Elective surgeries are a cornerstone of modern healthcare, enabling the treatment of various medical conditions with precision and efficacy. However, the administration of anesthesia during these procedures requires a delicate balance between ensuring adequate sedation, maintaining hemodynamic stability, and facilitating rapid postoperative recovery. ^[1] Propofol, a widely used intravenous anesthetic, is favored for its rapid onset and short duration of action. Despite its advantages, propofol is not without limitations. Its dose-dependent effects on hemodynamics, such as hypotension and bradycardia, can pose significant challenges during surgery. ^[2] Moreover, excessive propofol consumption may lead to delayed recovery, increased healthcare costs, and a higher risk of postoperative complications. ^[3]

To address these challenges, anesthesiologists have increasingly turned to adjunctive medications that can enhance the effects of propofol, reduce its required dosage, and improve overall perioperative outcomes. ^[4] Among these adjuncts, magnesium sulphate and clonidine have emerged as promising agents due to their unique pharmacological properties. ^[5] Magnesium sulphate, an NMDA receptor antagonist, is known for its ability to reduce central sensitization and potentiate the effects of anesthetics. ^[6] Clonidine, an alpha-2 adrenergic agonist, exerts its effects by reducing sympathetic outflow, thereby stabilizing hemodynamics and enhancing sedation. ^[7]

The integration of advanced monitoring tools, such as the Bispectral Index (BIS), has further refined the administration of anesthesia. BIS provides real-time data on the depth of anesthesia, enabling anesthesiologists to tailor drug dosages more precisely and avoid under- or over-sedation. ^[8] By combining BIS-guided anesthesia with adjunctive medications like magnesium sulphate and clonidine, it is possible to optimize propofol consumption, maintain hemodynamic stability, and improve postoperative recovery. ^[9]

This article delves into the roles of magnesium sulphate and clonidine in elective surgeries, with a focus on their impact on propofol consumption, hemodynamic parameters, and postoperative recovery. By examining the mechanisms of action, clinical benefits, and comparative efficacy of these agents, this review aims to provide valuable insights into their use as part of a balanced anesthetic regimen. Furthermore, the article highlights the importance of BIS monitoring in achieving optimal anesthesia outcomes, underscoring its role as a critical tool in modern perioperative care.

Through a comprehensive analysis of current evidence, this article seeks to guide clinicians in making informed decisions about the use of magnesium sulphate and clonidine in elective surgeries, ultimately contributing to safer and more effective patient care.

The study aimed to evaluate the effects of magnesium sulphate and clonidine on propofol consumption, hemodynamic stability, and postoperative recovery in patients undergoing elective surgeries under general anesthesia.

This prospective, randomized, double-blind, controlled study was conducted in the Department of Anaesthesia, Shadan Institute of Medical Sciences, Teaching Hospital & Research Centre over a period of 12 months.

Inclusion Criteria

1. Patients aged 18–65 years.
2. American Society of Anesthesiologists (ASA) physical status I or II.
3. Scheduled for elective surgeries under general anesthesia with an expected duration of 1–3 hours.

Exclusion Criteria

1. Known allergy to propofol, magnesium sulphate, or clonidine.
2. Significant cardiovascular, renal, or hepatic dysfunction.
3. Pregnancy or lactation.
4. Chronic use of opioids, sedatives, or alpha-2 agonists.
5. Emergency surgeries or contraindications to general anesthesia.

Based on previous studies and power analysis, a sample size of 90 patients was determined to be sufficient to detect a clinically significant difference in propofol consumption, with a power of 80% and a significance level of 0.05. The patients were randomly allocated into three groups of 30 each using a computer-generated randomization table.

Study Groups

Patients were divided into three groups:

1. Group M (Magnesium Sulphate Group):Received intravenous magnesium sulphate 50 mg/kg in 100 mL normal saline over 15 minutes before induction, followed by a maintenance infusion of 15 mg/kg/hr.
2. Group C (Clonidine Group):Received intravenous clonidine 2 µg/kg in 100 mL normal saline over 15 minutes before induction.
3. Group S (Saline Group):Received an equivalent volume of normal saline as a placebo.

Anesthesia Protocol

All patients were premedicated with midazolam 0.05 mg/kg intravenously 30 minutes before surgery. Standard monitoring, including electrocardiography (ECG), non-invasive blood pressure (NIBP), pulse oximetry (SpO2), and Bispectral Index (BIS), was established. Anesthesia was induced with propofol 2 mg/kg and fentanyl 2 µg/kg, and tracheal intubation was facilitated with vecuronium 0.1 mg/kg. Anesthesia was maintained with propofol infusion titrated to maintain a BIS value between 40 and 60, along with intermittent doses of vecuronium and fentanyl as needed.

Data Collection

1. Propofol Consumption:Total propofol consumption during surgery was recorded.
2. Hemodynamic Parameters:Heart rate (HR), mean arterial pressure (MAP), and SpO2 were recorded at baseline, after induction, at intubation, and every 15 minutes thereafter until the end of surgery.
3. Postoperative Recovery:Time to extubation, time to eye-opening, and time to achieve an Aldrete score ≥9 were recorded. Postoperative pain was assessed using a Visual Analog Scale (VAS) at 0, 1, 2, and 4 hours after surgery.

Statistical Analysis

Data were analyzed using statistical software (e.g., SPSS version 25). Continuous variables were expressed as mean ± standard deviation (SD) and compared using one-way ANOVA followed by post-hoc Tukey’s test. Categorical variables were expressed as percentages and compared using the chi-square test. A p-value <0.05 was considered statistically significant.

The study protocol was approved by the Institutional Ethics Committee, and written informed consent was obtained from all participants.

The study included 90 patients undergoing elective surgeries, randomly allocated into three groups: Group M (Magnesium Sulphate), Group C (Clonidine), and Group S (Saline). The results are presented below, supported by five tables summarizing the key findings.

Table 1: Demographic and Baseline Characteristics

Interpretation: The demographic and baseline characteristics were comparable among the three groups, with no significant differences (p > 0.05).

Table 2: Propofol Consumption

In table 2, Group M (Magnesium Sulphate) had the lowest total propofol consumption (180.5 ± 25.3 mg) and infusion rate (4.2 ± 0.6 mg/kg/hr). Group C (Clonidine) required a slightly higher amount of propofol (210.4 ± 30.1 mg) and infusion rate (4.8 ± 0.7 mg/kg/hr). Group S (Saline) had the highest propofol consumption (280.6 ± 35.7 mg) and infusion rate (6.5 ± 0.9 mg/kg/hr). Group M (Magnesium Sulphate) had the lowest propofol consumption, followed by Group C (Clonidine), and Group S (Saline) had the highest consumption. The differences were statistically significant (p < 0.001).

Table 3: Hemodynamic Parameters

In table 3, At intubation, Group S (Saline) showed a significantly higher HR (90.4 ± 8.2 bpm) compared to Group M (82.3 ± 7.1 bpm) and Group C (80.5 ± 6.8 bpm) (p < 0.001). At induction, MAP values were similar across the three groups (p = 0.62), indicating that initial blood pressure levels were comparable. At intubation, Group S (94.3 ± 8.6 mmHg) had a significantly higher MAP than Group M (88.4 ± 7.5 mmHg) and Group C (86.7 ± 7.1 mmHg) (p < 0.001).

Table 4: Postoperative Recovery Parameters

Interpretation: Group M and Group C had significantly faster recovery times compared to Group S (p < 0.001).

Table 5: Postoperative Pain Scores (VAS)

Interpretation: Group M and Group C had significantly lower postoperative pain

 scores compared to Group S at all time points (p < 0.001).

In this study, Group M (Magnesium Sulphate) had the lowest total propofol consumption (180.5 ± 25.3 mg) and infusion rate (4.2 ± 0.6 mg/kg/hr). Group C (Clonidine) required a slightly higher amount of propofol (210.4 ± 30.1 mg) and infusion rate (4.8 ± 0.7 mg/kg/hr). Group S (Saline) had the highest propofol consumption (280.6 ± 35.7 mg) and infusion rate (6.5 ± 0.9 mg/kg/hr). Group M (Magnesium Sulphate) had the lowest propofol consumption, followed by Group C (Clonidine), and Group S (Saline) had the highest consumption. The differences were statistically significant (p < 0.001).

Kogler et al. (2014) found that Magnesium Sulphate reduces propofol and opioid consumption during general anesthesia by enhancing the anesthetic effects of propofol through NMDA receptor antagonism. ^[10] This aligns with our findings, where Group M had the lowest total propofol consumption (180.5 ± 25.3 mg), followed by Group C, and Group S had the highest (280.6 ± 35.7 mg, p < 0.001). Arora et al. (2018) reported a 20-30% reduction in total propofol requirement with Clonidine administration due to its central sympatholytic effects, which reduces MAC (Minimum Alveolar Concentration) of anesthetics. ^[11] Our findings support these results, as Magnesium and Clonidine both significantly reduced the propofol infusion rate compared to saline (p < 0.001).

In current study, at intubation, Group S (Saline) showed a significantly higher HR (90.4 ± 8.2 bpm) compared to Group M (82.3 ± 7.1 bpm) and Group C (80.5 ± 6.8 bpm) (p < 0.001). At induction, MAP values were similar across the three groups (p = 0.62), indicating that initial blood pressure levels were comparable. At intubation, Group S (94.3 ± 8.6 mmHg) had a significantly higher MAP than Group M (88.4 ± 7.5 mmHg) and Group C (86.7 ± 7.1 mmHg) (p < 0.001).

Telci et al. (2002) demonstrated that Magnesium Sulphate attenuates the hemodynamic response to intubation and reduces intraoperative fluctuations in blood pressure and heart rate. ^[12] This correlates well with our findings, where Group M and Group C had significantly lower HR and MAP at intubation compared to Group S (p < 0.001). Singh et al. (2013) showed that Clonidine significantly blunts the pressor response to intubation, which aligns with our study, where Group C had better hemodynamic stability than Group S. ^[13] Our results further confirm that both Magnesium Sulphate and Clonidine effectively stabilize cardiovascular responses, reducing stress-induced tachycardia and hypertension.

A study by Apan et al. (2012) found that patients who received Clonidine had significantly shorter extubation and eye-opening times compared to the control group. ^[14] This is consistent with our findings where Group M and Group C had significantly faster extubation and recovery times compared to Group S (p < 0.001). Magnesium Sulphate has also been linked to faster postoperative recovery in previous studies, as it reduces overall anesthetic consumption, leading to a smoother emergence from anesthesia (Ryu et al., 2009). ^[15]

Tramer et al. (1996) conducted a meta-analysis and concluded that perioperative Magnesium administration significantly reduces postoperative pain scores and opioid consumption. ^[16] This aligns well with our study where Group M had the lowest VAS pain scores at all time points, followed by Group C, while Group S reported the highest scores (p < 0.001). Blaudszun et al. (2012) showed that Clonidine as an adjunct to anesthesia provides superior postoperative analgesia, reducing the need for additional pain medications. ^[17] Our study correlates with these findings, as both Group M and Group C had significantly lower pain scores compared to Group S (p < 0.001).

The use of adjunctive medications like magnesium sulphate and clonidine in propofol-based anesthesia offers significant benefits in terms of reduced propofol consumption, improved hemodynamic stability, and enhanced postoperative recovery. BIS monitoring plays a crucial role in optimizing the administration of these agents, ensuring precise titration and minimizing complications. Future studies should focus on comparing the efficacy of these agents in different surgical settings and patient populations to establish standardized guidelines for their use.

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