New Airway for Awake Intubation (McKay Airway)

Overview

When endotracheal intubation is known or predicted to be difficult, patients are intubated awake using a flexible bronchoscope (awake fibre-optic intubation: AFI) so that they can protect their airway with normal upper airway muscle activity until the endotracheal tube (ETT) is safely in place. New bite blocks have been invented for bag mask ventilation but are not suitable for AFI.1 A newly invented airway device, the McKay airway, may provide a better solution for AFI by enabling jaw thrust, a condition where the upper airway is opened more as the jaw is protruded forward. It may also be more comfortable for awake users. A study is proposed to assess the functionality of the device for this purpose. To protect the bronchoscope, a bite block is used during AFI to protect the very delicate glass fibres from damage from inadvertent biting by the patient. Currently used bite blocks protect the scope, but do not position the jaw optimally for scoping. The proposed device is an attempt to improve upon current bite blocks by both protecting the bronchoscope and positioning the jaw optimally. Hypothesis: Residents in training in the Division of Respirology have limited experience in fibre-optic bronchoscopy and perform it under the direct supervision of an expert. Null hypothesis: the time to visualization of vocal cords with a fibre-optic bronchoscope by residents learning in the Division of Respirology will be no different with the McKay airway than with the conventional bite block or Williams Airway.

INTRODUCTION When endotracheal intubation is known or predicted to be difficult, patients are intubated awake using a flexible bronchoscope so that they can protect their airway with normal upper airway muscle activity until the endotracheal tube (ETT) is safely in place. A newly invented airway device, the McKay airway, (Appendix 2) may provide a better solution to placing an ETT into the windpipe of an awake patient, (awake fibre-optic intubation: AFI) A study is proposed to assess the functionality of the device for this purpose. To protect the bronchoscope, a bite block is used during AFI to protect the very delicate glass fibres from damage from inadvertent biting by the patient. Currently used bite blocks (Appendix 2, figure 5) protect the scope, but do not position the jaw or bronchoscope optimally for scoping. This is not a problem for experienced bronchoscopists such as respirologists, but can be for those, like anesthesiologists, who do bronchoscopy infrequently. For these, the proposed device may be an improvement upon current bite blocks. Hypothesis: Residents in training in the Division of Respirology have limited experience in fibre-optic bronchoscopy and perform it under the direct supervision of an expert. Null hypothesis: the time to visualization of vocal cords with a fibre-optic bronchoscope by residents learning in the Division of Respirology will be no different with the McKay airway than with the conventional bite block. Experimental design: The proposed experiment is an unblinded repeated measures interventional clinical trial with concealed randomization of which device is used first and which second. Randomization will be by a computer-generated random number table (1s and 2s where 1 is conventional bite block is used first and 2 means McKay airway first) transcribed to paper cards in numbered opaque envelopes to be opened just prior to bronchoscopy. Primary outcome: Time from beginning insertion of bronchoscope into the bite block to visualization of vocal cords. Secondary outcomes: Scores will be recorded on rating scales for: ease of insertion, ease of obtaining proper position of teeth in the device by patients, assessment of gag reflex. Comments about overall impression will be recorded. Participants: Participants are of two kinds, patients and residents. Patients will be consenting patients booked for bronchoscopy by pulmonologists at Royal University Hospital. Excepted patients will be those who do not wish to participate and those with any health conditions that the attending pulmonologist feels puts them at any added risk by participating. Consent: With University of Saskatchewan Research Ethics Board approval, the investigators will recruit patients and obtain signed informed consent at the time of booking bronchoscopy or on arrival for bronchoscopy. Data and privacy concerns: As well as the primary and secondary outcomes, data collection on paper data sheets will include basic demographics. These are: age, gender, height, weight, and diagnosis as well as airway characteristics (see Appendix 1, Data Sheet). Because this may identify patients and breach their privacy, the data sheets will be identified only by number. The de-identified data collection sheets will be labeled with a unique numerical identifier (e.g., 1, 2, 3, etc). The data collection sheet will be linked to the patient Personal Health Number by way of a physically separate Master Data list (e.g., 1, 2, 3, etc.). (See attached - Master Data List) The de-identified data from the data collection sheet (See Attached - Data Collection Sheet) will be transcribed by Dr. McKay to data base on a password protected computer kept in a locked office in the Department of Anesthesiology at all times. Identifiable patient information will not be transcribed electronically. Upon completion of the study, Dr McKay will store electronic data files and paper forms in a locked filing cabinet in the Department of Anesthesiology (accessible only by key code), as per the University of Saskatchewan Research Integrity Policy (http://www.usask.ca/university\_secretary/policies/research/8\_25.php). The Master Data List (paper only) will be stored in a physically separate location from the data collection forms. The hard copies of the data collection forms, master list, and completed consent forms will be destroyed through the confidential paper disposal services of the SHR, while the electronic data will be permanently deleted after 5 years as per the above University of Saskatchewan Research Integrity Policy. We anticipate this data to be the basis for a publication in a peer-reviewed scientific journal and at a national scientific meeting. Patient safety: The experiment will be overseen by the attending specialist respirologist who will intervene immediately as needed and proceed as clinically indicated if any issue of patient safety arises at any time. This is normal practice. We expect that risk to participating patients is minimal. We anticipate the following incidence: 1) common (1-10%) side effects: none. 2) uncommon (0.1 to 1%) side effects: mild abrasion of the mouth (which can occur with the currently available awake intubation bite blocks and airways as often). 3) rare (0.01-0.1%) side effects: zero. 4) Very rare (\<0.01%) side effects: sensitivity to the plastic with irritation of the oral mucosa (which can occur with the currently available awake intubation plastic bite blocks and airways as often). The McKay airway is made of medical grade plastic. 5) Severe side effects: zero (prolonged hospital admission, admission to intensive care, loss of limb or vital organ, or death). We believe that risk of participation is not different from risk of bronchoscopy, and is safe in expert hands. Measurements. With a stopwatch, the investigator will measure the time from beginning to place the bronchoscope in the mouth following topicalization to visualization of vocal cords or epiglottis. Following bronchoscopy, the Respirologist will rate the modalities with rating scales (see attached Data Sheet). Number of participants: There is no similar study from which to calculate sample size. We will initially assuming that one modality is 0.2 times faster with standard deviation 0.2, paired t-test sample size is calculated at n = 10, then recalculate based on the primary outcome findings. Statistical analysis. Demographic and rating data will be tabulated as observational; time measurements compared by paired t-test or Mann-Whitney U test as mean ± standard deviation and \[95% Confidence Intervals\] or median and \[interquartile range\] as appropriate following a Kolmogorov-Smirnov test of normality.