| Summary: | Background:
Pre-emptive analgesia is a well-known practice that involves the blockage of nociceptors and inhibition of central sensitisation. Perioperative management of obese patients for bariatric surgery demands a tailored approach as it involves many challenges, such as airway management and associated respiratory complications. Magnesium is one such auxiliary agent which has potential in pre-emptive analgesia. Hence, magnesium, with its opioid-sparing pre-emptive analgesic properties, in conjunction with its haemodynamic response and analgesic properties, was evaluated in bariatric patients in the present study.
Aim:
To evaluate the effect of a single intravenous dose of magnesium sulphate as pre-emptive analgesia on haemodynamic response and postoperative analgesic requirement in patients undergoing Roux-en-Y gastric bypass surgery.
Materials and Methods:
This prospective randomised case–control study included 125 patients scheduled for Roux-en-Y gastric bypass (RYGB) surgery. Sixty-three patients who were administered MgSO4 3 g in 100 ml of 0.9% normal saline during pre-induction were classified in Group M. In contrast, 62 patients who received normal saline during pre-induction were matched in Group S. The haemodynamic parameters of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) were recorded at baseline, induction, laryngoscopy, incision, intraoperative, extubation and post-operative (1 h post-extubation). The endpoint of the study was marked by the time of administration of rescue analgesia, that is, the first post-operative analgesic dose administered to patients (Visual Analogue Scale score of 5 or more). The data were descriptively analysed using GraphPad Prism (version 9.2.0), and P < 0.05 was considered statistically significant.
Results:
Both study groups exhibited female dominance, with female-to-male ratios of 1.52:1 and 1.8:1 in Groups M and S, respectively. Apart from incision, there was no statistically significant difference in the haemodynamic parameters (SBP, DBP and MAP) between Group M and Group S (P > 0.05). The mean heart rates at baseline in Groups M and S were 86.8 ± 14.7 beats/min and 87.3 ± 13.9 beats/min, respectively. At all-time intervals, there was no significant difference in the HR between the groups (P > 0.05). Of the patients in Group M, 68.25% required rescue analgesics, compared with 40.32% in group S (P = 0.0017). However, patients in Group S (491.7 ± 290.7 min) received rescue analgesia for a longer duration than those in Group M (359.8 ± 350.6 min) (P < 0.05).
Conclusion:
Haemodynamic stability was observed in both groups, but patients undergoing elective RYGB surgery with magnesium supplementation consumed significantly more rescue analgesics in the post-operative period than the control group.
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