Safety and effectiveness of prilocaine for spinal anesthesia in day surgery setting: a retrospective study on a sample of 3291 patients

Spinal anesthesia is considered safe and reliable for most surgical procedures involving the lower part of the body, but its use in the ambulatory setting requires drugs with rapid onset and regression of the motor and sensory block-like prilocaine. The purpose of this study is to retrospectively analyze data from 3291 procedures recorded in our institutional database, to better define the safety profile of spinal prilocaine and the incidence of complications and side effects. All clinical data, prospectively collected from 2011 to 2019 in an Italian tertiary hospital, of patients treated with spinal anesthesia performed with 40 mg of hyperbaric 2% prilocaine, according to our internal protocol of day surgery, were analyzed. Surgical procedures included saphenectomy (28.5%, n = 937), knee arthroscopy (26.8%, n = 882), proctologic surgery (15.16%, n = 499), and inguinal canal surgery (14.9%, n = 491). Anesthesia-related complication was represented by urinary retention (1.09%, n = 36), lipotimia (0.75%, n = 25), and postoperative nausea (0.33%, n = 11); arrhythmic events were uncommon (0.18%, n = 6). One case of persistent hypotension and 2 cases of persistent hypertension were reported. Persistent motor or sensory block (lasting more than 5 h) was experienced by 7 patients. One patient (0.03%), who underwent knee arthroscopy, experienced pelvic pain lasting for 6 h, compatible with a transient neurological symptom. Proctologic surgery was a factor associated with unplanned admission due to anesthesia-related complications (OR = 4.9; 95% CI: 2–14%). The number of complications related to the method was low as well as the need for hospitalization. This drug is valid and safe for the most performed day surgery procedures; however, further trials are needed to investigate the incidence of complications in the days following the procedure.