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Preeclampsia in the Parturient Implications in Anesthesia

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Preeclampsia in the Parturient Implications in Anesthesia Robyn C. Ward, CRNA, MS LCDR, NC, USN Naval Medical Center San Diego www.anaesthesia.co.in anaesthesia.co.in ... – PowerPoint PPT presentation

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Title: Preeclampsia in the Parturient Implications in Anesthesia


1
Preeclampsia in the ParturientImplications in
Anesthesia
  • Robyn C. Ward, CRNA, MS
  • LCDR, NC, USN
  • Naval Medical Center San Diego

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om
2
Objectives
  • Discuss preeclampsia risk factors,
    pathophysiology, obstetric/anesthetic management
  • Discuss eclampsia
  • Discuss HELLP syndrome

3
Introduction
  • Preeclampsia is a major cause of maternal and
    perinatal morbidity and mortality
  • Direct fetal effects
  • Indirect effects due to preterm deliveries
  • Affects 5 of all pregnancies
  • 35-300 deaths per 1000 births (twice that of
    normotensive pregnancies)

4
Classification 4 Categories
  • Gestational hypertension
  • Chronic hypertension
  • Chronic hypertension w/ superimposed preeclampsia
  • Preeclampsia mild, moderate, or severe

5
Gestational Hypertension
  • Transient HTN of BP gt 140/90 without proteinuria
    or end-organ damage
  • May occur late in pregnancy, during labor, or
    within 24 hrs postpartum
  • BP returns to normal within 10 days postpartum

6
Chronic Hypertension
  • Begins prior to pregnancy
  • BP gt 140/90
  • Occurs prior to 20th week gestation
  • Not associated with proteinuria or end-organ
    damage
  • Continues well after delivery

7
Preeclampsia Mild to Severe
  • Occurs after 20 weeks gestation
  • Triad
  • Hypertension
  • Proteinuria
  • Edema

8
Preeclampsia - Mild
  • Hypertension SBP gt 140 mm Hg, DBP gt 90 mm Hg
  • Proteinuria gt 300 mg/24 hr
  • Generalized edema

9
Preeclampsia - Severe
  • Hypertension SBP gt 160 mm Hg, DBP gt 110 mm Hg
  • Proteinuria gt 5 g in 24 hr
  • Generalized edema
  • Evidence of end-organ damage
  • Oliguria U/O lt 400 ml/24 hr and/or elevated
    serum creatinine
  • Cerebral edema w/ visual disturbances (blurred
    vision) or headache

10
Preeclampsia Severe (cont)
  • Evidence of end-organ damage (cont.)
  • Pulmonary edema
  • Hepatocellular dysfunction
  • Elevated liver enzymes
  • Epigastric or RUQ pain
  • HELLP syndrome
  • Intrauterine growth restriction or
    oligohydramnios

11
Risk Factors
  • Maternal Pre-existing Conditions
  • Maternal Specific Factors
  • Partner-Related Factors
  • Pregnancy-Associated Factors

12
Maternal Pre-existing Conditions
  • Chronic hypertension
  • Renal disease
  • Diabetes mellitus
  • Obesity

13
Maternal Specific Factors
  • Advance maternal age gt 40
  • Familial predisposition
  • Nulliparity and young age
  • History of preeclampsia

14
Partner-Related Factors
  • Paternal antigens
  • Immune maladaptation
  • Trophoblastic invasion at 12 weeks
  • Second invasion at 14-16 weeks changes spiral
    arteries from high to low resistance vessels
    prostacyclin and nitric oxide are released from
    endethelium
  • Second invasion fails in preeclampsia

15
Pregnancy-Associated Factors
  • Multiple gestation increased risk
  • Congenital anomalies
  • Antepartum urinary tract infection

16
Pathophysiology
  • Immunologic factors
  • Genetic factors
  • Endothelial factors
  • Platelet factors
  • Calcium

17
Immunologic Factors
  • Fifty percent genes from father
  • Fetal trophoblast invades maternal deciduas after
    implantation
  • Second trophoblastic invasion at 14-16 weeks
    normally disrupts maternal spiral arteries
    changing them to low resistance vessels
  • This 2nd wave of invasion fails in preeclampsia

18
Genetic Factors
  • Possibly recessive genetic inheritance
  • Variant angiotensinogen gene T 235 if
    homozygous, 20 fold increased risk for
    preeclampsia

19
Endothelial Factors
  • Vascular endothelial damage
  • Occurs in placental deciduas, renal
    microvasculature and, potentially, hepatic,
    myocardial and cerebral circulations
  • Failure of trophoblast invasion causes increases
    production of free radicals which exacerbate
    endothelial damage
  • Overall result is deficiency of prostacyclin
    (vasodilator) in relation to thromboxane
    (vasoconstrictor)

20
Platelet Factors
  • Surface mediated platelet activation occurs in
    absence of prostacyclin
  • Favors platelet adhesion to damaged surface
    lining of spiral arteries
  • Further platelet aggregation promoted by platelet
    release of dense granules, including TXA2 and 5HT

21
Platelet Factors (cont.)
  • Mild preeclampsia, 5HT binds to endothelial 5HT-1
    receptors
  • stimulates partial recovery of endothelial
    prostacyclin and nitric oxide release
  • Prostacyclin stimulates renin angiotensin
    aldosterone system, which improves placental
    perfusion by inducing maternal HTN

22
Platelet Factors (cont.)
  • Severe preeclampsia, serotonin cannot interact
    with 5HT-1 receptors on endothelium
  • Binds instead to 5HT-2 receptors on vascular
    smooth muscle cells and platelet membranes
  • Results in worsening HTN and intravascular
    thrombosis

23
Calcium
  • Calcium increases slowly throughout normal
    pregnancy to maintain vascular tone
  • In preeclampsia, this increase is much greater by
    3rd trimester due to increased cellular membrane
    permeability

24
Clinical Manifestations
  • Cardiovascular
  • Respiratory
  • Neurologic
  • Renal
  • Hematologic
  • Hepatic
  • Uteroplacental unit

25
Cardiovascular
  • HTN
  • Intravascular volume depletion
  • shift of intravascular fluid and protein to
    extravascular space due to decreased colloid
    oncotic pressure and increased capillary
    permeability (due to endothelial cell damage)

26
Respiratory
  • Upper AW narrowing from pharyngolaryngeal edema
  • difficulty in intubation
  • Pulmonary edema in 3 of cases
  • Increased capillary permeability
  • Decreased colloid oncotic pressure
  • LV dysfunction
  • Excessive fluid administration

27
Neurologic
  • Cerebral irritation due to CNS edema
  • Headache 40 of patients
  • Nausea, excitability, apprehension and visual
    disturbances (blurred vision)
  • Hyperreflexia/Clonus seizures if progresses to
    eclampsia
  • Intracranial hemorrhage is leading cause of
    maternal death from preeclampsia

28
Renal
  • Diminished renal perfusion and glomerular
    filtration
  • Proteinuria
  • Decreased uric acid clearance
  • Oliguria lt 400 ml/24 hrs
  • Elevated serum creatinine

29
Hematologic
  • Elevated Hct secondary to plasma volume
    contraction
  • Thrombocytopenia in 30 of patients
  • PLT lt 100K correlates with severe disease
  • Activation of coagulation cascade can occur
  • Increased incidence of placental abruption which
    can result in DIC

30
Hepatic
  • Impaired liver function can be caused by
  • Periportal hepatic necrosis
  • Subscapular hemorrhages
  • Fibrin deposition in hepatic sinusoids
  • Elevated liver enzymes (HELLP)

31
Uteroplacental Unit
  • Uteroplacental insufficiency due to increased
    vascular resistance, decreased plasma volume, and
    increased blood viscosity
  • Compromises uterine blood flow by 50-70

32
Treatment
  • Obstetric management
  • Adequate fetal surveillance
  • Antihypertensive management
  • Anticonvulsant therapy
  • Anesthetic management of labor
  • Safe analgesia for labor and anesthesia for
    delivery

33
Obstetric Management
  • Expectant management (lt 34 weeks)
  • Bed rest and sedation
  • Antihypertensive therapy
  • Monitoring of weight, U/O and DTRs
  • MgSO4 for seizure prophylaxis

34
Obstetric Management
  • Aggressive management
  • Induction of labor/delivery within 48-72 hours
  • Delivery is only curative treatment
  • If possible, time allowed for 2 doses of steroids
    to mother to promote fetal lung maturity
  • Indications for immediate delivery
  • Uncontrolled HTN gt 160/110
  • Oliguria/renal dysfunction
  • Liver dysfunction
  • Imminent eclampsia
  • Pulmonary edema
  • Fetal compromise

35
Fetal Surveillance
  • Fetal ultrasound
  • Continuous electronic fetal monitoring
  • Monitor for
  • Loss of beat-to-beat variability of FHR and
    periodic late decelerations

36
Antihypertensive Management
  • Goal control HTN and maintain uteroplacental
    perfusion
  • Acute therapy Long Term
  • Hydralazine Alpha methyl dopa
  • Labetalol (IV) Labetalol (po)
  • Nifedipine
  • Nitroglycerin
  • Nitroprusside

37
Anticonvulsant Therapy
  • MgSO4 first line agent in U.S.
  • Cerebral vasodilator
  • Central anticonvulsant effect
  • Peripheral vasodilator effect
  • Other
  • Phenytoin (Dilantin)
  • Diazepam

38
Magnesium
  • Dose
  • 4-6 g over 20 min w/ infusion of 1-2 g/hr
  • Therapeutic range 4-8 mg/dl
  • Side effects sedation, skeletal/muscle
    weakness, decreased uterine activity, decreased
    FHR variability, prolonged labor, uterine atony,
    prolongation of NM blockade, neonatal hypotonia

39
Magnesium (cont.)
  • Toxicity
  • 4-8 mg/dl therapeutic
  • 10-12 mg/dl loss of DTRs
  • 12-15 mg/dl respiratory arrest
  • 20-25 mg/dl cardiac arrest
  • Treatment
  • Calcium gluconate 10 ml of 10 solution IV over 2
    minutes
  • Oxygen
  • Mechanical ventilation if necessary

40
Anesthetic Management of Labor
  • Preanesthetic assessment
  • Airway
  • Aspiration prophylaxis
  • Auscultation of lungs
  • Fluid balance
  • Hemodynamic status
  • Left uterine displacement
  • Renal function
  • Coagulation status

41
Analgesia for Labor
  • Continuous lumbar epidural Advantages
  • Decreased circulating catecholamines
  • Decreased uterine vascular resistance
  • Improved uteroplacental blood flow
  • Avoids risk of general anesthesia

42
Epidural Placement
  • R/O coagulopathy, LUD, oxygen, continuous fetal
    monitoring
  • Careful crystalloid preload (250-500 ml)
  • Local anesthetic Bupivicaine (slow onset)
  • Epinephrine consider avoiding
  • Slow, incremental dosing
  • Ephedrine (in smaller doses) for hypotension lt
    20 of baseline

43
Anesthesia for Delivery
  • Non-emergent C-section
  • Epidural anesthesia thought to allow for
    incremental dosing, potentially avoiding
    precipitous hypotension
  • Spinal anesthesia recent retrospective study
    (Hood Curry, 1999) found no difference in
    hemodynamic changes after spinal or epidural
    anesthesia
  • Conclusion spinal is safe alternative to
    epidural w/ added advantage of quicker onset and
    better quality of sensory blockade especially in
    urgent situations

44
Anesthesia for Delivery
  • Emergent C-section
  • Epidural previously placed, well functioning
  • Spinal if no epidural placed and if FHR stable
  • General anesthesia
  • Coagulopathy
  • Patient refusal of regional
  • Fetal bradycardia prohibits placement in time

45
Eclampsia
  • Convulsions that occur during pregnancy in a
    woman whose condition also meets criteria for
    preeclampsia and who has no other previous
    neurologic disease or diagnosis of epilepsy
  • Etiology uncertain cerebral edema, ischemia
  • Tonic-clonic in nature
  • Life threatening emergency

46
Eclampsia (cont.)
  • 50 have evidence of severe preeclampsia
  • Classical presentation of preeclampsia may be
    absent or mildly abnormal in 30 of patients

47
Management of Eclampsia
  • Goals
  • Stabilization of the mother/seizure control
  • MgSO4 therapy 4-6 g over 20 min followed by
    infusion of 1-3 g/hr, OR
  • Thiopental or diazepam followed by MgSO4 infusion
  • Avoid anticonvulsant polypharmacy
  • Airway management
  • Avoiding aspiration

48
Obstetric Management of Eclampsia
  • Factors to consider patients condition,
    gestational age, cervical exam, and fetal well
    being
  • Induction of labor if patient is seizure free,
    stable, favorable cervix, and reassuring fetal
    heart tracing
  • Urgent c-section if patient continues to have
    breakthrough seizures

49
Anesthetic Management of Eclampsia
  • Aspiration precautions
  • Careful airway assessment
  • Guidelines for use of regional vs. general
    anesthesia similar to patients with severe
    preeclampsia

50
ABCs of Seizure Control
  • Airway
  • Breathing
  • Circulation
  • Drugs
  • Blood Pressure

51
HELLP Syndrome
  • Severe preeclampsia complicated by
  • Hemolysis
  • Elevated liver enzymes
  • Low platelets
  • First reported by Weinstein in 1982
  • Occurs in 12 of pregnancies complicated by
    preeclampsia or eclampsia

52
HELLP Syndrome
  • Clinical presentation (extremely variable)
  • RUQ or epigastric pain
  • N/V
  • Malaise
  • Headache, visual disturbances
  • Weight gain/edema

53
Differential Diagnosis of HELLP
  • Biliary colic, cholecystitis
  • Hepatitis
  • Gastroesophageal reflux
  • Gastroenteritis
  • Pancreatitis
  • Ureteral calculi or pyelonephritis
  • ITP or TTP

54
Laboratory Findings in HELLP
  • Hemolysis
  • Abnormal peripheral smear
  • Total bilirubin gt 1.2 mg/dl
  • LDH gt 600 IU/L
  • Liver Enzymes
  • AST (SGOT) gt 70 IU/L
  • Platelet count
  • lt 100,000

55
Management of HELLP Syndrome
  • Stabilize mother control BP, prevent seizures
  • Evaluate fetus
  • Determine optimal timing and route for delivery
  • Provide continued monitoring and management
    during postpartum period
  • All women should receive MgSO4

56
HELLP New Treatments
  • Dexamethasone 10 mg IV q12hr when platelets lt
    100,000
  • Platelets for active bleeding, or if lt 20,000
  • Plasmapheresis limited success, but not
    routinely recommended

57
HELLP Syndrome
  • Expeditious delivery usually warranted
  • Poor maternal and fetal outcome if delivery
    delayed
  • Infants gt 28 weeks gestation are routinely
    delivered 48 hrs after first maternal dose of
    dexamethasone
  • Diagnosis occasionally missed as some patients
    present without triad of preeclampsia

58
HELLP Syndrome (cont.)
  • Regional Anesthesia?
  • Platelet counts gt 80-100K usually safe to receive
    regional without risk of hematoma
  • If lt 70-80K, risks of hematoma vs risks of GA
    must be weighed
  • In presence of easy predicted AW, regional
    generally avoided
  • Presence of difficult AW, regional anesthesia may
    be considered after platelet transfusion prior to
    procedure

59
References
  • Chandrasekhar, Datta Anesthetic management of
    the preeclamptic parturient Current Reviews for
    Nurse Anesthetists 25(3) 25-40, 2002.
  • Gambling D, Writer D Hypertensive disorders in
    pregnancy. In Chestnut DH Obstetric
    Anesthesia, Principles and Practice (3rd ed).
    Mosby, 2004.
  • Hood D, Curry R Spinal versus epidural
    anesthesia for cesarean section in severely
    preeclamptic patients A retrospective survey.
    Anesthesiology 90 1276-1282, 1999.

www.anaesthesia.co.in anaesthesia.co.in_at_gmail.c
om
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