Pocket ObGyn – Eclampsia
See Abbreviations
Definition
- New onset seizures in a woman w/ preeclampsia, not attributable to other causes
Epidemiology
- Accounts for 12% of mat deaths, worldwide (developing countries > developed countries) (Semin Perinatol 2009;33:130). ~38% occur w/o preceding
- 2% mortality; 23% will require ventilation; 35% have 1 major complication (pulm edema, renal failure, respiratory distress syn, dissem intravascular coagulation, stroke, cardiac arrest, acute respiratory distress syn)
- Seizures occur in 2–3% of pts w/ sev preeclampsia not receiving magnesium ppx; incid 1.6–10 cases per 10000 deliveries
- Distribution by GA:
<20 w GA: Consider molar Preg or antiphospholipid Ab syn
Antepartum: 38–55%
Intrapartum: 13–16%
Up to 48-h PP: 5–39%
>48 h PP: 5–17%, think AVM, ruptured aneurysm, carotid artery dissection, or idiopathic sz d/o
Pathophysiology (Am J Obstet Gynecol 2004;190:714)
- Cerebral autoregulation in resp to high systemic BP ® vasospasm of cerebral arteries, intracellular edema
- Loss of autoregulation of cerebral bld flow in resp to high systemic BP ®
hyperperfusion, endothelial damage, extracellular edema
Clinical Manifestations (Obstet Gynecol 2011;118:995)
- HA – cerebral edema (sens to predict eclampsia 98 [95% CI 0.87–1]) (Acta Obstet Gynecol Scand 2011;90:564)
- Vision changes – vasospasm of cerebral & retinal vessels
- Neurologic sx – most common premonitory sx (rates vary from 50–90%)
- Full PIERS model – odds ratio of 2.92 for predicting adverse outcomes in preeclampsia; calculator at: cfri.ca/PIERSCalculatorH.aspx (Lancet 2011;377:219)
- Note: Presence of HTN & proteinuria are poor predictors of eclampsia, rare See also chaps. 11 and 12 for preeclampsia.
Treatment and Medication
- Drug of choice = magnesium sulfate (calcium channel antagonism) 4–6 g IV bolus then 1–2 g/h. If no IV ® 5 g IM in each buttock (10 g total; rpt 3 g alternating buttock q4h). If seizing on magnesium, rebolus 2 g Therapeutic level 4–6 mEq/L.
- 2nd line: Phenytoin: Loading dose by weight (<50 kg = 1000 mg; 50–70 kg = 1250 mg;
>70 kg = 1500 mg). Therapeutic level 12–20 mcg/mL. Check 2 h after loading ® subseq dose; if <10 mcg/mL ® 500 mg IV, if 10–12 mcg/mL ® 250 mg. check level q12h.
- 3rd line: Diazepam 5–10 mg IV bolus, rpt q10–15min prn, max 30 mg in 8 h
- Diazepam, phenytoin were a/w increased recurrence of seizures compared w/ magnesium sulfate (Br J Obstet Gynaecol 1998;105:300; N Engl J Med 1995;333)
- Fetal brady occurs during eclamptic Recover mom; no need for urgent CS
- MagPIE trial: International RCT, >10000 w/ at least mild preeclampsia randomized to magnesium sulfate or Magnesium sulfate decreases relative risk of eclampsia by 58% (95% CI 40–71). No documented adverse effects on mom or baby in short-term or long-term period (Lancet 2002;359:1877; British J Obstet Gynecol 2006;114:300)
| Magnesium toxicity (approx levels) | |||
| Serum magnesium level | |||
| mmol/L | mEq/L | mg/dL | |
| ¯ patellar reflexes | 4 | 8 | 10 |
| Respiratory depression | 6 | 12 | 14 |
| Altered cardiac conduction | >7.5 | >15 | >18 |
| Cardiac arrest | >12.5 | >25 | >30 |
| Magnesium toxicity: Treat by stopping MgSO4, give Calcium gluconate 1 g IV, maintain airway, intubation if needed. Can use diuretics to remove excess magnesium. | |||