Feature-Based Modelling of Laryngoscope Blades for Customized Applications

AbstractLaryngoscopes 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

The quantal larynx: The stable regions of laryngeal biomechanics and implications for speech production

Purpose: Recent proposals suggest that (a) the high dimensionality of speech motor control may be reduced via modular neuromuscular organization that takes advantage of intrinsic biomechanical regions of stability and (b) computational modeling provides a means to study whether and how such modularization works. In this study, the focus is on the larynx, a structure that is fundamental to speech production because of its role in phonation and numerous articulatory functions. Method: A 3-dimensional model of the larynx was created using the ArtiSynth platform (http://www.artisynth.org). This model was used to simulate laryngeal articulatory states, including inspiration, glottal fricative, modal prephonation, plain glottal stop, vocal–ventricular stop, and aryepiglotto– epiglottal stop and fricative. Results: Speech-relevant laryngeal biomechanics is rich with “quantal” or highly stable regions within muscle activation space. Conclusions: Quantal laryngeal biomechanics complement a modular view of speech control and have implications for the articulatory–biomechanical grounding of numerous phonetic and phonological phenomen

Comparing the Effectiveness of the Video Laryngoscope with the Direct Laryngoscope in the Emergency Department: A Meta-Analysis of the Published Literature

Purpose: Rapid intubation is essential for the critically ill patient in the emergency department in order to ensure adequate oxygenation. Regardless of presenting illness or injury, the first pass success rate (FPSR) can impact patient morbidity and mortality. The study aim was to evaluate the FPSR of direct laryngoscopy (DL) compared with video laryngoscopy (VL) in adult patients intubated in the emergency department. Methods: Ovid Medline, Cochrane Library database, Embase, and Google Scholar were searched for peer-reviewed articles of studies of human subjects reporting a comparison of FPSR between VL and DL in adult patients who were orotracheally intubated in the emergency department. A meta-analysis was conducted using odds ratio (OR) as the summary effect measure for FPSR. A pooled effect size with the 95% Confidence Interval (CI) was calculated using a random effect model with inverse weighted method. Results: 8,428 intubations (5,840 DL and 2,588 VL) from nine studies (five observational and four randomized controlled trials) were included in the sample. The pooled OR for FPSR across all studies was 1.89 [95% CI = 1.17, 3.07; p \u3c 0.01], favoring VL when compared with DL. The results were limited by potential bias (selection and performance) and high levels of heterogeneity [I2 = 88%; 95% CI: 79%, 93%; Q = 64.61; p \u3c 0.01]. Conclusions: Threats to validity made it difficult to conclude with certainty that one device is better than the other for achieving a successful intubation on the first attempt in the emergency department

Automated location of orofacial landmarks to characterize airway morphology in anaesthesia via deep convolutional neural networks

Background:A reliable anticipation of a difficult airway may notably enhance safety during anaesthesia. In current practice, clinicians use bedside screenings by manual measurements of patients’ morphology. Objective:To develop and evaluate algorithms for the automated extraction of orofacial landmarks, which characterize airway morphology. Methods:We defined 27 frontal + 13 lateral landmarks. We collected n=317 pairs of pre-surgery photos from patients undergoing general anaesthesia (140 females, 177 males). As ground truth reference for supervised learning, landmarks were independently annotated by two anaesthesiologists. We trained two ad-hoc deep convolutional neural network architectures based on InceptionResNetV2 (IRNet) and MobileNetV2 (MNet), to predict simultaneously: (a) whether each landmark is visible or not (occluded, out of frame), (b) its 2D-coordinates (x, y). We implemented successive stages of transfer learning, combined with data augmentation. We added custom top layers on top of these networks, whose weights were fully tuned for our application. Performance in landmark extraction was evaluated by 10-fold cross-validation (CV) and compared against 5 state-of-the-art deformable models. Results:With annotators’ consensus as the ‘gold standard’, our IRNet-based network performed comparably to humans in the frontal view: median CV loss L=1.277·10-3, inter-quartile range (IQR) [1.001, 1.660]; versus median 1.360, IQR [1.172, 1.651], and median 1.352, IQR [1.172, 1.619], for each annotator against consensus, respectively. MNet yielded slightly worse results: median 1.471, IQR [1.139, 1.982]. In the lateral view, both networks attained performances statistically poorer than humans: median CV loss L=2.141·10-3, IQR [1.676, 2.915], and median 2.611, IQR [1.898, 3.535], respectively; versus median 1.507, IQR [1.188, 1.988], and median 1.442, IQR [1.147, 2.010] for both annotators. However, standardized effect sizes in CV loss were small: 0.0322 and 0.0235 (non-significant) for IRNet, 0.1431 and 0.1518 (p<0.05) for MNet; therefore quantitatively similar to humans. The best performing state-of-the-art model (a deformable regularized Supervised Descent Method, SDM) behaved comparably to our DCNNs in the frontal scenario, but notoriously worse in the lateral view. Conclusions:We successfully trained two DCNN models for the recognition of 27 + 13 orofacial landmarks pertaining to the airway. Using transfer learning and data augmentation, they were able to generalize without overfitting, reaching expert-like performances in CV. Our IRNet-based methodology achieved a satisfactory identification and location of landmarks: particularly in the frontal view, at the level of anaesthesiologists. In the lateral view, its performance decayed, although with a non-significant effect size. Independent authors had also reported lower lateral performances; as certain landmarks may not be clear salient points, even for a trained human eye.BERC.2022-2025 BCAM Severo Ochoa accreditation CEX2021-001142-S / MICIN / AEI / 10.13039/50110001103

Laringoscópio digital

Quatro páginas são dobráveisDocumento confidencial. Não pode ser disponibilizado para consultaTese de mestrado integrado. Engenharia Mecânica (Especialização Automação). Faculdade de Engenharia. Universidade do Porto. 201

Redesign Of The Standard Macintosh Laryngoscope To Improve Glottic Visualization During Endotracheal Intubation

University of Minnesota M.S.M.E. thesis. August 2016. Major: Mechanical Engineering. Advisor: Arthur Erdman. 1 computer file (PDF); x, 115 pages.Direct laryngoscopy is a procedure which allows for the visualization of the glottis during the process of endotracheal intubation (placement of the endotracheal tube into the trachea). The primary device used for this procedure is called the laryngoscope. The laryngoscope consists of a handle and a blade. During insertion of the blade, the curvature of the tongue is followed and the tip of the blade is inserted into the vallecula. In the vallecula resides the hyoepiglottic ligament, which connects the anterior surface of the epiglottis and the body of the hyoid bone. Different types of laryngoscopes exist, with the two most frequently used being the Macintosh and the Miller laryngoscope. The two laryngoscopes differ in the shape of the blade, one being curved (mac) and the other one straight (miller). During laryngoscopy with the Macintosh laryngoscope, the tip of the blade is used to push on the hyoepiglottic ligament, which lifts the epiglottis up and allows for exposure of glottis. In this procedure, the forces exerted on tissues can be significant (up to 50 N) and there can be complications as a result of the forces exerted on the soft tissues of the oropharynx and larynx. These complications can be esophageal intubation, hypoxia, and nerve damage. Furthermore, difficult intubations result in increased intubation time and a higher number of intubation attempts. The most common hurdle is the inability to successfully complete the endotracheal intubation. One of the reasons why the endotracheal intubation may not be successful is the inability to visualize the glottic opening. The level of intubation difficulty is based on the extent of the view of the glottis obtained during intubation and is classified into four grade views. A new type of laryngoscope blade, which looks like the Macintosh blade, but adds features that would allow to mitigate the aforementioned factors, was designed. The primary goal of the design was to provide a mechanism which could deliver a more anterior direct laryngoscopy view and allow for an enhanced lift of the epiglottis. This would be accomplished by adding a feature which would compress the body of the tongue and also lift the tip of the epiglottis more than the conventional Macintosh blade. The new design, unlike current blades, consists of three blade segments—one fixed and two movable. The fixed blade segment is the largest, with one end fixed to the laryngoscope handle and the other hinged to the first movable segment. The first movable segment is the second largest segment of the blade, and at one end is hinged to the fixed segment and at the other it is hinged to the third segment. The middle segment is designed to compress the tongue and push it out of the way to improve vocal cord visualization. The third (smallest) segment is the blade tip which is hinged at one end to the middle second segment. This is used to enter the vallecula and push against the hyoepiglottic ligament to lift the epiglottis. The design is purely mechanical with no electrical or electronic components.  A prototype was built and tested on manikins by anesthesiologists to primarily assess the change in the grade view of intubation by the flexible design. To evaluate the efficacy of the blade, a poor intubation grade view was forced and then without applying any incremental lifting forces, the mechanism was engaged to produce a final grade view. A qualitative pressure distribution was mapped for each attempt, and was compared to that obtained by a Macintosh blade. The improvement in the view with the flexible design was significant (p=0.000038). The pressures applied on the manikin airway by the flexible laryngoscope was less than that applied by the Macintosh laryngoscope to successfully intubate. The design of the flexible laryngoscope allowed for an improvement in the grade view of intubation and reduced the lifting forces applied on the airway. The built device proved that a flexible design can assist in difficult intubations

Models and Analysis of Vocal Emissions for Biomedical Applications

The Models and Analysis of Vocal Emissions with Biomedical Applications (MAVEBA) workshop came into being in 1999 from the particularly felt need of sharing know-how, objectives and results between areas that until then seemed quite distinct such as bioengineering, medicine and singing. MAVEBA deals with all aspects concerning the study of the human voice with applications ranging from the neonate to the adult and elderly. Over the years the initial issues have grown and spread also in other aspects of research such as occupational voice disorders, neurology, rehabilitation, image and video analysis. MAVEBA takes place every two years always in Firenze, Italy

Cable-driven parallel robot for transoral laser phonosurgery

Transoral laser phonosurgery (TLP) is a common surgical procedure in otolaryngology. Currently, two techniques are commonly used: free beam and fibre delivery. For free beam delivery, in combination with laser scanning techniques, accurate laser pattern scanning can be achieved. However, a line-of-sight to the target is required. A suspension laryngoscope is adopted to create a straight working channel for the scanning laser beam, which could introduce lesions to the patient, and the manipulability and ergonomics are poor. For the fibre delivery approach, a flexible fibre is used to transmit the laser beam, and the distal tip of the laser fibre can be manipulated by a flexible robotic tool. The issues related to the limitation of the line-of-sight can be avoided. However, the laser scanning function is currently lost in this approach, and the performance is inferior to that of the laser scanning technique in the free beam approach. A novel cable-driven parallel robot (CDPR), LaryngoTORS, has been developed for TLP. By using a curved laryngeal blade, a straight suspension laryngoscope will not be necessary to use, which is expected to be less traumatic to the patient. Semi-autonomous free path scanning can be executed, and high precision and high repeatability of the free path can be achieved. The performance has been verified in various bench and ex vivo tests. The technical feasibility of the LaryngoTORS robot for TLP was considered and evaluated in this thesis. The LaryngoTORS robot has demonstrated the potential to offer an acceptable and feasible solution to be used in real-world clinical applications of TLP. Furthermore, the LaryngoTORS robot can combine with fibre-based optical biopsy techniques. Experiments of probe-based confocal laser endomicroscopy (pCLE) and hyperspectral fibre-optic sensing were performed. The LaryngoTORS robot demonstrates the potential to be utilised to apply the fibre-based optical biopsy of the larynx.Open Acces

Towards 3D facial morphometry:facial image analysis applications in anesthesiology and 3D spectral nonrigid registration

In anesthesiology, the detection and anticipation of difficult tracheal intubation is crucial for patient safety. When undergoing general anesthesia, a patient who is unexpectedly difficult to intubate risks potential life-threatening complications with poor clinical outcomes, ranging from severe harm to brain damage or death. Conversely, in cases of suspected difficulty, specific equipment and personnel will be called upon to increase safety and the chances of successful intubation. Research in anesthesiology has associated a certain number of morphological features of the face and neck with higher risk of difficult intubation. Detecting and analyzing these and other potential features, thus allowing the prediction of difficulty of tracheal intubation in a robust, objective, and automatic way, may therefore improve the patients' safety. In this thesis, we first present a method to automatically classify images of the mouth cavity according to the visibility of certain oropharyngeal structures. This method is then integrated into a novel and completely automatic method, based on frontal and profile images of the patient's face, to predict the difficulty of intubation. We also provide a new database of three dimensional (3D) facial scans and present the initial steps towards a complete 3D model of the face suitable for facial morphometry applications, which include difficult tracheal intubation prediction. In order to develop and test our proposed method, we collected a large database of multimodal recordings of over 2700 patients undergoing general anesthesia. In the first part of this thesis, using two dimensional (2D) facial image analysis methods, we automatically extract morphological and appearance-based features from these images. These are used to train a classifier, which learns to discriminate between patients as being easy or difficult to intubate. We validate our approach on two different scenarios, one of them being close to a real-world clinical scenario, using 966 patients, and demonstrate that the proposed method achieves performance comparable to medical diagnosis-based predictions by experienced anesthesiologists. In the second part of this thesis, we focus on the development of a new 3D statistical model of the face to overcome some of the limitations of 2D methods. We first present EPFL3DFace, a new database of 3D facial expression scans, containing 120 subjects, performing 35 different facial expressions. Then, we develop a nonrigid alignment method to register the scans and allow for statistical analysis. Our proposed method is based on spectral geometry processing and makes use of an implicit representation of the scans in order to be robust to noise or holes in the surfaces. It presents the significant advantage of reducing the number of free parameters to optimize for in the alignment process by two orders of magnitude. We apply our proposed method on the data collected and discuss qualitative results. At its current level of performance, our fully automatic method to predict difficult intubation already has the potential to reduce the cost, and increase the availability of such predictions, by not relying on qualified anesthesiologists with years of medical training. Further data collection, in order to increase the number of patients who are difficult to intubate, as well as extracting morphological features from a 3D representation of the face are key elements to further improve the performance