What are the guidelines for administering thoracic spinal anesthesia?

Guidelines for Thoracic Spinal Anesthesia

Primary Recommendation

Thoracic spinal anesthesia is a feasible and safe technique for select thoracic and upper abdominal procedures, particularly in elderly or high-risk patients who may benefit from avoiding general anesthesia, though it requires specific technical expertise and careful patient selection. 1, 2

Technical Approach and Drug Selection

Needle Selection and Technique

• Use pencil-point (atraumatic) spinal needles rather than cutting-bevel needles to minimize the risk of post-dural puncture headache 3
• Perform aspiration for cerebrospinal fluid before injecting any local anesthetic, both the original dose and all subsequent doses, though negative aspiration does not guarantee against intravascular or subarachnoid misplacement 4
• Equipment, facilities, and support personnel must be immediately available to treat potential complications, comparable to those in the main operating suite 3

Local Anesthetic Dosing

• For thoracic puncture, use reduced doses of hyperbaric bupivacaine (7.5-10 mg) compared to lumbar puncture (15 mg) to achieve adequate sensory block with improved hemodynamic stability 5
• Hyperbaric 0.75% bupivacaine dissolved in dextrose or isobaric 0.5% bupivacaine dissolved in water are both acceptable options for thoracic-level procedures 1
• Add fentanyl 25 μg as an adjuvant to enhance analgesia and reduce local anesthetic requirements 5
• The total dose of local anesthetic is the most important determinant of both therapeutic and unwanted effects 6

Alternative Agents

• Levobupivacaine (the pure S(-)-enantiomer) and ropivacaine offer similar efficacy to bupivacaine with lower risk of cardiovascular and central nervous system toxicity 6, 7
• The 0.75% concentration of bupivacaine should be reserved for surgical procedures requiring high muscle relaxation and prolonged effect, and is contraindicated in obstetrical anesthesia 4

Hemodynamic Management

Hypotension Prevention

• Lower doses of local anesthetic (7.5-10 mg via thoracic puncture) reduce hypotension incidence by 52.2% compared to conventional lumbar doses (15 mg) 5
• Prepare volume expansion and vasoactive drugs immediately, as cardiovascular effects from sympathetic blockade are the most frequent complication 6
• Monitor for blockade of cardioaccelerator sympathetic fibers, which can cause significant hemodynamic instability 2

Contraindications with Vasopressors

• Do not use bupivacaine with epinephrine concomitantly with ergot-type oxytocic drugs due to risk of severe persistent hypertension 4
• Use extreme caution in patients receiving monoamine oxidase inhibitors or tricyclic/imipramine-type antidepressants, as severe prolonged hypertension may result 4

Block Characteristics and Duration

Sensory vs Motor Block

• Sensory block duration is approximately twice the motor block duration at all doses 5
• Time to reach T3 sensory level correlates with dose: 15 mg produces faster onset than 10 mg or 7.5 mg 5
• With low doses via thoracic puncture, 60% of patients can transfer from operating table to stretcher independently 5

Patient Selection and Indications

Appropriate Candidates

• Elderly patients with significant comorbidities (average age 82 years, ASA score 3.3 in case series) 1
• Patients requiring lower thoracic spine surgery (T11-T12, T12-L1 levels) 1
• Laparoscopic cholecystectomy with low-pressure pneumoperitoneum 5
• High-risk patients where avoiding general anesthesia complications is prioritized 2

Age Restrictions

• Bupivacaine administration is not recommended in pediatric patients younger than 12 years until further experience is gained 4

Safety Considerations and Complications

Critical Warnings

• Local anesthetics should only be employed by clinicians well-versed in diagnosis and management of dose-related toxicity and acute emergencies 4
• Delay in proper management of dose-related toxicity, underventilation, or altered sensitivity may lead to acidosis, cardiac arrest, and death 4
• The main concerns are iatrogenic spinal cord injury, cephalad spread causing complete spinal block, and hemodynamic instability 2

Methemoglobinemia Risk

• Monitor for methemoglobinemia, particularly in patients with glucose-6-phosphate dehydrogenase deficiency, congenital methemoglobinemia, cardiac/pulmonary compromise, or infants under 6 months 4
• Signs include cyanotic skin discoloration and abnormal blood coloration, which may occur immediately or hours after exposure 4
• Treatment includes discontinuing the anesthetic, oxygen therapy, and potentially methylene blue administration 4

Contraindicated Techniques

• Do not use bupivacaine for intravenous regional anesthesia (Bier Block) due to reports of cardiac arrest and death 4
• Do not use local anesthetic solutions containing antimicrobial preservatives (multiple-dose vials) for neuraxial anesthesia 4
• Avoid mixing or intercurrent use of different local anesthetics with bupivacaine due to insufficient safety data 4

Comparison with Alternative Regional Techniques

Thoracic Epidural vs Thoracic Spinal

• While thoracic epidural analgesia provides effective pain control for thoracic procedures, it requires higher patient monitoring compared to spinal blocks 8
• Thoracic epidural has higher failure rates (14.6% failure to identify epidural space) and increased hypotension risk compared to paravertebral blocks 8
• For single-procedure anesthesia rather than continuous postoperative analgesia, thoracic spinal offers practical advantages with single bolus dosing 8

Paravertebral Blocks

• Paravertebral blocks provide comparable analgesia to thoracic epidural with lower rates of urinary retention and hypotension 8
• The paralaminar approach for paravertebral blocks provides superior analgesia compared to intercostal approaches 3

Clinical Outcomes

Success Rates and Satisfaction

• All thoracic-level procedures in reported case series were completed successfully under spinal anesthesia 1, 5
• Patient satisfaction occurred in 99% of cases using thoracic spinal anesthesia for laparoscopic cholecystectomy 5
• The technique is feasible even in elderly patients with multiple comorbidities 1