L shunt)

4. Decreased O₂ transport to tissues by blood:

-anemia or abnormal Hb

-circulatory deficiency(general or local)

5. Decreased tissue use of O₂:

-deficiency of cellular oxidation enzymes

-cellular toxicity (e.g. cyanice poisoning)

-vitamin deficiency

Bluish or Purplish tinge of the skin caused by excessive amount of deoxygenated hemoglobin in the blood vessels of the skin

Difficulty breathing or feeling of shortness of breath.

Also called "air hunger"

Too much CO₂ in body fluids.

Associated with hypoxia when it is due to:

-hypoventilation

-circulatory deficiency

Causes:

-COPD, especially in those with emphysema

-High altitude

Pulmonary hypertension→ right ventricular hypertrophy(Cor pulmonale)→ right side heart failure

Hemothorax: Blood in intrapleural space. Will compress lungs and reduce compliance.

Spontaneous pneumothorax: Happens with tall people because they have more (-) pressure at their apex and that can rupture soe aveoli. Can also be secondary to lung disease like emphysema in which the tissue is damaged and can rupture easily.

Tension pneumothorax: MOST DANGEROUS. When air enters the intrapleural space with each breath, making the space more (+). Flap of tissue acts as one way valve letting air in but not out.

The airways of the lungs are obstructed by an intraluminal condition.

-Asthma

-Chronic Bronchitis

-Emphysema

Diseases in which expansion of the lungs is restricted.

Fibrosis

• Know that Obstructive shifts the curve left. Restrictive right.
• Be able to recognize the RV, TLC, and vital capacity.

Asthma: Most reversible. some sputum

Chronic Bronchitis: Most sputum. some aveolar damage. some reversibility.

Emphysema: Most aveolar damage. some sptum. very little reversibility.

A disease characterized by chronic bronchitis or emphysema and airflow obstruction. It is usually progressive and may be accompanied by airway hyperreactivity and may be partially reversible

• Abnormal permanent enlargement of the airspaces distal to the terminal bronchioles with destruction of their walls without fibrosis.
• High V/Q (more air than blood)

• Characterized by chronic productive cough for at least 3 months in each of 2 successive years.
• Low V/Q (more blood than air)
• Hypoxic vasoconstriction
• Cor pulmonale (right heart enlargement)