Obstetric Critical Care — Eclampsia, PPH, AFE

📘 1 · Obstetric Intensive Care · Washington Manual

Two Patients, Altered Physiology, a Time Limit

"The critically ill obstetric patient defies the usual rules: she is young and previously well, so her compensatory reserve masks deterioration until it is sudden and catastrophic; her physiology is remodelled by pregnancy, so 'normal' numbers may be abnormal and abnormal numbers ominous; and there are two patients, whose interests usually align but occasionally diverge. Above all, the single intervention that most often saves the mother — and sometimes the fetus — is delivery."

Adapted from Obstetric Intensive Care Manual, 5th Ed & the Washington Manual of Critical Care, 4th Ed.

Why she deteriorates late and fast

Increased blood volume and cardiac output mean a young mother can lose 1200–1500 mL before her BP falls — tachycardia and narrowing pulse pressure precede hypotension.
The gravid uterus compresses the IVC from ~20 weeks (or a fundus at/above the umbilicus), reducing venous return when supine — tilt her left.
The leading direct causes of maternal death worldwide and in India are haemorrhage, hypertensive disorders (eclampsia), and sepsis — with venous thromboembolism and amniotic fluid embolism close behind.

⚠️ "Treat the mother first" — the counter-intuitive truth

The best resuscitation for the fetus is a well-resuscitated mother. Give oxygen, fluids, blood, vasopressors, imaging with abdominal shielding and needed drugs to the mother without hesitation. Withholding maternal treatment out of misplaced fetal concern kills both. The exception during arrest: delivery of the fetus helps resuscitate the mother (relieves aortocaval compression).

📗 2 · Marino's The ICU Book, 5th Edition (2025)

How Pregnancy Remodels Physiology

"Pregnancy is a state of high-flow, low-resistance circulation, chronic respiratory alkalosis, dilutional anaemia and hypercoagulability. Every one of these adaptations changes the interpretation of a blood gas, a haemoglobin, a blood pressure and a D-dimer at the bedside. The intensivist who applies non-pregnant reference ranges will both over-treat the normal and under-treat the dangerous."

Marino PL. The ICU Book, 5th Ed. The Pregnant Patient. Wolters Kluwer; 2025.

🔬 How pre-eclampsia progresses to eclampsia & HELLP

TriggerAbnormal placentation — failed spiral-artery remodelling

Placental ischaemia → release of anti-angiogenic factors (sFlt-1 ↑, PlGF ↓)

Systemic endothelial dysfunction & vasospasm

Hypertension + proteinuria; cerebral vasospasm/oedema → seizure (eclampsia)

Microangiopathy → HELLP (haemolysis, ↑LFTs, low platelets), DIC, AKI

CureDelivery of the placenta — the only definitive treatment

📗 Marino — normal pregnancy values you must recalibrate to

Cardiovascular: CO ↑40–50%, HR ↑10–20 bpm, SVR ↓, BP falls mid-trimester. A "normal" BP may be relatively high; tachycardia is expected — so new hypotension is late and ominous.
Respiratory: minute ventilation ↑ → chronic respiratory alkalosis (PaCO₂ ~28–32 mmHg, HCO₃⁻ ~18–21). A "normal" PaCO₂ of 40 in a labouring woman signals impending respiratory failure. FRC falls and O₂ consumption rises → rapid desaturation on induction.
Haematological: plasma volume ↑ > red-cell mass → dilutional anaemia; physiological leucocytosis; hypercoagulable (↑ clotting factors, ↓ protein S) → VTE risk; D-dimer is unhelpful.
Renal: GFR ↑ → creatinine and urea run low (creatinine ~45–60 µmol/L); a "normal" creatinine may mean renal impairment.
Airway/GI: oedematous airway (use a smaller tube), delayed gastric emptying → high aspiration risk.

📗 Marino — aortocaval compression & arrest physiology

From the mid-second trimester the gravid uterus compresses the IVC and aorta when supine, dropping venous return and cardiac output. During CPR this means chest compressions are far less effective supine. Manual left uterine displacement (or left tilt) must be continuous, and if there is no ROSC, emptying the uterus by perimortem caesarean relieves the obstruction and can restore the mother's circulation.

📋 3 · NICE · ACOG · FOGSI · WOMAN Trial

The Big Four Obstetric Emergencies

Pre-eclampsia & eclampsia — magnesium is the drug Collaborative Eclampsia Trial · MAGPIE

Severe features: BP ≥160/110, symptoms (headache, visual disturbance, epigastric pain), thrombocytopenia, renal/hepatic impairment, pulmonary oedema.
Magnesium sulfate prevents (MAGPIE) and treats (Collaborative Eclampsia Trial — superior to diazepam/phenytoin) eclamptic seizures. Loading 4 g IV over 5–10 min, then 1 g/h infusion, continued 24 h after delivery or last seizure.
Control severe hypertension with IV labetalol, hydralazine, or oral nifedipine (target <160/110, avoid precipitous drops).
Definitive treatment is delivery — timing balances gestation against maternal risk. Magnesium is seizure prophylaxis/treatment, not an antihypertensive.

Postpartum haemorrhage (PPH) — the "4 Ts" + early TXA WOMAN Trial 2017

Causes: Tone (atony — commonest), Trauma, Tissue (retained products), Thrombin (coagulopathy).
Tranexamic acid 1 g IV within 3 hours of birth reduces death from bleeding (WOMAN trial) — give early.
Escalate: uterine massage + uterotonics (oxytocin → ergometrine → carboprost → misoprostol), balloon tamponade, examine for tears/retained tissue, activate massive transfusion (early fibrinogen/cryoprecipitate — aim fibrinogen >2 g/L in PPH), and surgical measures (B-Lynch, artery ligation, embolisation, hysterectomy).

Amniotic fluid embolism (AFE) — supportive & anticipate DIC

A rare, catastrophic anaphylactoid response to amniotic material: sudden hypoxia, cardiovascular collapse and coagulopathy around labour/delivery. It is a clinical diagnosis of exclusion. Management is supportive — high-quality resuscitation, oxygenation/ventilation, vasopressors and inotropes (RV support), and early, aggressive treatment of DIC with blood products (including fibrinogen). Consider ECMO in refractory cases. Perimortem caesarean if arrest.

Peripartum cardiomyopathy & the failing heart

New systolic heart failure (LVEF <45%) in late pregnancy to 5 months postpartum, without another cause. Treat as heart failure (careful diuresis, afterload reduction — avoid ACE inhibitors/ARBs antenatally, use hydralazine/nitrates), anticoagulate if LVEF very low, and consider bromocriptine in selected cases. Severe cases may need mechanical support/ECMO. Differentiate from pre-existing cardiac disease and pre-eclampsia-related pulmonary oedema.

🇮🇳 Indian Context

Haemorrhage and hypertensive disorders remain the leading direct causes of maternal death in India, alongside sepsis. Anaemia in pregnancy is highly prevalent, so women tolerate blood loss poorly and reach shock sooner — a low booking haemoglobin should heighten your PPH preparedness.

MgSO₄ regimens: both the Pritchard (IM) and Zuspan (IV) regimens are used where infusion pumps are limited; FOGSI endorses low-dose regimens in resource-limited settings. Monitor clinically (reflexes, respiratory rate, urine output) rather than relying on routine levels.

Sepsis: consider genital-tract sepsis, septic abortion, and (regionally) malaria, dengue and viral hepatitis (E) in the febrile or jaundiced pregnant patient.

💊 4 · Drug Doses

Drug Reference — Obstetric Emergencies

Drug	Indication	Dose	Notes
Magnesium sulfate	Eclampsia — treat/prevent seizures	4 g IV over 5–10 min → 1 g/h infusion; recurrent seizure: 2–4 g IV. Continue 24 h after delivery/last fit	Monitor reflexes, RR, urine output. Toxicity → calcium gluconate 1 g IV. Not an antihypertensive
Labetalol	Severe hypertension	20 mg IV → 40–80 mg every 10 min (max 300 mg) or infusion	Avoid in asthma/heart block; first-line IV
Hydralazine	Severe hypertension	5–10 mg IV every 20 min	Can cause reflex tachycardia/maternal hypotension → fetal distress
Nifedipine (oral)	Severe hypertension	10 mg PO, repeat per protocol	Do not use sublingual; oral immediate-release only
Tranexamic acid	PPH	1 g IV over 10 min within 3 h; repeat 1 g if bleeding continues	WOMAN trial — reduces death from bleeding; earlier is better
Oxytocin	Uterine atony (1st line)	Bolus (slow) + infusion per protocol	Rapid bolus → hypotension; titrate
Carboprost (15-methyl PGF₂α)	Atony refractory to oxytocin/ergometrine	250 µg IM, repeat every 15 min (max 8)	Contraindicated in asthma; causes bronchospasm
Ergometrine / carbetocin / misoprostol	Atony	Ergometrine 0.2–0.5 mg IM; misoprostol 800 µg PR/SL	Ergometrine avoided in hypertension/pre-eclampsia

🗺 5 · Clinical Flowchart

The Collapsing Obstetric Patient

Resuscitate the mother — with left uterine displacement

A–B–C; high-flow O₂ (desaturates fast); large-bore access above the diaphragm
Left lateral tilt / manual left uterine displacement if >20 weeks (relieve IVC compression)
Anticipate difficult airway + aspiration; RSI with cricoid, smaller tube

Identify the syndrome

Seizure + hypertension → eclampsia → magnesium
Bleeding → PPH → 4 Ts + TXA + uterotonics + MTP
Sudden hypoxia + collapse + DIC peripartum → AFE (supportive)
Breathlessness + failure signs → peripartum cardiomyopathy / pulmonary oedema

Deliver targeted treatment

Eclampsia: MgSO₄ load + infusion; control BP (labetalol/hydralazine/nifedipine); plan delivery
PPH: TXA within 3 h, uterotonics, balloon/surgery, early fibrinogen & MTP
AFE/PPCM: organ support, treat DIC, RV/LV support, consider ECMO

If cardiac arrest — the 4-minute rule

Standard ACLS plus continuous manual left uterine displacement and hands slightly higher on the sternum
If no ROSC and uterus at/above umbilicus: perimortem caesarean — aim to deliver within ~5 minutes of arrest (decision by ~4 min)
Give calcium if magnesium toxicity; treat reversible causes (H's & T's, plus AFE, eclampsia, haemorrhage, embolism)

Post-resuscitation & multidisciplinary care

Obstetrics, anaesthesia/intensive care, haematology, neonatology together
VTE prophylaxis once bleeding controlled (pregnancy is prothrombotic)
Continue MgSO₄ 24 h; monitor for HELLP progression, AKI, pulmonary oedema

⚠️ 6 · Common Mistakes

Common Mistakes in Obstetric Critical Care

❌ Mistake 1 — Under-resuscitating "to protect the fetus"

Oxygen, fluids, blood, vasopressors and necessary imaging/drugs go to the mother. A well-resuscitated mother is the best therapy for the fetus; withholding maternal treatment endangers both.

❌ Mistake 2 — Being reassured by a "normal" blood pressure or blood gas

A young mother maintains BP until she has lost a huge volume; a PaCO₂ of 40 in a labouring woman (whose normal is ~30) signals impending respiratory failure. Recalibrate to pregnancy reference ranges.

❌ Mistake 3 — Forgetting left uterine displacement

Resuscitating a >20-week patient supine leaves the IVC compressed and CPR ineffective. Tilt left or manually displace the uterus continuously.

❌ Mistake 4 — Treating eclampsia hypertension with magnesium (or seizures with lorazepam)

Magnesium is the anticonvulsant of choice (superior to diazepam/phenytoin) but does not control blood pressure — use labetalol/hydralazine/nifedipine for that. Don't confuse the two roles.

❌ Mistake 5 — Giving TXA and fibrinogen too late in PPH

TXA works best within 3 hours; fibrinogen falls early and predicts severity. Give TXA early and replace fibrinogen (cryoprecipitate/concentrate) aggressively — don't wait for it to bottom out.

❌ Mistake 6 — Delaying perimortem caesarean

In maternal arrest >20 weeks with no ROSC, delivery is part of maternal resuscitation. The decision should be made by ~4 minutes and delivery achieved by ~5 — waiting to "transfer to theatre" costs both lives.

❌ Mistake 7 — Missing magnesium toxicity

Loss of deep tendon reflexes → respiratory depression → cardiac arrest as levels rise, especially with renal impairment/oliguria. Monitor reflexes and urine output; treat toxicity with IV calcium gluconate.

🎓 7 · Exam Pearls — DrNB / PDCC / IFCCM / EDIC

Exam Pearls

Q: What is the drug of choice for eclamptic seizures, and its dose?
Magnesium sulfate — 4 g IV load then 1 g/h, continued 24 h after delivery/last seizure. Superior to diazepam and phenytoin (Collaborative Eclampsia Trial); MAGPIE showed prevention benefit.

Q: How is magnesium toxicity recognised and treated?
Progressive loss of deep tendon reflexes → respiratory depression → cardiac arrest. Monitor reflexes, RR, urine output. Treat with calcium gluconate 1 g IV and stop the infusion.

Q: What are the 4 Ts of PPH?
Tone (atony — commonest), Trauma, Tissue (retained products), Thrombin (coagulopathy).

Q: What did the WOMAN trial show?
Tranexamic acid 1 g IV given within 3 hours of birth reduces death due to bleeding in PPH, with no increase in thrombosis. Give it early.

Q: How does maternal CPR differ from standard ACLS?
Continuous manual left uterine displacement, access above the diaphragm, anticipate difficult airway/aspiration, and perimortem caesarean within ~5 minutes if no ROSC and uterus at/above the umbilicus.

Q: Why is a normal PaCO₂ concerning in a pregnant patient?
Pregnancy causes chronic respiratory alkalosis (PaCO₂ ~28–32). A "normal" 40 mmHg indicates CO₂ retention and impending respiratory failure.

Q: What is the triad of amniotic fluid embolism?
Sudden hypoxia, cardiovascular collapse, and coagulopathy (DIC) around labour/delivery — a clinical diagnosis of exclusion; management is supportive with aggressive DIC correction.

Q: Define peripartum cardiomyopathy.
New systolic heart failure (LVEF <45%) from the last month of pregnancy to 5 months postpartum, without another identifiable cause. Avoid ACE-I/ARB antenatally; consider bromocriptine in selected cases.

📚 8 · References

References

NICE. Hypertension in pregnancy: diagnosis and management. NICE Guideline NG133; 2019 (updated).
The Eclampsia Trial Collaborative Group. Which anticonvulsant for women with eclampsia? Evidence from the Collaborative Eclampsia Trial. Lancet. 1995;345:1455–1463.
Altman D, Carroli G, Duley L, et al. (MAGPIE). Do women with pre-eclampsia, and their babies, benefit from magnesium sulphate? Lancet. 2002;359:1877–1890.
WOMAN Trial Collaborators. Effect of early tranexamic acid administration on mortality in postpartum haemorrhage. Lancet. 2017;389:2105–2116.
ACOG. Practice Bulletin 222: Gestational Hypertension and Preeclampsia; Practice Bulletin 183: Postpartum Hemorrhage.
Jeejeebhoy FM, Zelop CM, Lipman S, et al. (AHA). Cardiac Arrest in Pregnancy: A Scientific Statement from the American Heart Association. Circulation. 2015;132:1747–1773.
FOGSI. Good Clinical Practice Recommendations on Eclampsia and Postpartum Haemorrhage. Federation of Obstetric and Gynaecological Societies of India.
Marino PL. Marino's The ICU Book, 5th Edition. The Pregnant Patient. Philadelphia, PA: Wolters Kluwer; 2025.