StATS: Differences between children and adults (October 13, 2006).

A recently published report from the Institute of Medicine, Emergency Care for Children--Growing Pains, has a very nice table in the introduction that highlights some of the differences between children and adults. This material is very helpful for a talk I am preparing, so I have adapted this material and placed it below.

The report first highlighted anatomical differences between children and adults.

Anatomical Differences Implications for Illness
and Injury
Implications for Care
Greater body to surface area to body mass ratio. Greater risk of excessive loss of heat and fluids; children are affected by more quickly and easily toxins that are absorbed through the skin. Increased body surface area makes children more susceptible to greater heat loss when they are exposed during resuscitation; the higher percentage of body surface area devoted to the head relative to the lower extremities must be taken into account when determining the percentage of body surface area involved in burn injuries.
Smaller airways; tongue is large relative to the oropharynx; larynx is higher and more anterior in the neck; vocal cords are at a more anterocaudal angle; epiglottis is soft and shaped differently from that in adults. A right main stem intubation can lead to iatrogenic complications; more susceptible to respiratory distress due to airway swelling from infection or inflammation. Special equipment and training are needed for intubation; appropriately sized endotracheal intubation tubes, stylettes, and laryngoscope blades are necessary. A childs airway is more difficult to maintain and intubate. Children are at higher risk for a right mainstem bronchus intubation.
Less protective muscle around internal organs. Internal organs are more susceptible to traumatic forces. Recognition of internal injury requires a high degree of suspicion, and such injury should not be ruled out based on the absence of external signs of trauma.
Small size. More vulnerable to exposure and toxicity from agents that are heavier than air, such as sarin gas and chlorine, and that accumulate closer to the ground.  
Less fat, less elastic connective tissue, and closer proximity of chest and abdominal organs. Higher frequency of multiple organ injury.  
Head is proportionally larger and heavier in children. Head injury is common in young children. Head size also makes children more susceptible to greater heat loss when they are exposed during resuscitation.
More pliable skeleton; thoracic cage of a child does not provide as much protection of organs as that of adults. More susceptible to fracture and other injuries from blunt trauma. Orthopedic injuries with subtle symptoms are easily missed; hepatic or splenic injuries can go unrecognized and produce significant blood loss, leading to shock.

The report also described physiological differences.

Physiological Differences Implications for Illness
and Injury
Implications for Care
Respiratory and heart rates vary with age. More susceptible to air
Knowledge of normal and abnormal rates based on age is required; normal vital signs differ for children and adults. An increased heart rate is often the first sign of shock in a pediatric patient, versus blood pressure in an adult. Children maintain heart rate during the early phases of hypovolemic shock, creating a false impression of normalcy.
Higher metabolic rates. More susceptible to contaminants in food or water; greater risk for increased loss of water and when ill or stressed. Medication doses must
be carefully calculated
based on the childs
weight and body size.
Lower blood pressure
levels than adults; levels
vary with age.
Indicators of serious illness may not appear until the child is near collapse. Vital signs are less reliable indicators of serious illness than in adults. Respiratory arrest is more common than cardiac arrest; cardiopulmonary arrest is signaled by respiratory arrest or shock, rather than by
cardiac arrhythmias.
Immature immunological systems. Greater risk of infection; less herd immunity from infections such as smallpox.  

There are also important developmental differences between children and adults.

Developmental Differences Implications for Illness
and Injury
Implications for Care
Communication barriers may exist in all pediatric age groups, but the nature of the barrier varies by age (i.e., infants and young children cannot articulate symptoms).   Assessment tools need to be tailored to reflect age-appropriate responses.

Finally, there are emotional differences.

Emotional Differences Implications for Illness
and Injury
Implications for Care
Greater, varying emotional needs based on developmental level.   Need for family-centered policies and a family-friendly environment in EDs. Depending on age, children require or prefer the presence of a parent during treatment.
Higher sensitivity to environmental factors during treatment. Age and developmental level of child, characteristics of event, and parental reactions play significant role in determining the childs reactions and recovery. Providers must manage the mental health needs of pediatric patients and parents reactions.

[[Update, October 17, 2006]] Another good source is the International Conference on Harmonisation (ICH) Topic E11, Clinical Investigation of Medicinal Products in the Paediatric Population. This report covers a wide range of issues but has an especially nice section covering the challenges of research involving pre-term infants.

Important features that should be considered for these patients include:

  1. gestational age at birth and age after birth (adjusted age);
  2. immaturity of renal and hepatic clearance mechanisms;
  3. protein binding and displacement issues (particularly bilirubin);
  4. penetration of medicinal products into the central nervous system (CNS);
  5. unique neonatal disease states (e.g., respiratory distress syndrome of the newborn, patent ductus arteriosus, primary pulmonary hypertension);
  6. unique susceptibilities of the preterm newborn (e.g., necrotizing enterocolitis, intraventricular hemorrhage, retinopathy of prematurity);
  7. rapid and variable maturation of all physiologic and pharmacologic processes leading to different dosing regimens with chronic exposure; and
  8. transdermal absorption of medicinal products and other chemicals.

Many of these issues also apply to full term infants less than 30 days of age.

Some informal comments I have received in conversations with some of the doctors here have also been eye-opening. The brain develops rapidly during the first year of life and anything that interferes with this process can cause serious developmental delays. For an adult, it's different--if we kill a few million brain cells by drinking a pint of Stout, that's not such a bad thing.

Well ya see, Norm, it's like this... A herd of buffalo can only move as fast as the slowest buffalo. And when the herd is hunted, it is the slowest and weakest ones at the back that are killed first. This natural selection is good for the herd as a whole, because the general speed and health of the whole group keeps improving by the regular killing of the weakest members. In much the same way, the human brain can only operate as fast as the slowest brain cells. Excessive intake of alcohol, as we know, kills brain cells. But naturally it attacks the slowest and weakest brain cells first. In this way, regular consumption of beer eliminates the weaker brain cells, making the brain a faster and more efficient machine. That's why you always feel smarter after a few beers.

Coagulation factors require higher doses in children, which has implications for the treatment of conditions like hemophilia.

Drugs that cause retention of water have a disproportionate impact on children because of their smaller size, and seizures from hyponatremia are a serious concern.

Many of the diseases in adults are caused (or at least exacerbated by) years of abuse and neglect (too much food, too little exercise, too many cigarettes). Children do not have enough years in their lives yet and they don't start many of these abusive and neglectful habits until they are well on their way into adulthood. As a result, most of the conditions that we treat children for stem from congenital causes rather than from abuse and neglect.

This page was written by Steve Simon while working at Children's Mercy Hospital. Although I do not hold the copyright for this material, I am reproducing it here as a service, as it is no longer available on the Children's Mercy Hospital website. Need more information? I have a page with general help resources. You can also browse for pages similar to this one at Category: Children in research.