Postoperative sore throat in patients undergone head and neck surgeries under endotracheal intubation and laryngeal mask anaesthesia

INTRODUCTION

Postoperative sore throat (POST) is a frequent complaint in subjects undergoing the surgical procedure under general anaesthesia. Different techniques have been adapted to avoid POST. William Macewen in 1880 first demonstrated the orotracheal intubation with the endotracheal tube (ETT) for anaesthesia and a century later in 1981, Dr. Archie Brain developed laryngeal mask anaesthesia (LMA).¹ The use of LMA is found to be increased because of the ease of insertion. Further, it is also used in anticipated or actual difficult airways and even in failed intubations. Some measures to decrease the POST like nebulising subjects with ketamine and magnesium prior to intubation had been tried with various results.^2,3

Previous studies indicate that ETT intubation is associated with higher incidence of POST than that with LMA.^4,5 The incidence of POST varies from 12% to 63% in various studies, Females were found to have a higher incidence of POST.^6-8 The wide variation could be the results of differences in the size of ETT, LMA, methods of insertion, cuff pressure and duration of surgeries etc.

Previous studies did not mention about physical findings in the throat and most of their evaluation was completed in the first 24 hours. Hence this study was aimed to analyze the incidence of POST in subjects undergoing the surgical procedure with ETT and LMA. Furthermore, any visible findings in the pharynx and larynx, as well as the duration of pain persisting after the procedure were evaluated so that an appropriate remedial measure can be sought.

METHODS

Study design

This prospective study was carried out from May 2016 to January 2017 in the department of Otorhinolaryngology, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India. The study protocol was approved by the Institutional Research Ethics Committee and complied with the declaration of Helsinki. A written informed consent was taken from each subject prior to the commencement of the study.

Subjects

Patients, between the ages of 10 and 79, undergoing head and neck surgeries by general anaesthesia given by ETT and LMA in the Department of Otorhinolaryngology, were included in the study. Surgical procedures done in the oral cavity, oropharynx or those with throat packed excluded from the study. Subject below the age 10 or above 80 years were also excluded from the study. Proseal and classical types were used commonly in the LMA group. Different cuff pressures and various sizes of the tube were used in ETT while various sizes of mask and cuff pressures were used in LMA. Pain score was graded by constructing a 10 point scale and asking the patient to touch the scale. The parameters were statistically analyzed.

Statistical analysis

The statistical analysis was performed using SPSS (version 16.0, IBM, CA, USA). Pearson Chi-Square was used to compare the correlation of size or pressure applied with pain in each group. P less than 0.05 were considered as significant.

RESULTS

Total 100 subjects from each group were enrolled in the study. Proseal (96%) and classical (4%) were used commonly in the LMA group. No statistically significant difference could be observed among the number of cases in both groups. Among the patients females were dominant (Figure 1). The commonly used size was 7.0 (66%) and 7.5 (19%) in ETT group, while the sizes were proceal 3 (65%) and 4 (26%) in LMA group. Cuff pressure of 30 mmHg (55%) was commonly applied in both groups. The second common pressure was 40 mmHg which was 15% in ETT and 22% in LMA. Thirty-seven patients in ETT and twenty six patients in LMA were reported with pain (Figure 2). However, no statistically significant change could be observed among them. The pain was gradually decreased during the post-surgical days in both groups (Table 1). However, on 1^st day, the pain frequency in the LMA group was less than that of ETT group. ETT group of patients showed pain score of 7 on day two and three, while none of the patients in LMA group showed pain score of 7 on these days. While an increase in size, the number of patients in both ETT and LMA groups showed no correlation with the frequency of pain (Table 2 and 4). However, with increase in cuff pressure, an increase in the number of patients with pain in both groups was observed (Table 3 and 5). An increase in patients with pain in LMA group while using large size of the mask was found whereas, in the ETT group, the size of the tube did not correlate with the incidence of POST. However, no statistically significance correlation was found. In the LMA group, only 1 patient with POST had inter arytenoid congestion, while in the ETT group 1 patient had congested anterior pillars, 3 had inter arytenoid congestion and 2 had congested arytenoids.

P = 0.775 (Pearson Chi-square test) not significant

P = 0.195 (Pearson Chi-square test) not significant

P = 0.416 (Pearson Chi-square test) not significant correlation

P = 0.32 (Pearson Chi-square test) not significantly correlated

DISCUSSION

The results of this study revealed that LMA was better than ETT in reducing the POST. This was evident by analyzing the frequency of pain in both groups. In the LMA group, the pain was less than that of ETT group on the 2^nd day. An increase in cuff pressure above 40 mm of Hg produced an increase in the number of patients with pain in both groups.

The use of LMA is increasing in recent days due to its ease of insertion, speed of insertion, need of less expertise and its improved hemodynamic stability at induction of anaesthesia and reversal. Many studies indicate that the frequency of POST and cough is less with LMA, as compared to ETT. The incidence of bronchospasm and laryngospasm was also seen to be less with LMA than with ETT. Some studies report a higher incidence of gastric insufflations and anesthetic gas leak due to low seal pressure with LMA.⁹ Apart from the POST and cough, there are postoperative nausea and vomiting, hemodynamic changes were affecting the heart rate and BP associated with general anaesthesia which is also less with LMA.¹⁰ The cause for POST and cough is not clear.¹¹ However, certain factors thought to cause the POST are size of the tube, gender – females more than males, cuff pressure and design, use of nitrous oxide, insertion techniques and its urgency, patient positioning, duration of surgery, obesity and pharyngeal suction, etc. The possible associated injuries include edema of the post cricoid region and tracheal rings, epithelial loss, mucosal injuries and hematoma.¹² Incidence of laryngospasm, cough at extubation, dysphagia, dysphonia, sore throat and hoarseness was found to be higher in ET than in supraglottic devices.¹³ Attempts have been made to prevent POST by application of benzydamine hydrochloride to the cuff and pharyngeal mucosa, inhalation of fluticasone propionate, etc, but have not been found to be definite.¹⁴

Our present study showed a higher incidence of POST with ETT (37%), as compared to LMA (26%), but this difference was not statistically significant. The pain was also found to be significantly higher on postoperative days 2 and 3, and the difference in both the groups and was found to be significant. The maximum intensity of pain was on the third day in both the groups.

CONCLUSIONS

The result of this study concluded that LMA was better than ETT in reducing the POST. No significant correlation of pain was found with increasing the cuff pressure or size of the device in both methods.

ACKNOWLEDGMENTS

The authors gratefully acknowledge the valuable help of Dr. Ajith TA, Professor of Biochemistry, Department of Biochemistry, Amala Institute of Medical Sciences during the preparation of the manuscript and Mr. Tom Thomas, Biostatistician, Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India for the statistical analysis.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

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