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Projects

Swiss Video Intubation Trial (SWIVIT) 1 & 2

SWIVIT 1 – a multicenter RCT
Video-laryngoscopes are marketed for intubation in difficult airway management. They provide a better view of the larynx and may facilitate tracheal intubation, but there is no adequately powered study comparing different types of video-laryngoscopes in a difficult airway scenario or in a simulated difficult airway situation.

Methods: The objective of this trial is to evaluate and to compare the clinical performance of three videolaryngoscopes with a guiding channel for intubation (Airtraq™, A. P. Advance™, King Vision™) and three videolaryngoscopes without an integrated tracheal tube guidance (C-MAC™, GlideScope™, McGrath™) in a simulated difficult airway situation in surgical patients. The working hypothesis is that each video-laryngoscope provides at least a 90% first intubation success rate (lower limit of the 95% confidence interval >0.9). It is a prospective, patient-blinded, multicenter, randomized controlled trial in 720 patients who are scheduled for elective surgery under general anesthesia, requiring tracheal intubation at one of the three participating hospitals. A difficult airway will be created using an extrication collar and taping the patients’ head on the operating table to substantially reduce mouth opening and to minimize neck movement. Tracheal intubation will be performed with the help of one of the six devices according to randomization. Insertion success, time necessary for intubation, Cormack-Lehane grade and percentage of glottic opening (POGO) score at laryngoscopy, optimization maneuvers required to aid tracheal intubation, adverse events and technical problems will be recorded. Primary outcome is intubation success at first attempt.

Discussion: We will simulate the difficult airway and evaluate different video-laryngoscopes in this highly realistic and clinically challenging scenario, independently from manufacturers of the devices. Because of the sufficiently powered multicenter design this study will deliver important and cutting-edge results that will help clinicians decide which device to use for intubation of the expected and unexpected difficult airway.

Trial registration: NCT01692535.

The study was supported by departmental research grants, a research grant from FLAVA, SGAR, and the Bangeter Stiftung
Data collection finished, manuscript pre-submission. April 2015.

SWIVIT 2 – was conducted in the same setting and design as SWIVIT 1 but we compared the non-channeled versions of the Airtraq™, A. P. Advance™, King Vision™ as well as the standard Macintosh blade investigating the same outcomes as in SWIVIT 1. An amendment from the cantonal ethic committee was granted. 480 elective patients were included and the data collection was closed recently.

Statistics on the results will be calculated soon and the manuscript will be written. April 2015.

Difficult Enviroment in Video-guided Intubation and Laryngoscopy (DEVIL) Study

No data about the performance of video-laryngoscopes under bright sunlight conditions are available. We will investigat the performance of a variety of video-laryngoscopes and the standard Macintosh laryngoscope under difficult environmental conditions (bright sunlight on a high altitude glacier on sun-reflecting snow). A variety of reports from in-hospital use reported better performance of video-laryngoscopes compared to standard Macintosh blade. Therefore we hypothesized that the Macintosh blade would perform inferiorly to the video-based devices and that the intubation devices’ performance would not be affected by varying environmental conditions. The study devices will be tested in five different environmental conditions: 1) Indoors at the respective University Hospitals of Bern, Lausanne and Geneva, Switzerland where the study participants work. 2) Indoors at 3450 meters above sea level at the High Altitude Research Station on the Jungfraujoch, Switzerland, 3) Outdoors in bright sunlight on snow with the unprotected eye, outside of the research station, 4) Outdoors in bright sunlight on snow with sunglasses, outside of the research station, 5) Outdoors in bright sunlight on snow outside of the research station, manikin and anesthesiologist covered with a dark blanket.

Methods: With local IRB approval, this prospective randomized study will include at least 20 physicians who will intubate identical manikins with limited mouth opening in the hospital and on the glacier at the Jungfraujoch in Switzerland at 3450m above sea level. Evaluated Devices to evaluate will be the Macintosh blade, McGrathä, Airtraqä, Glidescopeä, KingVisionä, C-MACä, A.P.Advanceä and Bonfilsä. Main outcome was intubation success rate; secondary outcomes included time for intubation, image visibility on the screen and obtaining a view of the glottic opening.

The data collection is finished, the manuscript submitted to a major international peer reviewed journal. April 2015.

Tube-exchange catheter as a guide for reintubation after anesthesia: a retrospective survey and flexible nasopharyngoscopy to assess the dislocation rate of Postoperative Airway Exchange Catheters in the post-operative care unit (PACU): a prospective observational study

The Cook Airway Exchange Catheter (CAEC) is designed to secure the patient´s airway in case there is a need to change the endotracheal tube. It is also used as a post-intubation aid to facilitate quick tracheal access in case of re-intubation. Therefore the correct location of the CAEC in the trachea is of utmost importance. We will screen our anesthesia and PACU records to compare our local incidence of the use of such catheters and compare that to current literature about that topic. Because only retrospective data on the use of CAEC is available and very little is known about the monitoring of the correct placement postoperatively.  Therefore we will perfume a prospective, observational study to gather information about the correct tracheal position of a CACE in the post-anesthesia care unit (PACU). 

Methods: With IRB approval we will screen all anesthesia and PACU records from the last 2 years on the use of CAEC, reintubation or surgical airway in the PACU to get the incidence of airway management pricedures with the aid of CAEC and without in the PACU. For the second part we will include with ethics committee approval and informed consent all consecutively patients entering the PACU with an oral or nasal CAEC after the extubation of the trachea over the CAEC in the OR. After PACU arrival we will continuously measure EtCO2 from the CAEC until its removal. Additionally, the position of the CAEC will be visualized with a flexible nasopharyngoscope at PACU admission, at CAEC removal and at changes of the ETCO2 waveforms indicate no gas flow. The primary outcome is failure rate defined as fiberoptically documented extra-tracheal position of the CAEC. Secondary outcomes are inappropriate EtCO2 measurement and re-intubation rate.

Study finished, data analyzed, manuscript in the writing process.

Learning the skills to manage rigid scopes for tracheal intubation – a cohort study comparing learning curves

Rigid intubation stylets are alternatives in the management of expected and unexpected difficulties in airway management. So far, no comparative studies investigated the learning of the Bonfils Intubation Endoscope (Karl Storz, stadt, Germany) and the SensaScope (Acutronic, adsfadfga, Switzerland). Previous reports mention that more than 20 attempts are needed for successful intubation with the Bonfils stylet  but only more than 2 attempts for the SensaScope. We are interested in the learning curves of the two devices used by senior anesthesiologists, experienced in flexible fibreoptic intubation (> 100 uses) as well as residents without fiberoptic experience.

Methods: All participants have no experience with the devices but will train five times with both devices in an intubation manikin (Leardal, adsffs, Huslöönuum, Norway). With ethics approval and patients’ informed consent we will intubated elective surgical patients without predictors for difficult airway management with the two devices in random order. Each participant will intubate 10 patients per device. Major outcome is the time needed until successful intubation. The time will be taken from the removal of the face mask until connection of the respiratory cycle.

Data collection is closed, analysis and manuscript writing on its way.

The performance of rigid scopes for intubation: A randomized controlled trial in patients with a simulated difficult airway

Rigid scopes are increasingly popular options for the management of predicted and unpredicted difficulties in airway management. This single-center, RCT compares the scopes Bonfils™ and SensaScope™ in a simulated difficult airway scenario.

Methods: 200 patients of both genders, aged 18-85, ASA physical status I-III, scheduled for elective surgery requiring general anesthesia with tracheal intubation with ethics committee approval and written informed consent will be included. Difficult airway will be simulated with a cervical extrication collar limiting mouth opening and movement of the neck. Primary outcome parameter is the overall success rate in a maximum of two intubation attempts of 120 seconds each. Secondary outcomes are first attempt success rate, intubation times, difficulty of positioning and intubation, fiberoptic view, and side effects.

Data collection is closed, manuscript written and closed to submission.

Pediatric supraglottic airway devices in clinical practice: A prospective observational cohort study

Supraglottic airway devices (SGA) are commonly used in pediatric anesthesia as primary or back-up devices for airway management. Most SGAs are marketed without proper clinical evaluation. In this study, we evaluate the performance of three standard SGA (i-gel®, Ambu® AuraOnce™, LMA Supreme™) and two intubation SGAs (Air-Q®, Ambu® Aura-i™). The primary hypothesis was that the mean airway leak pressure of all SGAs would be between 18 and 22 cmH2O.

Methods: With local IRB approval, this prospective controlled observational cohort study will evaluated 400 children, aged 0-17 years and weighing 5-30kg, scheduled for elective surgery and standardized anesthesia with a SGA. The primary outcome is mean airway leak pressure. Secondary outcome parameters include first attempt and overall success rate, insertion time, alignment with pharyngeal and laryngeal structures and adverse events.

Study is finished and the manuscript is ready to submit.

Problems with airway assessment: Accuracy, inter- and intra-observer variability of predictors

Problems with airway management are still the leading cause or anaesthesia related morbidity and mortality (persistent severe hypoxic brain damage and death). For the prevention of unexpected problems with airway management, the assessment of anatomical predictors for a difficult airway is crucial. One standard predictor is the Mallampati score with low negative predictive value of a score of 1 or 2. The sensitivity is poor being not more than 49%. Another parameter is the Cormack-Lehane classification evaluating the view on the glottis during laryngoscopy with a high inter-observer variability (Kappa=0.16). As the Cormack-Lehane class is a major outcome parameter in lots of airway studies, correct assessment is crucial to translate study results into clinical practice. A pilot study conducted by DARC verified the large inter-observer variability; anaesthesiologists graded the Mallampati score wrong in about 50%.

To know whether the quality of this assessment can be improved by educational interventions, we plan a prospective, randomised controlled before-and-after trial evaluating the airway assessment at baseline and after educational interventions. Participants will be randomised to different educational interventions. Primary outcome parameter is the percentage of correct assessments of the Mallampati score and Cormack-Lehane class.

Study starts after Cantonal Ethic Committee approval.

Train the Airway Trainer (TAT): Does a clinical teacher training-program improve teaching of airway management?

Most anaesthesiologists, are involved in clinical airway management teaching but only a few receive any formal training in teaching skills. The quality of residency training in airway skills can be enhanced though learner-directed, interactive teaching methods. Little is known about the efficacy of train-the-trainer programs to improve clinical airway teachers’ teaching competency. We designed this study to investigate the impact of such a program.

To answer the research questions of whether this faculty development program improved participants’ teaching abilities for airway management and if the program also enabled them to initiate improvements of clinical airway management teaching on an institutional level, we will conduct a qualitative research project with an open cohort of TAT-participants using structured interviews, assessment of post-course assignment reports and a pre-post course questionnaire as well as a 6 month follow-up questionnaire.

A subgroup of TAT-participants from a cohort in Turkey and in Switzerland (German) will participated in recorded structured interviews to obtain deeper insight into their successful experiences, obstacles encountered, and/or possible changes in their strategies for teaching airway management. We will investigate whether cultural differences exist between the two language cohorts of TAT-participants.

On-going study project.

Prospective Assessment Project of AirwaY management during Anaesthesia (PAPAYA)
(A prospective single centre observational study)

NAPs4 in the UK revailed several events of airway management with detrimental outcome (death, prolonged ICU stay) during standard anesthesia. To get a picture what happens in a central European university hospital we will assess all minor and major complications in airway management during general anaesthesia over 2 month. The used assessment toll will be evaluated for it’s used as generic assessment tool for such assessments.

We will record all major airway complications as primary endpoints and all minor complications as secondary endpoint from all consecutive patients with general research consent form of the University Hospital Bern (INSELSPITAL) undergoing general anaesthesia over a period of 2 month. To avoid selection bias we will not exclude patients (except no general consent is available). Data will be collected from the Anesthesia Information System and screening questionnaire will detect airway management complications. Those complications will be followed up for each patient affected until the problem has been solved. We estimate the number of patients from the clinical case reports during the last month and calculated that about 3500 patients will beincluded in this observational study.

Ethics committee approval is pending.

Clinical limitations of paediatric-sized supraglottic airway devices as a conduit for fibreoptic intubation. An in-vitro study.

Supraglottic airway devices (SAD) are not only used to establish a patent airway to ventilate the patients’ lungs but also as a conduit for rescue intubation providing easy passage of the tracheal tube for intubation and also easy passage of the cuff pilot balloon during SAD removal. Data are incomplete about safe advancement of tracheal tubes including their cuff-pilot balloons through SADs. Anaesthesiologists need to know which paediatric-sized SAD can be used as a conduit for intubation and also allows for safe removal.

Methods: This in-vitro study investigates four paediatric SADs of sizes 1.0 to 2.5 (Ambu AuraOnce™, Ambu Aura Straight™, LMA Unique™, i-gel™) and three paediatric SADs of the same size that are specifically marketed for intubation (air-Q™ (inflatable), air-Q™ (self-pressurizing), Ambu Aura-i™). Five cuffed paediatric tracheal tubes (Mallinckrodt™, Rüschelit™, KimVent™, Microcuff™ and Sheridan™) with internal diameter ranging from 3.0 to 5.5mm will be used. We will verify whether the tracheal tube and the cuff-pilot balloon will pass the lumen of the SAD and compare that with the manufacturers’ brochure.

Ongoing research project. April 2015.

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