Spinal anesthesia: bupivacaine compared with tetracaine

Area of Science:

• Anesthesiology
• Pharmacology

Background:

• Tetracaine (Pontocaine) is a commonly used local anesthetic for spinal anesthesia in the USA.
• Bupivacaine (Marcaine) is another local anesthetic with potential applications in spinal anesthesia.

Purpose of the Study:

• To compare the efficacy and safety of 0.75% bupivacaine in 8.25% dextrose with tetracaine for spinal anesthesia.
• To evaluate the impact of epinephrine on the duration of action and postoperative analgesia for both agents.

Main Methods:

• A randomized, double-blind study involving 435 patients undergoing spinal anesthesia.
• Standardized technique with two doses: 7.5 mg for lower extremity/perineal surgery and 12 mg for intra-abdominal gynecologic surgery.
• Comparison of anesthesia success rates, duration of motor blockade, and postoperative analgesia.

Main Results:

• With a 7.5-mg dose, bupivacaine resulted in only one unsatisfactory anesthesia case out of 121, versus 19 out of 114 for tetracaine.
• At the 12-mg dose, bupivacaine and tetracaine showed similar rates of unsatisfactory analgesia (12 vs. 14 patients).
• Motor blockade was significantly longer with tetracaine. Epinephrine prolonged the duration of action for both drugs, more so for tetracaine's postoperative analgesia.

Conclusions:

• 0.75% bupivacaine in 8.25% dextrose is a safe and reliable local anesthetic for spinal anesthesia.
• Bupivacaine demonstrates a significantly better success rate than tetracaine for lower dose spinal anesthesia.
• Epinephrine enhances the duration of action for both anesthetics, with a more pronounced effect on tetracaine's postoperative pain relief.