You arrive at a residence to find a 20-month-old male being held by his mother as she walks around nervously. She says something is wrong with her baby. You ask to see him and find that he is not very interactive with his environment and has a weak cry. He’s breathing at 64 times per minute, and you notice the bottom of his ribs are moving inward at the end of each inhalation, causing a seesaw motion between his chest and abdomen. He’s lifting his head as he breathes in, dropping it when he exhales. On closer inspection, you observe that he’s flaring his nostrils and he appears slightly pale.
Acrocyanosis: Cyanosis (bluish coloration) observed at the distal extremities (i.e., the hands and feet).
Alveoli: Pleural for alveolus, the primary respiratory unit of the lung; round sacs that serve as the main location of gas exchange, designed to increase overall surface area available for gas exchange.
Cricoid ring: The ring-shaped cartilage at the end of the larynx.
Glottic opening: The space, or opening, between the vocal cords.
Intercostal muscles: Muscles between successive ribs.
Pallor: Paleness, lack of color.
Phrenic nerve: The nerve that innervates the diaphragm.
Stridor: A high-pitched, harsh respiratory sound, resulting from laryngeal obstruction.
Respiratory dysfunction accounts for the majority of cardiopulmonary arrests in children, making prompt identification and treatment of respiratory distress the most important task of the health-care provider.(1,2) Unfortunately, the assessment of a child’s respiratory condition tends to be challenging for most health-care professionals—especially for prehospital providers whose education focuses on adults.
Depending on the population and geographic location of an EMS system, it’s generally accepted that 10% or less of total calls will be pediatric emergencies.(3,4) Also, children who require anything beyond basic care on the ambulance make up a small percentage of the prehospital pediatric patient load.(3,4) With such low frequency of use, what we learned as students often vanishes before the first critical pediatric call.
Knowledge—and periodic review—of the developing respiratory anatomy and physiology contributes to our understanding of the signs and symptoms exhibited by children in respiratory distress. By combining this understanding with a simple, effective assessment process, we can increase the likelihood of detecting respiratory dysfunction. The ideal assessment process should be applicable to children with injuries and illnesses of all types to prevent the necessity of memorizing multiple assessments.
•List anatomic differences between the respiratory systems of children and adults.
•Describe the standard approach to assessing the respiratory status of a pediatric patient.
•Explain the changes in the physiology of the pediatric respiratory system that lead to less efficient compensatory mechanisms for respiratory distress (compared with adults).
The developing respiratory system
All components of the respiratory system are present at birth. However, major structural and functional developments occur after birth and continue changing throughout childhood. Understanding these changes aids in our understanding of why children don’t respond to disease and injury in the same ways adults do. The respiratory system is divided into four components: the upper respiratory system, lower respiratory system, chest wall and diaphragm.
Upper respiratory system: The upper respiratory system comprises all structures and passages involved in the conduction of air from outside the body to the larynx. This system includes the nose, mouth and structures within the hypopharynx. Newborns and infants are often referred to as obligatory nose breathers due to the high resistance to air flow through the oral passage. Therefore, anything that increases resistance through the nose may result in respiratory distress, and a bilateral obstruction can be life-threatening.5 By five to six months of age, infants can take occasional effective oral breaths, and by eight months they’re capable of normal mouth breathing.(5,6)
The two major structures opposing efficient air passage through the mouth are the tongue and sucking pads. First, the tongue in infants and children up to two years old is large and rests entirely within the oral cavity.(6) It’s also lax, so it can easily fall back and obstruct the airway. Second, infants have sucking pads, composed of dense fatty tissue on the inside of each cheek, that improve suction when breastfeeding. The sucking pads slowly shrink as the child grows.
Major adjustments in the relative positions of upper respiratory structures begin to take place by the second year of life. The posterior third of the tongue descends into the neck and forms the upper anterior wall of the pharynx. The epiglottis descends from C1 as the neck elongates until it rests between C4 and C7 in adulthood.(6)
The lower airways extend from the larynx to the structures where gas exchange occurs. For the newborn, the trachea is short and funnel-shaped, with an average length of 4 cm and a diameter of 4 mm. The cricoid ring is narrower than the glottic opening. This means that an endotracheal (ET) tube that passes easily through the glottic opening may be tight at the level of the cricoid ring (see illustration).
Changes in head position result in ET tube movement due to the shortness of the trachea and the large tongue. Flexion of the neck moves the tip of the tube farther out of the trachea, and extension moves the tube farther into the trachea. Therefore, it’s necessary to stabilize the head of the intubated child with towel rolls and tape or a commercial device whenever possible.
Lower respiratory system: Most development of the respiratory unit where the blood-gas interface occurs takes place after birth. The respiratory unit of the lung consists of three orders of respiratory bronchioles, a generation of alveolar ducts and terminal clusters of alveolar sacs.(7,8) Alveoli are present at birth; however, they’re smaller and shallower than in older children and adults, resulting in less surface area for gas exchange.(8)
The number of alveoli increases dramatically in the first years of life, continuing to increase until approximately eight years of age. This increase is accomplished by the breakdown of the terminal bronchiole walls. Alveoli increase in size and depth until growth of the chest wall is complete. By eight years of age, a child has nearly 300 million alveoli.(9)
Neonates have thicker alveolar and capillary walls, increasing the diffusion distance for gas exchange.(9) Moreover, the premature neonate has a greater distance between the alveoli and capillaries, making diffusion more difficult than experienced by their full-term counterparts. This is counterproductive because the premature infant has greater oxygen requirements.
Chest wall: Of the chest wall and lungs, the lungs are the more compliant of the two structures in adults. The term compliance simply refers to an object’s ability to yield elastically in response to an applied force. Thus, when the chest wall moves outward as a result of diaphragmatic contraction, the lungs expand with it. Elastic recoil is required for passive expiration as the lung returns to a normal resting state. Lung elastic tissue and elastic recoil increase progressively until approximately 15 years of age.(8–10)
Children have a disadvantage in that their chest walls are very compliant due to cartilaginous and flexible ribs, and weak intercostal muscles.(9) By contrast, their lungs are less compliant than those of an adult; fortunately, lung compliance increases with age. In situations in which a disease process (such as asthma) or an injury decreases lung compliance, the chest wall becomes the most compliant structure.
Unlike the flexible, cartilaginous ribs of a child, the rib cage of the newborn is boxlike.9 The ribs come off the spine at closer to a 90° angle than at the approximate 45° angle of adult ribs.6 (See illustrations.) As a result, the ribs can’t be lifted to increase tidal volume, and the newborn is dependent on increasing respiratory rate rather than tidal volume to compensate for respiratory problems.
Diaphragm: The most important muscle of respiration is the diaphragm, a thin and dome-like sheet of muscle with two parts: an upper and a lower portion. The diaphragm is controlled by the phrenic nerve, which derives from C3, C4 and C5 nerve roots. In the adult, the upper portion is higher than the lower, and fibers of the upper and lower portions are also oriented differently than in children. The oblique insertion of the diaphragm and the orientation of its fibers cause the thoracic cavity to expand when the diaphragm contracts. During normal tidal breathing in the adult, the diaphragm will move only about 1 cm. However, during stressed or forced breathing, it may move as much as 10 cm.
In the infant, the diaphragm exists in a more horizontal orientation, and its dome shape appears less pronounced. This positioning is acceptable for normal breathing. However, during stressed breathing, the diaphragm contracts beyond the point where the dome is flattened. At this point, the contraction pulls the ribs inward rather than expanding them. This accounts for the seesaw motion observed during distressed breathing.
Although adult intercostal muscles are strong and effective accessory muscles of ventilation, the immature intercostal muscles of infants and young children serve only to stabilize the chest wall and cannot be effectively used to supplement ventilation.(9) Therefore, the younger the child, the more they rely on diaphragmatic and abdominal musculature for respiratory movement.
The diaphragm and intercostal muscles consist of two fiber types. Type I fibers are high-oxidative and are considered resistant to fatigue. Type II fibers, considered standard muscle fibers, are readily fatigued. The adult diaphragm is 50–55% type I fibers, whereas the term infant has 25% type I fibers and the premature infant has a mere 7–10%.(9,11) This means the muscles will likely fatigue more quickly. Coupled with the facts that infants and young children are rate dependent, have a higher oxygen utilization and the oxygen has a greater distance to cross the alveolar/ capillary membrane, decompensation occurs more rapidly once their respiratory muscles fatigue.(9)
The assessment of a child follows a very simple process, with the approach adjusted according to the age and developmental characteristics of the child. The initial assessment, consisting of the internationally recognized pediatric assessment triangle (PAT) and the hands-on ABCDE (airway, breathing, circulation, disability, exposure) assessment, actually begins when you first see the child.(12) The PAT is a screening tool that takes 30–60 seconds to complete, beginning as the provider enters the room. Attempt to obtain as much information as possible before ever touching the child to allow them to build familiarity with you.
The status of the child’s ventilation, oxygenation, perfusion and brain function can be quickly determined by assessing the child’s appearance, work of breathing and circulation to the skin.12 The assessment requires nothing but the provider’s eyes, ears and professional acumen.
PAT leg 1: Appearance
The child’s appearance can be the most important consideration because it reflects the adequacy of ventilation, oxygenation and brain perfusion. The severity of the child’s condition and their subsequent response to treatment are often reflected in their appearance. Use the mnemonic TICLS to assess a child’s appearance (see Table 1).
TABLE 1. TICLS
Evaluate the child’s position and their interactiveness with the environment. All healthy children should engage their environment.(12) Newborns engage their environment via crying or active sucking, and older infants will follow a penlight or other object with their eyes (tracking). Toddlers engage by exploring and touching, while verbal children engage through talking.
PAT leg 2: Work of breathing
How a child attempts to compensate for abnormalities in oxygenation and ventilation provides the most rapidly identifiable indicators of the adequacy of these two processes. Auditory clues of inadequate ventilation include snoring, muffled or hoarse speech, stridor, grunting or wheezing. These sounds are audible without a stethoscope and provide information about the location of any airway obstruction and the amount of effort required to breathe.
Snoring, muffled or hoarse speech, and stridor are all indicative of upper airway obstruction. Snoring suggests an obstruction in either the oropharynx or hypopharynx. Muffled or hoarse speech indicates obstruction at or near the level of the vocal cords, and stridor suggests obstruction at the level of the larynx or in the trachea.
Grunting occurs when air is being forced against a partially closed glottis, indicating severe distress. During times of distress, partial closure of the glottis becomes necessary to maintain pressure within the lungs, which keep the alveoli open. Grunting is best heard at the end of the expiratory phase and is often associated with pneumonia.
Wheezing is the result of air being forced through a partially obstructed lower airway. This obstruction is usually due to edema or bronchoconstriction. When it’s mild, it occurs at the end of the expiratory phase of breathing and can often be heard without a stethoscope. Wheezing diminishes as the child loses the ability to compensate and becomes incapable of generating enough force to produce the sound.
Abnormal positioning, retractions, nasal flaring and tachypnea are visual signs of increased work of breathing. Abnormal positioning includes a refusal to lie down and the assumption of the “tripod” or “sniffing” position as the child instinctively tries to line up the airways and use the accessory muscles of ventilation most effectively.
The identification of retractions is a more reliable indication of increased work of breathing in children than in adults. The weaker and less effective accessory muscles and the thin chest wall make it easier to see retractions in the supraclavicular, intercostal and substernal areas. However, they’re easily missed if the child is not exposed properly. Directly visualize the child’s chest by having either the caregiver or the child uncover their chest while still on the caregiver’s lap. Look at the suprasternal, substernal and intercostal areas for retractions and note their location and quality. Again, when a child is no longer able to compensate, begins to tire and approaches respiratory arrest, retractions may become less evident.
Another indication of increased work of breathing in infants is head bobbing. During inhalation, the infant extends the neck and during exhalation relaxes the neck, dropping the head. This is a visible form of accessory muscle use.
Nasal flaring is another visible sign of significantly increased work of breathing. The child instinctively tries to decrease resistance through the nasal passage by flaring the nostrils. This is also easily missed if not looked for specifically.
PAT 3: Circulation to the skin
The final component of the PAT is an evaluation of the child’s circulatory status. When determining the circulatory status of an adult, heart rate and blood pressure are the most valuable indicators; however, for kids, those vital signs can be deferred until the ABCDE phase of the initial assessment. In children, skin appearance is a reliable initial indication that something is wrong with their circulation.
The circulatory assessment establishes the adequacy of cardiac output and perfusion to vital organs. When perfusion to the skin or mucus membranes is poor, pallor is usually the first observable sign.(12) This is due to neuromuscular regulation of blood flow as the body attempts to maintain core perfusion. As the blood vessels to the skin constrict, mottling may also appear.
Cyanosis is a late sign of hypoxia in children.(12) Generally, the child will have shown pallor, mottling or other signs before becoming cyanotic. Also, it’s important to distinguish between acrocyanosis and true cyanosis. Acrocyanosis occurs in infants younger than two months old when they’re exposed to the cold.
When assessing the child’s skin signs, be sure the environment is warm. Infants and young children are very sensitive to cold, which is the most common reason for misinterpretation of skin signs.(12) When inspecting for signs of poor circulation to the skin, begin by looking at the chest, abdomen and extremities. Then look at the lips and the mucus membranes inside the mouth for signs of pallor or cyanosis.
ABCDE hands-on assessment
The second phase of the initial assessment of a child with respiratory distress is the hands-on ABCDEs. The assessment must be conducted in this order because it represents a prioritized sequence of events aimed at detecting life-threatening problems. Most assessment and management errors occur because the ABCDEs were not properly followed.(13)
Airway: The PAT will usually help the provider determine if the airway is open. If the airway is closed, attempt to open it manually and provide suction. If these maneuvers do not open the airway, consider obstruction, remembering that the tongue is a common culprit.
Breathing: When assessing breathing during the ABCDE phase of the initial assessment, start by counting the respiratory rate, then auscultate the chest for abnormal lung sounds, and obtain a pulse oximetry reading. The respiratory rate should be determined by counting a full 30 seconds and multiplying the resultant number by two. This is done to more accurately account for “periodic” breathing, which occurs normally in infants. Although tachypnea is usually the first sign of respiratory distress in young children, the rate must be interpreted carefully because a child’s respiratory rate is greatly influenced by other things, such as fever, pain or fear. Also, as a child fatigues, their rate may slow down and appear normal. For children younger than six years old, any rate greater than 60 or less than 20 per minute should be a red flag for the provider.(12)
Pulse oximetry is an excellent tool for helping determine the child’s respiratory status. However, it must be interpreted with knowledge of its limitations. For example, a cold environment may affect the device’s accuracy. Also, just because a child has a reading above 94% does not mean the child is not in respiratory distress. It may simply mean that they’re able to temporarily maintain saturation at that level due to physiological compensations. In the absence of such compensations, a reading above 94% suggests adequate oxygenation. A reading below 90% with 100% O2 via mask is an indication of the need to assist ventilations.(12)
Circulation: The assessment of circulation in children during this phase of the initial assessment is similar to that for an adult, with some exceptions in how we interpret the signs. These steps include assessment of pulse, skin temperature, capillary refill and blood pressure. The best location to obtain the pulse in young children is at the brachial or femoral arteries. If you can’t obtain the pulse at one of these locations, obtain the apical pulse via auscultation over the apex of the heart with a stethoscope.
When the environment is sufficiently warm, the child’s skin temperature should be warm at the ankles and wrists. As perfusion is compromised, palpably cool skin may be felt farther up the limbs. This is known as the skin temperature margin, or core-peripheral temperature gap.
Next, obtain the child’s capillary refill time at the kneecap or forearm. Capillary refill should take less than three seconds. The value of capillary refill as an assessment tool has been disputed by some. It must be understood that a cool environment may result in longer capillary refill times.
When obtaining a child’s blood pressure, remember that normal blood pressure, like pulse rates, varies with age. It’s often difficult to obtain a blood pressure reading on young children, but it should be attempted on all patients. Use a blood pressure cuff with a width that is two-thirds the length of the upper arm or thigh to obtain an accurate reading. To determine the minimum systolic blood pressure, multiply the patient’s age (in years) by two, then add 70 (70 + [2 × age]).(12)
Disability: When assessing disability, you’re observing the neurological status of the child. This is accomplished in part by the appearance phase of the PAT. Use the AVPU scale (see Table 2) to assess level of consciousness. (Note: The Pediatric Glasgow Coma Scale [PGCS] has never been validated.)(12) Also, assess pupils and motor movement. Adults with fixed and dilated pupils usually have a high mortality rate, whereas children with isolated fixed and dilated pupils usually have a low mortality rate.(14,15) However, if motor flaccidity is observed in addition to fixed and dilated pupils, children usually have a high mortality rate.(15)
TABLE 2. AVPU
V–Responsive to verbal stimuli
P–Responsive to painful stimuli
Exposure: To complete the initial assessment, the child must be exposed sufficiently to allow the provider to see the skin over the chest, back, arms and legs. In a warm environment, have the caregiver or child expose one body area at a time. Note any abnormalities observed. It’s important to note that some medical texts identify the “E” component of the ABCDE process as indicating the need for assessment of potential exposure to the environment.
When faced with a critically ill child, the prehospital provider may not have sufficient time to complete a thorough secondary examination, due to either resuscitation priorities or short transport times. Thus, it’s important to observe the environment where you contacted the child and to note the child’s interaction with the caregiver.
The secondary examination should be conducted in a toe-to-head sequence, rather than head-to-toe, because this is less frightening for the child.
Recognition of respiratory distress is the most important responsibility of health-care providers in preventing cardiac arrest in children. We must understand the anatomical differences between children and adults, because this helps us to better understand the child’s signs and symptoms. A standardized assessment can aid in early recognition of distress—and help avoid the need for memorization of several assessment techniques for a population infrequently encountered by EMS.
1. Perkin RM , Anas NG. “Acute Respiratory Failure.” In: Deickman RA, Grossman M editor. Pediatric Emergency Medicine: A Clinician’s Reference. Philadelphia: JB Lippincott Company; 1991.
2. American Heart Association, American Academy of Pediatrics: Pediatric Advanced Life Support (PALS) Provider Manual. American Heart Association, 2002. p. 23.
3. Joyce SM , Brown DE , Nelson EA . “Epidemiology of pediatric EMS practice: A multistate analysis.” Prehospital and Disaster Medicine. 1996;11(3):180–197.
4. Kallsen GW . Epidemiology of Pediatric Prehospital Emergencies. In: Dieckman RA editors. Pediatric Emergency Care Systems: Planning and Management. Baltimore: Williams & Wilkins; 1991;p. 153–158.
5. Polgar G , Weng TR . “The functional development of the respiratory system from the period of gestation to adulthood.” American Review of Respiratory Disease. 1979;120(3):625–695.
6. Van Stralen D, Perkin RM: “The pediatric airway, assessment and diagnosis.” Unpublished manuscript.
7. Emery JL . “The post-natal development of the human lung and its implications for lung pathology.” . Respiration. 1970;27(Suppl):41–50.
8. Charnock EL , Doershuk CF . “Developmental aspects of the human lung.” Pediatric Clinics of North America. 1973;20(2):275–292.
9. Blackburn S . “Alterations of the res-piratory system in the neonate: implications for clinical practice.” Journal of Perinatal and Neonatal Nursing. 1992;6(2):46–58.
10. Thurlbeck WN . “Postnatal growth and development of the lung.” American Review of Respiratory Disease . 1975;111(6):803–844.
11. Keens TG , Bryan AC , Levison H , et al. “Developmental pattern of muscle fiber types in human ventilatory muscles.” Journal of Applied Physiology. 1978;44(6):909–914.
12. American Academy of Pediatrics, American College of Emergency Physicians . In: APLS: The Pediatric Emergency Medicine Resource, Fourth Edition. Sudbury, Mass: Jones & Bartlett Publishers Inc; 2004;p. 21–49.
13. Bergman AB. In: 20 Common Problems in Pediatrics. McGraw Hill Professional; 2001;p. 128.
14. Lieberman JD , Pasquale MD , Garcia R , et al. “Use of admission Glasgow Coma Score, pupil size, and pupil reactivity to determine outcome for trauma patients.” Journal of Trauma . 2004;56(2):457.
15. Raimondi AJ , Hirschauer J . “Head injury in the infant and toddler. Coma scoring and outcome scale.” Child’s Brain. 1984;11(1):12–35.
James F. Goss, MHA, MICP, is program director and lead paramedic instructor for NCTI in Riverside, Calif. He’s also assistant professor of emergency medical care at Loma Linda University in Loma Linda, Calif., and a frequent contributor to JEMS. Contact him at firstname.lastname@example.org.