Case 55 - pre-eclampsia Flashcards
What is classified as HTN during pregnancy? what is the difference betewen chronic htn, pre-eclampsia, eclampsia, gestational htn?
HTN
- systolic BP > 140
- diastolic BP > 90
chronic htn
- htn before 20 weeks
gestational htn
- htn manifests after 20 weeks with NO symptoms
pre-eclampsia
- htn manifests after 20 weeks + proteinuria
- mild vs severe pre-eclampsia
elcampsia
- pre-eclampsia + seizures
what is the difference between mild vs severe pre-eclampsia?
Mild pre-eclampsia
- systolic > 140 or diastolic > 90
- protienuria > 0.3 mg over 24 hours
severe pre-eclampsia
- systolic > 160 or diastolic > 110
- proteinuria > 5 g over 24 hours
- headache
- epigastric pain
- HELLP
- renal failure
- visual distubances
what is the pathophysiology behind pre-eclampsia?
- abnormal implantation of placenta
- leads to poor perfusion of uterus and placenta (uteroplacenta ischemia)
- uteroplacenta ischemia results in inappropriate release of vasoactive mediators
-
imbalance between thromboxane and prostacyclin balance
- increase thromobxane leads to vasoconstriction, platelet aggregration, and decrease uterine blood flow
what systemic changes occur with pre-eclampsia?
Overall
- pre-eclampsia assoc with systemic vasospasm
-
assoc with inc aldosterone
- sodium and water retention -> generalized edema
CNS
- cerebral edema, cerebral vasospasm
- seizures, blindness, n/v
- cerebral hemorrhage - leading cause of death in pre-eclamptic pts
Pulm
- difficult intubation 2/2 laryngeal and upper airway edema
- pulm edema -> pulm capillary leak -> A-a gradient
CVS
- HTN
- LVH - > diastolic dysfunction
- 3rd spacing -> relative hypovolemia
Renal
- decrease RBF and GFR
Hepatic System
- subscapsular hemorrhage
- vasospasm of hepatic A -> decrease liver flow -> abnormal LFTs
Heme
- HELLP
- thrombocytopenia
- DIC
uterolplacental
- IUGR
- placental abruption
- premature labor
what is managemnt of pre-eclampsia?
control disease, prevent progression to eclampsia
- bed rest
- Left uterine displacement
- coag studies, LFTs, Renal studies
- constant monitor of fetal and materal well being
-
admin MgSo4
- helps prevent eclampsia
- therapeutic 4-8 mEq/L
-
definitive tx = delivery of fetus
- do if fetal distress
- do if mom becomes eclamptic or worsening pre-eclampsia
Why is MgSo4 used in pre-eclampsia, what are other properties seen with MgSo4?
MgSo4
- first line therapy for prevention of eclampsia
Properties
- CNS depressant
- anticonvulsant
- Muscle relaxation via NMJ
- potentiates NMBDs
- inhibit AcH releaes
- decrease AcH receptor sensitivity at NMJ
- vasodilator -> hypotension
- uterine relaxation
- crosses placenta -> neonatal depression, apnea, dec muscle tone
- toxicity treated with Calcium
how much mgso4 do you give as loading dose, what infusion rate do you run, when do you see loss of DTR, resp arrest, cardiac arrest?
MgSo4 admin
- loading dose 2-4g over 15 min
- mainteance 1-3g /hr
-
monitor signs of toxicity:
- EKG changes (widened QRS, prolong PR)
- loss of DTR
Mg plasma levels and systemic effects (meq/l)
- therapeutic = 4-8
- EKG changes = 5-10
- Loss of DTR = 10
- Resp arrest = 15
- cardiac arrest = 25
why is it important to control HTN in pre-eclamptic patients? What is your BP goal? what agents will you use?
Cerebral Hemorrhage
- leading cause of death in pre-eclamptic pts
- CONTROL BP to prevent this
BP goal
- do not acutely decrease BP
- may decrease uteroplacental flow
- cerebral ischemia 2/2 right shift of autoreg curve
- tx to w/i 20% of baseline
Agents (acute vs non-acute control)
Non-acute control
- hydralazine - Most commonly used
- labetolol
- do not use in reactive airway dz
Acute Control
- SNP -
- risk of cyanide toxicity in neonate (SNP crosses placenta)
- NTG - minimal effects on fetus
what benefits will an epidural provide for pre-eclamptic patients? Prior to placing an epidural, what important things do you need to look for, specifically for pre-eclamptic patients?
epidural benefits for pre-eclamptic patients
- pain control
- reduce hyperventilation -> better uteroplacental blood flow
- decreaes catecholamine release -> better uteroplacental blood flow
- avoid need for general anesthesia
- avoid difficult intubation
- avoid risk of maternal aspiratoin
considerations for epidural placement & pre-eclampsia
assess following before epidural placement:
1) diastolic < 110 mm Hg
2) intravascular repeltion
- pre-eclamptic pts typically fluid-depleted (3rd spacing, proteinuria)
3) COAG STUDIES
- risk for DIC
- thrombocytopenia
- HELLP
what would be your anesthetic plan for a pre-eclamptic patient undergoing elective c/s and emergent c/s?
Elective C/S
- assuming coag studies normal & BP under control, neuraxial anesthesia = safest option
- avoid difficult intubation
- avoid maternal aspiratoin
- avoid BP increase with laryngoscopy -> risk of cerebral hemorrhage
Emergent C/S
- dose pre-existing epidural to surgical anes
- no epidural, then General Anesthesia
- less prepartory time
General Anes
-
Control BP before induction even if emergent c/s
- decrease symp stim with laryngoscopy -> risk of cerebral hemorrhage
- anes machine set up with emergent drugs, emergent airway equip, suction, various blades, handles, ETTs
- GET HELP!
-
RSI&I
- pre-oxygentate
- glidescope, suction, emergent meds on stand by
- cricoid pressure
do you stop MgSo4 after delivery of fetus to help with uterine relaxation, do you stop after completion of c/s?
MGSo4 should be continued for at least 24 hrs after surgery
patient still at risk for eclampsia post-partum