What are the guidelines for spinal anesthesia using bupivacaine at a concentration of 0.75%?

Guidelines for Spinal Anesthesia Using Bupivacaine 0.75%

For spinal anesthesia, bupivacaine 0.75% is not recommended due to safety concerns and the availability of safer alternatives such as 0.5% concentration, which provides adequate anesthesia with lower risk of complications. 1

Dosage Recommendations

• The FDA recommends using the smallest dosage and concentration of bupivacaine required to produce the desired result for spinal anesthesia 1
• General dosage guidelines for bupivacaine spinal anesthesia include:
  • 6 mg for vaginal delivery 1
  • 7.5 mg for lower extremity and perineal procedures 1
  • 12 mg for lower abdominal procedures 1
  • 7.5-10.5 mg for Cesarean section 1
• The 0.5% concentration is the FDA-approved concentration for spinal anesthesia, not 0.75% 1

Safety Considerations

• Bupivacaine is known to be more potently toxic than other local anesthetics, with complications including hypotension, arrhythmias, and cardiac and respiratory arrest 2
• The 0.75% concentration of bupivacaine has been associated with reports of cardiac arrest during use in obstetrical anesthesia 1
• Sympathetic blockade due to spinal anesthesia may result in peripheral vasodilation and hypotension, requiring frequent blood pressure monitoring 1
• The toxic effects of local anesthetics are additive, requiring monitoring for neurologic and cardiovascular effects when additional local anesthetics are administered 1

Patient-Specific Considerations

• Geriatric patients (65 years and older), particularly those with hypertension, may be at increased risk for developing hypotension while undergoing spinal anesthesia with bupivacaine 1
• Administration of bupivacaine spinal anesthesia in patients younger than 18 years is not recommended 1
• Patients with moderate to severe hepatic impairment require increased monitoring for bupivacaine systemic toxicity 1

Alternative Approaches

• Levobupivacaine 0.5% isobaric solution shows equally effective potency for spinal anesthesia compared to hyperbaric bupivacaine 0.5%, with similar onset time and duration of sensory blockade 3
• For procedures requiring longer duration of action, a mixture of isobaric bupivacaine 0.5% and hyperbaric mepivacaine 4% can provide quick onset and extended duration (approximately 130 minutes) 4
• Different volumes of hyperbaric 0.5% bupivacaine (1.5,2,3, and 4 ml) produce varying levels of blockade, with 3-4 ml providing satisfactory surgical anesthesia for transurethral resection 5

Regional Anesthetic Techniques

• For spine surgery, multimodal perioperative analgesia is recommended, which may include the use of local anesthetics such as bupivacaine 2
• For video-assisted thoracoscopic surgery (VATS), erector spinae plane block with 20 ml bupivacaine 5 mg/ml provides effective analgesia with reduced pain scores and opioid consumption during the first 24 hours postoperatively 6
• For shoulder procedures, continuous interscalene block with ropivacaine 0.2-0.3% is preferred over single-shot interscalene block due to longer duration of analgesia and reduced rebound pain 7

Common Pitfalls and Caveats

• Unintended intravascular injection may be associated with systemic toxicities, including CNS or cardiorespiratory depression and coma, progressing ultimately to respiratory arrest 1
• Aspirate for blood and cerebrospinal fluid prior to each dose to avoid unintended intravascular injection 1
• Spinal anesthetics should not be injected during uterine contractions because cerebrospinal fluid current may carry the drug further cephalad than desired, resulting in a high motor block 1
• The extent of analgesia with plain bupivacaine 0.5% can be poorly predictable, and even with low doses, unacceptably high levels of block may sometimes be achieved 8
• The maximum cephalad spread of hyperbaric bupivacaine is directly related to the logarithm of the volume of the local anesthetic solution 5