LAUSR

BACKGROUND Assessment of the effectiveness of obstetric epidural analgesia may be difficult and techniques for objective assessment of epidural spread of local anesthetic would be useful. In this prospective cohort study we assessed whether obstetric epidural analgesia from a low concentration of ropivacaine led to significant change in cutaneous temperature, related to sympathetic block detected by infrared thermography, at dermatomes C4, T4, T10, L2 and L5. METHODS Women in spontaneous labor who requested epidural analgesia were consecutively recruited. Epidural analgesia was induced with a bolus of 10-15 mL of ropivacaine 1 mg/mL and sufentanil 0.5 µg/mL, followed by continuous epidural infusion. Skin temperature was measured using thermography before and 20 min after the epidural bolus. The verbal pain score using a numeric rating scale was recorded before and 60 min after the epidural bolus. The upper sensory block to cold sensation was tested 30 and 60 min after the bolus by a physician blinded to the skin temperature. Failed epidural analgesia was defined as verbal pain score >3 at 60 min. RESULTS Fifty-three parturients were included and analyzed. We found a significant increase in skin temperatures measured at T4, T10, L2 and L5 dermatomes, but not at C4, and a significant difference in the change in skin temperature at T10 between failed (n=3) and successful (n=50) epidural analgesia. CONCLUSIONS These results suggest that infrared thermography might be useful for the early diagnosis of successful obstetric epidural analgesia.