Intrathecal fentanyl-induced pruritus is more severe in combination with procaine than with lidocaine or bupivacaine

Background and Objectives: Fentanyl is used as an additive to prolong intra thecal anesthesia with both lidocaine and low-dose bupivacaine in the outpa tient setting to minimize voiding or discharge delays. Pruritus is the most common side effect. When using procaine as a substitute for lidocaine, we perceived an increased frequency and severity of pruritus. We compared pros pectively the frequency and severity of itching with combinations of fentan yl with lidocaine, bupivacaine, and procaine. Methods: After institutional review board approval, 135 patients requesting neuraxial anesthesia were asked to evaluate the presence and severity (usi ng a 100 point verbal pruritus score [VPS]) of itching 30 minutes after inj ection of their spinal anesthetic, on arrival to the postanesthesia care un it (PACU), and at the time of resolution of their block. Choice of anesthet ic drug and dose and the use of intravenous sedation was left to the discre tion of the attending and resident anesthesiologist. Results: Thirty-three patients received lidocaine and fentanyl, 47 received bupivacaine and fentanyl, and 55 received procaine and fentanyl. In the li docaine group, 21% of patients experienced pruritus compared with 55% of th e bupivacaine group and 55% of the procaine group (P = .003). The average V PS at 30 minutes postblock was 18.4 in the procaine group compared with 0 a nd 5.5 in the lidocaine and bupivacaine groups (P = .06). On admission to t he PACU, it was 37 compared with 16 and 20 for lidocaine and bupivacaine, r espectively (P = .006). Conclusions: Procaine produces a higher frequency of pruritus than that see n with lidocaine-fentanyl combinations and a greater severity of pruritus t han seen with lidocaine-fentanyl and bupivacaine-fentanyl spinal anesthesia .