Routine Tracheal Suctioning
The trachea should be suctioned before ventilation of the lungs
in certain situations, including meconium staining of the amniotic fluid and major
vaginal bleeding. I have found that most meconium is in major airways at birth and
that suctioning of the airway after birth removes most of this material from the
lungs.[68]
Meconium aspiration is rare in appropriate-for-gestational-age
neonates who weigh less than 2000 g at birth. Meconium aspiration has been reviewed
elsewhere.[69]
[70]
[71]
About 10% of pregnant women have meconium staining of their amniotic
fluid. Sixty percent of neonates born to mothers after meconium-stained amniotic
fluid have meconium in their tracheas at birth.[72]
If the airway is not suctioned before or shortly after the onset of breathing, meconium
in the airways will move into the alveoli and small airways with the onset of ventilation.
About 15% of meconium-stained neonates develop respiratory difficulties during the
first few days of life, and 10% develop a pneumothorax or pneumomediastinum on chest
roentgenogram. Most intrathoracic gas leaks are small and cause only tachypnea.
However, some large pneumothoraces cause collapse of the cardiovascular system and
death if they remain unrecognized and untreated.
Because of the seriousness of these complications, "pea soup"
or particulate meconium should be removed from the lung before breathing is established
to improve the survival of neonates with meconium aspiration.[73]
(Thin, watery meconium does not require suctioning.) The mouth and pharynx should
be suctioned as soon as the head is delivered. An endotracheal tube should be inserted,
a suction device especially designed for this purpose applied to the endotracheal
tube, and suction should be applied to the endotracheal tube as it is withdrawn from
the trachea.[74]
The laryngoscope should be left
in place as the endotracheal tube is removed. If meconium is retrieved from the
airway, the endotracheal tube should be quickly reinserted and the airway suctioned
again. The lungs should then be gently ventilated with oxygen. The
absence of meconium in the mouth and posterior pharynx does not preclude meconium
in the trachea.[72]
In one study, 13%
of neonates had meconium in the trachea,
but no meconium was found in the mouth or pharynx.[72]
The heart rate should be continuously monitored during laryngoscopy and suctioning
and 100% oxygen blown over the neonate's face. Suctioning the stomach removes meconium
that otherwise may be regurgitated and aspirated later. Some physicians have suggested
that neonates with Apgar scores of 9 or 10 do not require tracheal suctioning. This
is controversial. Wiswell and colleagues[75]
found
that removing thin watery meconium at birth had no beneficial effect, whereas removing
thick meconium was effective. Chest physical therapy and postural drainage done
every 30 minutes for 2 hours and hourly thereafter for the next 6 hours may help
remove residual meconium from the lung.
All neonates born after meconium aspiration should be observed
for 24 hours because they can develop persistent fetal circulation (PFC) syndrome,
[76]
the major cause of death after meconium aspiration.
When PFC occurs, blood is shunted right to left across the ductus arteriosus and
foramen ovale. Little blood perfuses the lung. Of these neonates, 50% die during
the first few days of life. Extracorporeal membrane oxygenation (ECMO) has been
used successfully to treat patients with severe hypoxia from meconium aspiration.
[77]
[78]
Several
days are required for pulmonary hypertension to abate and for ECMO to be no longer
required. The long-term outcome of children who had meconium aspiration at birth
is very good. Unless they were severely asphyxiated during the perinatal period,
they are intellectually intact. They also have normal pulmonary function at 6 to
11 years of age.[79]
[80]
