Subspecialty

Obstetric Anesthesia

Two patients, one anesthetic, zero margin.

OB anesthesia is high-volume, time-sensitive, and unforgiving. Maternal physiology (decreased FRC, increased oxygen consumption, aspiration risk, edematous airway) means failed intubation can become failed oxygenation within minutes.

Key concepts

Neuraxial analgesia for labor

Epidural with dilute LA + opioid (e.g., bupivacaine 0.0625–0.125% + fentanyl 2 mcg/mL). CSE for faster onset. Avoid dense motor block.

Spinal for C-section

Bupivacaine 0.75% hyperbaric 1.4–1.8 mL + fentanyl 10–15 mcg + morphine 100–200 mcg. Target sensory level T4 (cold) for visceral coverage.

Aortocaval compression

Left uterine displacement ≥15° after 20 weeks gestation — non-negotiable to maintain venous return.

Hypotension at C-section

Phenylephrine infusion (~25–50 mcg/min) titrated from spinal placement reduces nausea and fetal acidosis vs. ephedrine.

PPH

Quantify blood loss. Uterotonics: oxytocin → methergine (avoid HTN) → carboprost (avoid asthma) → misoprostol. Activate massive transfusion protocol early.

Monitoring

Non-invasive blood pressure (every 1–2 min after spinal)
Fetal heart tones
Pulse oximetry
Capnography

Common drugs

Bupivacaine (hyperbaric)FentanylMorphine (intrathecal)PhenylephrineOxytocinMethylergonovineCarboprostTranexamic acid

Clinical pearls

1Always have a difficult airway plan — the OB airway is the most feared.

2Failed intubation drill: maintain cricoid (or release if obstructing), bag-mask + LMA, wake or proceed per algorithm.

3Magnesium-treated preeclamptic patients — anticipate potentiation of NMBA.

References & Further Reading

1
Guideline
Kinsella SM, Carvalho B, Dyer RA, et al. International consensus statement on the management of hypotension with vasopressors during cesarean section under spinal anaesthesia. Anaesthesia. 2018;73(1):71-92.
2
GuidelineOpen source
American Society of Anesthesiologists. Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration. Anesthesiology. 2017;126(3):376-393.
3
Textbook
Gropper MA, Miller RD, Cohen NH, et al., eds. Miller's Anesthesia. 9th ed. Philadelphia: Elsevier; 2020.
4
Textbook
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC, Ortega R, Sharar SR, Holt NF. Clinical Anesthesia. 8th ed. Philadelphia: Wolters Kluwer; 2017.

Citations are provided to direct further study. Always check the most current edition of guidelines and society recommendations — the information in this chapter is a teaching summary, not primary source material.