Spinal anaesthesia with Chloroprocaine HCl 1% for elective lower limb procedures of short duration: a prospective, randomised, observer-blind study in adult patients.

Background: This prospective, randomised, observer-blinded study has been conducted in patients undergoing procedures of the lower extremities to evaluate the time to complete block resolution of 2-chloroprocaine 1% at three intrathecal doses (30, 40 and 50 mg).
Methods: After informed consent, we enrolled 45 male and female patients, aged 18-65 years, ASA score I-II, BMI 18-32 kg/m ² , undergoing elective lower limb procedures lasting ≤40 min and with a requested dermatomeric level of sensory block ≥ T12. The patients were randomised in a 1:1:1 ratio to receive Chloroprocaine HCl 1% at one of the three different intrathecal doses (Group 30 = 30 mg, Group 40 = 40 mg or Group 50 = 50 mg). The progression and regression of both sensory and motor blocks were evaluated blindly. Urine and venous blood samples were collected for pharmacokinetic analysis.
Results: Times to regression of spinal blocks were 1.76 ± 0.35 h, 2.13 ± 0.46 h and 2.23 ± 0.38 h, in Group 30, 40 and 50 respectively: the 30 mg dose showed a significantly faster resolution of spinal block than the 40 mg (p = 0.034) and the 50 mg (p = 0.006). Time to readiness for surgery was significantly reduced with the dose of 50 mg when compared to dose of 30 mg (p = 0.0259).
Conclusions: The doses of 50 mg and 40 mg yielded a longer resolution of spinal block than the dose of 30 mg. Nevertheless, the dose of 30 mg resulted in a higher secondary failure rate.
Trial Registration: Registration of clinical trial: clinicaltrials.gov ( NCT02481505 ).