The most sensitive indicator of depletion of intravascular volume in an infant is –
An increase in heart rate is the earliest and the most sensitive indicator to any reduction in intravascular volume.
Cardiac output and blood pressure are preserved initially because of compensatory mechanisms such as increase in heart rate and peripheral vasoconstriction.
Stroke volume is usually preserved in infants and compensatory increased in cardiac output is primarily achieved by increasing heart rate.
Cardiac output
Stroke volume
Heart rate
Blood pressure