there may be the chance of spinal canal stenosis. because of stenosis, xylocaine might have spread upwards. my senior collegue also had 2-3 experiences of dry tap and followed by good effect.

hi, recently we have an experence of dry tap in spinal anesthesia. even after repeated attempts of spinal, we were not able to locate space. i can feel the resistence, but csf was not coming out. after few attempts, i gave spinal with bupivacaine after feeling resistence even though there was no csf (dry tap). surprisingly there was full effect of spinal.
   what can be the cause of it? does anybody have similar experince? 

hi,
   we are doing total knee arthroplasy. we routinely use inj. clexane for prevention of D.V.T.
  We usually give spinal/epidural.
   my query is," when should we start clexane? preop or postop? if postop, then after how much time of spinal anesthesia? if we have traumatic spinal tap, then what to do?
   regards.

   hi kalpesh,
             we usually use sensorcaine alone. if we are expecting long duration, then we add clonidine. we encounter hypotension most of the time when we were using 45 mcg(0.3 ml). hypotension remain for long time and it is usually refractory to fluid. now we are using 15-20 mcg and that gives good hemodynemic stability.   
    regards.

hi, we are using clonidine in SA with bupivacaine regularly. very good results with extended duration of action and hemodynemic stability.