Madhu Kumar B S¹, Prameela V S^2*, Sunil Chhabria³, Brijesh K⁴, Srikanta Murthy TN⁵

^1,2Assistant Professor, ³Asociate Professor, ⁴Professor, ⁵Professor & HOD, Department of Anaesthesia, Akash Institute of Medical Sciences & Research Centre, Devanahalli, Bangalore, Karnataka – 562110 INDIA.

Email: ganeshbabu370@gmail.com

Table 2: Comparison of Heart rate (bpm) in the groups studied

Table 3:

In Magnesium group the post induction SBP was significantly lower compared to its baseline (P=0.008). Also at 5 min and 10 minutes value were significantly lower (p=0.001 and p<0.001 respectively) when compared to its baseline but this fall was not clinically significant (SBP < 25% from the baseline). Where as in Lignocaine group statistically significant fall in SBP compared to baseline was seen only after post induction and 10min following laryngoscopy Intergroup comparison between the two groups showed that the SBP at 1, 5 and 10 minute after laryngoscopy in magnesium group were statistically significantly lower compared to lignocaine group (P<0.05). At 3 minute SBP was lower in magnesium group but not statistically significant when compared with lignocaine group.

Table 3: Comparison of Systolic Blood Pressure (SBP) (mm Hg) in the two groups studied

Table 4: Comparison of Diastolic Blood Pressure (DBP) (mm Hg) in the two groups studied, In Magnesium group the post induction DBP values was significantly lower compared to its baseline with P value of 0.02. At 1 minute there was slight increase in mean DBP with P=0.03 which returned near baseline value by 3minute. At 5 min and 10 minutes values were significantly lower (P=0.02 and P=0.001 respectively) when compared to its baseline but this decrease was not clinically significant. Where as in Lignocaine group statistically significant increase in DBP compared to baseline was seen only at 1 minute after laryngoscopy with P value of <0.001.

Table 4: Comparison of Diastolic Blood Pressure (DBP) (mm Hg) in the two groups studied

Table 5: Shows the Comparison of Mean Blood Pressure (MBP) (mm Hg) in two groups studied. In Magnesium group the post induction MBP was significantly lower compared to its baseline (P<0.001). Also at 5 min and 10 minutes value were significantly lower (p=0.003 and p<0.001 respectively) when compared to its baseline but this levels are reduced. Where as in lignocaine group statistically significant fall in MBP compared to baseline was seen only after post induction and 10min following laryngoscopy. However there was statistically significant increase in MBP seen at 1 minute after laryngoscopy in lignocaine group with P<0.001. Intergroup comparison between the two groups showed that the MBP at 1 minute after laryngoscopy in magnesium group was statistically significantly lower compared to lignocaine group (P=0.03). At 3, 5 and 10 minutes MBP was lower in magnesium group but not statistically significant when compared with lignocaine group.

Table 5: Comparison of Mean Blood Pressure (MBP) (mm Hg) in two groups studied

DISCUSSION

The sequence of induction of anaesthesia, laryngoscopy and tracheal intubation are associated with marked haemodynamic changes and autonomic reflex activity which may be a cause of concern in many high risk patients because it is associated with rise in heart rate, blood pressure and incidence of cardiac arrhythmias 13. These potentially dangerous changes disappear within 5 minutes of onset of laryngoscopy. Although these responses of blood pressure and heart rate are transient and short lived they may prove to be detrimental in high risk patients especially in those with cardiovascular disease, increased intracranial pressure or anomalies of the cerebral blood vessels 14. Many factors influence the cardiovascular changes associated with laryngoscopy and intubation. Age, drugs, depth of anaesthesia, hypoxia, hypercarbia etc., influence the pressor response. These variations in heart rate decrease with increasing age. Young patients show more extreme changes, Marked fluctuations in haemodynamic responses are often seen in geriatric patients 15. In addition to attenuation of cardiovascular responses to laryngoscopy and intubation, Lignocaine prevents rise in intracranial pressure and rise in intraocular pressure associated with laryngo tracheal stimulation. It also suppresses cough related to extubation. The ability of magnesium ions to inhibit the release of catecholamines from both the adrenal glands and peripheral adrenergic nerves terminals and also produces vasodilation, directly. Many studies have showed that MgSO4 can attenuate cardiovascular responses to endotracheal intubation^16-18. The study was made to compare magnesium with lignocaine to find out whether it can be used as a suitable alternative to lignocaine or not. This clinical study is a randomized, prospective, double blind study, patients randomly allocated into two groups based on Patients belonging to Group A received 1.5mg/kg of lignocaine intravenously 90 seconds prior to laryngoscopy and intubation and In Group B patients received intravenous magnesium sulphate 30mg/kg 90 seconds prior to laryngoscopy and intubation. Similarly previously used similar dose of lignocaine and found it to be effective in attenuation of sympathetic responses of laryngoscopy and intubation 19. Another studies also done by using optimal dose of magnesium sulphate for attenuation of hemodynamic response to laryngoscopy and intubation and concluded that 30mg/kg as optimal dose and smaller dose was less effective and larger doses resulted in complications^20-22. Both the groups were well matched for demographic data and no statistically significant difference were found between groups with regard to age and gender. In lignocaine group, the heart rate decreased from baseline after induction, which was not statistically significant (P=0.77) and there was statistically significant increase following intubation only at 1 min and 3 min (P<0.001 and P=0.002) and At 5 minute heart rate was still above baseline and reached below baseline at 10 minute but these were not statistically significant (P=1.00 and P=0.44). Similarly another study reported that there was statistically significant increase in heart rate from baseline in lignocaine group at 1 and 3 minutes followed by statistically non-significant increase at 5 minute and They found statistically significant increase in mean heart rate after 1 min (P=0.001) and at 2 min (P=0.027) followed by statistically non-significant increase at 3, 4 and 5 minutes (P= 0.68, P=0.51, P=0.579)^23-24. In magnesium group the mean heart rate decreased from the baseline to post induction and it was statistically not significant (P=0.35). After intubation the mean heart rate increased at 1 and 3 minutes, however the increase in heart rate from baseline was statistically significant only at 1 min (P<0.001). It gradually reached the baseline by 5 minutes and was statistically significantly below baseline by 10 min (P=0.009) but this was not clinically significant. Our results correlated with the study noted that the significant increase in heart rate from base line at 1 min followed by non-significant increase at 3 min and fall below baseline at 5 minute both of which were not statistically significant²⁵. This was comparable to another study found that there was statistically significant difference in mean heart rates between magnesium and lignocaine groups at 1 minute after laryngoscopy (P<0.05). This can be attributed to the fact that the above mentioned authors have evaluated the difference in heart rate as % change from baseline whereas we have calculated the p values taking into consideration the difference in heart rate between both the groups at each given time interval. In lignocaine group, mean systolic blood pressure decreased from baseline after induction, which was statistically significant (P=0.004) but clinically not significant. There was statistically significant increase following intubation at 1 min P<0.001 followed by non-statistically significant increase at 3 min with P=1.00. At 5 minute and 10 minute systolic blood pressures were below baseline but statistically significant only at 10 minute P=0.002. Our results were consistent with study done by Navid nooraei et al.⁴⁴, who found a similar statistically significant increase in systolic blood pressure in lignocaine group at 1 min (P=0.0001), 2 min (P=0.001) from baseline after intubation. Though the mean systolic blood pressure was above baseline at 5 min it was not statistically significant (P=0.582) which is in accordance with our study. In magnesium group the mean systolic blood pressure decreased from the baseline to post induction and it was statistically significant (P<0.001) and After intubation the systolic blood pressure increased at 1 and 3 minutes, this increase from baseline was statistically significant only at 1 min (P=0.008), gradually reached the below baseline by 5 minutes and was statistically significantly below baseline by 5 min and 10 min (P=0.001 and P<0.001) however it was not clinically significant. Similarly another study noted a similar statistically significant increase in systolic blood pressure in magnesium group only at 1 min (P=0.011) followed by a stable systolic blood pressure as compared to baseline 26. In lignocaine group, mean diastolic blood pressure decreased from baseline after induction, which was not significant statistically (P=0.036) and clinically. There was statistically significant increase following intubation at 1 min P<0.001 followed by non-statistically significant increase at 3 min and 5 min with P=0.08 and P=1.00 respectively. At 10 minute diastolic blood pressures were below baseline but statistically not significant P=1.00. similarly another study found that statistically significant increase in diastolic blood pressure at 1 minute (P=0.046) followed by stable DBP and In magnesium group the mean diastolic blood pressure decreased from the baseline to post induction and it was statistically significant (P=0.02). After intubation there was a statistically significant increase in the diastolic blood pressure at 1 minute with P=0.03. It gradually reached the below baseline by 3 minutes and was statistically significantly below baseline by 5 min and 10 min (P=0.02 and P=0.001), however it was not clinically significant. No statistically significant increase in DBP from baseline at 1, 2, 3, 4 and 5 minutes 27. Along with the mean blood pressure decreased in lignocaine group from baseline after induction, which was statistically significant (P=0.001) but clinically not significant. There was statistically significant increase following intubation at 1and5 min P<0.001 followed by non-statistically significant increase at 3 and 10 min with P=0.40. Statistically significant difference in mean blood pressure at 1 after intubation followed by no statistically significant difference in the mean blood pressure at 3, 4 and 5 minute and Statistically significant increase in mean blood pressure from baseline in lignocaine group at 1 minute followed by statistically non-significant increase at 5 minute and In magnesium group the mean blood pressure decreased from the baseline to post induction and it was statistically significant (P<0.001) but not clinically significant 28. After intubation the mean blood pressure increased at 1 minute, this increase from baseline was neither statistically significant (P=0.43) nor clinically. It gradually reached the below baseline by 3 minutes and was statistically significantly below baseline by 5 min and 10 min (P=0.003 and P<0.001) however it was not clinically significant. Statistically significant difference in mean blood pressure only at 1 after intubation followed by no statistically significant difference in the mean blood pressure at 2, 3, 4 and 5 minute. In another similar study conducted study in 150 patients undergoing CABG receiving either magnesium sulphate 50mg/kg or lignocaine 1.5mg/kg andomly also showed similar statistically significant difference between lignocaine and magnesium groups in mean blood pressure after intubation (P=0.049) only at 1 minute.

CONCLUSION

On the basis of the present observation it can be concluded that Intravenous lignocaine and intravenous magnesium sulphate both significantly attenuates the sympathetic response to laryngoscopy and tracheal intubation, Intravenous magnesium sulphate at 30mg/kg is more efficient than lignocaine 1.5mg/kg in attenuating the sympathetic response to laryngoscopy and intubation and Hence we conclude that intravenous magnesium sulphate 30mg/kg 90 seconds prior to laryngoscopy and intubation is superior to lignocaine 1.5mg/kg prior to laryngoscopy and intubation.

ACKNOWLEDGEMENT

It is purely being done with the idea of research and all the cost of the study will be borne by the investigator.

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