Hyperosmolarity does not contribute to transient radicular irritation after spinal anesthesia with hyperbaric 5% lidocaine.
OBJECTIVE
In addition to major neurologic injury, local anesthesia toxicity may also include less severe but more common neurologic side effects. The authors recently observed symptoms suggestive of transient radicular irritation in one third of patients after spinal anesthesia with hyperbaric 5% lidocaine, whereas evidence of neurologic symptoms was lacking with hyperbaric 0.5% bupivacaine. The purpose of this prospective double-blinded study was to evaluate if the high osmolarity of hyperbaric 5% lidocaine solution might contribute to the development of transient radicular irritation.


METHODS
Forty-four patients undergoing brief gynecologic procedures under spinal anesthesia were randomly allocated to receive 1.5 mL of one of three study drugs: 5% lidocaine in 7.5% dextrose (drug A), 0.5% bupivacaine in 8.25% dextrose (drug B), or 5% lidocaine in 2.7% dextrose (drug C). Drug C was prepared by the pharmacy (University Hospital, Basel, Switzerland) with an osmolarity similar to that of drug B. Drugs A and B were commercially available. Patients were evaluated on postoperative day 1 for symptoms of transient radicular irritation by an anesthesiologist who was unaware of the drug given or details of the anesthetic technique.


RESULTS
Symptoms suggestive of transient radicular irritation were observed with a similar high incidence in patients receiving both lidocaine preparations, but in no patient receiving hyperbaric 0.5% bupivacaine (P < .01).


CONCLUSIONS
The results suggest that transient radicular irritation did not result from the marked hyperosmolarity of the hyperbaric 5% lidocaine. However, because lidocaine and bupivacaine were not administered at equipotent dosages, the relative potential for both drugs to induce transient radicular irritation remains to be determined.
Hampl
K F
KF
Department of Anesthesia, University of Basel/Kantonsspital, Switzerland.
Schneider
M C
MC
Thorin
D
D
Ummenhofer
W
W
Drewe
J
J
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000775:Anesthesia, Spinal / Q000009:adverse effects; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000009:adverse effects; D002045:Bupivacaine / Q000008:administration & dosage / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D005836:Genitalia, Female / Q000601:surgery; D006801:Humans; D015994:Incidence; D008012:Lidocaine / Q000008:administration & dosage* / Q000009:adverse effects; D008875:Middle Aged; D009460:Neurologic Examination; D009994:Osmolar Concentration; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced; D011312:Pressure; D011446:Prospective Studies; D012678:Sensation Disorders / Q000139:chemically induced*; D013126:Spinal Nerve Roots / Q000187:drug effects*
D000779:Anesthetics, Local; D008012:Lidocaine; D002045:Bupivacaine