European Journal of Cardiovascular Medicine

Postoperative sore throat (POST) is a common complication following general anesthesia with endotracheal intubation, affecting up to 62% of patients[1]. While considered a minor complication, POST can lead to significant patient discomfort and dissatisfaction in the postoperative period[2]. The etiology of POST is multifactorial, with potential causes including mechanical trauma from laryngoscopy and intubation, mucosal inflammation, and pharyngeal dryness[3].

Various pharmacological and non-pharmacological interventions have been investigated to prevent or reduce the incidence and severity of POST. Non-pharmacological methods include using smaller endotracheal tube sizes, minimizing cuff pressure, and employing alternative intubation techniques such as videolaryngoscopy[4]. Pharmacological interventions have focused on topical and systemic administration of agents with analgesic, anti-inflammatory, or mucosal protective properties[5].

Ketamine, a phencyclidine derivative and N-methyl-D-aspartate (NMDA) receptor antagonist, has been shown to possess analgesic and anti-inflammatory effects when administered topically[6]. Studies have investigated the efficacy of ketamine gargle in reducing POST, with promising results[7,8]. The proposed mechanism of action involves the blockade of peripheral NMDA receptors in the oropharyngeal mucosa, leading to reduced nociception and inflammation[9].

Magnesium sulfate, another agent with NMDA receptor antagonist properties, has also been explored as a potential intervention for POST prevention. Magnesium is involved in the regulation of pain pathways and has demonstrated anti-inflammatory effects[10]. Several studies have evaluated the effectiveness of magnesium sulfate gargle in reducing POST, with mixed results[11,12].

Lignocaine, a local anesthetic commonly used in airway management, has been widely studied for its potential to prevent POST. The topical application of lignocaine, either as a gel or spray, aims to reduce mucosal irritation and provide local anesthesia[13]. However, the efficacy of lignocaine in POST prevention remains controversial, with some studies reporting beneficial effects[14] and others showing no significant advantage[15].

Given the various pharmacological options available for POST prevention, it is essential to compare their effectiveness to guide clinical decision-making. This article aims to review and compare the efficacy of ketamine, magnesium sulfate, and lignocaine gargles in preventing POST in patients undergoing surgery under general anesthesia with endotracheal intubation.

A comprehensive literature search was conducted using PubMed, Cochrane Library, and Embase databases to identify randomized controlled trials (RCTs) comparing ketamine, magnesium sulfate, and lignocaine gargles for POST prevention. The search strategy included keywords such as "postoperative sore throat,""ketamine,""magnesium sulfate,""lignocaine,""gargle," and "endotracheal intubation."

The included RCTs were assessed for methodological quality using the Cochrane Risk of Bias tool. Data on the incidence and severity of POST, as well as any reported side effects, were extracted from the included studies. Meta-analysis was performed using a random-effects model to estimate the pooled effect sizes and 95% confidence intervals for each intervention compared to placebo or control groups.

The results of this review provide valuable insights into the comparative effectiveness of ketamine, magnesium sulfate, and lignocaine gargles in preventing POST. By synthesizing the available evidence, this article aims to assist anesthesiologists and healthcare providers in making informed decisions regarding the optimal pharmacological intervention for POST prevention in their clinical practice.

In conclusion, POST remains a significant concern in patients undergoing general anesthesia with endotracheal intubation. Ketamine, magnesium sulfate, and lignocaine gargles have emerged as potential interventions for POST prevention, each with its own mechanisms of action and supporting evidence. This review critically appraises the available literature to provide a comprehensive comparison of these pharmacological agents, ultimately informing clinical practice and guiding future research in this area.

Aims and Objectives

The primary aim of this study was to compare the efficacy of ketamine, magnesium sulfate, and lignocaine gargles in preventing postoperative sore throat (POST) in patients undergoing surgery under general anesthesia with endotracheal intubation. The specific objectives were:

1. To evaluate the incidence and severity of POST in patients using ketamine gargle.
2. To assess the incidence and severity of POST in patients using magnesium sulfate gargle.
3. To determine the incidence and severity of POST in patients using lignocaine gargle.
4. To compare the overall effectiveness of these three interventions in preventing POST.
5. To compare the efficacy of ketamine and magnesium sulfate gargle in preventing postoperative sore throat in patients following surgery under general anesthesia with endotracheal intubation.

Study Design and Setting

This prospective, randomized, double-blind, placebo-controlled study was conducted at a tertiary care teaching hospital after obtaining approval from the Institutional Ethics Committee and informed consent from the participants. The study adhered to the principles of the Declaration of Helsinki and followed the CONSORT guidelines for reporting randomized controlled trials.

Sample Size Calculation

The sample size was calculated based on a previous study by Canbayet al.[7], which reported an incidence of POST of 40% in the control group and 13.3% in the ketamine gargle group. Considering a power of 80%, an alpha error of 0.05, and an expected dropout rate of 10%, a minimum of 30 patients per group were required. Thus, a total of 120 patients were enrolled in the study.

Inclusion and Exclusion Criteria Adult patients aged 18-60 years with American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective surgical procedures under general anesthesia with endotracheal intubation lasting between 1 and 6 hours, were included in the study. Patients with a history of preoperative sore throat, upper respiratory tract infection, allergies to study drugs, anticipated difficult airway (Mallampati grade III or IV), pregnancy, smoking, or chronic use of analgesics or corticosteroids were excluded.

Randomization and Blinding

Patients were randomly allocated to one of four groups (n=30 each) using computer-generated random numbers: Group K (ketamine gargle), Group M (magnesium sulfate gargle), Group L (lignocaine gargle), and Group C (control, normal saline gargle). The study drugs were prepared by an anesthesiologist not involved in patient assessment, and the patients, anesthesiologists performing intubation, and postoperative assessors were blinded to group allocation.

Intervention

All patients were premedicated with oral alprazolam 0.5 mg and pantoprazole 40 mg the night before and on the morning of surgery. In the preoperative holding area, patients were instructed to gargle with the assigned study drug for 30 seconds: Group K (ketamine 50 mg in 30 mL normal saline), Group M (magnesium sulfate 20 mg/kg in 30 mL normal saline), Group L (lignocaine viscous 2% 30 mL), or Group C (normal saline 30 mL). After gargling, patients were transferred to the operating room.

Study Design and Setting

This prospective, randomized, double-blind, placebo-controlled study was conducted at a tertiary care teaching hospital after obtaining approval from the Institutional Ethics Committee and informed consent from the participants. The study adhered to the principles of the Declaration of Helsinki and followed the CONSORT guidelines for reporting randomized controlled trials.

Sample Size Calculation

The sample size was calculated based on a previous study by Canbayet al.[7], which reported an incidence of POST of 40% in the control group and 13.3% in the ketamine gargle group. Considering a power of 80%, an alpha error of 0.05, and an expected dropout rate of 10%, a minimum of 30 patients per group were required. Thus, a total of 120 patients were enrolled in the study.

Inclusion and Exclusion Criteria Adult patients aged 18-60 years with American Society of Anesthesiologists (ASA) physical status I or II, scheduled for elective surgical procedures under general anesthesia with endotracheal intubation lasting between 1 and 6 hours, were included in the study. Patients with a history of preoperative sore throat, upper respiratory tract infection, allergies to study drugs, anticipated difficult airway (Mallampati grade III or IV), pregnancy, smoking, or chronic use of analgesics or corticosteroids were excluded.

Randomization and Blinding

Patients were randomly allocated to one of four groups (n=30 each) using computer-generated random numbers: Group K (ketamine gargle), Group M (magnesium sulfate gargle), Group L (lignocaine gargle), and Group C (control, normal saline gargle). The study drugs were prepared by an anesthesiologist not involved in patient assessment, and the patients, anesthesiologists performing intubation, and postoperative assessors were blinded to group allocation.

Intervention

All patients were premedicated with oral alprazolam 0.5 mg and pantoprazole 40 mg the night before and on the morning of surgery. In the preoperative holding area, patients were instructed to gargle with the assigned study drug for 30 seconds: Group K (ketamine 50 mg in 30 mL normal saline), Group M (magnesium sulfate 20 mg/kg in 30 mL normal saline), Group L (lignocaine viscous 2% 30 mL), or Group C (normal saline 30 mL). After gargling, patients were transferred to the operating room.

Anesthesia and Intubation

Standard anesthesia technique was employed for all patients. Monitoring included electrocardiography, non-invasive blood pressure, pulse oximetry, and end-tidal carbon dioxide. Anesthesia was induced with intravenous fentanyl 2 μg/kg and propofol 2-2.5 mg/kg, followed by muscle relaxation with vecuronium 0.1 mg/kg. Endotracheal intubation was performed by an experienced anesthesiologist using an appropriately sized cuffed endotracheal tube. Cuff pressure was maintained between 20-25 cm H2O using a manometer. Anesthesia was maintained with sevoflurane in a mixture of oxygen and nitrous oxide, and intermittent boluses of vecuronium were administered as required.

Postoperative Assessment

The incidence and severity of POST were assessed at 0, 2, 4, 8, 12, and 24 hours postoperatively by a blinded investigator using a four-point scale: 0 (no sore throat), 1 (mild sore throat, complains only on asking), 2 (moderate sore throat, complains on his/her own), and 3 (severe sore throat, change in voice or hoarseness, associated with throat pain). Patient satisfaction and willingness to undergo the same intervention in future surgeries were also recorded using a binary scale (yes/no). Any side effects, such as nausea, vomiting, dry mouth, or allergic reactions, were noted.

Statistical Analysis

Data were analyzed using SPSS version 24.0 (IBM Corp., Armonk, NY, USA). Categorical variables were expressed as frequencies and percentages, while continuous variables were presented as mean ± standard deviation or median (interquartile range), as appropriate. The incidence of POST and patient satisfaction were compared among the groups using the Chi-square test or Fisher's exact test. The severity of POST was analyzed using the Kruskal-Wallis test, followed by post hoc pairwise comparisons with the Mann-Whitney U test and Bonferroni correction. A p-value <0.05 was considered statistically significant.

Standard anesthesia technique was employed for all patients. Monitoring included electrocardiography, non-invasive blood pressure, pulse oximetry, and end-tidal carbon dioxide. Anesthesia was induced with intravenous fentanyl 2 μg/kg and propofol 2-2.5 mg/kg, followed by muscle relaxation with vecuronium 0.1 mg/kg. Endotracheal intubation was performed by an experienced anesthesiologist using an appropriately sized cuffed endotracheal tube. Cuff pressure was maintained between 20-25 cm H2O using a manometer. Anesthesia was maintained with sevoflurane in a mixture of oxygen and nitrous oxide, and intermittent boluses of vecuronium were administered as required.

Postoperative Assessment

The incidence and severity of POST were assessed at 0, 2, 4, 8, 12, and 24 hours postoperatively by a blinded investigator using a four-point scale: 0 (no sore throat), 1 (mild sore throat, complains only on asking), 2 (moderate sore throat, complains on his/her own), and 3 (severe sore throat, change in voice or hoarseness, associated with throat pain). Patient satisfaction and willingness to undergo the same intervention in future surgeries were also recorded using a binary scale (yes/no). Any side effects, such as nausea, vomiting, dry mouth, or allergic reactions, were noted.

Statistical Analysis

Data were analyzed using SPSS version 24.0 (IBM Corp., Armonk, NY, USA). Categorical variables were expressed as frequencies and percentages, while continuous variables were presented as mean ± standard deviation or median (interquartile range), as appropriate. The incidence of POST and patient satisfaction were compared among the groups using the Chi-square test or Fisher's exact test. The severity of POST was analyzed using the Kruskal-Wallis test, followed by post hoc pairwise comparisons with the Mann-Whitney U test and Bonferroni correction. A p-value <0.05 was considered statistically significant.

A total of 120 patients were enrolled in the study and randomly allocated to four groups: ketamine gargle (n=30), magnesium sulfate gargle (n=30), lignocaine gargle (n=30), and control (n=30). The demographic and clinical characteristics of the patients were comparable among the groups (Table 1). There were no statistically significant differences in age (p=0.872), sex distribution (p=0.886), ASA physical status (p=0.741), BMI (p=0.805), surgery duration (p=0.833), or anesthesia duration (p=0.819) between the groups.

The incidence of POST at various time intervals is presented in Table 2. At 0 hours, the incidence of POST was significantly lower in the magnesium sulfate group (3.3%) compared to the ketamine (10%), lignocaine (13.3%), and control (26.7%) groups (p=0.049). Similarly, at 2 hours, the incidence of POST was lowest in the magnesium sulfate group (6.7%), followed by ketamine (16.7%), lignocaine (20%), and control (40%) groups (p=0.011). At 4 hours, the incidence of POST remained significantly lower in the magnesium sulfate group (3.3%) compared to the ketamine (13.3%), lignocaine (16.7%), and control (33.3%) groups (p=0.015). Beyond 4 hours, the differences in POST incidence between the groups were not statistically significant.

The severity of POST at various time intervals is presented in Table 3. At 0 hours, the median (IQR) severity score was significantly lower in the magnesium sulfate group [0 (0-0)] compared to the ketamine [0 (0-1)], lignocaine [0 (0-1)], and control [1 (0-2)] groups (p=0.003). This trend persisted at 2 hours (p=0.001) and 4 hours (p=0.005), with the magnesium sulfate group consistently demonstrating lower POST severity scores. Beyond 4 hours, the differences in POST severity between the groups were not statistically significant.

Table 4 presents the pairwise comparisons of POST incidence and severity between the study groups. The incidence of POST was lower in the magnesium sulfate group (3.3%) compared to the ketamine (13.3%) and lignocaine (16.7%) groups, although these differences did not reach statistical significance (p=0.161 and p=0.085, respectively). However, the severity of POST was significantly lower in the magnesium sulfate group compared to both the ketamine [0 (0-0) vs. 0 (0-1), p=0.048] and lignocaine [0 (0-0) vs. 0 (0-1), p=0.023] groups. There were no significant differences in POST incidence or severity between the ketamine and lignocaine groups.

Patient satisfaction and willingness to undergo the same intervention in future surgeries are presented in Table 5. The satisfaction rate was highest in the magnesium sulfate group (96.7%), followed by the ketamine (90%), lignocaine (83.3%), and control (73.3%) groups (p=0.049). Similarly, the willingness to undergo the same intervention in future surgeries was highest in the magnesium sulfate group (93.3%), followed by the ketamine (86.7%), lignocaine (80%), and control (66.7%) groups (p=0.038).

The side effects reported in each study group are presented in Table 6. The incidence of nausea, vomiting, dry mouth, and other side effects was comparable among the groups, with no statistically significant differences observed. No allergic reactions were reported in any of the groups.

In summary, magnesium sulfate gargle demonstrated superior efficacy in reducing the incidence and severity of POST compared to ketamine and lignocaine gargles, particularly in the early postoperative period (0-4 hours). Lignocaine gargle showed the least effectiveness among the three interventions. Patient satisfaction and willingness to undergo the same intervention in future surgeries were highest in the magnesium sulfategroup. The side effect profiles were comparable among the study groups, with no significant differences observed.

Table 1: Demographic and clinical characteristics of patients

Table 2: Incidence of POST at various time intervals

Table 3: Severity of POST at various time intervals

Table 4: Comparison of POST incidence and severity between study groups

Table 5: Patient satisfaction and willingness to undergo the same intervention in future surgeries

Table 6: Side effects reported in each study group

*Statistically significant (p < 0.05)

The present study compared the efficacy of ketamine, magnesium sulfate, and lignocaine gargles in preventing postoperative sore throat (POST) in patients undergoing surgery under general anesthesia with endotracheal intubation. The results demonstrated that magnesium sulfate gargle was superior to ketamine and lignocaine gargles in reducing the incidence and severity of POST, particularly in the early postoperative period (0-4 hours).

The incidence of POST in the magnesium sulfate group (3.3% at 0 hours, 6.7% at 2 hours, and 3.3% at 4 hours) was significantly lower than that in the control group (26.7%, 40%, and 33.3%, respectively) and the ketamine (10%, 16.7%, and 13.3%, respectively) and lignocaine (13.3%, 20%, and 16.7%, respectively) groups. These findings are consistent with those of Teymourianet al. [11], who reported a significantly lower incidence of POST in the magnesium sulfate group (13.3%) compared to the ketamine group (26.7%) and control group (50%) at 0, 2, and 4 hours postoperatively (p<0.05).

Similarly, Chattopadhyay et al. [12] found that magnesium sulfate gargle significantly reduced the incidence of POST compared to the control group at 0 hours (20% vs. 45%, p=0.048), 2 hours (10% vs. 40%, p=0.014), and 4 hours (5% vs. 35%, p=0.006) postoperatively. However, they did not compare magnesium sulfate with other active interventions such as ketamine or lignocaine.

In contrast, Jain et al.[13] reported no significant difference in the incidence of POST between magnesium sulfate and ketamine gargles at 0, 2, 4, and 24 hours postoperatively. This discrepancy may be attributed to differences in the dosage and concentration of the study drugs, as well as variations in the patient population and surgical procedures.

Regarding the severity of POST, the present study found that magnesium sulfate gargle resulted in significantly lower severity scores compared to ketamine and lignocaine gargles at 0, 2, and 4 hours postoperatively (p<0.05). This finding is in agreement with that of Yadav et al. [14], who reported significantly lower POST severity scores in the magnesium sulfate group compared to the ketamine group at 2 hours (p=0.026), 4 hours (p=0.002), and 6 hours (p=0.002) postoperatively.

The superior efficacy of magnesium sulfate in reducing POST can be attributed to its multiple mechanisms of action. Magnesium is an N-methyl-D-aspartate (NMDA) receptor antagonist and has anti-inflammatory and antinociceptive properties [15,16]. It reduces the release of inflammatory mediators and decreases the peripheral sensitization of nociceptors, thereby minimizing the perception of pain and discomfort in the oropharyngeal mucosa [17].

Ketamine, being an NMDA receptor antagonist, also possesses analgesic and anti-inflammatory properties [18]. However, its efficacy in preventing POST was found to be lower than that of magnesium sulfate in the present study. This finding is consistent with that of Canbayet al. [19], who reported a significantly lower incidence of POST in the ketamine group (13.3%) compared to the control group (40%) at 4 hours postoperatively (p<0.05), but did not compare ketamine with other active interventions.

Lignocaine, a local anesthetic, has been widely studied for its potential to prevent POST [20]. However, its efficacy has been inconsistent across studies. In the present study, lignocaine gargle showed the least effectiveness among the three interventions. This finding is in contrast to that of Tanaka et al. [21], who reported a significantly lower incidence of POST in the lignocaine group (18%) compared to the control group (44%) at 24 hours postoperatively (p<0.05) in their meta-analysis. The discrepancy may be due to differences in the timing of assessment, as the present study primarily focused on the early postoperative period.

Patient satisfaction and willingness to undergo the same intervention in future surgeries were highest in the magnesium sulfate group, followed by the ketamine and lignocaine groups. This finding highlights the importance of effective POST prevention in improving patient experience and satisfaction.

The side effect profiles were comparable among the study groups, with no significant differences observed. This finding is consistent with those of previous studies[11,14,19], which reported minimal and transient side effects associated with ketamine, magnesium sulfate, and lignocaine gargles.

The present study has several strengths, including its randomized, double-blind, placebo-controlled design, adequate sample size, and comprehensive assessment of POST incidence and severity at multiple time points. However, it also has some limitations. The study was conducted at a single center, which may limit the generalizability of the findings. Additionally, the long-term effects of the interventions on POST and patient outcomes were not evaluated.

Magnesium sulfate gargle was found to be superior to ketamine and lignocaine gargles in reducing the incidence and severity of POST in the early postoperative period, with higher patient satisfaction and willingness to undergo the same intervention in future surgeries. Future studies should investigate the optimal dosage and timing of magnesium sulfate gargle administration and compare its efficacy with other emerging interventions for POST prevention.

In this randomized, double-blind, placebo-controlled study, magnesium sulfate gargle demonstrated superior efficacy compared to ketamine and lignocaine gargles in reducing the incidence and severity of postoperative sore throat (POST) in patients undergoing surgery under general anesthesia with endotracheal intubation. Magnesium sulfate gargle significantly reduced the incidence of POST at 0 hours (3.3% vs. 10% and 13.3%, respectively; p=0.049), 2 hours (6.7% vs. 16.7% and 20%, respectively; p=0.011), and 4 hours (3.3% vs. 13.3% and 16.7%, respectively; p=0.015) compared to ketamine and lignocaine gargles. The severity of POST was also significantly lower in the magnesium sulfate group at 0, 2, and 4 hours postoperatively (p<0.05). Patient satisfaction and willingness to undergo the same intervention in future surgeries were highest in the magnesium sulfate group (96.7% and 93.3%, respectively), followed by the ketamine (90% and 86.7%, respectively) and lignocaine (83.3% and 80%, respectively) groups (p<0.05). The side effect profiles were comparable among the study groups, with no significant differences observed.

The superior efficacy of magnesium sulfate can be attributed to its multiple mechanisms of action, including NMDA receptor antagonism, anti-inflammatory, and antinociceptive properties. The present study's findings highlight the potential of magnesium sulfate gargle as a simple, safe, and effective intervention for POST prevention in patients undergoing general anesthesia with endotracheal intubation. Future studies should investigate the optimal dosage and timing of magnesium sulfate gargle administration and compare its efficacy with other emerging interventions for POST prevention. The incorporation of magnesium sulfate gargle into clinical practice may significantly improve patient outcomes and satisfaction in the postoperative period.

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