Progressive Care Nursing Certification (PCCN) Practice Exam

Which of the following is a physiological reason for sinus tachycardia?

1. Elevated serum potassium

2. Elevated creatinine

3. Decreased urine output

4. Tissue hypoxia

The correct answer is: Tissue hypoxia

Sinus tachycardia is a physiological response that can occur in response to various stimuli, including the body's need for increased oxygen delivery to tissues. Tissue hypoxia is a condition where there is insufficient oxygen reaching the tissues, which could be due to various reasons, such as anemia, respiratory issues, or circulatory problems. When tissues are hypoxic, the body compensates by increasing the heart rate to enhance cardiac output and thereby improve oxygen delivery to the affected tissues. In this context, the correct answer of tissue hypoxia emphasizes the body's natural compensatory mechanisms. The heart beats faster in an attempt to circulate more blood, which carries oxygen, to remedy the oxygen deficit that tissues are experiencing. This response is regulated by the autonomic nervous system, particularly through sympathetic stimulation, which is triggered during instances of inadequate oxygenation. The other options do not directly relate to a compensatory physiological mechanism like hypoxia does. Elevated serum potassium can lead to changes in heart rhythm and potential bradycardia instead of tachycardia. Elevated creatinine typically indicates impaired kidney function rather than an immediate heart rate increase. Decreased urine output is often a sign of fluid retention or kidney dysfunction but does not directly cause sinus tachycardia as a physiological response