Medical Archive

Introduction

General principles

Obstetrical Anesthesia Services

Analgesia and sedation during labor

Parenteral agents

Agent	Usual Dose	Frequency	Onset	Neonatal Half-Life
Meperidine	25–50 mg (IV)	Q 1–2 hr	5 min (IV)	?18–20 hr
	50–100 mg (IM)	Q 2–4 hr	30–45 min (IM)	?60 hr
Fentanyl	50–100 ?g (IV)	Q 1 hr	1 min	?5 hr
Morphine	2–5 mg (IV)	Q 4 hr	5 min (IV)	?7 hr
	10 mg (IM)		30–40 min (IM)

Nitrous oxide

Regional analgesia

Anesthetic agents

Central Nervous System Toxicity

Cardiovascular Toxicity

Management of Local Anesthetic Systemic Toxicity

Pudendal Block

Paracervical Block

Neuraxial analgesia

Spinal (Subarachnoid) Block

Spinal anesthesia – through the sacrospinous lig.

Labor pain (vaginal)	T10~L1
C-sec	~T4 (under xiphoid)
Perineal stretching	Pudental nerve – S2~S4
Absolute contraindications	Refractory ???, Coagulopathy, Infection, IICP

Epidural Analgesia

Continuous Lumbar Epidural Block

Technique

Complications

• Higher or total spinal blockade
  • When local anesthesia ascends toward the head. It may happen with intrathecal injection or overdose of the anesthetic.
  • Depressed cervical spinal cord and brainstem activity.
• Ineffective analgesia
• Hypotension
  • ~10%, when the sympathetic nerve fibers responsible for vascular tone are blocked. ? vasodilation & decreased venous return
  • It can be prevented by aggressive IV fluid volume expansion prior to epidural placement.
  • Treatment
    • Left uterine displacement to improve venous return
    • Additional IV fluid bolus, or vasopressor administration.
• Maternal fever
• Back pain
• Miscellaneous complications
  • Spinal/epidural hematoma
  • Epidural abscesses
  • Plastic epidural catheter can be sheared off

• Postdural puncture headache (PPH)
  • Positional (worse when upright, improves when supine), neck stiffness
  • Photophobia, diplopia, hearing loss, tinnitus
  • Correlates with the increased and decreased herniation/pressure on the brain, within 72 hours of the procedure.
  • Typically self-limited. Epidural blood patch

Effects on labor

• Fetal heart rate
• Cesarean delivery rates

Timing of epidural placement

Safety

Contraindications

• Thrombocytopenia
• Anticoagulation
• Severe preeclampsia-eclampsia

Combined Spinal–Epidural Analgesia

Continuous Spinal Analgesia During Labor

Local infiltration for cesarean delivery

General anesthesia

Patient Preparation

Induction and Intubation

Failed Intubation

Inhalational Anesthetics

Extubation

Aspiration

Postpartum analgesia