Effect of magnesium sulphate on quality of subarachnoid block in terms of onset and duration of motor and sensory block, APGAR score of the neonate and haemodynamic status of the patient

Abstract

Background In obstetrics, pregnancy induced hypertension is still a burning question and complicates a large number of pregnancies in developing countries. Chance of hypotension is more in patients getting magnesium sulfate with subarachnoid block but it may be managed with adequate preloading and by pressor agent ephedrine.

Objectives This study was designed to observe the effect of magnesium sulphate on quality of subarachnoid block in terms of onset and duration of motor and sensory block, APGAR score of the neonates and haemodynamic status of the patients.

Methods Sixty parturients undergoing caesarian sections under subarachnoid block were enrolled for the study. They were divided into two groups. Group-A include normal parturient undergoing caesarian section and group-B include pre-celamptic parturient treated with magnesium sulphate within 1 to 2 hours before block. After recording of base line haemodynamic status (BP, HR, SPO₂) all patients received subarachnoid block with 2 ml (10 mg) hyperbaric bupivacaine at L_3-4 level. Onset of sensory block was assessed by using pinprick, onset of motor block was assessed by onset time of weakness of lower limb and onset time of complete paralysis of lower limb after SAB. Duration of motor block was assessed by modified bromage scale. Height of the block was assessed by using pin prick at the intercostals space in the mid axillary line after 5 minute of SAB. Neonatal assessment was done by using apgar score in 1 and 5 minutes after delivary of baby. Blood pressure was recorded normally at 2 min interval until 15 minutes then every 5 minutes interval till the surgical procedure is completed.

Results Duration of motor block in group B is significantly higher 276 ± 44.92 min compared with group A which was 197.96 ± 24.25 min (P = 0.000). Duration of sensory block in group B also significantly higher with 308.76 ± 61.43 min compared with group A which was 264 ± 30.57 min, and (P = 0.001). Changes in systolic blood pressure in group B patient is more and highly significant (P < .05), for upto 60 min. But changes in diastolic blood pressure in-group B was only highly significant with group A for upto 9 minutes. APGAR score was significantly low both in 1 minute and 5 minutes, in group B patients which was 5.80 ± .61 at 1 minute and 7.73 ± .827 at 5 minutes and in group A which was 6.60 ± .85 at 1 minute and 8.30 ± .595 (mean ± SD) at 5 minutes. Onset of sensory block and onset of motor block revealed on significant difference between groups.

Conclusions Chance of hypotension is more in patients getting magnesium sulfate but it may be managed with adequate preloading and by pressor agent ephedrine. APGAR score of baby of magnesium sulfate getting patient is low but it is acceptable.

DOI: http://dx.doi.org/10.3329/jbsa.v24i2.19800

Journal of Bangladesh Society of Anaesthesiologists 2011; 24(2): 41-47