In a healthy individual, weighing 70 kg at rest, the stroke volume is about?

Appeared in: AIIMS Patna NO - 2020

Explanation

Stroke volume (SV) is the volume of blood ejected from the left ventricle during one contraction (systole).
In a typical healthy adult weighing around 70 kg and at rest, the average stroke volume is approximately 70 mL per beat.
This value is a standard physiological parameter used to calculate cardiac output (CO), which is the product of stroke volume and heart rate (CO = SV x HR).
The normal range for stroke volume in a resting adult is generally considered to be between 50 and 75 mL.

Option A: This value is excessively high for a resting individual and is typically only achieved by elite athletes during maximal physical exertion.
Option B: This represents a higher-than-average resting stroke volume, characteristic of a well-trained athlete, not a typical healthy adult.
Option C: While this is at the lower limit of the normal range (50-75 mL), 70 mL is the widely accepted average. A consistently low SV of 50 mL could indicate conditions like dehydration or reduced cardiac contractility.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physiology of cardiac function, specifically the normal value of stroke volume as background academic context rather than a clinical decision trigger.
Assessing stroke volume is crucial for evaluating a patient's cardiac efficiency. A low stroke volume can be an early indicator of heart failure, shock, or dehydration.
Nurses monitor parameters related to stroke volume (like blood pressure and pulse pressure) to guide interventions such as fluid administration or the use of inotropic medications.
What if? If the patient had chronic hypertension, the heart would have to pump against increased resistance (afterload). Over time, this could lead to a decreased stroke volume as the heart muscle weakens, contributing to heart failure.

How to Approach the Question

First, identify the key terms in the question: 'healthy individual,' 'at rest,' and 'stroke volume.'
This is a factual recall question that tests knowledge of standard physiological values.
Recall the average stroke volume for a non-athletic adult at rest. The standard textbook value is approximately 70 mL.
Evaluate the options. 150 mL and 100 mL are too high for a typical resting person and are associated with exercise or athletic conditioning. 50 mL is on the low end of normal. 70 mL is the most accurate average.

Concept Tested & Keywords

Concept Tested: Physiology of cardiac function, specifically the normal value of stroke volume.
Stem keywords: healthy individual, 70 kg, at rest, stroke volume
Lead-in keywords: is about

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