Important physiologic differences between pediatric and adult patients
Newborns: larger total body water compared to adults (75% vs. 60%) with the majority of it being in the extracellular fluid (ECF) (~40% vs. 25%) 
Percentage of ECF decreases throughout childhood
Large surface area to weight ratio --> younger kids may have more fluid losses from ECF and intravascular space with short illness/environmental exposure decreased preload
May present profoundly volume depleted and need more aggressive volume repletion
Percentage of ECF decreases throughout childhood
May present profoundly volume depleted and need more aggressive volume repletion
Infants have immature myocardial calcium regulation system, difficulty storing/releasing calcium highly dependent on extracellular calcium for contractility
Check iCal, replete calcium earlier, do NOT give CCBs to infants with tachydysrhythmias
Stiffer, less compliant myocardium in infants-->increasing heart rate is main compensatory means for increasing BP
BUT higher resting heart rate--> less room to go up (e.g. adult with resting heart rate of 60 can double to 120 but a neonate doubling resting heart rate of 120 to 240 is not sustainable)
Heavily rely on vasoconstriction, which can further decrease cardiac output
Less beta-adrenergic receptors/sympathetic innervations + more dominant parasympathetics --> exaggerated vagal response
Hypotension is a ‘’’late’’’ finding in<unk> !
Check iCal, replete calcium earlier, do NOT give CCBs to infants with tachydysrhythmias
BUT higher resting heart rate--> less room to go up (e.g. adult with resting heart rate of 60 can double to 120 but a neonate doubling resting heart rate of 120 to 240 is not sustainable)
Heavily rely on vasoconstriction, which can further decrease cardiac output
Undifferentiated shock 
Hypovolemia
Neurogenic shock
More common and more profound in peds
Spinal shock
hemorrhage,
Cardiogenic shock
Hemorrhagic shock