In maintaining normal hydration infant are dependent on their attendants (Mother, nurse, etc) to suply a sufficient quantity of fluid. For a variety of phsyological and practical reason, dehydration can arise easily and rapidly in infancy. Early detection and determination of the degree of dehidration is therefore esential.
Why is Dehydraton is common in infant?
- Infant have a different body composition to adult--> 70-80% body water content versus 60% in adult.
- High fluid intake --> 150 ml/kg/day compared to 30-40 ml/kg/day in adults.
- Daily water turnover of 10-15% of body weight compared to 3-5% in adults.
- Relative reduction in renal ability to concentrate urine.
- Greater surface area/mass ratio reesulting in high insensible fluid losses through skin and respiratory tract.
- Higher basal metabolic rate plus greater febrile response to infection.
- Infants have little of no control over fluid intake.
A normal state of hydration is manifest by bright eyes, moist tongue and good skin turgor. fat infants (in whom skin turgor is difficult to determine) may deceive by concealing degydration, especially of the hypertonic type. Appreciation of normal skin turgor or elastic is best established by examining lots of normal infants.
Sign of dehydration
Dehydration in infancy is manifest by:
- A sunken anterior fontanelle
- Dull, dry eyes with reuces eyeball turgor (as most of us do not normally assess eyeball turgor in normal infants, one can be uncertain of this sign)
- dry tongue and mouth
- diminished skin turgor or elasticity, which is best elicited by picking up abdominal or thigh skin
- letharhy and weak cry
- diminished pulse volume
- diminished urine output (more dry nappies)
- reduce blood pressure
The Degree od dehydration
- Mild (<5%>
- Modemic (5-10% loss of body weight) = obvious clinical signs of loss of interstitial fluid - sunken fontanelle, dry tongue, reduced skin turgor.
- Severe (10-15% loss of body weight) = seriously ill. Sign of loss of intravaskular volume - weak, fast pulse, low blood pressure, poor urine output - plus earlier signs.