FIGURE 71.1 A: Approach to the child with respiratory distress B: Approach to the child with respiratory distress Spo2 , percentage oxygen saturation; O2 , oxygen; EtCO2 , end-tidal carbon dioxide; CNS, central nervous system Vital sign abnormalities provide important clues about the severity of illness and adequacy of compensatory mechanisms Tachycardia is one of the early signs of respiratory compromise Bradycardia in a hypoxic child is a late and ominous sign that often signals impending cardiac arrest Cardiac arrhythmias that compromise cardiac output may result in respiratory distress Respiratory rate in children varies with age ( Table 71.7 ) Tachypnea is a compensatory mechanism for hypoxia, hypercapnia, and acidosis, and it also occurs with pain, anxiety, and increased activity Fever increases respiratory rate by up to 10 breaths per degree above normal, particularly in younger children Although not specific for respiratory distress, tachypnea is one of the findings most consistently present with respiratory distress and is particularly pronounced with lower airway processes Tachypnea may be the only manifestation of lower respiratory infection in children younger than months Bradypnea may reflect central respiratory depression, increased intracranial pressure, or fatigue of respiratory muscles It is often an ominous sign that heralds impending respiratory arrest Pulsus paradoxus, an exaggeration (more than 10 mm Hg) of the normal decrease in blood pressure during inspiration, correlates with degree of airway obstruction Hypotension in a child is a late and extremely worrisome finding It suggests profound shock, significantly decreased cardiac output, and impending cardiorespiratory arrest Oxygen saturation of ≥97% while awake is normal Central cyanosis usually reflects at least g/dL of unsaturated hemoglobin and an O2 saturation of less than 90% Peripheral cyanosis alone is not usually associated with a decrease in systemic O2 saturation On inspection, in addition to respiratory rate, one should appreciate depth, rhythm, and symmetry of respirations; the use of accessory muscles; and perfusion Rapid and shallow breathing may result from air trapping in obstructive lower airway disease It may also result from chest pain, chest wall musculoskeletal dysfunction, or abdominal pain and/or distention Kussmaul respirations (deep, regular, sighing breaths) are seen with metabolic acidosis, particularly diabetic ketoacidosis Cheyne–Stokes respirations (respirations with increasing then decreasing depth alternating with periods of apnea) are seen with CNS immaturity in otherwise normal neonates and infants, particularly during sleep In older children, this respiratory pattern is concerning for inadequate cerebral perfusion, brain injury, increased intracranial pressure, and central narcotic depression Biot, or ataxic, respirations (breaths of irregular depth