18.2 Obstetric Pharmacology, Delivery, and Postpartum Care
Key Takeaways
- Magnesium toxicity announces itself as lost reflexes then respiratory depression; stop the infusion and give calcium.
- ACOG-style acute antihypertensives in pregnancy are labetalol, hydralazine, and nifedipine; ACE inhibitors, ARBs, and warfarin on the sending list are why you read the medication reconciliation.
- Do not try to stop a crowning baby; prepare for delivery, reduce or clamp-and-cut a nuchal cord, use McRoberts and suprapubic pressure for shoulders, and keep hands off a breech until the scapulae.
- Newborn first actions are warm, dry, stimulate, then positive-pressure ventilation; the cabin will steal heat faster than any other insult.
- Postpartum hemorrhage is fundal massage, uterotonics, tranexamic acid per protocol, and a balloon only if you are trained; do not pull an inverted uterus by the cord.
A crowning infant does not wait for a lower cabin. Domain 5.A of the August 2026 Board of Certification for Emergency Nursing (BCEN) Certified Flight Registered Nurse (CFRN) outline still owns pharmacological care, delivery, and post-partum problems after you have named the medical and trauma diagnoses in 18.1. Drug names below are typical critical-care and American College of Obstetricians and Gynecologists (ACOG)-style teaching. BCEN does not publish a dose table.
Magnesium, calcium, and blood pressure drugs
Magnesium sulfate is the eclampsia and severe-preeclampsia seizure drug. Toxicity is a staircase: first loss of deep-tendon reflexes, then respiratory depression, then cardiac conduction failure. Check reflexes and respiratory rate on every cabin reassessment. If she is areflexic or hypoventilating, stop the infusion and give calcium—calcium gluconate on most obstetric protocols; some racks use calcium chloride through a reliable large line. Do not "catch up" a missed bolus after she has stopped breathing.
Severe-range blood pressure still needs treatment so she does not stroke in cruise. ACOG-style first-line acute agents are labetalol, hydralazine, and immediate-release nifedipine. Labetalol is a poor solo plan in asthma or decompensated heart failure. Hydralazine can cause reflex tachycardia. Nifedipine is oral; a vomiting eclamptic does not absorb it.
Read the sending medication reconciliation. Angiotensin-converting enzyme inhibitors (ACEIs), angiotensin-receptor blockers (ARBs), and warfarin are classic fetal-harm drugs. An ACEI infusion or a warfarin bridge copied onto the transport sheet is why sending meds matter. You are the last person who can stop a teratogenic drip before climb.
Oxytocin, TXA, and postpartum hemorrhage
After the placenta delivers, oxytocin is the first-line uterotonic for postpartum hemorrhage (PPH). Run it as an infusion. A slammed concentrated intravenous bolus can drop blood pressure. Tranexamic acid (TXA) is used in many PPH bundles when given early. Label that as protocol teaching, not a BCEN number.
PPH is still uterine atony until you prove otherwise:
- Fundal massage—a real two-handed massage, not a polite pat through the blanket.
- Empty the bladder if it is lifting the fundus.
- Oxytocin, then the next uterotonic your program carries.
- TXA if protocol.
- A uterine balloon (Bakri-type) if you are trained and privileged to place it.
- Blood early if she is emptying the tank (Chapter 8).
Uterine inversion is shock plus a mass at the introitus and a fundus you cannot find. Do not pull on the cord to hurry the placenta. If inversion is immediate and you are trained, attempt replacement before the cervix contracts; leave an attached placenta attached. If it is late, she is shocked, or you are not trained, stop pulling, resuscitate, and fly to an operating room.
| Drug or action | Transport job | Toxicity or trap |
|---|---|---|
| Magnesium sulfate | Seizure control | Lost reflexes, then hypoventilation; give calcium |
| Labetalol / hydralazine / nifedipine | ACOG-style acute severe hypertension | Wrong drug for the comorbidity |
| Oxytocin | Tone after the placenta | Bolus hypotension; atony if the drip is clamped |
| TXA | Early PPH antifibrinolysis if protocol | Waiting until she has already exsanguinated |
| ACEI / ARB / warfarin on the rec | Stop or do not start | Fetal renal and teratogenic harm |
Imminent delivery: do not hold the head in
If the infant is crowning, you are delivering. Do not clamp the mother's knees. Do not ask the pilot to hold a high hover until the pad. Boyle's law expands maternal gut gas and makes the cabin smaller; it does not reverse labor, and a higher cabin will not buy time. Precipitous delivery at altitude is a space, heat, and airway problem. Open the obstetric kit before the head is out.
Vertex, nuchal, shoulder, breech
- Control the head and check for a nuchal cord. A loose cord reduces over the head. A tight cord that will not reduce is clamped and cut.
- If the head is out and the body will not follow, think shoulder dystocia: McRoberts (hyperflex the maternal hips) and suprapubic—not fundal—pressure.
- If a breech presents, hands off until the scapulae are visible. Do not pull. Support the body and use a familiar head maneuver only if you are trained.
Have clamps, a bulb, and a bag-mask that fits a neonate. The cabin is a wind tunnel. A wet newborn will be hypothermic before the next radio call.
Neonatal first minute and the altitude cabin
Start neonatal resuscitation the same way you would on the ground: warm, dry, stimulate. If the infant is apneic or the heart rate is under 100 after stimulation, begin positive-pressure ventilation (PPV). Compressions follow only after effective ventilation if the heart rate stays under 60. You do not need a full Neonatal Resuscitation Program (NRP) cart to start those actions. You do need heat.
Boyle's law still works on the mother's stomach and on a bagged neonate. Expanding gut gas can make her vomit; protect her airway. If you bag the infant, watch the belly—overdistention steals venous return. If she delivered and then bleeds, assign tasks out loud: one clinician owns the infant's heat and PPV; one owns the fundus and the mother's blood pressure.
An eclamptic patient on a magnesium infusion loses her deep-tendon reflexes and her respiratory rate falls to 8 in cruise. What is the correct next action?
At 3,000 feet cabin altitude a multiparous patient begins to crown. What is the correct action?
After a cabin delivery the fundus is boggy and the mother soaks two pads in minutes. What is the best first bundle?