The duration of spinal anesthesia as ordinarily managed is not affected by any measures undertaken after the anesthetic has once been placed in the subarachnoid space. Studies on the concentration of procaine in the cerebrospinal fluid of patients under spinal anesthesia1 have shown that after an initial period during which mechanical distribution away from the site of injection takes place there is a gradual disappearance of the procaine from the cerebrospinal fluid. These findings suggested that it might be possible to terminate anesthesia more quickly by removing the procaine from the subarachnoid space.
Adult patients were anesthetized by the subarachnoid injection of 150 mg. of procaine hydrochloride between the second and the third lumbar vertebra, 3.5 cc. of cerebrospinal fluid being used as the solvent.2 In different patients at various intervals after the initial injection a needle was reinserted at the site of injection and another was inserted