... must always precede ... when performing spinal anesthesia.Sensory level testing; intrathecal anesthetic injectionInsertion of epidural catheter; intrathecal injectionSkin anesthesia; intrathecal anesthetic injectionIntrathecal anesthetic injection; skin anesthesiaSensory level testing; skin anesthesia

... is performed before inserting the spinal needle into the ...Insertion of the spinal introducer; subarachoid spaceInsertion of the spinal introducer; epidural spaceIntrathecal injection of local anesthetic; subarachoid spaceIntrathecal injection of anesthetic; epidural spaceIntrathecal injection of anesthetic; local infiltration of local anesthetic into the skin

What is a prerequisite to performing spinal anesthesia?A low body mass indexA lateral decubitus positionCorrection of hypovolaemiaOnset of laborPrevious spinal anesthesia

What is a relative contraindication to performing spinal anesthesia?Infection overlying the spinal injection siteMultiple sclerosisUncorrected hypovolemiaPrevious epidural anesthesiaAllergy to the anesthetic agent

Which layers are punctured in the delivery of spinal anesthesia?I. SkinII. Subcutaneous tissueIII. Arachnoid materIV. Dura materV. Pia mater

Examine the drugs used for spinal anesthesia and explanin its mechanism of action.