Delivery room management
Tooley and Phibbs (1975) describe measures taken
immediately after birth:
"...when the newborn infant may have cardiac
arrest and apnea.
... Although infants must make a number of
crucial adjustments immediately after birth,
none is of more immediate importance than lung
expansion and a change in the circulation, so
that the blood returning to the heart goes
through the lung." [1, p111]
Fetal and neonatal circulation are described and
illustrated. The illustration (fig 9-1) of fetal
circulation shows the umbilical arteries and vein
connected with the placenta. Figure 9-2 on the next
page illustrates the prior arterial and venous
connections tied off, and the placenta is gone.
Tooley and Phibbs describe the beginning of
neonatal circulation as follows:
"With the first breath the lungs expand, the
pulmonary vascular resistance decreases and,
when the cord is clamped, the systemic vascular
resistance increases and left atrial pressure
rises." [1,p112]
They proceed to describe closure of the fetal shunts,
the foramen ovale and ductus arteriosus in terms of
perivascular pH and oxygen tension, and state that
hypoxia causes the release of vasoconstrictor
substances that activates a mechanism by which
vasoactive substances constrict the precapillary
arterioles.
These statements do not clarify how any specific
biochemical processes go into effect, and would
better be replaced with a statement that no one has
yet really been able to explain how the alveoli open
and receive the first breath. Instead attempts are
made to explain constriction of the ductus arteriosus
in terms of bradykinin, serotonin, and acetylcholine.
Then:
"However, even when newborn infants are well
oxygenated, closure does not always occur.
Persistent patency of the ductus arteriosus is
particularly common in prematurely born
infants." [1, p113]
The chapter proceeds to explain:
"If, in the minutes following delivery, the infant
does not expand his lung and establish
respiration...
...When right atrial pressure is greater than left
atrial pressure, the foramen ovale opens and
blood flows through it right-to-left. This return
to a fetal-like circulation is diagrammed in figure
9-3. In this situation, even vigorous assisted
ventilation may be inadequate to decrease the
pulmonary vascular resistance and promote
conversion of the fetal to an adult type
circulation.
...a shock-like state develops. Unchecked, this
will progress to severe acidosis and hypoxia
and cause myocardial failure and brain
damage." [1, p115]
At least these authors acknowledge that the brain
can be damaged when transition from fetal to
neonatal circulation fails to take place. Again, figure
9-3 shows the umbilical arteries and vein tied off.
The placenta is not part of the picture.
Thus we get a taste of how specialists in the field
manage, rather than provide care for, the newborn
baby in the delivery room.
(in progress)
- Tooley WH, Phibbs RH
(1975) Delivery room
management of the newborn.
- Tooley WH, Phibbs RH Delivery room management of the newborn. In
Avery . Neonatology