Glycopyrrolate pretreatment before phenylephrine infusion during spinal anesthesia for cesarean delivery: Effect on cardiac output and hemodynamic control
Abstract Number: OP2-4
Abstract Type: Original Research
Phenylephrine (PHE) given during spinal anesthesia (SA) for cesarean delivery (CD) often induces a baroreceptor-mediated decrease in heart rate (HR) which may decrease cardiac output (CO) . Anticholinergic drugs may attenuate this effect but may also cause more labile blood pressure (BP) control. Our aim was to evaluate glycopyrrolate (GLY) given at the start of a standardized PHE infusion. The primary outcome was non-invasively measured CO. Accuracy of BP control was assessing using performance error calculations (PEC) .
With IRB approval and written consent, 104 healthy patients scheduled for elective CD were recruited in a prospective randomized double-blinded controlled trial. After SA using hyperbaric bupivacaine 11 mg + fentanyl 15 mcg, IV GLY 4 mcg/kg or saline placebo was given. Systolic BP measured at 1-min intervals was maintained near baseline using closed-loop feedback computer-controlled PHE infusion (range 0-100 mcg/min) with fluid cohydration . CO was measured using suprasternal Doppler ultrasonography by the same experienced blinded operator at baseline and 5-min intervals for 20 min. Standard neonatal assessment was performed and patients were asked if they had dry mouth in the PACU. HR and CO data were standardized to % of baseline and CO changes over time were summarized as area under the curve. Data were compared using the Mann-Whitney test. P<0.05 was considered significant.
11 patients were excluded for shivering or technical problems. For GLY vs placebo, serial CO was greater (Fig 1), mean HR until uterine incision was greater (118.2 (SD 13.5) vs 95.8 (7.0) %, P<0.001) and median PHE infusion rate was lower (29.1 vs 34.1 mcg/min, P=0.006). PEC analysis of BP control showed greater positive bias, greater inaccuracy and greater wobble in the GLY group (all P<0.05). For GLY vs placebo, nausea incidence (7/44 vs 4/49) and neonatal outcome were similar but more patients had dry mouth (16/44 vs 3/49, P=0.0002).
GLY given with a PHE infusion increases CO and HR and decreases PHE requirement, but also decreases accuracy of BP control and causes a dry mouth. No difference in neonatal outcome is seen in low risk patients.
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