1. Feasibility of a combined use of a video-laryngoscope with a novel flexible video-stylet for predicted difficult intubation Rainer Lenhardt, MD, MBA, Rachana Sharma, MD, Mary Tyler Burkhart, MD, Sunitha Kanchi Kandadai, MD University of Louisville, Louisville, KY Background Results Patients with predicted and unanticipated difficult airways may pose a challenge to intubate via direct laryngoscopy. The development of video- assisted intubation tools such as videolaryngoscopes (VLS) or flexible bronchoscopes (FB) has contributed greatly to facilitate intubation. A VLS (e.g. GlideScope®, Verathon Medical, Bothell, WA) is a plastic laryngoscope that incorporates a high-resolution video camera on the inferior aspect of the blade. VLS assures easier laryngeal visualization compared to a regular laryngoscope. However, it may not guarantee endotracheal tube placement. To facilitate intubation rigid or malleolable stylets can be used along with VLS. The GlideScope- specific rigid stylet and standard malleable stylet are equally effective for GlideScope use. Occasionally, intubation will fail even with a VLS despite the use of rigid or malleolable stylets. The reason is that the inflexible tip of these stylets may make it difficult to position the tube in front of the glottic opening. Thus, the operator may visualize the glottis, but may be unable to pass the tube through the vocal cords. A possible way to increase successful intubation is the use of a flexible tracheoscope. The advantage of a flexible tracheoscope is that it can be used as a stylet and can be maneuvered during the intubation process. Recently, flexible, disposable tracheoscopes have been developed (aScope®, Ambu Inc. 6740 Baymeadow Drive Glen Burnie, MD 21060). However, using a tracheoscope or a disposable flexible bronchoscope without an additional intubating blade may render intubation difficult. The combination of the VLS and a flexible tracheoscope used as a flexible video- stylet may guarantee a very high success rate for difficult intubation. Objective No systematic comparison has been made between video-laryngoscopy with rigid stylet versus video-laryngoscopy with flexible tracheoscope. We therefore tested the hypothesis that a combination of a video- laryngoscope with a flexible video-stylet is a feasible way to facilitate intubation in patients with a predicted difficult airway. Results Methods With IRB approval and informed, written consent from the patients or their legal representatives, we conducted a randomized, prospective trial in patients with anticipated difficult airways. We enrolled 140 patients scheduled for elective or urgent surgery under general anesthesia with endotracheal intubation. Patients were aged 18-81 years with a American Society of Anesthesiologist (ASA) physical status 1- 3. Patients qualified for the trial, if they were considered a difficult airway as determined by measurement of at least one common predictive index for difficult intubation (see below). Patients were randomly assigned to either having their tube placed with use of a pre-formed stylet provided by the manufacturer of the glidescope (control group) or with a flexible, disposable tracheoscope (intervention group). The randomization was stratified as to whether patients were categorized as predicted difficult airway or had an immobilized cervical spine. Inclusion Criteria VLS in conjunction with a rigid stylet has improved the success rate of intubations in patients with predicted difficult airways. However, on occasion, oral intubation using this method may still be impossible. A flexible tracheoscope used in combination with VLS may further increase the success rate of intubation and speed up the intubation process in patients with a proven difficult airway. All patients were successfully intubated. The number of intubation attempts was similar (1.2 ± 0.6 control vs. 1.1 ± 0.4 intervention group, p = 0.4). The average time to successful intubation did not differ between the groups (104 ± 100 in control group vs. 95 ± 63 seconds in intervention group, p = 0.6). There was no difference from visualization to intubation in the control group (69 ± 74 VLS vs. 61 ± 37 intervention group, p = 0.1). In a subgroup of patients with the time interval of visualization to intubation of more than 60 seconds, intubation was significantly faster in the intervention group (164 ± 127 control group vs. 100 ± 38 intervention group, p = 0.04). The operators rated ease of intubation as similar. Four patients could not be intubated with the VLS and rigid stylet. They were subsequently intubated using the flexible tracheoscope. No serious complications were encountered. Tyromental distance< 6 cm Sterno-mental distance < 12 cm Mallampati grade: 3 and 4 Inter-incisor distance < 38 mm Status of dentition: presence of buck teeth Neck movement< 35° Cervical spine pathologies History of difficult intubation Body Mass Index (BMI)>35 Neck-circumference >43 g Results Conclusion