| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2757521 | International Journal of Obstetric Anesthesia | 2015 | 5 Pages |
•The effect of pencil-point needle bevel direction on intrathecal ropivacaine and fentanyl for cesarean delivery was examined.•Using dose-finding methodology the ED50 of isobaric ropivacaine was determined.•Subjects were randomized to have the aperture of the spinal needle directed cephalad or caudad.•The ED50 of isobaric ropivacaine with fentanyl was significantly higher when the aperture was directed caudally.
BackgroundThere is little evidence on the influence of bevel direction of a pencil-point needle on the median effective dose (ED50) of isobaric ropivacaine and fentanyl in spinal anesthesia for cesarean delivery.MethodsIn this prospective, double-blind, sequential allocation study, 82 parturients scheduled for elective cesarean delivery under combined spinal-epidural anesthesia were included. We sought to determine the median effective dose of intrathecal 0.75% isobaric ropivacaine plus fentanyl 15 μg with two different bevel directions of a 26-gauge Whitacre needle using up-down sequential allocation. Parturients were randomly allocated to either Group Ce (needle aperture oriented in a cephalad direction) or Group Ca (aperture directed caudally). The initial dose was 0.75% ropivacaine 11.25 mg plus fentanyl 15 μg in both groups. Each dose was classified as effective if, after 15 min and during the next 60 min, there was inability to appreciate pin-prick as sharp at T4, a visual analogue pain score <2 and no requirement for an epidural rescue bolus.ResultsEighty patients were included in the analysis. The ED50 in group Ca was significantly higher (13.09 mg, 95% CI 12.19–14.00) than in group Ce (10.10 mg, 95% CI 9.54–10.65, P <0.001).ConclusionThe orientation of the distal aperture of a 26-gauge Whitacre needle during induction of spinal anesthesia for cesarean delivery influences the ED50 of 0.75% ropivacaine.
