วันพุธที่ 22 เมษายน พ.ศ. 2569

Anesthesia for Cesarean Delivery (CD)

Anesthesia for Cesarean Delivery (CD)

🔹 1. Preoperative Assessment

  • Focused Hx + PE: airway assessment สำคัญมาก (pregnant = difficult airway risk )
  • Lab: individualized
    • Type & screen (high bleeding risk)
    • Hb, platelet, coagulation (specific indication)
  • High-risk antenatal anesthesia consult

🔹 2. Preparation

Aspiration prophylaxis

  • Pregnancy = aspiration risk
  • Elective: fasting ตาม guideline ปกติ
  • Urgent: ไม่ delay ให้ prophylaxis
    • nonparticulate antacid
    • H2 blocker
    • metoclopramide

Premedication

  • Avoid sedative (placental transfer + amnesia)
  • ถ้าจำเป็น midazolam low dose (1–2 mg IV)

Fetal monitoring

  • ตรวจ FHR ก่อน–หลัง neuraxial block

🔹 3. Choice of Anesthesia

First-line: Neuraxial anesthesia (>95%)

Types

  • Spinal
  • CSE (combined spinal-epidural)
  • Epidural

🔥 Indications for General Anesthesia (GA)

  • Emergency (no time)
  • Failed neuraxial
  • Contraindication (coagulopathy, infection, hypovolemia)
  • Massive hemorrhage / complex surgery
  • Maternal refusal

🔹 4. Neuraxial Anesthesia (Key Points)

🎯 Target level

  • Sensory level T4

📌 Spinal anesthesia (นิยมที่สุด)

  • Drug:
    • Bupivacaine (hyperbaric)
    • fentanyl 10–15 mcg intraop analgesia
    • morphine postop analgesia
  • Advantages:
    • rapid onset, reliable, low dose

📌 Epidural anesthesia

  • ใช้เมื่อมี labor epidural อยู่แล้ว
  • Drug:
    • Lidocaine 2% + epinephrine ± bicarbonate
    • หรือ chloroprocaine (emergency)
  • ต้อง titrate dose

📌 CSE (combined spinal-epidural anesthesia)

  • combine rapid onset + flexibility
  • ใช้ใน case prolonged surgery / high risk

🔹 5. Intraoperative Management

Position

  • Left uterine displacement (LUD) ลด aortocaval compression

Hemodynamic

  • Spinal hypotension common (sympathetic block)

🎯 Goal BP

  • Maintain within ±10–20% baseline

💊 Vasopressor (first-line)

  • Phenylephrine infusion
    • start 25–75 mcg/min
    • bolus 50–100 mcg PRN
  • Better than ephedrine ( fetal acidosis)

Fluid

  • Co-loading crystalloid 500–1000 mL

PONV prophylaxis

  • Ondansetron 4 mg IV

Oxytocin

  • Start infusion after delivery
  • Avoid rapid bolus hypotension risk

🔹 6. Complications

Hypotension

  • Most common
  • Manage: vasopressor + fluid

High spinal block

  • Symptoms: dyspnea, weak grip
  • Severe respiratory failure intubation

Inadequate block

  • ห้ามผ่าตัดถ้า block ไม่พอ
  • Options:
    • เติม epidural
    • convert GA

Pain during surgery (~15%)

  • Treat aggressively
  • escalate GA if needed

🔹 7. General Anesthesia (Key Clinical Points)

⚠️ Risks

  • Difficult airway
  • Awareness (สูงกว่า surgery ทั่วไป)

Induction

  • RSI (rapid sequence induction)
  • Drugs:
    • Propofol / etomidate
    • Ketamine (shock)

Maintenance

  • High volatile agent until delivery
  • หลัง delivery:
    • fentanyl + midazolam

🔹 8. Postoperative Analgesia

Multimodal (standard)

  • Neuraxial opioid (gold standard)
  • acetaminophen
  • NSAIDs
  • opioid systemic PRN

🔹 9. Key Takeaways (High-yield)

  • Neuraxial = first choice
  • Phenylephrine = vasopressor of choice
  • Target T4 block
  • Avoid hypotension fetal outcome
  • Never proceed surgery with inadequate block
  • GA reserved for emergency / contraindication

 

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