Does Spinal Tetracaine as Part of a Combined Spinal Epidural Technique Enhance Labor Analgesia Compared to Bupivacaine ?
Abstract Number: 88
Abstract Type: Original Research
Introduction: Combined spinal epidural labor analgesia (CSE) with bupivacaine, fentanyl, and epinephrine is a common and popular technique for providing rapid relief of labor pain with minimal motor blockade. However, duration of spinal analgesia with a traditional CSE technique is often limited to less than 1-2 hours. The goal of this study was to determine if tetracaine, fentanyl and epinephrine versus an equivalent dose of bupivicaine, fentanyl and epinephrine would maximize duration of spinal analgesia.
Methods: Following IRB approval and written informed consent, 37 out of a planned 60 healthy parturients in active labor were randomized into one of two groups receiving CSE labor analgesia. Group one received spinal bupivicaine 2 mg, fentanyl 20 mcg and epinephrine 50 mcg as part of a CSE technique, while group two received spinal tetracaine 2 mg, fentanyl 20 mcg and epinephrine 50 mcg. After spinal injection, the epidural catheter was placed, but left untested. A continuous epidural infusion was withheld until additional analgesia was requested. The primary outcome was total duration, defined as time from spinal injection to time of request for additional analgesia. Secondary outcomes included time from onset of analgesia (VAS<=3) to time of request for additional analgesia, highest level of sensory blockade, and degree of lower extremity motor blockade. The priori power analysis suggested 28/gp is needed (power=0.80 & α=0.05) to detect a 25% difference in analgesic duration.
Results: Our interim data had 37 evaluable subjects. All the demographics and patient parameters were similar between groups (P>0.05). Duration of spinal analgesia was similar between groups, but measured Bromage scores demonstrated greater motor block in the tetracaine group (P<0.047). There was no significant difference in duration of analgesia between groups, but there was greater variability and range in duration of analgesia with tetracaine.
Conclusion: To our knowledge, this is the first study to examine the use of tetracaine for CSE analgesia in laboring parturients. Tetracaine was not associated with an increase in duration of spinal analgesia as part of a CSE technique when compared to bupivacaine. The onset and duration of analgesia was similar between groups. However, there was an increase in motor block associated with tetracaine.
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