Cervical epidural pressure measurement: comparison in the prone and sitting positions.
BACKGROUND
The hanging drop technique is used for identifying the cervical epidural space, using its negative pressure. However, it is doubtful whether the epidural space intrinsically exhibits a negative pressure. We designed this study to test the hypothesis that the cervical epidural pressure (CEP) is significantly higher in the prone position than in the sitting position. To evaluate this hypothesis, we measured and compared 30 CEP values in the prone and sitting positions.


METHODS
We measured and compared 15 CEPs in the prone group and 15 in the sitting group using a closed pressure measurement system under fluoroscopic guidance.


RESULTS
All CEPs in the prone group were consistently positive (median, 10 mmHg; range, 4.8-18.7; mean+/-SD, 10.5+/-4.4) in contrast to the sitting group (median, -0.3 mmHg; range, -2.4-7.9; mean+/-SD, 0.5+/-2.8). CEPs in the prone group were significantly higher than in the sitting group (P<0.001).


CONCLUSIONS
CEP was found to be significantly higher in the prone position than in the sitting position. Furthermore, CEPs were not consistently negative even in the sitting position. These results suggest that the hanging drop technique is inappropriate for identifying the cervical epidural space in either the prone or sitting positions. Clinical Trials Ref: NCT01009385.
Moon
Jee Y
JY
Department of Anesthesiology and Pain Medicine, East and West Neo Medical Center, Kyung Hee University Medical School, and Seoul National University Hospital, Seoul, Republic of Korea.
Lee
Pyung-Bok
PB
Nahm
Francis Sahngun
FS
Kim
Yong-Chul
YC
Choi
Jong-Bum
JB
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000502:physiology*; D004824:Epidural Space / Q000502:physiology*; D005260:Female; D006801:Humans; D007268:Injections, Epidural; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D011312:Pressure; D016684:Prone Position / Q000502:physiology*