Comparison of Three Modalities for Assessing Block Levels during Spinal or Combined Spinal Epidural Anesthesia for a Cesarean Delivery

Kim, Jie Ae; Kim, Do Hyun; Kim, Sung Oh; Cheong, Il Young; Choi, Duck Hwan

Abstract

BACKGROUND: Assessing block levels during regional anesthesia has been mainly performed by three sensory modalities: cold, sharp pinprick (analgesia), and pinprick touch (anesthesia). Though sharp pinprick is more commonly used, pinprick touch has been emphasized to be more accurate and predictive by some. We compared block levels and discriminating power between the three modalities in spinal anesthesia (SA) and combined spinal epidural anesthesia (CSEA).
METHODS
Forty-six cesarean parturients were randomly given SA (n = 23) or CSEA (n = 23). SA was performed with intrathecal hyperbaric bupivacaine 0.5%-9 mg and fentanyl 20 microgram, and CSEA with intrathecal hyperbaric bupivacaine 0.5%-6 mg and fentanyl 20mug followed by epidural bupivacaine 0.25%-10 ml 5 min later. Upper block levels were measured with cold (alcohol swab), sharp pinprick (25G Whitacre) and pinprick touch (25G Whitacre) at 5, 10, 15, 20, 30, 60, 90, and 120 min after intrathecal injections.
RESULTS
There were no complaints of pain through the operation by any patient. The maximum levels (median) using cold, sharp pinprick, or pinprick touch were T1, T2, and T4 in SA and T1, T3, and T4 in the CSEA group and there was no differences between groups. At every measuring time, there were significant differences in block heights of the three modalities in the upper mentioned order. In 5 patients (3 in SA, 2 in CSEA), there was a reverse order between the levels of cold sensation and analgesia. Pinprick touch was kept at the lowest levels at all times, and could discriminate the two blocks at two onset times (5, 10 min), sharp pinprick at one time (5 min) but cold sensation could not.
CONCLUSIONS
There were marked differences in block heights measured by the three modalities in the decreasing order of cold, sharp pinprick, and pinprick touch. At the onset of the blocks, pinprick touch was the most discriminating to differentiate the two blocks, followed by a sharp pinprick.