Cardiac output (CO) is a measure of the volume of blood pumped by the heart in one minute.
It is an important indicator of the efficiency of the heart and the circulatory system in delivering oxygen and nutrients to the body's tissues.
Factors Determining Cardiac Output
Cardiac output is determined by two primary factors:
1. Heart rate (HR):
Definition: The number of times the heart beats per minute.
Influencing Factors: Age, fitness level, emotional state, and the balance between the sympathetic and parasympathetic nervous systems..
2. Stroke volume (SV):
Definition: The volume of blood pumped by the heart with each beat.
Influencing Factors:
Preload: The amount of blood in the ventricles before contraction.
Afterload: The resistance the ventricles must overcome to pump blood.
Contractility: The strength of the heart muscle's contractions.
Formula for Cardiac Output
Cardiac Output (CO) = Heart Rate (HR) × Stroke Volume (SV)
Units: Cardiac output is typically expressed in liters per minute (L/min).
Average Cardiac Output
For a healthy adult at rest, the average cardiac output is approximately 5 to 6 liters per minute.
This value can vary based on factors such as age, gender, body size, and physical fitness.
Importance of Cardiac Output
CO is vital for maintaining adequate blood flow to the body's tissues and organs.
It can increase during exercise or stress and decrease during rest or changes in posture.
The heart and circulatory system continuously adapt to ensure optimal cardiac output, ensuring the body's tissues receive sufficient oxygen and nutrients for proper function