This randomised control study was carried out at Dhiraj hospital, Piparia, Vadodara in Department of Anaesthesiology, from February 2019 to November 2020. The randomised controlled study was conducted after clearance from the Institutional Ethical Committee (Study Approval No. SVIEC/ON/MEDI/BNPG18/D19046.

Inclusion Criteria

Exclusion Criteria

Sample size calculation: The power of study was calculated by using software G Power 3.0.10, taking the incidence of POST from the study of Canbay O et al., (65%) and considering a probability level of 0.05 (α-error) and power of 0.80 (1-β) yielded a sample size of 25 patients in each group [16].

Randomisation: Patients were allocated in a randomised manner by chit method into two groups of 25 each as group K to receive ketamine with normal saline and group C to receive normal saline. A consort flow diagram of patients and their progress through the various phases of this randomised trial is outlined in [Table/Fig-1].

[Table/Fig-1]:

CONSORT flow diagram.

Intervention: Group K: ketamine 50 mg in 29 mL normal saline. Group C: 30 mL normal saline. Patients as well as anaesthesiologist for data collection were blinded for the study. Drug solution for the study were prepared by a different anaesthesiologist not involved in the study.

Patient intravenous access was obtained on the forearm with 18G i.v. cannula and fluids were started, after shifting to operating room. Heart rate, non-invasive blood pressure, SpO₂ were monitored in multipara monitor. All patients were made to gargle for 30 seconds with the either ketamine or normal saline according to assigned group, 5 minutes prior to induction.

Intravenous injection ondansetron 0.1 mg/kg, injection glycopyrolate 0.04 mg/kg were given as premedication. Induction done with IV injection propofol 2 mg/kg and injection succinylcholine 2 mg/kg. Intubation was done with a soft seal cuffed sterile poly vinyl chloride endotracheal tube of 8-8.5 mm Internal Diameter (ID) in male and 7-7.5 mm ID in female. Endotracheal tube cuff inflated until no audible leak was heard. Anaesthesia was maintained on isoflurane, O2+ N2O (40-60) % mixture and IV atracurium 0.5 mg/kg bolus and then 0.1 mg/kg maintenance doses monitored on peripheral nerve stimulator. Inhalational agents were stopped and 100% oxygen was administered at the end of the surgery. Neuromuscular block was reversed. Oral suction was done under gentle direct laryngoscopy. After gaining consciousness the cuff was deflated and patients were extubated. Patients were shifted to postoperative ward with head up position and oxygen support through facemask.

Assessment of patients were done for POST, HOV, cough at 1,2,4 and 24 hours postextubation. Patients were assessed as per the four point scale (0-3) grading system [Table/Fig-2,3 and 4] [13].

Unpaired t-test was performed for statistical analysis. Results was considered statistically significant, if p-value was <0.05. The software used was Microsoft excel version 2012.

[Table/Fig-5] shows the baseline characteristics of the study population. There was no significant difference observed amongst both the groups.

Three categorical outcomes were considered for analysis with reference to their timeframe of occurrence.

POST: No statistical significance was observed four and 24 hours onwards in terms of POST grading in both K and C group. However, in the beginning and at two hours, there were significant differences in observation of the POST grading [Table/Fig-6].

HOV: There was significant difference observed in the severity of HOV till 4 hours in group K and group C. It shows that ideal time duration to reduce voice quality issues with the drug was 4 hours [Table/Fig-7].

Cough: It was observed that at four and 24 hour postsurgery, no drug was found to produce significant difference in terms of resolution of the coughing issues [Table/Fig-8].

This study was carried out to observe the effect of ketamine gargles on POST, HOV and cough following endotracheal intubation in patients undergoing surgeries under general anaesthesia. Unlike other studies the patients in this study were not posted for a specific type of surgery but lasting for not more than 90 minutes.

Dose of ketamine employed and administration: All the studies showed attenuation of POST after ketamine gargle. The researchers [3,7,13,16-20] used a dose range of 40-50 mg of ketamine with 29 mL of normal saline and 30 mL of normal saline in control group as oral rinse prior to intubation [Table/Fig-9]. Thus, looking at the doses of ketamine gargles in this study the dose was comparable.

Patients were intubated with high volume low pressure cuffed polyvinyl chloride ETT of 7.0-7.5 mm ID (in females) and 8.0-8.5 mm ID (in males). The cuff was inflated till the disappearing of the air leak from trachea [17-20].

In this study, a four-point scale (0-3) [13] was used. Other studies used similar scales and have been tabulated in [Table/Fig-9]. POST, HOV and cough were assessed at 1 hour after arrival at the post anesthetic care unit at 2, 4 and 24 hours later.

In present study, the incidence of POST was significantly reduced at 1 and 2 hours in group K compared to group C postoperatively, the results were similar to the study conducted by Chan L et al., [19]. In contrast to the present study Rudra A et al., Lalwani J et al., Canbay O et al., Kamble N et al., and Shrestha SK et al., observed that incidence of POST was less in ketamine group as compared to control group upto 24 hours [Table/Fig-6,9] [7,13,16,18,20].

In present study the incidence of hoarseness in group C was higher compared to group K at one, two, four hours. In contrast Lalwani J et al., found that HOV was less in ketamine group upto 24 hours [Table/Fig-7,9] [13]. Incidence of cough in present study was higher in group C compared to group K at 1 and 2 hours. In contrast Lalwani J et al., observed that incidence of cough was significantly less in ketamine group upto 24 hours [Table/Fig-8,9] [13]. It was concluded that gargles with ketamine decreased the incidence of severity of POST, HOV and cough.

Sore throat due to endotracheal intubation can manifest by local trauma with instrumentation, oedema, pain, congestion leading to inflammation of pharyngeal mucosa. Ketamine gargle can be the reason for the reduction of inflammation and help in decreasing the incidence of POST [11-13]. There is a growing amount of experimental data on NMDA receptors present in peripheral nerves where the peripherally applicated NMDA receptor antagonists are studied for antinociception [13-15].

Though similar studies were carried out in the past it is not a common practice in routine surgeries prior to intubation. But the present study shows the benefits of such inexpensive and easily applicable procedure to reduce the incidence of POST, HOV and cough which are small yet neglected factors in view of patients’ comfort in immediate postoperative period.

Absence of the measurement of plasma levels of ketamine. Reduction of the inflammation by ketamine gargling may be the reason for decrease in POST, HOV and cough in the present study. However, a peripheral and central action following systemic absorption cannot be ignored.

Ketamine gargles given in a dose of 50 mg in 29 mL of 0.9% normal saline significantly reduces the incidence of POST and cough upto 2 hours and HOV upto 4 hours in immediate postoperative period after extubation. It is a fairly easy, accessible, not expensive and applicable procedure.