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Pregnancy and Postpartum Considerations 711

TABLE 26.1 ICU interventions required by pregnant and postpartum women in ICU

6
10
ICU intervention Pollock (Australia)* (n = 33) Hazelgrove (UK) (n = 210) Zwart (Netherlands) (n = 837)
#
7
#
Mechanical ventilation 67% 45% 35%
Inotrope infusion 18% 19% 9%
Pulmonary artery catheter 6% 13% 3%
Renal replacement therapy 9% 3% 2%
*Tertiary ICU level only.
# National/regional study, all ICU levels.

developed countries like Australia, the mortality of preg- reduction in all the placental hormonal levels, such as
nant and postpartum women admitted to ICU is rela- progesterone and oestrogens, and thus begins the physi-
tively low at around 3% compared to the 15% mortality ological process for returning the woman’s body to the
observed in the regular ICU population. 3 non-pregnant state.

CARDIOVASCULAR SYSTEM
Practice tip The cardiovascular system undergoes a series of anato-
mical and physiological changes during pregnancy to
Any maternal death, death of a woman during pregnancy or support both the mother and fetus during this period.
within 42 days of having been pregnant, should be reported to
the relevant state authority in Australia and to the Perinatal and Anatomical Changes
Maternal Mortality Review Committee in New Zealand, even if The heart undergoes anatomical change during preg-
the pregnancy is not thought to have contributed to the cause nancy including left ventricular hypertrophy and the
of death.
cross-sectional areas of the aortic, pulmonary and mitral
valves increase by 12–14%. ECG changes include non-
specific ST segment changes, the development of a Q
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ADAPTED PHYSIOLOGY OF wave in Lead III and a left-axis deviation pattern. These
are evident by the end of the first trimester and remain
PREGNANCY throughout the pregnancy. As with the interpretation
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Conception results in extensive physiological adaptations of any ECG, consider other information like the
across most body systems (Table 26.2). The physiological patient presentation (signs and symptoms) and blood
adaptations most relevant to critical care nursing include test results to form a complete assessment of the woman’s
cardiovascular, respiratory, renal, gastrointestinal and condition.
coagulation and the role of the placenta as the maternal–
fetal interface. The uterus and breasts obviously undergo Blood Volume
major change in pregnancy and any basic midwifery or Very early in the pregnancy there is generalised vasodila-
obstetric textbook, such as Myles’ Textbook for Midwives or tation resulting in sodium and water retention. The causes
Midwifery: preparation for practice will describe these in of the vasodilatation are likely to include hormonal
detail. 11,12 The physiological adaptations described in this factors (e.g. progesterone), peripheral vasodilators like
chapter refer to a singleton pregnancy only, as women nitric oxide, and potentially, an as-yet unidentified
with a multiple pregnancy (i.e. twins) may undergo pregnancy-specific vasodilatory substance. The end
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further changes. The physiological changes described result is a 40–50% increase in blood volume as well as
13
refer to a non-labouring pregnant woman. Labour induces reduced normal serum sodium level, from 140 to
further changes to physiology, such as increased cardiac 136 mmol/L and a reduced plasma osmolality from 290
output. 14 to 280 mosmol/kg. These changes persist throughout
pregnancy and the osmoreceptor system resets to accept
The puerperium, also referred to as the postpartum or these values as normal. 18
postnatal period, is the 6 weeks following the end of
pregnancy during which time the woman’s body returns The red cell mass increases 20–40% whilst the plasma
to the pre-pregnant state. The physiology of the puerpe- volume increases 40–50%. The resultant physiological
rium is outlined below for the major body systems, with haemodilution produces a relative anaemia which is
content specific to the uterus and breasts covered later in thought to be beneficial for utero-placental perfusion.
the section on postnatal assessment and lactation. Our Venous haematocrit typically falls from a non-pregnant
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knowledge of the timing and completeness of the reversal value of 40% to 34% near term. The increase in blood
of the physiological adaptations in pregnancy is incom- volume is evident from seven weeks’ gestation and peaks
plete. Delivery of the placenta results in an abrupt at around 30–32 weeks’ gestation, normally remaining at