What is the recommended dose of bupivacaine for spinal anesthesia in patients undergoing Lower Segment Caesarean Section (LSCS)?

Bupivacaine Dosage for Spinal Anesthesia in LSCS

For spinal anesthesia in patients undergoing Lower Segment Caesarean Section (LSCS), use 8-12 mg of hyperbaric bupivacaine 0.5%, with doses at the lower end of this range (8-10 mg) preferred to reduce hypotension while maintaining adequate surgical anesthesia. 1, 2

Standard Dosing Approach

The optimal dose range is 8-12 mg of hyperbaric bupivacaine 0.5%, which provides adequate surgical anesthesia while minimizing maternal hypotension 1. The ED95 (dose effective in 95% of patients) for caesarean delivery is approximately 10 mg bupivacaine, which falls within the range of both isobaric and hyperbaric formulations 1.

Evidence-Based Dosing Strategy:

• Doses <10 mg are associated with significantly less hypotension (62.9% vs 75.8% incidence) compared to doses ≥10 mg, with an adjusted odds ratio of 0.774 for hypotension 2
• The minimum effective dose is approximately 0.06 mg/cm of patient height (ED95), which translates to roughly 9-10 mg for average-height women 3
• Doses as low as 7.5-10 mg (based on height) have been successfully used with head-down tilt positioning, achieving T3 sensory level with only 4.5% hypotension incidence 4

Adjuvant Opioids for Dose Reduction

Adding intrathecal fentanyl allows for significant bupivacaine dose reduction while maintaining surgical anesthesia:

• Bupivacaine 5 mg + fentanyl 25 mcg provides adequate spinal anesthesia with markedly reduced hypotension (31% vs 94%), less vasopressor requirements (2.8 mg vs 23.8 mg ephedrine), and less nausea (31% vs 69%) compared to 10 mg bupivacaine alone 5
• This low-dose combination achieves adequate surgical anesthesia in all patients despite lower sensory levels (T4.5 vs T3) and less motor block 5

Height-Based Dosing Considerations

For parturients of short stature (≤148 cm):

• Mean effective dose is 9.8 ± 1.0 mg for spinal anesthesia and 10.5 mg (IQR 9-10.9) for combined spinal-epidural 6
• Reduced dosing achieves adequate surgical levels without increased failure rates or high spinal blockade 6

Practical Dosing Algorithm

Follow this stepwise approach:

1. Standard patients (height 150-170 cm): Start with 8-10 mg hyperbaric bupivacaine 0.5% 2, 3
2. Add fentanyl 15-25 mcg to reduce bupivacaine requirements and improve anesthesia quality 5, 7
3. Short stature patients (<150 cm): Use 9-10 mg bupivacaine 6
4. Tall patients (>170 cm): May require up to 12 mg, but avoid exceeding this to minimize hypotension 2

Critical Safety Considerations

Common pitfalls to avoid:

• Doses ≥10 mg significantly increase hypotension risk without proportional improvement in block quality 2
• Hyperbaric solutions are preferred over isobaric as they produce more predictable spread with fewer high blocks 1, 7
• Position patient with left uterine displacement immediately after injection to prevent aortocaval compression 4
• All doses still carry hypotension risk—even low-dose techniques require vasopressor availability and close hemodynamic monitoring 2

Intrathecal Catheter Technique (After Inadvertent Dural Puncture)

If extending labor analgesia via intrathecal catheter for caesarean delivery:

• Use incremental dosing of 1.25-2.5 mg bupivacaine every 3 minutes until T4 sensory level is achieved 1, 7
• Total doses typically range 7.5-15 mg (mean 8.8-15 mg depending on patient response) 1, 7
• Initial bolus should not exceed 2.5 mg to minimize high block risk 1, 7
• Test dose should not exceed 10 mg bupivacaine equivalent to allow recognition of intrathecal placement while minimizing total spinal risk 1

FDA-Approved Dosing Parameters

According to FDA labeling:

• Epidural dosing for obstetrics: 0.5% and 0.25% concentrations only, with incremental doses of 3-5 mL (not exceeding 50-100 mg per interval) 8
• The 0.75% concentration is contraindicated for obstetrical anesthesia 8
• Maximum single dose experience is up to 225 mg with epinephrine or 175 mg without epinephrine, though spinal doses are far lower 8