The study was a prospective, double-blinded, randomised clinical trial conducted at Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pune, Maharashtra, India from September 2022 to September 2024. Institutional Ethics Committee (IEC) clearance (Ref. no. IESC/404/2022) was obtained and the trial was registered with CTRI (CTRI/2023/12/060483). All participants provided written informed consent.

Inclusion criteria: Eighty haemodynamically stable patients, aged 18 to 60 years, with American Society of Anaesthesiologists (ASA) grades I or II, undergoing surgery under general anaesthesia and with normal routine investigations and willing to participate in the study, were included in the study.

Exclusion criteria: ASA grade III or higher, age outside the specified range, emergency procedures, drug allergies, anticipated difficult intubation, obesity, or significant co-morbidities were excluded from the study.

Sample size: Comparing the mean and SD of SBP at 5 minutes between the dexmedetomidine group [2] and the magnesium sulphate group [7], the values were 109.50±16.83 mmHg and 120.64±10.25 mmHg, respectively. The minimum sample size needed, at 80% power and a 5% significance level, came to be 28 in each group. However, considering the drop-out rate and the need for an effective study, 40 patients in each group of patients were taken, making the total sample size 80. The formula used for sample size calculation was two-sample t-test sample size formula.

Patients underwent preanaesthetic evaluation, including medical history, systemic examination and necessary investigations were instructed to fast for eight hours before surgery. Patients were randomised using a computer-generated random number sequence to assign them evenly across treatment groups. group A received 1 μg/kg dexmedetomidine [2] nebulisation and group B received 240 mg magnesium sulphate nebulisation [5], both diluted in normal saline to a 3 mL solution and administered over 15 minutes, ending 10 minutes before anaesthesia induction.

An independent investigator was responsible for administering nebulisation and closely monitoring haemodynamic parameters, including HR, SBP, DBP, MAP and Oxygen Saturation (SpO₂) at specific time intervals during the perioperative period. Baseline measurements were recorded prior to nebulisation, followed by subsequent recordings after nebulisation and before the induction of anaesthesia. Parameters were recorded during laryngoscopy and intubation, as well as every minute for 10 minutes following intubation. The investigator also documented the physiological response to the initial surgical skin incision and observed for adverse effects after no longer getting involved in this research.

An intravenous cannula measuring 20 G was implanted in the operating room and standard monitoring was established, including Non Invasive Blood Pressure (NIBP), SpO₂, Electrocardiogram (EKG) and End-tidal Carbon Dioxide (EtCO₂). Premedication included intravenous midazolam (20 μg/kg), fentanyl (1-2 μg/kg) and glycopyrrolate (4 μg/kg), after which 200% oxygen was used for three minutes of preoxygenation. Anaesthesia induction was achieved with propofol (2 mg/kg) and succinylcholine (2 mg/kg) for intubation, with haemodynamic parameters monitored every minute for 10 minutes postlaryngoscopy. Intubation was confirmed using EtCO₂ and bilateral air entry. Maintenance of anaesthesia involved oxygen and nitrous oxide combined (40:60), isoflurane (0.6-1%) and vecuronium (0.1 mg/kg). Ventilation was accordingly altered to keep EtCO₂ levels between 32 and 35 mm Hg. The response to skin incision was assessed through changes in HR and SBP. Following surgery, neostigmine (50 μg/kg) and glycopyrrolate (20 μg/kg) were used to reverse neuromuscular inhibition. After the patient was able to obey commands and had a Train-Of-Four (TOF) ratio of 0.9 or greater, they were extubated and taken to the Post-Anaesthesia Care Unit (PACU).

Patients were evaluated for POST at intervals of 0,2,4,6,12 and 24 hours following extubation. An anaesthesiologist, who was unaware of the study details, performed these evaluations. The assessment involved inquiring about the presence of a sore throat, pain, voice changes, or any throat discomfort. POST severity was categorised using a 4-point scale (0-3), outlined in [Table/Fig-1] [8].

Continuous variables, including age, height, weight, HR, systolic SBP, diastolic DBP, MAP and SpO₂, were expressed as mean±standard deviation and compared between the two groups using an unpaired t-test. Categorical variables, such as adverse effects, were presented as both the number and percentage of patients and comparisons between the two groups were made using Pearson’s Chi-square test for independence. Statistical analysis was performed using SPSS version 20. An alpha level of 5% was set, meaning that p-values <0.05 were considered statistically significant. Paired t-tests were employed to compare the means of continuous variables.

Eighty patients were randomly divided into two groups. The study revealed comparable demographic data between the groups, including age, gender, ASA classification and body weight [Table/Fig-2]. Haemodynamic parameters, including HR, SBP, DBP, MAP and SpO₂, were measured at 14 intervals.

Initially, group A had a significantly higher HR of 90±8.8 compared to group B, which had 84.3±8.2 (p-value=0.003). After nebulisation, HR became similar between the groups (p-value>0.05). Throughout the study, HR decreased from baseline in both groups, with no significant differences at later intervals [Table/Fig-3].

Group A presented a significantly higher SBP of 118.8±8.2 mmHg before nebulisation compared to group B 113.7±8.8 mmHg (p-value=0.009). Postnebulisation and during subsequent measurements, SBP values between groups became comparable, remaining below baseline during laryngoscopy and intubation, with no significant differences observed (p-value>0.05) [Table/Fig-4].

While group A had a slightly higher baseline DBP, it was significantly lower during laryngoscopy and intubation at 73.8±5.6 mmHg compared to group B 78.2±5.3 mmHg (p-value=0.001). This trend continued postintubation, with significant differences observed for up to 8 minutes after intubation and during skin incision responses (Group A: 74.3±6.6 mmHg vs. Group B: 79.3±5.1 mmHg, p-value<0.001) [Table/Fig-5].

Group A exhibited higher initial MAP values of 91.8±5.9 mmHg, which were statistically significant compared to group B 88.5±6.9 mmHg (p-value=0.025). During laryngoscopy, intubation and the first five minutes postintubation, group A consistently demonstrated lower MAP values than group B, with statistically significant p-values ranging from 0.008 to 0.046. However, from six minutes post-intubation through the ten-minute interval, the differences in MAP between the two groups were no longer statistically significant, with p-values ranging from 0.058 to 0.521 [Table/Fig-6].

Both groups maintained SpO₂ levels above 98%, with no significant differences throughout the study (p-value>0.05). Postoperatively, a lower incidence of sore throat was noted in Group A, with only one patient (2.5%) reporting symptoms at four hours compared to two patients (5%) at four and six hours in group B. However, this difference was not statistically significant (p-value=0.36), indicating a low overall incidence of POST [Table/Fig-7].

The study compared 80 patients, equally divided into two groups undergoing elective surgery under general anaesthesia. Preoperatively, group A was nebulised with dexmedetomidine (1 μg/kg), while group B received nebulised magnesium sulphate (240 mg). The haemodynamic response to laryngoscopy and intubation was noted and incidence of POST was also compared. Both groups showed comparable HR and SBP throughout the study after the initial measurements. However, the dexmedetomidine group exhibited significantly lower MAP and DBP during laryngoscopy and intubation and at various time intervals after intubation. The results were comparable to various studies, including the study performed by Grover N et al., where a comparison was done between nebulised fentanyl, dexmedetomidine and magnesium sulphate for attenuating the haemodynamic response to laryngoscopy and intubation. It concluded that dexmedetomidine and magnesium led to a more significant reduction in pressor response after intubation [9].

In another study comparing nebulised magnesium sulphate with normal saline, conducted by Elmeligy M and Elmeliegy M, it was concluded that preoperative nebulisation with magnesium sulphate effectively attenuates the stress response to endotracheal intubation [5]. The study by Paul NS et al., revealed that nebulised dexmedetomidine effectively blunted the increase in HR and blood pressure associated with laryngoscopy and intubation [10]. The systematic review and meta-analysis by Gupta M et al., examined the effectiveness of nebulised dexmedetomidine in attenuating the haemodynamic response to laryngoscopy and intubation, concluded that nebulised dexmedetomidine significantly reduces HR and blood pressure during these procedures [11].

The current study suggests a lower DBP and MAP at various time intervals, including during laryngoscopy and intubation and even response to skin incision, can be attributed to the centrally acting, alpha-2 agonistic action of dexmedetomidine, leading to a sympatholytic response [9]. In this study, the overall incidence of POST was lower in the dexmedetomidine group compared to the magnesium sulphate group, but this difference was statistically non significant. The results were comparable with a study conducted by Yadav M et al., who concluded that nebulisation with magnesium sulphate significantly reduces the incidence and severity of POST compared to a control group [4]. Another study by Thomas D et al., also showed similar results while investigating the efficacy of nebulised dexmedetomidine in reducing POST in patients undergoing thyroidectomy, comparing it with nebulised ketamine [8]. The results demonstrated that dexmedetomidine significantly decreased both the incidence and severity of POST compared to ketamine.

A key limitation of this study was the absence of a control group, which would have provided a baseline comparison for evaluating the efficacy of nebulised dexmedetomidine and magnesium sulphate more robustly. Further studies incorporating a control group would offer a more detailed assessment and clearer evidence of the relative benefits of dexmedetomidine and magnesium sulphate.

The study demonstrated that both nebulised dexmedetomidine and magnesium sulphate effectively decreased the sympathetic responses associated with laryngoscopy and intubation, though the dexmedetomidine group showed a statistically significant decrease in DBP and MAP, which can be attributed to its highly specific alpha-2 adrenergic agonistic action. Both groups experienced a lower incidence of POST, indicating that these interventions may help enhance recovery after surgery. Importantly, there were no reported side-effects in either group, suggesting that both agents are safe for use in this context.