Respiratory Effort

Breathing usually begins by 30 seconds of extrauterine life and is sustained by 90 seconds of age. Within a few minutes after birth, the respiratory rate of normal neonates is between 30 and 60 breaths/min. There is no pause between inspiration and expiration, which helps to develop and maintain a normal FRC. At these rates, the time constants of the lung are too short for the FRC to be exhaled. Apnea and bradypnea prolong exhalation, which reduces FRC and causes hypoxia. Apnea and bradypnea are often caused by severe acidosis, asphyxia, maternal drugs, infections (e.g., meningitis, septicemia, pneumonia), and CNS damage. Tachypnea (>60 breaths/min) occurs with hypoxemia, hypovolemia, metabolic and respiratory acidosis, CNS hemorrhage, pulmonary gas leaks, pulmonary disease (e.g., hyaline membrane disease, aspiration syndromes, infections), pulmonary edema, and maternal drugs (e.g., narcotics, alcohol, magnesium, barbiturates).

Resuscitation with 100% oxygen may be detrimental. One study demonstrated that there was no difference in ability to resuscitate neonates if room air or oxygen was used during resuscitation.^[49] Less cerebral hydrogen peroxide was produced in animals resuscitated with air than in those resuscitated with oxygen.^[50] Hoehn and colleagues^[51] reported less activation of polymorphonuclear cells from the umbilical cord with hypoxia but increased activation when oxygen was used compared with nitrogen or room air. Both of these studies and many others indicate that oxygen administration increases the likelihood of a heightened inflammatory response when high concentrations of oxygen are administered. However, there is still not enough information to definitely state that room air rather than oxygen should be used to resuscitate neonates.