July 2004
12
References: Embryology, Fetal circulation,
Oxygen, a continuous need,
Placental to pulmonary blood-volume shift with the first breath,
Alveolar expansion
Oxygen, a continuous need,
Placental to pulmonary blood-volume shift with the first breath,
Alveolar expansion
space
walk, with electronic sensors and signals to maintain air
flow and optimum oxygen supply. How far removed we are from
helping with human birth at home or observing birth of farm animals.
Pulsations
in the umbilical cord of a newborn child signal
that oxygen and/or additional blood volume are still needed from
the mother. Most infants do breathe within seconds
after birth, thus gain the placental transfusion needed for activation of
the lungs [5]. For those few who
are slow to take the first breath, White's comment on neonatal
transition bears repeating:
"The lungs must be fully
expanded with air, and the whole mass of blood instead of one fourth part be circulated through them; the
ductus venosus, foramen ovale, ductus arteriosus, and the umbilical arteries and vein must all be
closed, and the mode of circulation in the principal vessels entirely altered – Is it possible that this wonderful alteration in
the human
machine should be properly brought about in one instant of time, and at the
will of a by-stander?" – White
1773, p 45 [9].
•
Return
to:
References:
Embryology
1.Mäkikallio K, Tekay A, Jouppila P
(1999) Yolk sac and umbilicoplacental hemodynamics during early human embryonic development.
Ultrasound in Obstetrics and Gynecology 14:175-179.
2. FitzGerald MJT, FitzGerald M (1994) Human Embryology. Baillière Tindall,
London.
Fetal circulation
3. Brezinka C (2001)
Fetal hemodynamics. J Perinat Med
29:371-380.
Oxygen, a continuous need
4.DarwinE (1801) Zoonomia; or, The Laws of Organic Life, Third Edition, Vol. II, London: J Johnson, p 192.
Placental to
pulmonary blood-volume shift with the first breath
5. Redmond A, Isana
S, Ingall D (1965) Relation of onset
of respiration to placental transfusion. Lancet 1 (6 Feb):283-285.
Alveolar expansion
6.Jäykkä, S (1958) Capillary erection and the structural appearance of fetal and neonatal lungs. Acta Pædiatrica 47:484-500.
7.Mercer JS, Skovgaard RL. (2002) Neonatal transitional physiology: a new paradigm. J Perinat Neonatal Nurs. 2002 Mar;15(4):56-75.
