A patient who has a history of chronic bronchitis is admitted to the medical unit. The nurse notes the red blood cell count is elevated. Which of these is the likely contributing factor to this lab result in this patient?

Appeared in: GMCH Chandigarh - 2019

Explanation

Chronic bronchitis leads to impaired gas exchange and results in chronic hypoxia (low oxygen levels in the blood).
The kidneys respond to chronic hypoxia by increasing the secretion of the hormone erythropoietin (EPO).
Erythropoietin stimulates the bone marrow to increase the production of red blood cells (erythropoiesis).
This compensatory increase in RBC mass, known as secondary polycythemia, aims to improve the oxygen-carrying capacity of the blood.
This is a direct and expected physiological adaptation to long-standing pulmonary disease.

Option B: Hypercapnia (elevated CO2) is a common finding in chronic bronchitis but it is not the primary stimulus for red blood cell production. The key driver for erythropoiesis is tissue hypoxia.
Option C: Decreased fluid intake leads to dehydration and hemoconcentration, which causes a relative increase in the RBC count due to lower plasma volume. It does not cause a true increase in the total number of red blood cells (absolute polycythemia).
Option D: Similar to decreased fluid intake, excessive insensible water loss (e.g., from fever or tachypnea) can cause dehydration and hemoconcentration. This results in a relative, not absolute, increase in RBCs.

Clinical Relevance

Nursing practice connection: Use the key finding related to Pathophysiology of secondary polycythemia in chronic bronchitis to guide bedside assessment, documentation, and the next nursing action.
Patients with COPD and secondary polycythemia have thicker, more viscous blood, which increases the risk for thromboembolic events like stroke, myocardial infarction, and pulmonary embolism.
Nursing care involves promoting adequate hydration to decrease blood viscosity, monitoring for signs of thrombosis (e.g., calf pain, shortness of breath, chest pain), and administering oxygen therapy cautiously to maintain target saturation (typically 88-92%) without suppressing the hypoxic drive to breathe.
What if? If the patient's hematocrit becomes dangerously high (e.g., greater than 55-60%), the treatment may involve therapeutic phlebotomy (removal of blood) to reduce blood volume and viscosity, thereby lowering the risk of thrombosis.

How to Approach the Question

First, identify the key elements in the question: the patient has a 'history of chronic bronchitis' and an 'elevated red blood cell count'.
Think about the pathophysiology of chronic bronchitis. It's a lung disease that impairs oxygenation over a long period.
Consider how the body compensates for chronic low oxygen (hypoxia). The body's goal is to increase its oxygen-carrying capacity.
Evaluate the options based on this physiological principle. Chronic hypoxia directly triggers a mechanism to produce more oxygen carriers (RBCs).
Differentiate between a true increase in RBCs (absolute polycythemia) and a relative increase due to dehydration (hemoconcentration). The context of a chronic disease points towards a long-term compensatory mechanism, not an acute fluid balance issue.
Select the option that describes the primary, long-term compensatory mechanism for chronic low oxygen.

Concept Tested & Keywords

Concept Tested: Pathophysiology of secondary polycythemia in chronic bronchitis.
Stem keywords: chronic bronchitis, elevated red blood cell count
Lead-in keywords: likely contributing factor

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E6 Nursing Brunner Adult Health 3SA Vol 1 Part 3 p. 149-151

E6 Medicine Harrison 22e Part 1 p. 492-494

E6 Physiology Guyton 4SAE Part 1 p. 187-189

Practise the full GMCH Chandigarh - 2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.