DG Journal club
AUTHORS: Yi Chen, Lili Zou et al.
METHODS Patients were randomly assigned into groups to receive normal saline (NS) or one of four different prophylactic doses (0.025 [NE25], 0.05 [NE50], 0.075 [NE75], and 0.1 [NE100]ug/kg/min) of norepinephrine. The primary end point was the incidence of postspinal anesthesia hypotension (systolic blood pressure [SBP]<80% of baseline) within 15 minutes after spinal anesthesia. Secondary outcomes included the overall stability of SBP control versus baseline (median performance error [MDPE] and median absolute performance error [MDAPE]), the dose that would be effective in preventing postspinal anesthesia hypotension in 50% (effective dose, ED 50) and 90% (ED90) of patients, other adverse events (bradycardia, nausea, vomiting, hypertension, and the total additional bolus of norepinephrine and atropine), and neonatal outcomes (blood gas values and Apgar scores).
RESULTS The incidence of postspinal anesthesia hypotension in NS, NE25, NE50, NE75, and NE100 groups was 68.42% (13/19), 40.00% (8/20), 20.00% (4/20), 15.00% (3/20), and 10.00% (2/20), respectively. With increasing prophylactic doses of norepinephrine, the incidence of postspinal anesthesia hypotension decreased (p<0.001), SBP was maintained closer to the baseline (MDPE, p<0.001; MDAPE, p = 0.001), and the total additional bolus of norepinephrine decreased (p<0.001). The ED50 and ED90 values of norepinephrine were 0.016 (95% CI: -0.014 – 0.033) and 0.088 (95% CI: 0.068 – 0.133) ug/kg/min, respectively. Other adverse effects, neonatal outcomes, and the total additional bolus of atropine did not differ among the five groups.
CONCLUSION A prophylactic dose of 0.05 or 0.075 μg/kg/min norepinephrine prevents postspinal anesthesia hypotension in patients undergoing cesarean section.