Intubation Ineffective in Vigorous Meconium-Stained Infants

CLINICAL QUESTION: Does the apparently vigorous newborn infant need to be intubated and undergo intratracheal suctioning after delivery through meconium-stained amniotic fluid (MSAF)?

BACKGROUND: Approximately 13% of all newborns are delivered through MSAF. Based on reports from the 1970s, newborns born through MSAF were believed to have a lower risk of developing meconium aspiration syndrome (MAS) if they were electively intubated and had intratracheal suctioning immediately after delivery, regardless of their clinical appearance or Apgar score. Other investigators have proposed that clinically vigorous infants may not need to be intubated and can be managed expectantly.

POPULATION STUDIED: The study population included 2094 newborn infants born to mothers from 12 participating birth centers in the United States and South America, from both university and predominantly clinical centers. Inclusion criteria included birth through MSAF, Ž37 weeks’ gestation, and apparent vigor of the child 10 to 15 seconds after birth as defined by a heart rate >100 beats per minute, reasonable tone, and spontaneous respirations. Study subjects represented a diverse population in regard to ethnicity, sex, maternal age, gravidity, and consistency of meconium fluid. Mode of delivery was mostly vaginal (78%).

STUDY DESIGN AND VALIDITY: Using computer-generated random numbers, infants were assigned to intubation and intratracheal suction (INT, n=1051) or to expectant management only (EXP, n=1043). Group assignment was concealed by using sealed opaque envelopes opened immediately before deliveries complicated by meconium staining. The policy at all birth sites was to suction the oropharynx of each meconium-stained neonate with either a catheter or bulb syringe before delivery of the infant’s shoulders or trunk. The INT group subjects were significantly more likely to have lower 1-minute Apgar scores (P <.0018). There were no other significant differences between the 2 groups. Study personnel responsible for assessing outcomes were blind to the treatment group assignment. All of the investigators remained blind to the results until the completion of the trial. Data analysis was by intention to treat.

OUTCOMES MEASURED: The major outcome studied was the development of MAS or other respiratory disorders. The time period of observation for development of these complications was not quantified.

RESULTS: Only 149 (7%) of all infants had respiratory distress, 62 (3%) of whom had MAS. There was no significant difference between the INT and EXP groups in the incidence of MAS (3.2% vs 4.5%, respectively) or in the incidence of other respiratory disorders (3.8% vs 4.5%, respectively). There was a low rate of complications from intubations (3.8%), which were generally mild and short-lived. The development of MAS was associated with cesarean birth, less than 5 maternal prenatal visits, birth through thick meconium versus thin, and not having oropharyngeal suctioning before the delivery of the shoulders. However, even in the presence of the thickest consistency MSAF, intratracheal suctioning was no better than expectant management at preventing respiratory complications. Some crossover between treatment groups did occur: 17 of the 1051 infants randomized to INT were not intubated, mostly because of difficulty with intubation. None of these infants developed MAS. A total of 64 of the 1043 infants in the EXP group were intubated after their clinical status deteriorated, and either MAS or another respiratory disorder developed in 11 of these infants.