Accuracy of ultrasound imaging versus manual palpation for locating the intervertebral level.

Abstract

Background and Aims:Efficacy of epidural analgesia depends on placement of the epidural catheter at the appropriate level. Manual palpation using surface landmarks to identify the desired intervertebral level may not be a reliable method. Ultrasonography (USG) is an alternative technique but requires training and may increase procedure time. The objective of this study was to compare the accuracy of ultrasound (US) imaging with manual palpation for locating the intervertebral level.Material and Methods:We included postoperative adult patients without an epidural catheter who were scheduled to have a chest radiograph in the recovery room. A radio-opaque marker was placed at random at an intervertebral space along the thoracic or lumbar spine of the patient (in the field of the chest radiograph). The level of intervertebral space corresponding to the radio-opaque marker was determined by palpation technique by one anesthetist. Two other anesthetists (A and B) blinded to the result of manual palpation, independently used USG to determine the level of intervertebral space. A consultant radiologist assessed the radiographs to determine the correct position of the marker, which was judged to be the accurate space.Results:We recruited a total of 71 patients, of which 64 patients were included in the final analysis. Accurate identification by manual method was 31/64 (48%), by US A was 27/64 (42%) and by US B was 22/64 (34%). The difference in accuracy between manual palpation and US imaging was not statistically significant (P = 0.71).Conclusion:US imaging may not be superior to manual palpation for identifying intervertebral level.