PHYSIOLOGICAL CONSIDERATIONS

Vital signs
Infants and children have a more rapid metabolic rate than adults. This is reflected in their normal vital signs.



Temperature regulation
Children lose heat more rapidly than adults because they have a greater relative surface area and are poorly insulated. Hypothermia can affect drug metabolism, anaesthesia and blood coagulation. Children are especially prone to hypothermia in the operating room.

Prevent hypothermia by:

It is easier to keep children warm than to warm them up when cold. Encourage the mother to keep the child warm.

Compensatory mechanisms for shock
Children compensate for shock differently from adults, mainly by increasing their heart rate. A rapid heart rate in a child may be a sign of impending circulatory collapse. Do not ignore a decreased blood pressure. A slow heart rate in a child is hypoxia until proven otherwise.

Blood volume

Children have smaller blood volumes than adults

See The Clinical Use of Blood (WHO, 2000) for additional information on the use of blood in paediatrics and neonatology.



Nutrition and hypoglycaemia

Infants and children are at special risk for nutritional problems because of their higher caloric needs for growth. Poor nutrition affects response to injury and ability to heal wounds. Many surgical conditions, such as burns, increase caloric needs or prevent adequate intake of needed nutrition.

Good nutrition helps healing. Poor nutrition prevents it.

Infants are at risk for developing hypoglycaemia because of a limited ability to utilize fat and protein to synthesize glucose. If prolonged periods of fasting are anticipated (>6 hours), give intravenous fluids that contain glucose.

Fluid and electrolytes

Baseline fluid and electrolyte requirements are related to the child’s weight. However, the actual fluid requirements may vary markedly, depending on the surgical condition.



Hourly maintenance fluid requirements can be calculated using the 4:2:1 rule.



Fluid requirements in surgical patients commonly exceed maintenance requirements. Children with abdominal operations typically require up to 50% more than baseline requirements and even larger amounts if peritonitis is present. Special care is needed with fluid therapy in children; pay close attention to ongoing losses (e.g. nasogastric drainage) and monitor urine output. In the case of fever, add 12% to total maintenance requirements per 1°C rise above 37.5°C temperature measured rectally.

The most sensitive indicator of fluid status in a child is urine output. If urinary retention is suspected, pass a Foley catheter. A catheter also allows hourly measurements of urine output that can prove invaluable in the severely ill patient.

Normal urine output: Infants 1–2 ml/kg/hour
Children 1 ml/kg/hour

Infants are unable to concentrate urine as well as adults, making them more susceptible to electrolyte abnormalities.

Establishing intravenous access in paediatric patients can be challenging. See pages 13–11 to 13–16 for IV access techniques.

Anaesthesia and pain control

Anaesthesia in children poses special problems. The smaller diameter airway makes children especially susceptible to airway obstruction. Children often need intubation to protect their airway during surgical procedures. Ketamine anaesthesia is widely used for children in rural centres (see pages 14–14 to 14–21), but is also good for pain control.

Children suffer from pain as much as adults, but may show it in different ways. Make surgical procedures as painless as possible:

The pre- and postoperative care of children with surgical problems is often as important as the procedure itself. For this reason, surgical care of children does not begin or end in the operating room. Good care requires teamwork, with doctors, nurses and parents all having important roles to play: