Withdrawal forces during removal of lumbar extradural catheters

After performing successful continuous lumbar extradural conduction block, we investigated the effects of the extradural insertion technique (midline (M) or paramedian (P)) and patient position during extradural catheter removal (flexed lateral (L) or sitting (S)) on the force required to remove extradural catheters. One hundred parturients were allocated randomly to four groups: ML, MS, PL, PS. The results indicated that neither the midline nor paramedian approach affected withdrawal forces. However, more than 2.5 times as much force was required to remove the catheters when patients were in the flexed sitting compared with the lateral position (P < 0.005). For ease of removal of catheters from the lumbar extradural space we therefore strongly recommend the flexed lateral position.