Effect of intravenous dexamethasone, video laryngoscopy or their combination on post operative sore throat in adults undergoing surgery: A randomized double blinded placebo control trial

Introduction Postoperative sore throat  is a distressing complication following tracheal intubation, with reported incidence ranging from 30 percent to 70 percent, varying in severity . Factors such as repeated airway instrumentation during direct laryngoscopy, endotracheal suctioning, oversized endotracheal tubes, or excessive ETT cuff pressure can induce local tissue trauma and inflammation, contributing to POST. Effective treatment of POST is crucial to mitigate its impact on patient recovery and enhance overall patient satisfaction.

The use of VL and dexamethasone among anaesthesiologists in the perioperative setting is well-established. Independently, both interventions have demonstrated efficacy in decreasing the occurrence and severity of POST. However, the combined effect of these interventions on POST remains unexplored in the literature. Therefore, our study aims to investigate the impact of combining these interventions or using them individually on reducing the incidence of POST. We hypothesize that combination of VL and iv dexamethasone will be superior to either intervention used alone.

Aim To determine the effect of combination of intravenous dexamethasone and VL guided intubation on incidence of POST compared to either intervention alone or placebo.

Study methodology

Final eligible patients will be divided into 4 groups and block randomisation will be done by computer generated codes and allocation concealment will be done by sealed opaque envelopes. Seal will be broken by anaesthetic assistant not participating in study who will be preparing and administering the drugs.

Group A is Video laryngoscope with Dexamethasone 8mg

Group B is Video laryngoscope with equivalent volume of NS 2ml

Group C is Dexamethasone 8mg with Direct laryngoscopy guided intubation

Group D is Equivalent volume of NS plus direct laryngoscopy guided intubation which is placebo group

2X2 factorial design table will be made. Assessment of primary outcome will be done by factorial design in which there will be 2 intervention groups all which is VL and all Dexamethasone and 1 placebo group.

Video laryngoscope received

Video laryngoscope not received

Margins

|Dexamethasone received

Group A is Factor 1 with Factor 2

N is 55

Group C is Factor 1 only

N is 55

All dexa A and C

N is 110

|Dexamethasone not received

Group B is Factor 2 only

N is 55

Group D is Placebo

N is 55

All non dexa B and D

N is 110

|Margins

All VL A and B

N is110

All non VL C and D

N is110

Total is 220

Margin of table analysis  To assess efficacy of dexamethasone by comparing all dexa to all non dexa and efficacy of video laryngoscopy by comparing all VL to all non VL.

Within the table analysis

Between group A and group B To assess simple effect of dexamethasone on VL

Between group A and group C To assess simple effect of VL on dexamethasone

All patients will be made familiar with the scoring scales used for POST, hoarseness, cough and post operative satisfaction during pre-operative visit.

All patients will be receiving T. Alprazolam 0.25 mg night before surgery

Anaesthesia will be standardised in all groups

Study drugs dexamethasone or normal saline will be given just before premedication as 2ml solution.

Patients will be premedicated with midazolam 0.1 mg per kg and Fentanyl 2 mcg per kg followed by induction with Propofol 2mg per kg and Vecuronium 0.1 mg per kg as neuromuscular blocking agent.

Intubation will be done by anaesthesiologist more than 2 years of experience who is not taking part in the study. C MAC video laryngoscope with MacIntosh No. 3 or 4 size blade will be used for all patients. Intubation will be done with Polyvinyl single lumen ETTs with stylet with low pressure high volume cuffs of size standardised as 8.0 for males and no 7.5 for females.

Duration of laryngoscopy, number of attempts at intubation, time taken for intubation defined as time interval between insertion of laryngoscope to appearance of capnograph on monitor, CL grading of patient, presence of any oropharyngeal bleeding at time of intubation or laryngoscopy will be noted.

ETT will be inflated with air and cuff pressures will be maintained between 20 to 30 cm H2O which will be monitored intra operatively throughout the procedure half hourly with cuff pressures monitors.

Appropriate ultrasound guided blocks will be given intra operatively for adequate pain relief.

Maintenance with Isoflurane end tidal MAC between 0.9-1.0 with O2 50 percent and air percent

Doses of vecuronium and fentanyl will be repeated as required. Intra operative fentanyl use will be documented.

Reversal with glycopyrrolate 0.01 mg per kg and neostigmine 0.05 mg per kg. Gentle oropharyngeal suctioning with pressure less than -50cm H2O will be done before extubation. Any coughing at time of extubation will be noted.

Use of PCM and opioids in the post operative period will be recorded. All patients will receive inj. PCM 8th hourly and inj. Tramadol 1mg per kg as rescue analgesic if required for VAS more than 4

Patient will be observed in PACU at 0th, 1st, and 2nd hr, and in the ward at the 6th and 24th hour to assess the presence and severity of POST along with incidence and severity of post operative cough and hoarseness of voice will also be noted by observers blinded to study interventions.