Comparative Study Between Combined Video Laryngoscope and Video Stylet Intubation Versus Combined Video Laryngoscope and Fiberoptic Intubation in a Simulated Difficult Airway

Before the study been conducted, the investigator, will give a 10 minutes briefing and explanation regarding the study and consent will be taken from the participants. Based on the previous study, a video demonstration on using these devices will be shown to participants as well. Participants will be informed at least a day prior to the study conducted so that the investigator and participants can have time to prepare and allocate time for participating in the study respectively.

This study will evaluate three techniques of ETI by participants in a simulated difficult airway scenario. Participants will start off with the single technique using a VL only, which serves as the control and standard care. After completing the single technique, participants will then proceed with both combination techniques, which are combined VL with VS and combined VL with FOB. As this is randomized comparative cross-over simulation study, participants will pick an envelope that randomly stated the sequence of combination techniques which generated using computer randomisation. Each participant on each session may get the same sequence or may not. However, the sequence for the study will be in equal proportion. There will be a washout period of five minutes between each technique. This allows the investigator and participants to chart the results and get ready for the other technique respectively.

The investigator will prepare the video laryngoscope C-MAC® with blade size 3, preformed rigid stylet, monitor, C-MAC® Video Stylet and Karl Storz Fibreoptic Scope which are standardised for all participants. Besides, standard endotracheal tube (ETT) size 8mm internal diameter will be used and lubricated with KY jelly.

Participants will attempt intubation using half body Laerdal Airway Management Trainer manikin. The neck immobilisation will be made by placing a hard cervical collar on the manikin to mimic difficult airway. Before attempting intubation, participants are allowed to practice intubation using VL, combination of VL with VS and combination of VL with FOB for familiarisation with the devices after briefing and video demonstration. Participants need to practice on the normal airway manikin and need to have successful intubation for at least five attempts for each technique which are VL, combined VL with VS and combined VL with FOB before commencing the study on a simulated difficult airway.

As for the study control, participants will start by intubating the manikin using VL C-MAC® with blade size 3. The intubation time for VL will start from VL C-MAC® blade size 3 passes upper incisor till successful ETI using ETT loaded preformed rigid stylet. For the combination techniques, the participant will manoeuvre the VL to optimal position and then held by an assistant. With the VL in situ by the assistant, each participant will advance the VS or FOB through the vocal cord and then the ETT will be advanced under indirect visualisation. The investigator will time the intubation attempts using a standard stopwatch. This study will divide the intubation time for the combined technique into three parts. For the first part, the time will start from the VL blade passes the upper incisors till glottic view (V-G) is obtained. The second intubation time will start when the ETT loaded FOB or VS passes the upper incisors and stops once the ETT loaded FOB or VS passes through the glottic opening (I-G time). For the third part, the timing will start when the ETT loaded FOB or VS passes through the glottic opening and stop upon successful ETI (G-E time). Successful ETI is defined once the real time video monitoring shows the ETT passes through the vocal cord and chest inflation is observed upon bag insufflation within 60 seconds of intubation by the participant. This 60-second time limit is established based on findings from previous difficult airway study. Participants are allowed up to three attempts for each technique. Participants will be considered as drop outs if they do not perform VL and two combination techniques of VL with VS and VL with FOB in one setting, and wish to withdraw from the study even after completing the procedure.

Failure of intubation is defined when the intubation done lasted longer than 60 seconds or if the ETT is placed in the oesophagus. Total time (TT) of intubation for combined techniques will be the sum of V-G, I-G and G-E time. Other variables that will be recorded in this study include glottic visualization which is described according to the Cormack-Lehane (CL) classification and the Percentage of Glottis Opening (POGO) scale even though the CL and POGO scales are used in direct laryngoscopy and VL respectively.

At the end of each technique, participants will be asked to rate the ease of intubation by a 5-point Likert scale from very difficult to very easy and their preference on the combination devices of VL with VS and VL with FOB also will be recorded. All these data will be collected using data collection sheet.