The Accuracy of 7th Cervical Spinous Process Identification Using Ultrasound Transverse Scan and Parasagittal Scan Compared to Palpation Technique
Pawinee Pangthipampai MD*, Manoj Kumar Karmakar MD, PhD**, Banchobporn Songthamwat MD***, Jatuporn Pakpirom MD****
Affiliation : * Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand ** Department ofAnaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong *** Department of Anesthesiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand **** Department of Anesthesiology, Faculty of Medicine, Prince of Songkla University, Songkhla, Thailand
Objective : To obtain the adequate surgical anesthesia from thoracic paravertebral block (TPVB), identifying the correct
thoracic spine level is mandatory. Ultrasound has become a recent standard to perform regional anesthesia including TPVB.
This study aimed to investigate two techniques of using ultrasound to identify C7 spinous process compared with the palpation
method.
Material and Method: Twenty volunteers were invited to participate in the investigation. Each volunteer was evaluated using
palpation method with flexion and extension maneuver, ultrasound transverse scan (US-TS) and parasagittal scan (US-PS)
to identify C7 spinous process. All volunteers were scanned on both sides randomly, and finally checked with fluoroscope. The
examinations were independently performed by different investigators. The invisible marker pen was used to locate C7
spinous process from each technique. The accuracy and frequency of identified level, both correction and errors, were
recorded and compared.
Results : The accuracy of palpation method with flexion and extension maneuver for C7 spinous process identification was
72.5%. While identifications of C7 by using US-TS and US-PS were correct 52.5% and 30% respectively. Interestingly, most
errors were one level higher than actual C7 spinous process.
Conclusion : Identifying C7 spinous process using ultrasound assisted, both US-TS and US-PS techniques had a lower
accuracy compared with palpation method with flexion and extension maneuver. Thus, the technique of ultrasound assisted
C7 spinous process identification need to be modified.
Keywords : C7 spinous process identification, Ultrasound assisted, Thoracic paravertebral block, Palpation method with flexion and extension maneuver
