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Background: The Ventrain® emergency ventilation device allows active inspiration and expiration through transtracheal catheters or the lumen of an airway exchange catheter. This single-use handheld device is manually operated and driven by an external pressurized oxygen source. The Ventrain® may be used to ventilate patients with a complete or pending upper airway obstruction reducing the risk of barotrauma due to the possibility of active expiration. However tidal volumes (V T) applied and withdrawn with the Ventrain® can only be controlled by visual inspection of chest movements; V T monitoring is not provided. Excessive inspiratory volumes or air trapping due to insufficient expiration may remain clinically undetected until pulmonary trauma and/or cardio-respiratory deterioration occur. Active expiration itself carries the risk of overwhelming lung deflation with the formation of atelectasis. Thus, an inspiratory and expiratory tidal volume monitor is urgently required. The aim of this study was to evaluate efficacy and precision of the Florian respiratory function monitor (RFM) to monitor in- and expiratory V T administered by the Ventrain® emergency ventilation device through a small cannula to the ASL 5000 test lung (ASL)., Methods: In an in-vitro setting the RFM was used with its neonatal flow sensor to monitor inspiratory and expiratory V T applied by the Ventrain® emergency ventilation device through a 2 mm internal diameter (ID) transtracheal catheter to the ASL. Driving flows of 6, 9, 12 and 15 l min(-1) were chosen to vary tidal volumes at a constant respiratory rate of 15 min(-1) and an I:E ratio of 1:1. Experiments were repeated five times with two flow sensors. An initial set-up calibration run was performed to calculate a bias correction factor for inspiratory and expiratory V T measured by the RFM. This bias correction factor was used to simulate a correction of the in the RFM programmed linearization table. In a second, identical setting the experiments were repeated five times with two flow sensors. V T measured by the adjusted RFM were compared with those obtained from the ASL 5000 in this second run and the percentage differences were calculated. Bland Altman analysis was used to investigate the agreement of inspiratory or expiratory VT measured by both methods (ASL and RFM). Calculation of the mean of differences between both methods is given as bias and the 95 % agreement interval as precision., Results: Tidal volumes measured by the ASL ranged from 140 to 675 ml. The percentage correction factor was 16.27 % (2.60 %) during inspiration for V T ranged from 0 to 700 ml and 11.51 % (2.56 %) during expiration for V T of 0 to 225 ml, 7.41 % (2.94 %) for VT 226 to 325 ml and 5.35 % (3.57 %) for TV e > 325 ml. Inspiratory and expiratory tidal volumes measured by the adjusted RFM demonstrated a percentage deviation (mean [SD]) of 2.59 % (1.86 %) during inspiration and 1.66 % (1.14 %) during expiration when compared with the ASL 5000. Bias (precision) of the Bland Altman plot for the adjusted RFM is 2.05 ml (23.20) during inspiration and 4.62 ml (10.40) for expiration., Conclusion: The tested respiratory function monitor using hot-wire anemometer technology has the potential to monitor tidal volumes applied by the Ventrain®. With the software thus adapted, the RFM measures precise inspiratory and expiratory tidal volumes within common technical tolerance. This could help perform adequate patient ventilation with Ventrain® and reduce the potential risk of patient trauma.

Introduction: Securing the airway with a tracheal tube is essential in emergency situations, in the intensive care setting as well as during anesthesia for surgery and other interventions. Current methods of airway assessment are poor screening tests for predicting difficult direct laryngoscopy due to a generally low positive predictive value; therefore, successful endotracheal intubation requires a high level of expertise, regular training and practice and sometimes additional tools. Currently, several video laryngoscopes (VL) with different designs are commercially available and have been investigated in a wide variety of settings. To our knowledge there is no prospective study evaluating and comparing performance among these three groups of VL; therefore, the aim of this study was to compare performance of five VL and conventional direct laryngoscopy in an intubation manikin model, both in a normal and simulated difficult intubation setting., Methods: In this study 10 residents, 12 senior staff physicians and 5 anesthesia nurses, all experienced in conventional direct laryngoscopy and inexperienced with VL underwent theoretical and hands-on training with all VL lasting 60 min. Afterwards participants performed intubation with all 5 VL and conventional direct laryngoscopy in a randomized sequence using an intubation manikin with normal intubation settings. Thereafter participants performed intubation in a simulated difficult intubation setting using the same intubation manikin with a neck collar to immobilize the cervical spine. In this study, the C-MAC(®) with Macintosh blade size 3, GlideScope(®) size 3, McGrath(®) series 5, King Vision(®) and Airtraq(®) size 2 were used. Time to intubation served as primary outcome and time to glottis visualization, number of intubation attempts, success rate and subjective evaluation of difficulty served as secondary outcomes., Results: In the normal intubation setting, time to intubation ranged from 16.0 s (conventional direct laryngoscopy) to 34.3 s (McGrath). GlideScope and conventional direct laryngoscopy were successful in 100 % followed by C-MAC (96.7 %), Airtraq (88.9 %), King Vision (77.8 %) and McGrath VL (44.4 %). In the simulated difficult intubation setting, time to intubation ranged between 20.3 s (Airtraq) and 26.7 s (McGrath). Success rate with C-MAC was 100 %, followed by GlideScope (96.7 %), Airtraq (85.2 %), conventional direct laryngoscopy (85.2 %), King Vision (81.5 %) and McGrath VL (70.4 %)., Conclusion: In the manikin with normal intubation setting, conventional direct laryngoscopy using a Macintosh blade was convincing and superior to any VL used in this study. During simulated difficult intubation, a blade with video transmission, such as C-MAC and the GlideScope were superior compared to conventional direct laryngoscopy and any other VL tested.

Preoperative fasting is essential to reduce the risk of a perioperative pulmonary aspiration in patients undergoing anaesthesia for elective surgery. Evidence and expert opinion-based guidelines suggest two, four and six hours of fasting for clear fluids, breast milk and light meals/non-clear fluids respectively to improve anaesthesia safety, patient's comfort and homeostasis. Prolonged fasting is observed in daily clinical routine but should be prevented since there are no benefits. Abnormal gastric emptying has an impact on preoperative fasting times and the choice of the anaesthesia technique. A safe anaesthesia technique is most important since gastric emptying differs in patients and there is no guarantee that the stomach is empty after fasting according to guidelines.