Appraisal of the Effect of Norepinephrine Versus Phenylephrine on Blood Pressure and Heart Rate During Spinal Anaesthesia for a Caesarean Section; A Quasi-Experimental Study

Objectives: To compare the effects of Norepinephrine and Phenylephrine on blood pressure and heart rate during spinal anaesthesia for caesarean section. Study Design: Quasi-experimental study. Place and Duration of Study: Department of Anaesthesia Combined Military Hospital, Multan Pakistan, from May to Nov 2019. Methodology: Women (age: 18 to 45 years) with singleton pregnancy planned for caesarean section in spinal anaesthesia were included. Women with pregnancy-induced hypertension, placenta previa, placenta accreta, diabetes mellitus, and any other cardiovascular disease were excluded. After distribution into groups, Group-A was given a 20μg Norepinephrine bolus, and Group-B was given a 50μg bolus of Phenylephrine just after spinal anaesthesia. At five time points, systolic, diastolic, and mean blood pressures and heart rate were measured: baseline, block of the highest sensory level, oxytocin injection, delivery, and operation completion. If hypotension developed, the same rescue drug was repeated. Bradycardia was countered by 0.5 mg of Atropine. Results: The frequency of hypotension in the Norepinephrine group was 5 (16.67%), and in the Phenylephrine Group, it was 19 (63.33%) (p=0.0001). The frequency of bradycardia in the Norepinephrine Group was 6 (20%), and in the Phenylephrine Group, it was 17 (56.67%) (p=0.003). Conclusion: The frequency of hypotension and bradycardia is less after prophylactic 20 μg of Norepinephrine during spinal anaesthesia for a caesarean section than 50 μg of Phenylephrine.