Question

. A patient with chronic bronchitis is brought into the emergency room with complaints of sudden-onset chest pain, shortness of breath, and coughing up blood. His lab work shows hypoxemia, respiratory acidosis, and elevated red blood cell (RBC) count, white blood cell count, hemoglobin, and hematocrit.

1.Utilizing your understanding of the process of erythropoiesis, why do you think this patient has elevated RBCs, hemoglobin, and hematocrit?

2.What is the most likely cause of the patient’s acute symptoms?

3.How do you explain this?

Answer 1

1. Since the patient has hypoxemia that is less oxygen in the blood, Hypoxia-inducible factor 1 (HIF-1) is stimulated. It allows cells to respond to changing levels of oxygen in the body. It binds top Hypoxia Response Elements (HRE) in the promoters of target genes involved in angiogenesis and cell proliferation including vascular endothelial growth factor (VEGF) and erythropoietin. This erythropoietin released mainly from kidney and liver, stimulates erythropoiesis in marrow of long bones. So, therefore the patient has elavated RBC count, WBC count, hemoglobin and hematocrit.

2.  The most commonly identified factor
implicated in causation of chronic bronchitis is heavy smoking. Heavy cigarette smokers have
4 to 10 times higher proneness to develop chronic bronchitis.

3. Prolonged cigarette smoking appears to act on the lungs in a number of ways:
i) It impairs ciliary movement.

ii) It inhibits the function of alveolar macrophages.

iii) It leads to hypertrophy and hyperplasia of mucus-
secreting glands.

iv) It causes considerable obstruction of small airways.

v) It stimulates the vagus and causes bronchoconstriction.

Now,

Bronchitis is defined clinically as persistent cough with expectoration on most days for at least three months of the year for two or more consecutive years.

So, impaired ciliary movement hamper upward escalation of toxic particles out of airway.

Inhibition of function of alveolar macrophages prevents phagocytosis of toxic particles.

Hypertrophy and hyperplasia of mucous glands cause excessive mucous secretion or expectorations.Since accumulation of these toxic particles will cause inflammation blood may be seen in expectoration. This is known as hemoptysis.

Obstruction to airflow (due to excessive mucus) and bronchoconstriction causes shortness of breath, dyspnea and chestpain.

As a consequence of obstruction to the airflow, less oxygen is available which leads to the development of hypoxemia and respiratory acidosis.