The influence of neck flexion and extension on the distribution of contrast medium in the high thoracic epidural space.
BACKGROUND
For safe and effective thoracic epidural analgesia (TEA), it is important to control the level of TEA and to identify factors that influence its spread. In this study, we observed the distribution of contrast injected into the high thoracic epidural space during neck flexion and extension.


METHODS
An epidural catheter was inserted into the epidural space until its tip was located at the T1-2 intervertebral level. Patients were randomly allocated to three groups (extension, flexion, and neutral groups), and were injected with 5 mL of contrast when the neck was extended, flexed, or in the neutral position. Extent of contrast spread was determined by counting the number of vertebral body units (VBUs) through lateral epidurography.


RESULTS
Forty-two patients were equally allocated to the three groups. Radiographic spreads in the cephalad direction (median) was 1.0, 5.5, and 1.5 VBUs in the extension, flexion, and neutral groups, and spread was greater in the flexion than in the other two groups (P < 0.001). Median radiographic caudal spread was 10.0, 10.0, and 7.0 VBUs in the extension, flexion, and neutral groups, respectively, which was not significantly different among groups (P = 0.145).


CONCLUSIONS
Cranial spread of contrast in the high thoracic epidural space is limited. However, neck flexion increases cranial spread. These results suggest that when TEA is high, the tip of the epidural catheter should be located at the upper part of the level to be blocked and that neck flexion may cause an unwanted cervical block.
Lee
Chul Joong
CJ
Department of Anesthesiology and Pain Medicine, Samsung Seoul Hospital, Samsung Medical Center, Seoul, Korea.
Jeon
Yunseok
Y
Lim
Young Jin
YJ
Bahk
Jae Hyon
JH
Kim
Yong Chul
YC
Lee
Sang Chul
SC
Kim
Chong Sung
CS
D000328:Adult; D000368:Aged; D000767:Anesthesia, Epidural / Q000009:adverse effects / Q000379:methods; D003287:Contrast Media / Q000008:administration & dosage* / Q000032:analysis; D004824:Epidural Space / Q000000981:diagnostic imaging; D005119:Extravasation of Diagnostic and Therapeutic Materials / Q000150:complications / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck; D011187:Posture; D011859:Radiography; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging
D003287:Contrast Media