Fact file

Preeclampsia : Principles in Fluid management

Dr Ajay S Dhawle

Asst Professor JNMC

Sawangi (Meghe) Wardha

Understanding the Basics: Total Body Water

Forces important in balancing the fluid distribution:

• Hydrostatic pressure: Difference between the pressure at the arteriolar end and the venular end of a capillary

• Colloid osmotic pressure: Pressure exerted by the intravascular proteins which retains fluid inside

• Capillary permeability

• Interstitial lymphatic drainage:

8

12

8-10

26

24

26-28

66

64

64

0% 20% 40% 60% 80% 100%

Non Pregnant

Pregnant

Pre eclampsia Intravascular Compartment

Interstitial Compartment

Intracellular Compartment

Parameter Non pregnant Pregnant Preeclampsia

SVR (dyne/cm/sec) 1530 ± 520 1210 ± 266 (-21%)

Colloid osmotic pressure

20.8 ± 1.0 18.0 ± 1.5 (-14%)

Capillary permeability

-

Why?

Forced Diuresis

Renal Protection Lung protection

‘DRY’ management

The Forced Diuresis theory

• Preeclampsia -decreased intravascular volume

• Renal dysfunction is a norm rather than an exception

• Oliguria -common feature & marker of renal function

• It is tempting to ‘fill up’ the intravascular space with a fluid challenge and/ or use diuretics to force the urine out.

TrienniumDeaths

ICH Pulmonary

1982-84 13 03

1985-87 11 10

1988-90 12 10

1991- 93 05 11

1994-96 04 08

1997-99 07 02

2000-02 09 01

• Tried in the Uk in the late eighties and early nineties

• CEMACH Report 1991-93: Pulmonary complications outstripped the deaths from ICH in a ratio of 2:1

• Swing towards ‘fluid restriction’: Pulmonary deaths

What we now know:

• Though renal dysfunction is ubiquitous, renal failure is uncommon

• Recovery rates in short to medium term : very High

• No residual impairment

• Oliguria does not necessarily indicate fluid depletion

Renal Failure is a significant threat

only if preeclampsia is associated with

Abruptio, HELLP, IUD & DIC

Some facts :

• Pulmonary edema : ~ 2.9% of patients with severe preeclampsia

• Preeclampsia is the admitting diagnosis in 18–28% of pregnant patients presenting with pulmonary edema

• Preeclampsia associated with pulmonary edema: significant maternal (11%) and perinatal (9– 23%) mortality rates

• 70 % of the cases occurred postpartum, 72 hours after delivery

• Pulmonary edema usually occurs as a part of multi- system disorder rather than an isolated complication.

Fluid management in preeclampsia

• Strict monitoring of the Input- output status• Renal function test• Most patients DO NOT require ICU care

or invasive monitoring• Restrict fluids- approx 80ml/hour

- 1 ml/kg/hour• Use pediatric microdrip sets

(at 64drops/min, deliver 60ml/hr) in the absence of infusion pumps

• Oxytocin: ADH properties- fluid retention Use concentrated infusion drip (infusion set/ micro drip set)

Preloading for spinal anaesthesia (SA)• Regional anesthesia : the method of choice for cesarean deliveries

due to its proven record of maternal and fetal safety (Hawkins JL, Koonin

LM, Palmer SK, et al. Anesthesia related deaths during obstetric delivery. Anesthesiology 1997;86:277–84)

• Preeclamptic women : depleted intravascular volume & decreased uteroplacental perfusion.

• SA: rapid sympathetic blockade and profound hypotension

• Additive hypotension : the vasodilatory actions of magnesium and the use of antihypertensives like labetalol

• Despite these concerns, recent evidence indicates that spinal

anesthesia may be safely used with no adverse maternal or fetal

sequelae (Hood D, Curry R. Spinal versus epidural anesthesia for cesarean section in severely

preeclamptic patients. Anesthesiology 1999;90:1276–82.)

Consensus:

• Patients with mild pre-eclampsia do not need any special monitoring and will tolerate prophylactic hydration.

• In most instances, patients with severe preeclampsia can be similarly managed, especially if the urine output is adequate.

Oliguria

• If the urine output is inadequate, a fluid challenge is done with 250 to 500 mL of crystalloid infused over 20 minutes.

• If the patient responds with an increase in urine output, additional fluid boluses may be given cautiously before the regional block.

• If there is no response to the initial fluid bolus, CVP or PCWP monitoring becomes necessary.

Invasive monitoring

CVP: measures the RA pressure

correlates with intravascular volume

PCWP: measures the LA pressure

correlates with diastolic filling(preload of the left heart)

or hydrostatic pressure in the pulmonary capillaries

The need for invasive monitoring of filling pressures is seen in very specific cases:

•Severe Oliguria, not responding to fluid challenge, Anuria, ARF•Uncontrolled HTN•Pulmonary edema

• Volume expansion to CVP of at least 6 to 8 mm Hg is generally considered to be safe and effective.

• However, the CVP–PCWP gradients in severe pre-eclampsia may be as high as 8 to10 mm Hg. (Therefore, a CVP of 8 mm Hg might

correspond to a PCWP as high as 18 mm Hg.) This results in volume overload and possibly pulmonary edema.

• In a study of 50 patients with pre-eclampsia, Wallenburg et al showed that none of the patients with a CVP of 4 mm Hg or less had PCWP values exceeding 12 mm Hg [52]. (Wallenburg

HCS. Hemodynamics in hypertensive pregnancy. In: Rubin PC, editor. Handbook of hypertension. The Netherlands: Elsevier; 1988. p. 66– 101)

• Therefore, if CVP alone is being monitored for fluid management, volume expansion to achieve a CVP of 4 mm Hg or less is sufficient [18].

Typical volemic effects of different intravenous fluids after 1 ltr infusion

Crystalloids/ Colloids

• Crystalloids: usually the first choice for preloading. In theory, volume expansion: further reduction the COP. therefore, it would be advantageous to use colloid for volume expansion.

• A review comparing albumin for volume expansion in NON pregnant women concluded: albumin increased the risk of death (Cochrane Injuries Group Albumin Reviewers. Human albumin administration in critically ill patients: systematic review of randomized controlled trials. BMJ 1998;317:235– 40.)

• Also, increased mortality was associated with the use of colloid for resuscitation when compared with crystalloid. (Alderson P, SchierhoutG, Roberts I, et al. Colloids versus crystalloids for fluid resusitation in critically ill patients. (Cochrane Review). In: The Cochrane Library, Oxford: Update Software. Issue 1, 2003.)

• At this time, there is insufficient evidence to choose colloid over crystalloid in patients with pre-eclampsia . (Bolte AC, Geijn HP, Dekker GA. Management and monitoring of severe pre-eclampsia. Eur J Obstet Gynaecol Reprod Biol 2001;96:8–20.)

• If large volumes of colloid are chosen for hydration, invasive monitoring of filling pressures is recommended

Summary: RCOG Guideline No 10 A

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