Lecture on Thoracic Segmental Spinal Anesthesia (TSSA)

Thoracic Segmental Spinal Anesthesia (TSSA) Overview

• Thoracic level: ample space between posterior structures and spinal cord
• Thin and light nerve roots
• Low CSF volume, effective block with low drug dose
• Key distances between posterior structures and spinal cord measured in mm:
  • T2: 5.19mm
  • T5: 7.75mm
  • T10: 5.88mm
  • T6: 5.95mm (mid-thoracic)
• Technique requires 40-45 degree angulation
• More space at mid and upper thoracic levels
• Less risk of damaging spinal cord during TSSA

Needle Selection for Segmental Spinal Anesthesia

• Debate between pencil point and cutting needles:
  • Pencil point: orifice starts 0.8mm from tip, ends at 1.7mm
  • Cutting needle: CSF appears immediately
  • Pencil point causes more membrane damage
  • Cutting needle preferred, lower risk of neurological injury
• Size: 26 gauge cutting needle recommended
• Confidence with needle type is crucial

Technique Differences: Thoracic vs Lumbar Spinal Anesthesia

• Greater angulation needed in thoracic spine, prefer paramedian approach
• Midline approach less effective due to narrow interlaminar space
• Frequent checking for CSF necessary
• Drug spread and volume considerations
  • 1ml covers approximately 6 segments (3 up, 3 down)
  • Dosage varies with surgical site

Indications and Contraindications

• Indications:
  • High-risk cardiac and respiratory patients
  • Short procedures
  • Specific surgeries: breast surgery, laparoscopic cholecystectomy, colonic resection, nephrectomy, etc.
• Contraindications:
  • Severe hypovolemia
  • Neurological disorders
  • Long-duration surgeries (unless combined with catheter techniques)
  • Local infection, increased intracranial pressure

Advantages over General Anesthesia and Lumbar Spinal Anesthesia

• Hemodynamic stability
• Early recovery and ambulation
• Less risk of DVT and postoperative complications
• Ideal for day care surgeries

Adjuvants and Sedation

• Safe adjuvants: fentanyl, dexmedetomidine, clonidine, ketamine, midazolam
• Avoid drugs causing excessive respiratory depression or nausea
• Sedation can be used, especially in cases with OT distractions

Challenges and Management

• Shoulder pain during laparoscopic surgery:
  • Slow insufflation, low pressure
  • Local anesthetic infiltration
  • Sedation if necessary
• Monitoring CO2 levels during laparoscopic surgery
  • Use nasal prongs or ETCO2 monitoring devices
  • Manage subcutaneous emphysema if detected

Special Situations

• Pediatric practice: feasible with caution
• Full stomach patients: similar precautions as lumbar spinal
• Anticipated difficult airway: careful consideration required
• Intra-abdominal bleeding: stable hemodynamics crucial
• Antiplatelet/anticoagulant therapy: similar protocols as lumbar spinal
• Research: robust literature support and ethical considerations

Tips and Tricks

• Detailed pre-procedure planning
• Gentle needle advancement, frequent CSF checks
• Use preferred position (sitting or lateral)
• Backup plans for any complications
• Avoid excessive sedation, monitor for warning signs like paresthesia

Summary

• TSSA is an effective and safe technique with several advantages over conventional methods
• Requires meticulous planning and execution
• Suitable for a variety of surgeries, especially in high-risk patients
• Ongoing research and sharing of clinical experiences are crucial for wider adoption and standardization