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This contribution quantifies the birefringence within injection-molded cyclic olefin copolymer plates and discusses its impact on the mechanical properties of the plates. It also focuses on the impact of birefringence on integrated waveguides and Bragg gratings and provides fabrication guidelines for such structures. The anisotropy in all three dimensions of the workpiece is examined by means of polarimetry and a prism coupler. It is found that the birefringence is inhomogenously distributed within the workpieces, whereas the maximum birefringence not only varies locally, but also depends on the observation direction. Overall, a maximum birefringence of 10 × 10-4 is found at the plate's surface near the injection gate. The anisotropy then reduces exponentially towards the center of the workpiece and saturates at 1.8 × 10-4, in a depth of 0.4 mm. Thus, the birefringence strongly affects near-surface photonic structures. It is found that, depending on their orientation and the local birefringence of the substrate, waveguides and Bragg gratings fabricated with comparable parameters behave completely differently in terms of polarization-dependent optical attenuation, cross-sectional intensity distribution and Bragg reflection signal. For example, the support of the TM mode can vary between total loss and an optical attenuation of 0.9 dB × cm-1. In consequence, this study underlines the importance of quantifying the birefringent state of an injection-molded cyclic olefin copolymer workpiece if it is supposed to serve as a substrate for integrated photonic structures. The study furthermore demonstrates that birefringence effects can be omitted by burying the photonic structures deeper into the volume of the thermoplastic.

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BACKGROUND: A variety of instruments are used to perform airway management by tracheal intubation. In this study, we compared the MacIntosh balde (MB) laryngoscope with the Bonfils intubation fibrescope as intubation techniques. The aim of this study was to identify the technique (MB or Bonfils) that would allow students in their last year of medical school to perform tracheal intubation faster and with a higher success probability. Data were collected from 150 participants using an airway simulator ['Laerdal Airway Management Trainer' (Laerdal Medical AS, Stavanger, Norway)]. The participants were randomly assigned to a sequence of techniques to use. Four consecutive intubation 'trials' were performed with each technique. These trials were evaluated for differences in the following categories: the 'time to successful ventilation', 'success probability' within 90 s,'time to visualisation' of the vocal cords (glottis), and 'quality of visualisation' according to the Cormack and Lehane score (C&L, grade 1-4). The primary endpoint was the 'time to successful ventilation'in the fourth and final trial. RESULTS: There was no statistically significant difference in the 'time to successful ventilation' between the two techniques in trial 4 ('time to successful ventilation': median: MB: 16 s, Bonfils: 14 s, p = 0.244). However, the 'success probability' within 90 s was higher when using a Macintosh blade than when using a Bonfils (95 vs. 87%). The glottis could be better visualised when using a Bonfils (C&L score of 1 (best view): MB: 41%, Bonfils: 93%), but visualisation was achieved more rapidly when using a Macintosh blade (median: 'time to visualisation': MB: 6 s, Bonfils: 8 s, p = 0.003). CONCLUSIONS: The time to ventilation using the MacIntosh blade and Bonfils mainly did to differ, however success probabilities and time to visualisation primary favoured the MacIntosh blade as intubation technique, although the Bonfils seem to have a steeper learning curve. The Bonfils is still a promising intubation technique and might be easier to learn as the MB, at least in a manikin.

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BACKGROUND: Supraglottic devices are helpful for inexperienced providers who perform ventilation in emergency situations. Most supraglottic devices do not allow secondary tracheal intubation through the device. The novel intubating laryngeal tube (iLTS-D) and the intubating laryngeal mask (Fastrach) are devices that offer supraglottic ventilation and secondary tracheal intubation. METHODS: We evaluated the novel iLTS-D and compared it to the established Fastrach using a manikin-based study. Participants used both devices in a randomised order. The participants conducted four consecutive trials on a manikin. One trial was composed of the following procedures. First, participants ventilated the manikin using either iLTS-D or Fastrach. 'Time to ventilation', success rates and number of attempts were recorded for the supraglottic device. Second, participants intubated the manikin through the previously inserted supraglottic device. 'Time to tracheal ventilation', success rate and tube localisation were recorded. The primary endpoint was the results of the final fourth trial, which mirrored the standardised training of trials 1, 2 and 3. RESULTS: A total of 64 participants were enrolled. All of the participants successfully inserted both devices on their first attempt in trial 4. Fastrach was applied 1 s faster in trial 4 than the iLTS-D (median 'time to ventilation' Fastrach: 13.5 s., iLTS-D: 14.5 s., p = 0.04). All participants successfully intubated through both devices in trial 4. There was no difference in 'time to tracheal ventilation' by tracheal intubation between either device (median 'time to tracheal ventilation': Fastrach: 14.0 s., iLTS-D: 14.0 s., p = 0.16). CONCLUSION: The iLTS-D performed similarly to the ILMA in insertion and intubation times in a manikin setting.

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