Life Span Development

Two separate dimensions change with age

Two separate dimensions of a person change with age. Physiologic development is the physical change in the body: the maturing of the organs, the shifting ranges of normal vital signs, and the growth of motor ability. Psychosocial development is mental and social change: the growth of trust, of independence and of identity. Development is divided into 8 stages of life, which follow one another in order: infancy, the toddler years, the preschool years, school age, adolescence, early adulthood, middle adulthood and late adulthood.

Infancy (birth – 1 year)

Infancy runs from birth to 1 year, and the newborn's vital signs differ from those of the older infant. The table below gives the normal ranges.

Table 8.1Infancy (birth – 1 year)

A newborn weighs 6.6 to 7.7 lbs at birth. That weight doubles by 6 months and triples by 12 months, and the head alone accounts for 25% of total body weight. The infant airway is shorter, narrower, less stable and more easily obstructed than at any other stage of life. Infants breathe through the nose until they are at least 4 weeks old, and they breathe with the diaphragm, so the abdomen moves more than the chest. Because the accessory muscles of breathing are less mature, an infant in respiratory distress tires easily.

The bones of the skull have not yet fused, leaving soft spots called fontanelles. The posterior fontanelle closes by 2 to 3 months and the anterior fontanelle by 9 to 18 months. Until then they are a useful window: a sunken fontanelle suggests dehydration, and a bulging fontanelle in an infant who is not crying suggests increased intracranial pressure (ICP). Infants are also protected during their first months by passive immunity, acquired from the mother during pregnancy and through breast milk.

Newborns arrive with a set of reflexes, which the table below describes.

Table 8.2Infancy (birth – 1 year)

Psychosocially, the infant's primary means of communication is crying. Bonding is the infant's sense that its needs will be met, and it is the foundation of the balance between trust and mistrust: a consistent, responsive environment builds trust. Scaffolding is learning by building on what is already known, and temperament is the infant's characteristic reaction to its environment.

Toddler (12–36 months) & preschool (3–5 years)

The toddler stage runs from 12 to 36 months. A toddler's heart rate (HR) is 80 to 140, the respiratory rate (RR) is 24 to 40, and the temperature is 96.8 to 99.5°F. Toddlers gain about 4.4 lbs per year. The terminal airways branch and grow, the brain reaches 90% of its adult weight, muscle mass and bone density increase, and all the primary teeth are in by 36 months. Toilet training illustrates the gap between physical and psychological readiness: it is physiologically possible at 12 to 15 months, but the child is not psychologically ready until 18 to 30 months, and completion averages about 28 months. Separation anxiety between 18 and 24 months, and magical thinking and play-acting between 24 and 36 months, are normal features of this stage.

The preschool years span ages 3 to 5. The HR is 70 to 120 and the RR is 22 to 34. Peer groups become a major influence, and a sense of belonging and group identity develops. Preschoolers may still engage in magical thinking, and one consequence is that they may believe an illness or injury is a punishment. Be reassuring, and keep explanations simple.

School age (6–12) & adolescence (13–18)

School age covers ages 6 to 12. The HR is 65 to 120 and the RR is 18 to 30. The primary teeth are lost and replaced by permanent teeth. Self-esteem develops during these years, shaped by popularity or rejection among peers and by support or neglect. Moral development also begins, as control of behavior shifts from external sources, chiefly the parents, to internal self-control. School-age children can understand explanations, so involve them in their own care.

Adolescence covers ages 13 to 18. Vital signs approach adult values: the HR is 60 to 100, the RR is 12 to 20, and the systolic blood pressure (BP) is about 107 to 117. A rapid growth spurt lasting 2 to 3 years proceeds in a set order, the feet and hands first, then the arms and legs, then the chest and trunk. Reproductive maturity and secondary sexual development arrive, and puberty is the point at which American Heart Association (AHA) cardiopulmonary resuscitation (CPR) guidelines switch from pediatric to adult protocols. Psychosocially, adolescents strive for independence. Concern with body image can lead to eating disorders, self-destructive behaviors are possible, and there is a risk of depression and suicide. Privacy is critical: an adolescent may not want to answer questions in front of friends or parents.

Adulthood — early, middle & late

Early adulthood spans ages 19 to 40. Heart rate, respiratory rate and blood pressure are near the standard adult norms, and physical condition peaks between ages 19 and 26. These are the years of the highest job stress and the years in which childbirth is most common, and accidents are the leading cause of death.

Middle adulthood spans ages 41 to 60. Vision problems appear, chiefly presbyopia; cholesterol becomes a concern; the risk of cancer rises; and women reach menopause in the late 40s to early 50s. Heart disease is the major killer after age 40. Psychosocially, this is the period of the so-called "midlife crisis," of empty-nest syndrome when the last child leaves home, and of concern for aging parents.

Late adulthood begins at 61. The cardiovascular system becomes less efficient and tolerates tachycardia less well, the respiratory system deteriorates, metabolism slows, and the sleep-wake cycle is disrupted. The psychosocial challenges of this stage include the living environment, self-worth, financial burden, and death and dying.

EMS application notes

You do not need to memorize every vital sign range in this chapter. What you need is a general sense of what is normal and what is abnormal at the key ages, and a feel for how each stage changes the way you approach a patient. With infants and toddlers, keep the parent close, because separation anxiety interferes with assessment. Preschoolers may think their illness is a punishment, so use simple, reassuring language. With adolescents, privacy is critical, and you should watch for signs of eating disorders and self-harm. In the elderly, do not assume that confusion is normal, remember that tachycardia is less well tolerated, and keep in mind that the risk of falls is high.

Across the whole life span, one general trend holds: as age increases, the heart rate decreases, the respiratory rate decreases, and the blood pressure increases.