PROSPECTIVE-STUDY OF THE INCIDENCE OF TRANSIENT RADICULAR IRRITATION IN PATIENTS UNDERGOING SPINAL-ANESTHESIA

Background: There is considerable controversy regarding the role of su barachnoid 5% hyperbaric lidocaine in the syndrome transient radicular irritation (TRI), This randomized, double-blinded, prospective study was designed to determine the incidence of TRI and identify factors po ssibly contributing to its development. Methods: One hundred fifty-nin e ASA physical status 1 or 2 patients undergoing outpatient knee arthr oscopy or unilateral inguinal hernia repair were prospectively randomi zed to receive spinal anesthesia with 5% hyperbaric lidocaine with epi nephrine (60 mg with 0.2 mg epinephrine for arthroscopy or 75 mg with 0.2 mg epinephrine for hernia repair), 2% isobaric lidocaine without e pinephrine (60 mg for arthroscopy or 75 mg for hernia repair), or 0.75 % hyperbaric bupivacaine without epinephrine (7.5 mg for arthroscopy o r 9.0 mg for hernia repair) in a double-blinded fashion, On the 3rd po stoperative day, patients were contacted by a blinded investigator and questioned regarding the incidence of postoperative complications inc luding TRI, defined as back pain with radiation down one or both butto cks or legs occurring within 24 h after surgery, Postoperatively, time from injection to block resolution, ambulation, voiding, and ready fo r discharge were recorded by a postanesthesia care unit nurse blinded to the group assignment, Results: The incidence of TRI was greater in patients receiving lidocaine than in those receiving bupivacaine (16% vs, 0%; P = 0.003). There was no difference in the incidence of TRI be tween the patients receiving 5% hyperbaric lidocaine with epinephrine and those receiving 2% isobaric lidocaine without epinephrine (16% vs, 16%; P = 0.98), The incidence of TRI was greater in patients undergoi ng arthroscopy than in those undergoing hernia repair (13% us. 5%; P = 0.04). There was no difference in discharge times in patients receivi ng bupivacaine versus those receiving hyperbaric lidocaine with epinep hrine (292 vs. 322 min; P = 0.61). Conclusions: The incidence of TRI i s greater with lidocaine than bupivacaine, decreasing the lidocaine co ncentration to 2% does not prevent TRI, and surgical position may be a n important contributing factor. Discharge times at our institution ar e not different when equipotent doses of 0.75% hyperbaric bupivacaine or 5% hyperbaric lidocaine with 0.2 mg epinephrine are used in ambulat ory patients undergoing spinal anesthesia.