A prospective randomized comparative study of low dose versus high dose bupivacaine along with fentanyl and with or without intravenous phenylephrine infusion during caesarean section deliveries under spinal anaesthesia

Abstract

Introduction: It is imperative on the part of anesthesiologist to be well versed with the anatomy of the vertebral column epidural space and the sub arachnoids space for successful sub arachnoids block. The aim of the study was to quantitatively compare the effect of level of blockade, duration of motor block, changes in haemodynamics and motor block recovery in patients receiving low dose bupivacaine (7 mg) versus high dose bupivacaine (10 mg ) with or without phenylephrine infusion under spinal anesthesia for caesarean section deliveries.Materials and Methods: This study was carried out on eighty healthy pregnant women of ASA grade I, posted for elective caesarean section under spinal anaesthesia in Government General Hospital, Vijayawada between January 2010 to August 2011, after obtaining ethical committee approval. The patient’s age ranging from 19-28 years with normal pregnancies were selected. The height of the patients varied between 150 – 160 cm. Patients were divided randomly in to four groups of 20 each Group A, Group B, Group C and Group D, without any bias. Type of surgery and average duration of surgery were similar in all 4 groups. All patients were informed before surgery about the study and their consent obtained for the same. Results: The incidence of hypotension was highest in group B patients (14 out of 20(70%) who received 10 mg of bupivacaine without phenylephrine infusion and lowest in group C patients (2 out of 20 (10%) who received 7 mg of bupivacaine with phenylephrine infusion which is statistically significant (P value < 0.05). Conclusion: When given along with a small dose of opioid like fentanyl, low dose bupivacaine (1.4 ml / 7 mg) was as effective as of high dose buypivacaine (10 mg12 ml) in producing adequate relaxation and analgesia. Addition of low dose phenylephrine infusion decreased the incidence of hypotension and maintained better hemodynamic stability in low dose bupivacaine (1.4 ml / 7 mg) group. The Apgar scores of fetus were not affected by dose of bupivacaine, fentanyl or by phenylephrine infusion. The motor recovery was quick in case of low dose bupivacaine groups (B-7mg) with or without phenylephrine which aids in early mobilization of patient.