A Comparative Crossover Randomized Study of Miller and Macintosh Blade for Laryngoscopic View and Ease of Intubating Conditions in Adults

Background: Although several types of laryngoscope blades of different sizes and shapes are present, Miller (MIL) blade is the most preferable blade among paediatric population. However, there is dearth in the literature regarding the use of these blades in the adult population. This study aimed to compare the laryngoscopic view and ease of intubation using MIL and Macintosh (MAC) blade among adults. Methods: A total of 172 patients who were >18 years age, with ASA grades I and II, undergoing elective surgeries with general anaesthesia were included. Patients were distributed in two groups (MAC/MIL and MIL/MAC), where laryngoscopy was first done with MAC blade, followed by MIL blade in the MAC/MIL group and vice-versa in the MIL/MAC group. Grading of laryngoscopic views, number of attempts, ease of intubation and use of backward, upward, rightward pressure (BURP) were noted. R v 3.6.0 was used for statistical analysis and P values≤0.05 were considered as statistically significant. Results: MIL blade showed better laryngoscopic view compared to MAC blade (32.6% vs. 15.1%; P< 0.002). BURP application helped improve the laryngoscopic views with MAC blade. Intubation with MIL blade was easier with regards to ease of intubation and number of attempts 19 (P value<0.05). Conclusion: Glottis visualization is better with the MIL blade as compared to the MAC blade. Therefore, the MIL blade might be helpful in securing the airway among adult patients.

Two-Segment Flexible Macintosh Laryngoscope to Improve Glottic Visualization During Endotracheal Intubation

Endotracheal intubation is a frequently performed life-saving procedure in medicine. Obtaining view of glottic structures is essential for successful completion of endotracheal intubation. Most frequently used devices called laryngoscopes sometimes fail to obtain view, which would allow for a successful completion of endotracheal intubation. To improve visualization of glottic structures practitioners can use high-tech video-laryngoscopes, but these are not available to everyone, especially not in the third world countries. Alternatively practitioners can use two segment laryngoscopes. We developed a prototype of a two-segment flexible laryngoscope and tested it in simulated environment. Our study strengthens available evidence that multi-segment laryngoscope blades can improve glottic visualization and decrease forces exerted on soft tissues of larynx.

Feature-Based Modelling of Laryngoscope Blades for Customized Applications

Laryngoscopes are used as diagnostic devices for throat inspection or as an aid to intubation. Their blade must be geometrically compatible with patients’ anatomy to provide a good view to doctors with minimal discomfort to patients. For this reason, this paper was aimed to investigate the feasibility of producing customized blades.The customizable blade model was developed following a feature-based approach with eight morphological parameters. The thickness of such a blade was determined through numerical simulations of ISO certification tests, where the finite element mesh was obtained by morphing a ‘standard’ mesh.The following procedure was applied: the model was built from the selected parameters; the blade was tested in silico; finally, the blade was produced by additive manufacturing with an innovative biodegradable material (Hemp Bio-Plastic® -HBP-) claimed to feature superior mechanical properties. The procedure evidenced that the mechanical properties of current biodegradable materials are unsuitable for the application unless the certification norm is revised, as it is expected.

Design and Optimization of Patient-Specific Pediatric Laryngoscopes

Pediatric laryngoscope blades do not vary in size and shape as patients’ airways do. Difficult airway intubations may require physicians to try different blade sizes and even improvise. In addition to physical trauma and complications, difficult intubations may result in longer operating room times. As advanced three-dimensional (3D) imaging, modeling, and printing technologies become more ubiquitous at the point-of-care, so will the development and fabrication of patient-specific solutions. Here we introduce a method for the design and fabrication of patient-specific, single-use pediatric laryngoscope blades. The process seeks to optimize procedures and mitigate complications by providing physicians with the right tool at the right time.