Thermographic Temperature Measurement Compared with Pinprick and Cold Sensation in Predicting the Effectiveness of Regional Blocks

Abstract

We designed this study to evaluate the usefulness of thermographic temperature measurement with an infrared camera, compared with patient response to cold and pinprick, as a means of assessing the success or failure of axillary blockades. Axillary blocks were performed on 25 patients undergoing surgery on the hand or forearm using a nerve stimulator technique with mepivacaine 1.5%. Pinprick and cold sensation were assessed on the operative site at 5-min intervals for 30 min. A thermographic image of the operative limb was recorded at similar time intervals. Thermographic images of the unblocked limb were taken before block placement and at 30 min. Temperature values at the operative site and unblocked limb were calculated from the thermographic images. Results revealed that thermography had higher combined values for sensitivity, specificity, and positive and negative predictive values than both cold and pinprick at all time intervals, with statistically significant differences at 15 min (thermography versus cold, P = 0.006; thermography versus pinprick, P = 0.026) and 30 min (thermography versus cold, P = 0.038; thermography versus pinprick, P = 0.040). For thermography as a method of block assessment, an optimal time of 15 min after mepivacaine local anesthetic injection gives the highest combined values for predicting a successful block (P = 0.004). We conclude that thermography provides an early and objective assessment of the success and failure of axillary regional blockades.

Regional Hemodynamic Changes After an Axillary Brachial Plexus Block

“…There were 7 men and 1 woman with a mean (SD) age of 47 (16) years, weight of 66 (2.3) kg, height of 172 (5) cm, and a body mass index 22.4 (1.6) kg/m 2 . All the axillary BPBs were successful and provided adequate surgical anesthesia.…”

The Efficacy of Skin Temperature for Block Assessment After Infraclavicular Brachial Plexus Block

“…We hypothesized that a noncontact infrared temperature probe may provide an easier and less expensive tool to use in clinical practice, although previous investigations described conflicting results for the evaluation of nerve blocks of the lower extremities. [2][3][4] The aim of the study was to determine whether an infrared thermometer can be used as a reliable method to predict block success, defined as complete sensory block after infraclavicular brachial plexus block. 5…”

Evaluation of the success of sciatic nerve blockade by skin temperature measurement through infrared thermography

“…[3] Other research showed that the temperature rise in the limb is general when performing an axillary plexus block. [4] In studies by Werdehausen et al and Stevens et al the rise in skin temperature after epidural, spinal and combined sciatic and femoral blocks showed an evident proximal to distal gradient. [7,8] However, because a whole limb was blocked, no definite statement could be made on the difference in temperature effects of the sciatic and femoral nerve.…”

“…Sensory assessment was performed by systematic pinprick testing with a 24G needle, consecutively from the lateral side of the lower leg (below the knee) over the lateral malleolus to the heel (1), the dorsal and lateral side of the foot (2), every toe separately (3), the plantar side of the foot (4). Results where noted as 'sharp' = 'normal' = 'positive' or 'numb' = 'negative'.…”

“…This seems only partially possible. [3,4,5,6] Research concerning the lower extremity is scarcer. [7,8] In the present study we observed the relationship between ultrasound guided subgluteal sciatic nerve blocks and skin temperature by infrared thermography in the lower extremity.…”