Certified Transport Registered Nurse Certification Practice Exam

In clinical practice, a leftward shift indicates which of the following?

1. Increased affinity of hemoglobin for oxygen

2. Decreased affinity of hemoglobin for oxygen

3. Normal oxygen transport

4. Improved carbon dioxide transport

The correct answer is: Increased affinity of hemoglobin for oxygen

A leftward shift in the oxygen-hemoglobin dissociation curve indicates an increased affinity of hemoglobin for oxygen. This phenomenon means that under the same set of conditions (such as pH, temperature, and carbon dioxide levels), hemoglobin is more likely to bind oxygen and hold onto it, making oxygen delivery to tissues more challenging at lower partial pressures of oxygen. This shift can occur in various physiological conditions, such as increased pH (alkalosis) or decreased levels of carbon dioxide, both of which can lead to hemoglobin retaining oxygen more tightly. Understanding this shift is crucial for healthcare professionals as it can significantly impact oxygen delivery and the management of patients with respiratory or metabolic disorders. In contrast, a rightward shift would indicate a decreased affinity, facilitating oxygen unloading to the tissues. Normal oxygen transport typically does not involve a shift in the curve either way, and carbon dioxide transport is affected differently, often described in terms of the Haldane effect, which is not directly related to the leftward shift of the curve in terms of hemoglobin's affinity for oxygen.