Laparoscopic cholecystectomy has become the standard surgical approach for gallbladder diseases due to reduced postoperative pain, shorter hospital stay, and early recovery [1]. However, despite its minimally invasive nature, the procedure is associated with significant hemodynamic disturbances caused by laryngoscopy, tracheal intubation, and creation of carbon dioxide pneumoperitoneum [2,3].

Pneumoperitoneum increases intra-abdominal pressure and causes absorption of carbon dioxide, resulting in hypercarbia, increased systemic vascular resistance, and stimulation of the sympathetic nervous system [4]. These physiological changes manifest as tachycardia, hypertension, and increased myocardial oxygen demand, which may be detrimental in patients with limited cardiovascular reserve [5].

Magnesium   has   the   ability   to   block   the   release   of catecholamines  from  both  the  adrenal  gland  and  the adrenergic nerve terminals. Apart from that, magnesium can  produce  vasodilatation  by  acting  directly  on  blood vessels  and  is  also  capable  of  attenuating  vasopressin stimulated vasoconstriction. Intravenously administered magnesium sulphate is capable of attenuating the   adverse   hemodynamic   responses   associated   with endotracheal intubation also.So it has been hypothesized that   intravenously   administered   magnesium   sulphate would     be     efficacious     to     attenuate     the    adverse hemodynamic  responses  in  patients  undergoing  elective laparoscopic    cholecystectomy    with    carbon    dioxide pneumoperitoneum [1].

Various pharmacological agents including opioids, beta-blockers, alpha-2 agonists, vasodilators, and intravenous anesthetics have been used to attenuate these responses, but their use is often limited by side effects such as excessive sedation, respiratory depression, and delayed recovery [6–8].

Magnesium sulphate is an attractive alternative due to its ability to inhibit catecholamine release, block calcium channels, and antagonize NMDA receptors [9,10]. These properties contribute to its sympatholytic, vasodilatory, and anesthetic-sparing effects [11]. Several studies have shown that magnesium sulphate reduces the hemodynamic response to intubation and pneumoperitoneum and decreases anesthetic and opioid requirements [12–15].

Despite growing evidence, data on the use of magnesium sulphate during laparoscopic cholecystectomy in Indian tertiary care settings remain limited. Therefore, the present study was designed to evaluate the efficacy and safety of intravenous magnesium sulphate in attenuating hemodynamic changes during laparoscopic cholecystectomy.

MATERIAL AND METHODS

A prospective comparative observational study was conducted in the Department of Anaesthesiology at a tertiary care teaching hospital over a period of 18 months after institutional ethical committee approval.

Study Population

Forty adult patients aged 18–60 years, belonging to ASA physical status I and II, scheduled for elective laparoscopic cholecystectomy under general anesthesia were enrolled.

Inclusion Criteria

• Age 18–60 years
• ASA I–II
• Elective laparoscopic cholecystectomy
• Written informed consent

Exclusion Criteria

• Patient refusal
• Severe cardiac or respiratory disease
• Renal impairment
• Known hypersensitivity to magnesium
• Electrolyte imbalance

Group Allocation

Patients were randomly divided into two equal groups (n=20):

• Group M: Magnesium sulphate 40 mg/kg diluted to 15 ml, administered over 15 minutes before induction, followed by continuous infusion at 10 mg/kg/hr.
• Group S: 15 ml of 0.9% normal saline over 15 minutes, followed by infusion at 0.1 ml/kg/hr.

Anesthetic Technique

All patients received standardized general anesthesia with intravenous induction agents, muscle relaxants, endotracheal intubation, and controlled ventilation. Pneumoperitoneum was maintained with intra-abdominal pressure of 12–14 mmHg.

Data Collection

Heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, end-tidal CO₂, and SpO₂ were recorded at baseline, post-intubation, during pneumoperitoneum at regular intervals, and postoperatively. Rescue propofol infusion was initiated if MAP increased by >25% from baseline.

Statistical Analysis

Data were analyzed using statistical software. Continuous variables were expressed as mean ± SD. Intergroup comparisons were performed using appropriate statistical tests. A p-value <0.05 was considered statistically significant.

RESULTS

Both groups were comparable with respect to age, weight, sex distribution, duration of surgery, and duration of pneumoperitoneum, with no statistically significant differences (p>0.05). This ensured baseline homogeneity between the groups.

Heart rate increased following laryngoscopy and pneumoperitoneum in both groups; however, the increase was consistently lower and more stable in the magnesium group throughout the intraoperative period. Although intergroup differences did not reach statistical significance at all time points, the overall trend indicated attenuation of sympathetic response in Group-M.

Systolic, diastolic, and mean arterial pressures showed significant increases in the saline group following pneumoperitoneum, particularly between 15 and 90 minutes. In contrast, Group M demonstrated significantly lower blood pressure values during the same period (p<0.05), indicating better hemodynamic control.

Eleven patients in the saline group developed significant hypertension requiring propofol infusion, whereas none in the magnesium group required rescue anesthetic intervention. End-tidal CO₂ increased progressively after pneumoperitoneum in both groups but remained within physiological limits, with no significant intergroup difference. Oxygen saturation remained at 100% throughout surgery in both groups.

Adverse effects related to magnesium sulphate were minimal and included mild sedation and warmth. No serious complications such as hypotension, respiratory depression, or arrhythmias were observed.

Table 1: Physical Parameters – Age and Weight

The mean age in Group M was 42.7 ± 2.31 years and in Group S was 44.6 ± 2.26 years. The mean weight in Group M was 57.65 ± 2.59 kg and in Group S was 56.85 ± 1.31 kg. The difference in mean age and weight between the two groups was not statistically significant.

Table 2: Sex Distribution

Table 3: Comparison of Duration of Surgery

The mean duration of surgery in Group M was 107 ± 4.54 minutes and in Group S was 110 ± 2.71 minutes. The duration of surgery was comparable between both groups, and no statistically significant difference was observed.

Table 4: Comparison of Duration of Pneumoperitoneum

The mean duration of pneumoperitoneum in Group M was 87 ± 4.54 minutes, while in Group S it was 88.5 ± 2.93 minutes. The difference between the two groups was not statistically significant.

Table 5: Changes in Mean Pulse Rate (beats/min) at Different Time Intervals –

Comparison Between Groups

Changes in Mean Pulse Rate

Group M:

Baseline pulse rate (PR) was 86.15 ± 1.79 beats/min. Following laryngoscopy, PR increased from 95 ± 3.02 to 100.35 ± 2.76 beats/min at 1 minute (increase of 5.63%). After initiation of pneumoperitoneum (PP), PR gradually increased from 85.3 ± 2.78 to 90.05 ± 2.49 beats/min at 35 minutes (increase of 5.57%). Thereafter, PR remained stable for the next 60 minutes. A further rise was observed after 90 minutes, reaching 101.14 ± 3.14 beats/min at 110 minutes (increase of 18.57%).

Group S:

Baseline PR was 83.5 ± 1.89 beats/min. Following laryngoscopy, PR increased from 84.7 ± 4.14 to 95.3 ± 2.97 beats/min at 2 minutes (increase of 12.51%). After pneumoperitoneum, PR showed a similar trend, with an increase of 11.9% at 35 minutes. A further increase of 14.62% was observed at 60 minutes (86.15 ± 2.69 to 98.75 ± 2.65 beats/min). PR increased further to 106.2 ± 5.83 beats/min at 120 minutes (increase of 23.04%).

The differences in PR between the groups were not statistically significant throughout the study period (p > 0.05).

Table 6: Changes in Mean Systolic Blood Pressure (mm Hg) at Different Time Intervals – Comparison Between Groups

Changes in Mean Systolic Blood Pressure

Group M:

Baseline systolic blood pressure (SBP) was 124.3 ± 3.17 mmHg. Following laryngoscopy, SBP increased from 118.9 ± 4.74 to 133.6 ± 4.58 mmHg at 1 minute (increase of 12.36%). At initiation of pneumoperitoneum, SBP was 113.9 ± 3.39 mmHg. SBP showed a rising trend with a maximum increase at 30 minutes post-PP (130.3 ± 2.68 mmHg; increase of 14.4%). SBP remained stable until 90 minutes, with a marginal rise noted between 110–130 minutes.

Group S:

Baseline SBP was 125.3 ± 2.75 mmHg. Following laryngoscopy, SBP increased from 117.55 ± 4.85 to 146.3 ± 3.95 mmHg at 1 minute (increase of 24.4%). At initiation of PP, SBP was 114.65 ± 3.16 mmHg. Following pneumoperitoneum, SBP continued to rise with a maximum increase of 34.8% at 25 minutes. The SBP was stable thereafter, possibly due to propofol infusion in many patients.

The systolic blood pressure showed a statistically significant increase in Group S compared with Group M from 15 minutes post-PP up to 110 minutes (p = 0.004).

Table 7: Changes in Mean Diastolic Blood Pressure (mm Hg) at Different Time Intervals –

 Comparison Between Groups

Changes in Mean Diastolic Blood Pressure

Group M:

Baseline diastolic blood pressure (DBP) was 79.75 ± 1.72 mmHg. Following laryngoscopy, DBP increased to 84.15 ± 2.71 mmHg at 1 minute (increase of 11.31%). At initiation of PP, DBP was 75.35 ± 2.03 mmHg. DBP gradually increased, with a rise of 9.22% at 15 minutes post-PP. DBP remained stable until 100 minutes, when a rise of 14.57% was noted.

Group S:

Baseline DBP was 80.6 ± 1.42 mmHg. Following laryngoscopy, DBP increased from 72.05 ± 2.20 to 89.15 ± 1.72 mmHg at 1 minute (increase of 23.74%). At initiation of PP, DBP was 74.9 ± 2.35 mmHg. DBP increased up to a maximum of 26.7% at 20 minutes post-PP, after which no further rise was observed.

In comparison with Group M, the rise in DBP was statistically significant in Group S from 20 minutes to 90 minutes post-PP (p = 0.004).

Table 8: Changes in Mean Arterial Pressure (mm Hg) at Different Time Intervals –

 Comparison Between Groups

CHANGESINMEANARTERIAL PRESSURE (mmIlg) AT

DIFFERENTTIMEINTERVALS-comparison between groups

Changes in Mean Arterial Pressure

Group M:

Baseline mean arterial pressure (MAP) was 94.65 ± 2.18 mmHg. Following laryngoscopy, MAP increased to 100.7 ± 3.19 mmHg at 1 minute (increase of 11.7%). MAP decreased gradually and was 88.2 ± 2.32 mmHg at initiation of PP. MAP then increased, reaching a peak of 98.25 ± 1.61 mmHg at 15 minutes post-PP. MAP remained stable until 100 minutes, with a rise observed between 100–130 minutes.

Group S:

Baseline MAP was 95.4 ± 1.77 mmHg. Following laryngoscopy, MAP increased from 86.75 ± 3.04 to 113.75 ± 6.31 mmHg at 1 minute (increase of 31.12%). At initiation of PP, MAP was 87.95 ± 2.56 mmHg. MAP increased to a maximum of 113.4 ± 1.74 mmHg at 20 minutes post-PP.

The difference in MAP between the two groups was statistically significant from 15 minutes up to 90 minutes post-PP (p = 0.004).

Table 9: Changes in Mean End-Tidal CO₂ (mm Hg) at Different Time Intervals – Comparison Between Groups

Graph No. 1: Changes in Mean End-Tidal CO₂ (mm Hg) at Different Time Intervals – Comparison Between Groups

Changes in End-Tidal CO₂

Group M:

Baseline end-tidal CO₂ (EtCO₂) at 1 minute post-intubation was 27.75 ± 0.52 mmHg. At the beginning of PP, EtCO₂ was 30.85 ± 1.12 mmHg and showed a progressive increase throughout surgery, reaching a maximum of 39.5 ± 2.33 mmHg at 120 minutes (28% increase).

Group S:

Baseline EtCO₂ was 27.15 ± 0.50 mmHg. At the beginning of PP, it was 29.3 ± 0.84 mmHg. A similar progressive increase was observed, with a maximum value of 39.17 ± 0.83 mmHg at 110 minutes (33.69%).

The changes in both groups were similar and not statistically significant (p > 0.05).

Table 10: Changes in Mean SpO₂ (%) at Different Time Intervals –

Comparison Between Groups

Changes in SpO₂

SpO₂ values showed no variation in either group following intubation and remained at 100% throughout the surgery. The changes were not statistically significant (p > 0.05).

Requirement of Propofol Infusion

In the saline group, 11 patients developed a significant increase in mean arterial pressure (>25% from baseline), necessitating the use of propofol infusion. No patient in the magnesium group required rescue propofol.

Table 11: Requirement of Propofol Infusion in Saline Group

In the saline group 11 patients had a very significant increase (+25% from baseline) in the mean arterial pressure necessitating the use of propofol infusion.

Adverse Effects of Magnesium Sulphate

Intraoperative adverse effects were minimal. Warmth and flushing were observed in 10 patients (50%), and mild sedation in 2 patients (10%). No hypotension, respiratory depression, ECG changes, or cardiac arrest were reported.

Postoperatively, headache occurred in 2 patients (10%), nausea in 1 patient, and mild sedation in 3 patients (15%). No serious adverse events were observed

Table 12: Incidence of Adverse Effects and Complications of Magnesium Sulphate

Table 13: Incidence of Adverse Effects and Complications of

 Magnesium Sulphate in the Post-Operative Period

Graph no. 2: Incidence of Adverse Effects and Complications of Magnesium Sulphate in the Post-Operative Period

DISCUSSION

The present study demonstrates that intravenous magnesium sulphate effectively attenuates hemodynamic responses associated with pneumoperitoneum during laparoscopic cholecystectomy. Magnesium’s ability to inhibit catecholamine release and reduce calcium-mediated vasoconstriction explains the observed stability in blood pressure and heart rate [9,11].

The significantly lower systolic, diastolic, and mean arterial pressures observed in the magnesium group from 15 to 90 minutes after pneumoperitoneum are consistent with findings reported by Ryu et al. and Jee et al. [13,14]. The reduced requirement for rescue propofol infusion further highlights magnesium’s anesthetic-sparing effect.

Heart rate responses were attenuated in the magnesium group, although not statistically significant, which aligns with previous studies demonstrating blunted sympathetic responses with magnesium administration [12,15]. Stable end-tidal CO₂ and SpO₂ values confirm that magnesium does not adversely affect respiratory parameters.

The safety profile of magnesium sulphate observed in this study is consistent with earlier reports showing minimal adverse effects when administered in recommended doses [16–18]. The absence of serious complications supports its routine use as an adjunct in laparoscopic anesthesia.

Overall, magnesium sulphate offers a simple, effective, and economical strategy to improve intraoperative hemodynamic stability during laparoscopic cholecystectomy.

Moreover, magnesium sulphate, being a cheaper andeasily available drug  compared  to  other  drugs  and  methods  used  for blunting     the     haemodynamic     stress     response     of pneumoperitonium can be a novel alternative [19].

CONCLUSION

Intravenous magnesium sulphate significantly attenuates hemodynamic responses to pneumoperitoneum during laparoscopic cholecystectomy, reduces anesthetic requirements, and is associated with minimal adverse effects. It is a safe and effective adjunct to general anesthesia.

Limitations of the Study

• Single-center study
• Small sample size
• Long-term postoperative outcomes not evaluated
• Results may not be generalizable to high-risk cardiac patients

Declarations:

Conflicts of interest: There is not any conflict of interest associated with this study

Consent to participate: There is  consent to participate.

Consent for publication: There is  consent for the publication of this paper.

Authors' contributions: Author equally contributed the work.

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