European Journal of Cardiovascular Medicine

Postoperative sore throat (POST) is one of the most common and distressing complications following general anesthesia with endotracheal intubation1,2. The incidence of POST ranges from 21% to 65%, depending on factors such as airway management techniques, patient characteristics, and the nature of the surgery. While POST is generally considered a minor complication, its impact on patient comfort and recovery can be significant. Symptoms of POST include laryngitis, hoarseness, cough, and throat pain, which can last from a few hours to several days, causing discomfort during the immediate postoperative period3,4.

Several strategies, both pharmacological and non-pharmacological, have been employed to mitigate POST. Non-pharmacological interventions include using smaller-sized endotracheal tubes, proper cuff management, and careful airway instrumentation5,6. However, these approaches do not always effectively prevent POST. On the other hand, pharmacological measures, such as the use of steroids, local anesthetics, and gargles with various agents, have shown some promise in reducing the severity of POST.

Ketamine and magnesium sulfate, both of which are NMDA (N-methyl-D-aspartate) receptor antagonists, have emerged as potential candidates for reducing POST. Ketamine has well-documented analgesic properties, particularly through its action on NMDA receptors in the central nervous system. Similarly, magnesium sulfate, often used in clinical practice for its neuromuscular blocking and anti-inflammatory effects, has been suggested to attenuate pain by inhibiting NMDA receptor activity.

The aim of this study is to compare the efficacy of ketamine versus magnesium sulfate gargles in preventing POST in patients undergoing general anesthesia with endotracheal intubation. This study is particularly relevant in exploring alternative approaches to reduce the incidence and severity of POST, improving patient recovery and comfort post-surgery.

This study was conducted at HSK Hospital and Medical Research Centre, Navanagar, Bagalkot, from January 2016 to December 2016. A randomized controlled clinical trial design was employed to compare the efficacy of ketamine and magnesium sulfate gargles in preventing postoperative sore throat (POST) in patients undergoing general anesthesia with endotracheal intubation.

Study Population:

A total of 90 patients, aged between 18 and 60 years, of both sexes, were enrolled in the study. The participants were classified as ASA (American Society of Anesthesiologists) grade I and II. The patients were randomly assigned to one of two groups:

Group A (Ketamine Gargle): 45 patients received 50 mg of preservative-free ketamine in 29 mL of normal saline.

Group B (Magnesium Sulfate Gargle): 45 patients received magnesium sulfate at a dose of 20 mg/kg (up to 30 mL of normal saline).

Inclusion Criteria:

ASA physical status I and II

Patients aged 18–60 years

Patients undergoing elective surgeries under general anesthesia with endotracheal intubation

Mallampati grade I and II airway

Exclusion Criteria:

Patients who were unwilling to provide informed consent

Patients with anticipated difficult intubation

Head and neck surgeries

Duration of surgery exceeding 3 hours

History of any contraindications to ketamine or magnesium sulfate

Preoperative Protocol:

After obtaining ethical approval and written informed consent, patients were randomly assigned to the two groups using a computer-generated randomization table.

Prior to induction, patients in both groups were instructed to gargle the assigned solution (ketamine or magnesium sulfate) for 30 seconds, 5 minutes before being moved to the operating room.

Standard non-invasive monitoring was applied throughout the anesthesia procedure. Preoxygenation was performed, followed by premedication with Inj. Glycopyrrolate (0.005 mg/kg IV), Inj. Midazolam (0.05 mg/kg IV), and Inj. Fentanyl (2 mcg/kg IV).

Induction and Maintenance of Anesthesia:

Anesthesia was induced with 2 mg/kg of Inj. Propofol IV, sufficient to abolish the eyelash reflex, followed by 0.1 mg/kg of Inj. Vecuronium IV for neuromuscular blockade.

Endotracheal intubation was performed by an experienced anesthesiologist with over 3 years of expertise. The endotracheal tube was lubricated with 2% lignocaine jelly at room temperature.

The cuff of the endotracheal tube was inflated with the volume of room air required to prevent a palpable air leak.

Anesthesia was maintained with isoflurane, fentanyl, and vecuronium, supplemented with 33% oxygen in nitrous oxide. Intracuff pressure was maintained between 18–22 cm H₂O using a handheld pressure gauge.

Postoperative Protocol:

After surgery, patients were monitored in the recovery room, where they were asked if they experienced any sore throat. If they did not report sore throat spontaneously, a direct question was asked about the presence of sore throat.

The severity of POST was graded using a four-point scale:

Grade 0: No sore throat

Grade 1: Mild sore throat (complaints only upon inquiry)

Grade 2: Moderate sore throat (complaints on their own)

Grade 3: Severe sore throat (change in voice or hoarseness, associated with throat pain)

Postoperative Time Points:

The incidence and severity of sore throat were assessed at the following intervals:

0 hours (immediately post-operation)

4 hours

8 hours

12 hours

24 hours

Statistical Analysis:

Data were entered into an MS-Excel sheet and analyzed using SPSS version 22. Descriptive statistics such as mean and standard deviation were used for quantitative data. Chi-square tests were used to analyze categorical data and determine the statistical significance of differences in the incidence and severity of sore throat between the two groups. A p-value of <0.05 was considered statistically significant.

In this controlled randomized comparative clinical trial, we assessed the efficacy of Ketamine versus Magnesium Sulfate gargle in preventing postoperative sore throat (POST) in patients undergoing general anesthesia with endotracheal intubation. The demographic data for both groups are presented in Table 1. The mean age for Group A (Ketamine) was 32.11 ± 10.27 years, while for Group B (Magnesium Sulfate), it was 33.24 ± 10.42 years. Gender distribution in Group A consisted of 22 females (48.9%) and 23 males (51.1%), whereas Group B had 27 females (60%) and 18 males (40%). The mean weight in Group A was 61.42 ± 8.73 kg, and in Group B, it was 60.22 ± 7.82 kg. The mean duration of surgery for Group A was 122.44 ± 18.08 minutes, compared to 119.67 ± 17.10 minutes in Group B.

Table 1: Demographic Data

Incidence of Postoperative Sore Throat

The incidence of postoperative sore throat was evaluated at multiple time points post-surgery (0, 4, 8, 12, and 24 hours) and is presented in Tables 2–6.

At 0 hours, Group A (Ketamine) exhibited a significantly higher proportion of patients with moderate (53.3%) and severe (31.1%) sore throat (Table 2). In contrast, Group B (Magnesium Sulfate) showed a higher incidence of mild sore throat (62.2%) and a much lower incidence of severe sore throat (4.4%). The Chi-square value for the comparison between the two groups at 0 hours was 26.87, with a highly significant P-value of <0.001.

Table 2: Incidence of Postoperative Sore Throat at 0 Hours

At 4 hours, Group A showed a similar trend with a higher percentage of moderate (55.6%) sore throat cases, whereas Group B had a larger proportion of mild sore throat (55.6%) and fewer moderate cases (11.1%). The difference between the groups was again statistically significant, with a Chi-square value of 22.86 and a P-value of <0.001 (Table 3).

Table 3: Incidence of Postoperative Sore Throat at 4 Hours

At 8 hours, Group A had 60% of participants reporting mild sore throat, with 20% experiencing moderate sore throat (Table 4). In contrast, Group B demonstrated a significantly better outcome with 77.8% reporting no sore throat, and only 22.2% experiencing mild sore throat. The difference between the two groups was significant, with a Chi-square value of 32.17 and a P-value of <0.001.

Table 4: Incidence of Postoperative Sore Throat at 8 Hours

At 12 hours, Group A showed a dramatic improvement, with 53.3% of patients reporting no sore throat and 46.7% experiencing mild sore throat (Table 5). On the other hand, Group B had a significantly lower incidence of sore throat, with 95.6% of patients reporting no sore throat and only 4.4% reporting mild sore throat. This difference was also highly significant, with a Chi-square value of 21.08 and a P-value of <0.001.

Table 5: Incidence of Postoperative Sore Throat at 12 Hours

At 24 hours, Group A showed an improvement in the incidence of sore throat, with 84.4% reporting no sore throat and 15.6% experiencing mild sore throat (Table 6). In contrast, Group B had no reported cases of sore throat, with 100% of patients showing no symptoms. The difference between the two groups was statistically significant with a Chi-square value of 7.59 and a P-value of 0.006.

Table 6: Incidence of Postoperative Sore Throat at 24 Hours

Statistical Significance Across All Time Points

The statistical significance for the incidence of postoperative sore throat across all time points is summarized in Table 7. At all assessed time points (0, 4, 8, 12, and 24 hours), Group A consistently showed a higher incidence of postoperative sore throat in varying degrees, with a significantly worse outcome compared to Group B (Magnesium Sulfate). At 0, 4, and 8 hours, Group A had higher proportions of moderate and severe sore throat cases, and this difference was statistically significant (P-value < 0.001). By 12 and 24 hours, Group A showed a significant improvement, but Group B maintained a much better outcome in terms of sore throat prevention, with the majority of patients reporting no sore throat at 24 hours (Table 7).

Table 7: Statistical Significance for Postoperative Sore Throat Across All Time Points

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Postoperative sore throat (POST) remains one of the most common complications following general anesthesia with endotracheal intubation, affecting a significant proportion of patients. Although generally considered a minor complication, POST can cause considerable discomfort and affect recovery, with the incidence varying between 21% and 65%. Several factors, including patient demographics, airway management techniques, and the nature of the surgical procedure, influence the occurrence of POST.

Our study compared the efficacy of ketamine and magnesium sulfate gargles in preventing POST in patients undergoing general anesthesia with endotracheal intubation. The findings demonstrated that magnesium sulfate significantly reduced the incidence and severity of POST compared to ketamine at all postoperative time points (0, 4, 8, 12, and 24 hours). At 0 hours postoperatively, only 4.4% of patients in the magnesium sulfate group reported severe sore throat (Grade 3), while 31.1% in the ketamine group experienced similar severity. This difference was statistically significant, highlighting the superior efficacy of magnesium sulfate in reducing POST at the earliest postoperative stage.

Consistent results were observed at subsequent time points, with the magnesium sulfate group exhibiting a marked reduction in sore throat severity. By 24 hours, 100% of patients in the magnesium sulfate group had no sore throat (Grade 0), compared to 15.6% in the ketamine group who still reported mild soreness (Grade 1). This continuous reduction in the severity of POST in the magnesium sulfate group supports its superior effectiveness over a prolonged period, in line with previous studies suggesting the benefits of magnesium sulfate in preventing POST [7, 8, 9, 12].

Several mechanisms may explain the observed superiority of magnesium sulfate. Both ketamine and magnesium sulfate are NMDA receptor antagonists, which could contribute to their ability to reduce pain and inflammation. Ketamine is well recognized for its central analgesic effects, particularly in the central nervous system, where it inhibits NMDA receptors involved in pain transmission. However, its effects on POST are less pronounced than magnesium sulfate. Magnesium sulfate also acts as a physiological calcium channel blocker, inhibiting calcium influx at the cellular level, which modulates the inflammatory response involved in POST [9, 11, 12].

In addition to its NMDA receptor antagonism, magnesium sulfate has been shown to reduce muscle tone and prevent bronchospasm. These actions may play a significant role in alleviating the mechanical irritation that contributes to POST. This combination of muscle-relaxant and anti-inflammatory effects, along with NMDA receptor antagonism, likely provides a more comprehensive approach to preventing POST compared to ketamine alone. Previous studies have also reported similar findings, emphasizing the potential of magnesium sulfate in mitigating postoperative throat complications [8, 10, 12].

In contrast, the effectiveness of ketamine, although beneficial, may be limited due to its central analgesic properties, which may not address the inflammatory and mechanical factors contributing to POST as effectively as magnesium sulfate. This supports our findings that magnesium sulfate is more effective in preventing postoperative sore throat than ketamine, especially over extended periods following surgery [7, 8].

Clinical Implications

The findings of this study have important clinical implications for anesthesia practice. Given the significant reduction in POST observed with magnesium sulfate gargle, it may be considered a preferred prophylactic measure for patients undergoing endotracheal intubation, particularly in surgeries that involve prolonged intubation or those with a higher risk of POST. On the other hand, while ketamine is still a useful agent for other aspects of anesthesia and analgesia, its efficacy in preventing POST appears to be inferior to magnesium sulfate in this context.

Additionally, magnesium sulfate's minimal side effects, such as its well-established safety profile and ease of administration, make it an attractive alternative to other pharmacological interventions, such as steroids or local anesthetics, which may have undesirable side effects or limited availability.

Limitations and Future Directions

Despite the promising results of this study, several limitations need to be addressed in future research. The study population was limited to patients undergoing elective surgeries with a maximum duration of 3 hours, and the generalizability of the findings to different surgical populations or those undergoing longer surgeries remains to be determined. Furthermore, long-term follow-up data on the potential benefits of magnesium sulfate in preventing POST beyond 24 hours would provide more insights into its sustained efficacy.

Future studies could also explore the optimal dosage and timing of magnesium sulfate and ketamine for preventing POST, as well as investigate the potential for combining these agents with other interventions to further reduce the incidence and severity of sore throat.

our study demonstrated that magnesium sulfate gargle is more effective than ketamine gargle in preventing postoperative sore throat in patients undergoing general anesthesia with endotracheal intubation. The significant reduction in both the incidence and severity of POST in the magnesium sulfate group at all postoperative time points suggests that magnesium sulfate should be considered a valuable intervention in clinical practice to enhance postoperative comfort and recovery.

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