OP25 Low-dose spinal anesthesia in outpatient settings: a prospective cohort study

<h3>Background and Aims</h3> Low-dose, short-acting spinal anesthetics are promising for early recovery in outpatient surgery, yet comparative data are scarce. This study compares their effects on block duration, mobilization, urination and adverse events. <h3>Methods</h3> In this prospective cohort study, 75 patients undergoing outpatient urological or proctological surgery received spinal anesthesia with 2 mL of either 40 mg Prilocaine (n=33) or 20 mg 2-Chloroprocaine (n=42). Motor blockade was assessed via the Bromage scale; sensory block was evaluated using the ice test across dermatomes. Mobilization was deemed successful if patients could walk unassisted. Adverse events—including block failure, urinary retention, hypotension, and bradycardia—were recorded. Data analysis was conducted using Microsoft Excel and IBM SPSS. <h3>Results</h3> The median motor block duration was significantly longer in the Prilocaine group (60 min, IQR=55) compared to the 2-Chloroprocaine group (0 min, IQR=46, p&lt;0.001). In the latter, 61.9% of patients developed no motor block. Sensory block lasted longer in the Prilocaine group (165 min, IQR=68, p&lt;0.001) than in the 2-Chloroprocaine group (130 min, IQR=50, p&lt;0.001). Sensory block height was also greater in Prilocaine group, with 36.3% of patients reaching T10 or higher, compared to 2.4% in the 2-Chloroprocaine group (p&lt;0.001). Mobilization was achieved earlier in the 2-Chloroprocaine group (107 min, IQR=48, p&lt;0.001) versus Prilocaine group (165 min, IQR=75, p&lt;0.001). Time to urination was shoerter with 2-Chloroprocaine group (152 min, IQR=75 vs. 215 min, IQR=25, p=0.02). One patient in the 2-Chloroprocaine group required conversion to general anesthesia. No patients experienced urinary retention requiring catheterization. Two patients in the Prilocaine group and one in the 2-Chloroprocaine group developed vasovagal syncope before spinal anesthesia administration. No significant bradycardia or hypotension was observed. <h3>Conclusions</h3> Both low-dose Prilocaine and ultra-low-dose 2-Chloroprocaine were effective for spinal anesthesia. However, 20 mg of 2-Chloroprocaine resulted in significantly shorter motor and sensory blockade, allowing for faster mobilization and shorter time to spontaneous urination.