Page 743 - ACCCN's Critical Care Nursing

720 S P E C I A LT Y P R A C T I C E I N C R I T I C A L C A R E

Prevention of eclampsia
Magnesium sulphate has received the most attention as BOX 26.3 Management of women with
an anticonvulsant in preeclampsia, with its mechanism HELLP syndrome using steroids
of action thought to be connected to the release of pros-
tacyclin from the endothelium, reversing the vasocon- The use of steroids has been evaluated in the management
striction that is the basis of the disease. 80,81 Magnesium is of HELLP syndrome in the belief that steroids may mitigate
the anticonvulsant of choice to reduce the incidence of the severity of the disease. However, a Cochrane Review con-
eclampsia. 82,83 A common magnesium regimen is: 68,82 cluded that there was insufficient evidence to determine
whether steroid use as a treatment for HELLP syndrome had
l 4g IV loading dose given over 15–20 minutes a favourable outcome for mothers and babies, although
l an ongoing infusion of 1 g/hr steroids may be beneficial if an increase in platelet count was
l an additional 2–4 g IV loading dose should be admin- imperative. 88
istered over 10 minutes to treat a recurrent eclamptic
seizure
l continue infusion until 24 hours following delivery or
24 hours following the last eclamptic fit; whichever
occurs the later. preeclampsia, to optimise plasma volume and organ per-
87
fusion without the development of pulmonary oedema.
The optimal therapeutic level of magnesium required to Central venous pressure is universally accepted as unhelp-
reduce the risk of fitting is not well understood and many ful to guide fluid management in preeclampsia. See also
advocate against the need to monitor serum magnesium Box 26.3.
levels on the basis that clinical assessment of deep tendon
reflexes, urine output and respiratory rate is adequate to Thrombophylaxis
identify potentially toxic magnesium levels, 68,82 although
evidence is inconsistent. Other opinions suggests a thera- Preeclampsia is an independent risk factor for thrombo-
peutic serum magnesium level of 2 mmol/L but there is embolic disease and when combined with prolonged bed
no rationale provided for this level. 84 rest, as may occur with caesarean section, ICU admission,
obesity and age ≥35 years, due consideration must be
Control hypertension made on the need for thrombophylaxis (in the absence
Obtaining control of high blood pressure remains a pri- of any contraindications). Thus women with severe pre-
ority not only to improve organ perfusion but to mini- eclampsia admitted to ICU may meet the requirements
mise the risk of cerebral haemorrhage, a well-demonstrated for treatment with compression stockings and low mole-
30
24
hazard of hypertension in preeclampsia. Both systolic cular weight heparin for a minimum of 7 days.
and diastolic pressures are important and care should be
taken to ensure a controlled lowering of blood pressure, Betamethasone
as a rapid drop can compromise fetal wellbeing. There is Women in late pregnancy with severe preeclampsia diag-
no evidence for the superiority of any specific antihyper- nosed prior to 34 weeks’ gestation are normally pre-
tensive, although there is some evidence that diazoxide scribed a single dose of betamethasone (11.4 mg IM), to
may result in a potentially-harmful rapid drop in the promote fetal lung maturity and surfactant production. A
woman’s blood pressure, and that ketanserin may not be Cochrane Review has shown that treatment with antena-
83
as effective as hydralazine. Intravenous hydralazine is tal corti costeroids reduces the risk of neonatal death,
the most common drug used to treat very high blood respiratory distress syndrome, cerebroventricular haem-
pressure with IV labetalol increasingly being used. Severe orrhage, necrotising enterocolitis, infectious morbidity,
hypertension may be treated with IV GTN or nitroprus- need for respiratory support and neonatal intensive care
side. The target blood pressure is not well described, other unit admission, with no adverse effects on the mother. 89
than to avoid precipitous drops in BP and to maintain
adequate placental perfusion. Research has used a target Optimal timing of delivery
diastolic BP of 85–95 mmHg. 85 Women with severe preeclampsia can only be definitively
cured by delivery, no matter what the gestation. A number
Optimal fluid management of studies have trialled ‘temporising treatments’, aimed at
Despite being hypertensive, preeclamptic women are prolonging the pregnancy especially when a woman
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usually plasma-volume depleted. In the past, intrave- develops early onset severe preeclampsia (<34 weeks’ ges-
nous fluid was administered in an attempt to restore the tation). Whilst some have found that treatment with
deficit, with no advantage noted between colloids and vasodilators and fluid administration prolongs pregnancy
crystalloids. More recently, there has been a move towards with no adverse effect, the general belief is that prolong-
more conservative plasma volume expansion due to the ing the pregnancy is associated with an increased chance
risk of pulmonary oedema. In reviews of maternal deaths of the maternal complications of preeclampsia, such as
associated with preeclampsia, it was noticed that some eclampsia, pulmonary oedema and cerebral haemor-
women were dying from complications of fluid overload. rhage. 68,90 Consequently, a woman with severe preeclamp-
Careful titration of intravenous fluid is required with the sia is usually stabilised (magnesium sulphate commenced
use of pulmonary artery catheters advocated by some to and hypertension controlled) and arrangements for
guide the administration of fluid in women with severe delivery are made. Ideally, women <34 weeks’ gestation