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PIHPreeclampsia

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Pathogenesis. Etiology unknown. Related to degree of trophoblastic ... Pathogenesis. Occurs only in presence of placental issue. Strong genetic component ... – PowerPoint PPT presentation

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Title: PIHPreeclampsia

1
PIH/Preeclampsia

Jeff Katz, MD

2
Gestational Hypertension

Systolic gt 140 mmHg
Diastolic gt 90 mmHg
Occurs after 20 weeks in gestation
Returns to baseline postpartum

3
Preeclampsia

Gestational HTN Proteinuria
Occurs after 20 weeks in gestation
Returns to baseline postpartum
Dx
Pt was previously normotensive
BP gt 140/90 after 20 weeks
Proteinuria urinary excretion of gt 0.3 g of
protein in a 24 hr urine specimen

4
Preeclampsia

Scope of Problem
Hypertensive Disease
Occurs in 12-22 of pregnancies
Responsible for 17.6 of maternal deaths in USA
Preeclampsia
Approx. 5-8 of pregnancies
Primarily the 1st pregnancy (gt80)
Genetic disposition

5
Classification

Hypertensive Disorders
Gestational HTN
Preeclampsia mild and severe
Eclampsia
HELLP Syndrome Hemolysis, Elevated Liver
enzymes, Low Plts
Chronic HTN pre-pregnancy
Chronic HTN w/ superimposed gestational HTN
Superimposed preecampsia
Superimposed eclampsia

6
Pathogenesis

Etiology unknown
Related to degree of trophoblastic invasion by
the placenta
In preeclampsia, the invasion is incomplete
Severity of invasion may be related to degree of
invasion
Associated with alterations in immune response

7
Pathogenesis

Occurs only in presence of placental issue
Strong genetic component
Associated with failure of 2nd trophoblastic
invasion (14-16 weeks)
Results in high resistance low-flow
uteroplacental circulation (ischemia)
Very complicated vascular active proteins
involved - PGs, TXs, Endothelin, Endothelium
derived relaxing factor
Plt dysfunction (aggregation)

8
Hypertensive Disease

Risks
Group 1 (Hypertensive dz)
Previous preeclampsia
Systolic HTN lt 20 wks gest
H/o chronic HTN
Family h/o previous PIH

9
Hypertensive Disease

Risks
Group 2 (Coexisting vascular and endothelial dz)
Chronic renal dz
Lupus erythematous
Protein S deficiency
Circulating anticardiolipin antibodies

10
Hypertensive Disease

Risks Group 3 (obstetric factors)

AA
Angiotensin gene T235
Nulliparity
gt 40 yrs old
H/o not smoking
Obesity
Inc trophoblastic mass

Large for gestational age
Diabetes
Erythroblastosis fetalis
Polyhydramnios (young primups)

11
Preeclampsia

Severe preeclampsia signs
BP gt 160 sys., gt 110 dias.
Proteinuria gt 5 gm in 24 hrs
Oliguria lt400 ml in 24 hrs
Cerebral/visual disturbances
Pulmonary edema (cyanosis)
Epigastric/RUQ pain
Impaired liver function, rupture
Thrombocytopenia
HELLP syndrome
IUGR, oligohydramnios

12
Preeclampsia - Pathophsiology

Cardiovascular
Blood Pressure
Labile
Hypersensitive to vasoactive hormones
? Sympathetic overactivity
Vascular spasm
Inc SVR
Sustained HTN

13
Preeclampsia - Pathophsiology

Cardiovascular
Blood Volume
Reduced 9-40 depending on severity
Behave as if vasoconstricted
HR, BP variability increased
Replace volume carefully be careful of
pulmonary edema
Hemodynamic change
Initially hyperdynamic, later dec CO w/ inc SVR
Great variation
CO/SVR change throughout pregnancy

14
Preeclampsia - Pathophsiology

Cardiovascular
Cardiac function
Normal heart rate
Poor correlation b/w CVP PCWP
Variable
V. sensitive to rapid fluid bolus
Colloid oncotic pressure
Dec in nml pregnancy, more w/ preeclampsia
Drops from 22 mmHg to 17 mmHg in nml 22 to 14 in
PIH
Low COP, inc vasc permeability, and loss of fluid
protein into tissues makes edema likely

15
Preeclampsia - Pathophsiology

Hematological
Hypercoagulability
Accelerated PT increased common pathway
activity, inc activity of Factors II, V, X,
reduced fibrinogen
RBC membrane anomaly triggers thrombin
formation
Reduced Antithrombin III normally inhibits
coagulation factors

16
Preeclampsia - Pathophsiology

Hematological
Fibrinolysis
Variable opinions
Reduced fibrinolytic activity altered activity
b/w plasminogen activators and inhibitors adds to
presence of fibrin in renal and placental
vasculature
Higher Lipoprotein (a) concentration competes
with plasminogen for binding sites

17
Preeclampsia - Pathophsiology

Hematological
Platelet activation Thrombocytopenia
In 15-30 of PIH/eclampsia
lt 10 have PLT count lt 100,000
Marked daily variation
Prolonged bleeding time in some
Inc release of beta- thromboglobulin by PLTs
Shorter PLT production time
Appearance of megathrombocytes

18
Preeclampsia - Pathophsiology

Renal Function
Glomerulopathy
Glomerular enlargement w/ ischemia as a result of
swollen intracapillary cells
GFR 25 below nml gestational
Non-pregnant 122ml/min
Pregnant 170ml/min
Proteinuria
Inc permeability to large moleclar wt proteins
Amt of proteinuria correlates w/ histological
change and HTN

19
Preeclampsia - Pathophsiology

Renal Function
Glomerulopathy
Oliguria
Parallels severity of eclampsia lt400ml/24 hr
calls for intravascular fluid volume evaluation
Renal failure is rare, recovery is expected

20
Preeclampsia - Pathophsiology

Renal Function
Edema weight gain
Generalized edema is common
Important in airway mgmt difficult airway and
bleeding
Assoc w/ excessive wt gain through pregnancy
If severe PIH then pulmonary edema may follow

21
Preeclampsia - Pathophsiology

Respiratory
Pharyngolaryngeal edema
Airway narrowing
Fragile mucous membranes - bleeding
Pulmonary edema
More likely in severe PIH, or eclampsia
Occurs in 3 of cases
Occurred antepartum in 30 of cases
Occurred postpartum in 70 of cases

22
Preeclampsia - Pathophsiology

Hepatic Changes
Elevated transaminases
Subcostal/ RUQ pain caused by edema or bleeding
Subcapsular bleeding
Suspect w/ severe abd pain
Could also be parenchymal bleeding
If capsule disrupted intraperitoneal hemorrhage
surgical emergency

23
Preeclampsia - Pathophsiology

Neurological
HA, visual disturbances, CNS hyperexcitability,
hyperreflexia
Seizures eclampsia causes
Hypertensive encephalopathy
Loss of cerebral autoregulation
Vasospasm
Microinfarctions, punctate hemorrhages
Thrombosis
Cerebral edema

24
Preeclampsia - Pathophsiology

Uteroplacental perfusion
Decreased
Common in IUGR, oligohydramnios
High resistance low flow (nml is low resistance
high flow)
Fetus does not tolerate the hypotension assoc w/
regional anesthesia monitor FHR

25
Preeclampsia - Prevention

Aspirin prophylaxis
Based on reversing the PLT abnormalities
Increases PGI2 production, inhibits TXA2
synthesis
Use low doses 60 mg/day
Early studies encouraging
Later studies showed no benefit
Calcium prophylaxis
No benefit

26
Effect of Pregnancy on Preeclampsia

Only cure for PIH is to end pregnancy
Women w/ placenta previa at less risk for PIH
Placenta previa and PIH not mutually exclusive

27
Effect of Preeclampsia on Pregnancy

Position pt in lateral recumbent position to
maximize uteroplacental perfusion
Induce labor if
gt 37 wks
Fetal lungs are matue
Favorable cervix
Increasing BP despite tx

28
Drug Therapy

Magnesium Sulfate
Anticonvulsant of choice
Tocolytic
Loading dose 4-6 gm over 20 mins
Maint dose 1-2 gm/hr infusion
Therapeutic range 5-9 mg/dL
Monitor
Reflexes, UO, resp rate, muscle strength
If toxic
Discontinue, give Ca2, support ventilation

29
Drug Therapy

Magnesium Sulfate
Does not prolong nml/induced labor
Does not inc rate of C/S
Requires inc oxytocin for labor
Better results than phenytoin, diazepam

30
Drug Therapy

Antihypertensives
Methyldopa choice of OBs
Parenteral drugs if severe or acute
No adverse effect on uteroplacental perfusion,
fetal circulation
Do not defer or prevent PIH, IUGR, or perinatal
death

31
Drug Therapy

Antihypertensives
Hydralazine
Used for acute control IV
5 mg IV Q 20 mins w/ a max of 20 mg
Side effects tachycardia (inc SV, CO), HA,
nausea, hypotension
Labetalol
Combined alpha and beta
Ratio of 17 if given IV
Initial dose 10-20 mg IV. Can double dose every
10 mins if necessary max 300mg
Reduces BP, SVR, slows HR.

32
Drug Therapy

Antihypertensives
Nitroglycerine
Relaxes smooth muscle
Venous gt Arterial
Reduces preload gt afterload
Always expand volume before using because of
sudden drop
Dilute to 50 mg/ 500 ml (100 mcg/ml)
Initial dose 0.5-1 mcg/kg/min
Increase by 0.5 mcg/kg/min until satisfactory

33
Drug Therapy

Antihypertensives
Sodium nitroprusside
Arterial dilator reduces afterload
Less preload reduction
Crosses placenta could cause fetal cyanide
toxicity
Initial dose 0.5 mcg/kg/min
Toxicity seen if dose gt 4 mcg/min

34
Drug Therapy

Antihypertensives
Nifedipine
Calcium channel blocker
Effects mainly arterial smooth muscle
10 mg sublingual, repeat in 30 mins
10-20 mg Q 3-6 hrs
Could see exaggerated response w/ MgSO4
Facial fkushing, HA, tachycardia

35
Oliguria

lt 30 ml/hr for 3 hrs
Confirm Foley location
300-500 ml fluid challenge
If still a problem, insert a CVP
If CVP low, give fluids. If OK, give
nitroglycerine to dilate renal artery
CVP does not mirror PCWP in severe PIH
Can push PCWP to 12-14 mmHg

36
HELLP Syndrome

Hemolysis, Elevated Liver Enzymes, Low Platelets
and PIH
Differential Dx
Hepatitis, gallbladder dz, acute fatty liver of
pregnancy, thrombocytopenic purpura (TTP)
Etiology unknown
20 present postpartum, the rest preterm
Peak is 24-48 hrs postpartum
Initial c/o RUQ pain
50 have NV
80 have PIH before dx

37
HELLP Syndrome

Complications
DIC
Placental abruption
Need for blood transfusion
Pleural effusion
Acute renal failure
Wound infection
If develops postpartum there is a higher
incidence of pulmonary edema and renal failure

38
HELLP Syndrome