BACKGROUND: 

Laryngoscopy is a procedure by which a tube is placed into the windpipe of a person for breathing during general anesthesia to facilitate surgery, abolish anxiety, memory and provide immobility for surgery, this is generally done by the use of a Macintosh laryngoscope. In our institution, we use double lumen tubes for certain thoracic surgeries as we need to isolate/collapse one of the lungs so that the surgeon has a better view of the operating site and also provide them ease for surgical dissection. These Double lumen tubes are bigger in diameter, rigid in structure and longer than a normal tube that we place into the wind pipe. Due to their larger size, the insertion of these are difficult even in patients with normal airway anatomy and is challenging to anesthetists. Thus complications are more due to its insertion like airway trauma, sore throat, postoperative hoarseness especially when the view of the glottis is not complete during direct laryngoscopy. The potential advantages of the use of a video laryngoscope include a better view of the cords, close view of the double lumen tubes when it passes the vocal cords, assists the staff providing external laryngeal pressure and also the external monitor can be a teaching tool. Studies have also shown that the video laryngoscope can result in less use of force required for laryngoscopy. This may result in less intubation response and hence fewer complications. This CMAC D Blade video laryngoscope has been used in difficult airway scenarios in our institution.In our study we are comparing two different laryngoscopes for tube insertion; a new type of video laryngoscope and the traditional Macintosh laryngoscope and try to compare which scope is better for Double lumen tube insertion. 


AIM: 

Primary aim: To compare the time taken for successful intubation for a double lumen tube with CMAC video laryngoscope and Macintosh laryngoscope.

Secondary aims: 1) To compare the hemodynamic response to intubation in both groups.

                            2) To assess Intubation difficulty scale in both groups.

                            3) To compare the incidence of complications in both groups.

DESIGN: a Randomized control study.

METHODS:

The aim of the study is to compare Direct Laryngoscopy with Macintosh (MAC#3) blade versus CMAC D blade video laryngoscope for intubation with a double lumen tube.Eighty patients who are posted for elective thoracic surgery who if consent for the study will be randomly divided into either group A (CMAC) or group B(Macintosh).Airway assessment will be done preoperatively for all patients by looking at their Mallampatti grade, Neck extension, Mouth opening, Jaw movement, Thyromental distance, Previous failed intubations and assessing them for any pathologies associated with the difficult airway.The risk will be assessed using a standardized scoring system which is the  El Ganzdouri Risk Index for difficult tracheal intubation(EGRI).A score less than or equal to 4 is taken as less likely to be a difficult intubation. If the patient has difficult airway they will not be included in the study.Eighty patients with no anticipated difficult airway will be recruited and informed consent will be taken.The anesthetist who has significant experience with both scopes and DLT will do the intubation.(Experience is defined as any anesthetist who has experience of putting more than 10 Double lumen tubes and who has used both scopes more than 10 times on an intubating manikin and 5 times in patients). Randomization will be computer generated and will be informed to the anesthetist just before induction of anesthesia.The patient will be pre oxygenated (etO2 >85), anesthesia induced with adequate standard doses of propofol, fentanyl and muscle relaxant of choice.Adequacy of muscle relaxation will be ensured by using a TOF watch and getting a TOF ratio of zero. An appropriate size Double lumen tube will be chosen as per the routine guidelines for our institution. After induction, a pre-curved double lumen tube is to be inserted with either of the scopes.A successful intubation will be confirmed by 3 capnographic cycles and bilateral chest auscultation.Time taken for intubation is defined as the time from introduction of the scope till 3 complete capnographic cycles.The position of the tube is confirmed by fiber optic bronchoscope.An independent observer (an instrument technician) will measure the time taken for successful intubation. He will also document the use of additional maneuvers or laryngeal pressure applied. Another anesthetist in the theatre will then examine the oral cavity, pharynx, and larynx using the laryngoscope for any airway trauma.Hemodynamic response (Heart Rate, Blood Pressure, and MAP) to intubation will be monitored at 0(baseline),1 min,3 min, and 5 min.Post operatively an independent observer will look for hoarseness of voice and sore throat. The data will be entered into the epidata software and will be analyzed for the results.