Every parent with an infant or child with vomiting and/or diarrhea is concerned that he or she might be getting seriously dehydrated. Recognizing serious dehydration is important because it is the leading cause of hypovolemic shock which means inadequate blood flow that can lead to cardiopulmonary failure or even cardiac arrest.
To determine if a child is seriously dehydrated we look at the child’s general appearance and mental status. Does the he look normal or does he look out of it or irritable and unable to be consoled?
Can the child make tears or are his eyes abnormally dry?
Are the child’s mucous membranes moist or dry? To determine this, pull down your lower lip and look at the moisture in your mouth (in the mirror) and then do same for your child.
When you gently pinch the skin over the breast bone, does it spring back or does it stay up (called tenting) and only slowly go back down?
Is he breathing faster or deeper than normal?
Is his heart rate faster than normal?
Is the blood pressure lower than normal?
Is the capillary refill time longer than normal? When you gently press your thumb on the infant or child’s forehead, breast bone, or kneecap does the color return in two second or less (which is normal).
If an infant or child has clinically signficant dehydration (acute fluid loss), he will have one or more of the symptoms above. And the presence of one or more of those symptoms means he should be immediately evaluated.
The normal pulse rate, respiratory rates and blood pressures are given in the post What the Pediatric Respiratory Rate, Pulse Rate, and Blood Mean at
Reference: Pediatric Advanced Life Support Provider Manual, c2011, American Heart Association.