Comparison of intravenous Dexmedetomidine alone versus Dexmedetomidine plus Ketamine combination on sedation, intubation response, safety profile and patient satisfaction during awake fiberoptic nasotracheal intubation.

Awake fiberoptic intubation is useful in cases of anticipated difficult airway, failed intubation, nil mouth opening and unstable cervical spine injury where optimum positioning for laryngoscopy is difficult to achieve. It is done with help of Flexible fibreoptic bronchoscope.

The Flexible fibreoptic bronchoscope is a flexible instrument which is capable of transmitting an image from the distal tip to the proximal end. The motion of the tip of the fiberscope can be controlled which enables the operator to direct the scope in any desired direction. The combined characteristics of controllability, flexibility and image transmission permit an anesthesiologist to employ the fiberscope as an aid to tracheal intubation. Intravenously used Dexmedetomidine is a highly selective and specific alpha 2 adreno receptor agonist. It is well known for its cooperative sedation property. It has  anxiolytic, analgesic, sedative, sympatholytic, and antisecretory properties. It has minimal  respiratory depression and easy arousability. And stress response to intubation is also minimized. However, it may produce bradycardia and hypotension occasionally. Addition of low dose of Ketamine, a sympathomimetic intravenous induction agent with potent analgesic properties,  to Dexmedetomidine  provides additional analgesic effect and helps in preventing Dexmedetomidine induced bradycardia and hypotension, while undesirable increase in airway secretion with Ketamine is attenuated by Dexmedetomidine. Opposing action of Ketamine and Dexmedetomidine on cardiac and sympathetic system provide more stable hemodynamic response apart from better sedation and intubation condition.

The aims of the study are –

To Evaluate the effect of addition of intravenous Ketamine to Dexmedetomidine and compare with Dexmedetomidine alone during awake nasotracheal fiberoptic  on   following parameters:

Sedation during the procedure judged by Ramsay sedation score starting before the insertion of fiberscope into nose till completion of intubation.

To assess the Intubation response to tracheal intubation as judged by coughing score and grimace score .

To assess the Safety profile by observing hemodynamic changes such as heart rate, SBP, DBP incidence of desaturation  pre, intra and post intubation.

To assess patient’s satisfaction by post-operative evaluation of recall of event and pain during awake fiberoptic intubation by visual analogue scale.

Complications during procedure if any

All the patients will be kept NBM at least for 6 hours. Tab. Ranitidine (150mg) will be given night before the surgery.

After thorough pre-anesthetic evaluation,  patients falling in the inclusion criteria will be selected. Procedure, their role, assessment method all will be explained (patient information sheet) and an informed written consent will be taken.

Patient will be explained about the visual analogue scale about the severity of pain on horizontal line and it will be assessed post operatively after 24 hour.

Premedication;

Inj. Glycopyrrolate 0.2mg IV

Inj. Ondansetron 4mg IV

 Induction:

Patient preparation :

Baseline vitals of every patients will be noted.

Nasal patency confirmed & 2-3 drops of 0.1% xylometazoline will be inserted in both nostrils.

Lignocaine up to maximum dose of 5mg/kg will be used to topicalize the airway of patient.

Nebulization with 2% Lignocaine will be done.

2-3 puffs of 10% lignocaine sprayed on oropharynx and base of tongue

The superior laryngeal nerves blocked bilaterally  with 2ml of 2% lignocaine & recurrent laryngeal nerve blocked by transtracheal approach with 2ml 2% lignocaine.

All the patients will be given Inj. Dexmedetomidine 1mcg/kg in 100 ml normal saline bolus over 10 minutes followed by 0.5mcg/kg/hour infusion till completion of fiberoptic intubation.

Grouping of Patients:

The study population will be randomly allocated into two groups  of patients each, using envelope method.

Group A - In this group after giving bolus of Dexmedetomidine Patient will receive Inj. Ketamine 15 mg as a bolus of 5 ml followed Inj. Ketamine 20mg/hour infusion by syringe infusion pump till completion of intubation.

Group   B  -   In this group  after giving bolus of Dexmedetomidine Patient will receive normal saline as a bolus of 5 ml followed normal saline  infusion by syringe infusion pump till completion of intubation.

Ramsay sedation scale (RSS) will be assessed after the loading dose of Dexmedetomidine+ ketamine in group A and Dexmedetomidine in group B.

After confirming  RSS ≥2 ,  fiberoptic bronchoscopy ( using adult fiberoptic bronchoscope) will be done by me after a learning curve of 10 cases.

While preparing the equipment patient is adequately oxygenated by means of mask ventilation. Lubricate the endotracheal tube & then thread it over the fiberoptic scope.

For Nasal approach length of the scope to be inserted through nose to visualize epiglottis is predicted by measuring distance from ala of nose to tragus.

Check to ensure that the fiberscope is flexible and provides a focused view, apply an antifogging agent to the tip of the scope and then connect the oxygen source to the fiberscope.

Attachment of suction canula to suction port of fiberscope and camera to eyepiece of scope will be checked.

The Scope is advanced from the nose to the larynx, from the larynx trachea is entered to the subglottic area.

Once the vocal cords are passed, the scope is slightly flexed downwards to follow the curve to the carina,

After visualizing carina , loaded endotracheal tube  Polyvinylchloride(PVC)  endotracheal tube will be slided over the bronchoscope to the trachea and tube is positioned 2-3 cm above the carina, the cuff will be inflated and scope is withdrawn.

Placement of endotracheal tube is confirmed by direct vision, recording end tidal carbon dioxide and chest auscultation and after checking air entry bilaterally equal,  tube is fixed.

After the confirmation of intubation study drug will be discontinued and Subsequently general anesthesia will be  administered as per routine protocol .

The induction of anaesthesia will be done by:

Inj. Propofol 2mg/kg IV

Inj. Vecuronium 0.1 mg/kg IV

Maintenance of anaesthesia  with Oxygen, Nitrous oxide, along with Sevoflurane. Muscle relaxation is maintained by Vecuronium 0.02mg/kg iv as an when required.

After completion of surgery reversal is given:

Inj. Neostigmine 0.05mg/kg

Inj. Glycopyrrolate 0.01mg/kg.

Monitoring:

SEDATION: Ramsay  sedation scale will be assessed just after the completion of loading dose of drug in both group. As follows

RAMSAY SEDATION SCALE

SCORE

RESPONSE

|1

Anxious or restless or both

|2

Cooperative, oriented and tranquil

|3

Responding to commands only

|4

Brisk response to stimulus (light glabellar tap or loud auditory stimuli)

|5

Sluggish response to stimulus

|6

No response to stimulus

2. INTUBATION RESPONSE: by coughing score and patient tolerance.

Coughing:

Score 1= no cough.

Score 2=  slight cough (no more than 2 cough in sequence).

Score 3=  moderate cough (3-5 cough in sequence).

Score 4=  severe cough (more than 5 cough in sequence)

Patient tolerance will assessed by facial grimace score:

Score 1=  Mild grimace.

Score 2=  Moderate grimace.

Score 3=  Severe grimace

HAEMODYNAEMIC STABILITY:by monitoring vital parameters throughout the procedure.

Post-operative monitoring: At the 24 h postoperative follow-up, the patient will be assessed for satisfaction in terms of recall and pain during AFOI. It is assessed by using 10 cm visual analogue scale.

Proposed Advantages of the study- Awake fiberoptic intubation is an essential skill in the management of an airway for anaesthesiologist. During awake fiberoptic intubation for better patient cooperation we require better sedation. Dexmedetomidine is well known drug for such procedure but sometimes it can causes bradycardia and hypotension which can be prevented by using  ketamine along with it so, The study will provide an idea about a sedative drug combination suitable for gaining better patient cooperation during awake nasal fibreoptic tracheal intubation.