Standard Mouthpiece Research Articles

Tongue Displacement Device in Decreasing the Radiation Dose to Tongue and Preventing Proton Beam Overshoot in Proton Therapy for Unilateral Head and Neck Cancer

The aim of this study was to evaluate the dosimetric characteristics of a semi-customized tongue displacement device (SCTDD) fabricated using a 3D printer for patients receiving unilateral head and neck irradiation with intensity-modulated proton therapy (IMPT) and assess its feasibility as a proton beam stopper compared to a standard mouthpiece (SMP). Seven consecutive patients, three with tonsil cancer, and four with oral cavity cancer were included in this retrospective study. Planning computed tomography (CT) images of each patient were acquired for each device. Both the SCTDD and SMP plans were generated using a single-field optimized IMPT. The clinically relevant dose-volume parameters for the organs at risk (OARs), especially the tongue, were compared between the SCTDD and SMP plans. Additionally, to assess the feasibility of SCTDD as a proton beam stopper, the dose to the contralateral oral mucosa (COM) was compared with that from sMP use. The use of scTDD resulted in a statistically significant decrease in the radiation dose to the tongue and COM compared to sMP. The median mean dose to the tongue was significantly reduced with SCTDD (18.3 Gy(RBE)) compared to the SMP (22.9 Gy(RBE)) (p = 0.016). The percentages of tongue volume receiving doses between 15 and 60 Gy(RBE) were significantly lower with SCTDD. In the COM, SCTDD resulted in a significantly lower median mean (2.9 Gy(RBE) vs. 7.9 Gy(RBE), p = 0.018) and maximum dose (39.1 Gy(RBE) vs. 41.6 Gy(RBE), p = 0.018) doses compared to SMP. The SCTDD effectively decreased the radiation dose to the tongue compared to SMP in patients undergoing unilateral head and neck irradiation with IMPT and acted as a proton beam stopper to protect normal tissues located behind the target volume, such as the COM.

Temporomandibular disorders in scuba divers: a systematic review

Introduction The number of divers has grown a lot in recent years [1]. The characteristics of the equipment that the divers use in the oral cavity to be able to breathe during the immersion are susceptible to provoke temporomandibular disorders (TMDs) [2]. These patients have specific characteristics related to difficulties in the temporomandibular joint (TMJ), in the masticatory muscles and tissues of the oral cavity. All these complaints are known as "Diver's Mouth Syndrome" [3]. The objective of this study was to obtain what’s known about TMDs in scuba diving. Materials and methods Pubmed, cochcrane and B-on were used with the keywords "Temporomandibular Disorders" Mesh Term, AND/OR "Scuba Divers". Studies published in Portuguese, Spanish and English between 2018-1998 on humans were included. We included all clinical trials. Results We found 6543 citations of which 2238 duplications were excluded. After screening based on title and abstract analysis, we arrive on 62 full-text articles to assess and selected 8 studies. In terms of study characteristics they can be divided in TMD caused by lack of experience or lack of training in scuba diving [3]; history of TMD previous to scuba diving [4,5]; temperature of the water and facial pain [5]; and TMD and design, material and universal or customised mouthpiece (MP) and TMD [5–8]. Discussion and conclusions: Diving in colder waters is related with an increase in facial pain due to muscle contraction and clenching of masticatory muscles thus inducing facial pain [5]. In terms of TMD and MP for oxygen bottles the major part of the studies reveal the more customised the MP the less prone to TMD the subject is, so we have the standard MP, less efficient assuming that the same measure is for all mouths; the temperature mouldable MP to the mouth after being softened in hot water which deform with ease and the customised MP that are more effective, more expensive and constructed in the likeness of each one by the dentists so recognised by the sleep society [5]. Inexperienced divers tend to be more prone to TMD due to the mistake they make and stress they are exposed to. Due to the study design being so weak until now more studies should be carried out on the clinical side in a standardised way so that studies can be compared rather than based only on self-report.

Development of a Tongue Immobilization Device Using a 3D Printer for Intensity Modulated Radiation Therapy of Nasopharyngeal Cancer Patients.

PurposeThis study aimed to reduce radiation doses to the tongue, a patient-specific semi-customized tongue immobilization device (SCTID) was developed using a 3D printer for helical tomotherapy (HT) of nasopharyngeal cancer (NPCa). Dosimetric characteristics and setup stability of the SCTID were compared with those of a standard mouthpiece (SMP).Materials and MethodsFor displacement and robust immobilization of the tongue, the SCTID consists of four parts: upper and lower tooth stoppers, tongue guider, tongue-tip position guide bar, and connectors. With the SCTID and SMP, two sets of planning computed tomography and HT plans were obtained for 10 NPCa patients. Dosimetric and geometric characteristics were compared. Position reproducibility of the tongue with SCTID was evaluated by comparing with planned dose and adaptive accumulated dose of the tongue and base of the tongue based on daily setup mega-voltage computed tomography.ResultsUsing the SCTID, the tongue was effectively displaced from the planning target volume compared to the SMP. The median mucosa of the tongue (M-tongue) dose was significantly reduced (20.7 Gy vs. 27.8 Gy). The volumes of the M-tongue receiving a dose of 15 Gy, 30 Gy, and 45 Gy and the volumes of the mucosa of oral cavity and oropharynx (M-OC/OP) receiving a dose of 45 Gy and 60 Gy were significantly lower than using the SMP. No significant differences was observed between the planned dose and the accumulated adaptive dose in any dosimetric characteristics of the tongue and base of tongue.ConclusionSCTID can not only reduce the dose to the M-tongue and M-OC/OP dramatically, when compared to SMP, but also provide excellent reproducibility and easy visual verification.

Analysis of impedance characteristics of the respiratory system of animals and humans

The aim of the study was to modify the method of pulsed oscillometry of the respiratory system of biological objects in the interests of the possibility of its application to extrapolate the medical and biological effects of extreme physical factors of the conditions of professional activity from animals to humans. The method is based on a verified algorithm for determining the impedance characteristics of the human lungs (resonant frequency, active and reactive frequency–dependent components of the impedance) using a two-microphone technique. The impedance characteristics of the respiratory system of animals (30 rats, 15 rabbits, and 15 sheep) in the frequency range from 5 to 100 Hz were measured on decapitated animals when the trachea was connected to an experimental setup including a loudspeaker, waveguide, two measuring microphones, an impedance wall, and a connecting tube designed to connect the installation to the trachea. The impedance characteristics of the respiratory system in humans (40 athletes aged 20–30 years) in the same frequency range were measured during free breathing: a standard mouthpiece was installed as a perforated panel at the end of the waveguide. As a result of the experiment, the resonance frequency of the respiratory system, the absorption coefficient of acoustic vibrations and the resistance at the resonance frequency and the acoustic quality factor of the respiratory system were determined. The results of theoretical and experimental studies indicate that the resonant frequencies of the respiratory system in humans, rabbits and sheep are close to each other, and the resonant frequencies of the respiratory system of rats and humans are significantly different. This allows the use of rabbits and sheep as an adequate biological model for extrapolating the effects of extreme factors from animals on humans in terms of the state of the respiratory system. Extrapolation of similar results from rats to humans should be carried out taking into account the ratio of the impedance characteristics of the respiratory systems.

Development of a semi-customized tongue displacement device using a 3D printer for head and neck IMRT

PurposeTo reduce radiation doses to the tongue, a patient-specific semi-customized tongue displacement device (SCTDD) was developed using a 3D printer (3DP) for head and neck (H&N) radiation therapy (RT). Dosimetric characteristics of the SCTDD were compared with those of a standard mouthpiece (SMP).Materials and methodsThe SCTDD consists of three parts: a mouthpiece, connector with an immobilization mask, and tongue displacer, which can displace the tongue to the contralateral side of the planning target volume. Semi-customization was enabled by changing the thickness and length of the SCTDD. The instrument was printed using a 3DP with a biocompatible material. With the SCTDD and SMP, two sets of planning computed tomography (CT) and tomotherapy plans were obtained for seven H&N cancer patients. Dosimetric and geometric characteristics were compared.ResultsUsing the SCTDD, the tongue was effectively displaced from the planning target volume without significant tongue volume change compared to the SMP. The median tongue dose was significantly reduced (29.6 Gy vs. 34.3 Gy). The volumes of the tongue receiving a dose of 15 Gy, 30 Gy, 35 Gy, 45 Gy, and 60 Gy were significantly lower than using the SMP.ConclusionThe SCTDD significantly decreased the radiation dose to the tongue compared to the SMP, which may potentially reduce RT-related tongue toxicity.

Using Navier-Stokes modeling to design a better recorder

We use the Navier-Stokes equations to model how air flows in the mouthpiece region of the recorder. Different geometrical designs for this region are investigated, and the effect of these modifications on the tonal properties are studied. We find that simple changes from the standard mouthpiece geometry can have large effects on the resulting spectra which we have traced to changes in the vortex patterns near the labium. Our modeling results have been tested by using 3D printing to make instruments suggested to be most promising. The modeling results also reveal how subtle changes in features like the sharpness of the labium can have a profound effect on the behavior. [Work supported by NSF grant PHY1513273.]

Reliability of respiratory pressure measurements in ventilated and non-ventilated patients in ICU: an observational study

BackgroundAssessment of maximum respiratory pressures is a common practice in intensive care because it can predict the success of weaning from ventilation. However, the reliability of measurements through an intubation catheter has not been compared with standard measurements. The aim of this study was to compare maximum respiratory pressures measured through an intubation catheter with the same measurements using a standard mouthpiece in extubated patients.MethodsA prospective observational study was carried out in adults who had been under ventilation for at least 24 h and for whom extubation was planned. Maximal respiratory pressure measurements were carried out before and 24 h following extubation.ResultsNinety patients were included in the analyses (median age: 61.5 years, median SAPS2 score: 42.5 and median duration of ventilation: 7 days). Maximum respiratory pressures measured through the intubation catheter were as reliable as measurements through a standard mouthpiece (difference in maximal inspiratory pressure: mean bias = − 2.43 ± 14.43 cmH2O and difference in maximal expiratory pressure: mean bias = 1.54 ± 23.2 cmH2O).ConclusionMaximum respiratory pressures measured through an intubation catheter were reliable and similar to standard measures.Clinical trial registration Retrospectively Registered in ClinicalTrials.gov (NCT02363231).

Pre-oxygenation using a mouthpiece

Several authors have previously published studies on pre-oxygenation using a mouthpiece 1, 2. We would like to remind readers of the utility of this technique for pre-oxygenating patients who find close-fitting facemasks alarmingly claustrophobic. Using a standard mouthpiece (Intersurgical Ltd, Wokingham, UK) routinely used in obstetric patients for inhaling oxygen/nitrous oxide mixtures, which is detached from the filter it is usually supplied with and attached to the catheter mount of an anaesthetic breathing circuit (Fig. 3), allows for suitable pre-oxygenation when the patient forms a seal around the mouthpiece with their lips and inspires normal tidal ventilations with a fresh gas flow of 10 l.min−1 and an FiO2 of 1.0. The mouthpiece is changed to a standard anaesthetic mask following induction of general anaesthesia, once pre-oxygenation is complete.

Complex chromosomal rearrangements in a patient with oligozoospermia and Charcot–Marie–Tooth disease

Complex chromosomal rearrangements in a patient with oligozoospermia and Charcot–Marie–Tooth disease

Prevalence of neuromuscular disorders in Italian Navy scuba divers: Personalized vs standard mouthpiece

Prevalence of neuromuscular disorders in Italian Navy scuba divers: Personalized vs standard mouthpiece

Validation Of The Pre-vent??? Mask For Maximal Metabolic Exercise Testing

The standard mouthpiece is an important component for metabolic exercise testing. However, the mouthpiece can fatigue jaw muscles and cause dryness in the throat; thus, resulting in discomfort to its users. The Pre-Vent™ Mask is an alternative, which eliminates these discomforting factors, especially during maximal effort. PURPOSE To validate the use of the Pre-Vent™ Mask versus the mouthpiece during maximal treadmill exercise testing. METHODS Data were gathered on 19 subjects [11 women (24.7±3.2 years; 64.5±8.1 kg) and 8 men (30.9±7.3 years; 81.1±9.0 kg)] who visited the laboratory on two different occasions. During each visit, the subjects performed a maximal treadmill exercise test randomized to either the mouthpiece or the Pre-Vent™ Mask. A Modified Bruce Protocol was used which initially started at 2.5 m.p.h. and 0% grade with increments of 0.5 m.p.h. and 2% grade every two minutes. Gas was collected using the Medical Graphics Cardio II gas analysis module (BreezeSuite software version 6.0 A). Heart rate was determined by using a 3-lead ECG (Cardio Control Workstation version 1.3.1). Values at maximal levels were analyzed by paired t-test (mouthpiece versus mask) using the 0.05 level of significance. Results Maximal relative volume of oxygen consumption (VO2) (ml/kg/min), absolute VO2 (Mask: 3.7±1.0, Pre-Vent™ 3.6±0.8 L/min) volume of carbon dioxide expired (VCO2) (Mask: 4.3±1.2, Pre-Vent™ 4.1±0.9 L/min), respiratory exchange ratio (RER), ventilation volume (VE; L/min), and heart rate (HR; bpm) were not significantly different between the mouthpiece and the Pre-Vent™ Mask. CONCLUSION The Pre-Vent™ Mask is a valid device for maximal metabolic exercise treadmill testing, as well as at submaximal levels. The Pre-Vent™ Mask may be a more comfortable alternative to the traditional mouthpiece.

Validation Of The Pre-vent™ Mask For Maximal Metabolic Exercise Testing

The standard mouthpiece is an important component for metabolic exercise testing. However, the mouthpiece can fatigue jaw muscles and cause dryness in the throat; thus, resulting in discomfort to its users. The Pre-Vent™ Mask is an alternative, which eliminates these discomforting factors, especially during maximal effort. PURPOSE To validate the use of the Pre-Vent™ Mask versus the mouthpiece during maximal treadmill exercise testing. METHODS Data were gathered on 19 subjects [11 women (24.7±3.2 years; 64.5±8.1 kg) and 8 men (30.9±7.3 years; 81.1±9.0 kg)] who visited the laboratory on two different occasions. During each visit, the subjects performed a maximal treadmill exercise test randomized to either the mouthpiece or the Pre-Vent™ Mask. A Modified Bruce Protocol was used which initially started at 2.5 m.p.h. and 0% grade with increments of 0.5 m.p.h. and 2% grade every two minutes. Gas was collected using the Medical Graphics Cardio II gas analysis module (BreezeSuite software version 6.0 A). Heart rate was determined by using a 3-lead ECG (Cardio Control Workstation version 1.3.1). Values at maximal levels were analyzed by paired t-test (mouthpiece versus mask) using the 0.05 level of significance. Results Maximal relative volume of oxygen consumption (VO2) (ml/kg/min), absolute VO2 (Mask: 3.7±1.0, Pre-Vent™ 3.6±0.8 L/min) volume of carbon dioxide expired (VCO2) (Mask: 4.3±1.2, Pre-Vent™ 4.1±0.9 L/min), respiratory exchange ratio (RER), ventilation volume (VE; L/min), and heart rate (HR; bpm) were not significantly different between the mouthpiece and the Pre-Vent™ Mask. CONCLUSION The Pre-Vent™ Mask is a valid device for maximal metabolic exercise treadmill testing, as well as at submaximal levels. The Pre-Vent™ Mask may be a more comfortable alternative to the traditional mouthpiece.

Assessment of the lactate and ventilatory thresholds by breathing frequency in runners

The aim of this study was to establish the validity of the breakpoint in breathing frequency for the assessment of the lactate threshold and the ventilatory threshold during incremental running exercise. Twelve trained runners (mean +/- s: age 29 +/- 8 years; body mass 68.7 8.8 kg; V O 2m ax 57.9 +/- 4.1 ml . kg -1 . min -1 ) performed randomly assigned incremental treadmill tests on separate days. In addition to the assessment of the V O 2m ax (Test 1), the subjects performed two standard multi-stage treadmill tests (4-min stages) for the assessment of the lactate threshold while wearing (Test 2) and not wearing (Test 3) a standard mouthpiece and noseclip arrangement. Breathing frequency was measured by a thermistor, which was positioned in the back of the mouthpiece for Test 2, and fixed 3 cm in front of the mouth using a headband and flexible wiring for Test 3. All exercise tests were recorded on videotape and mean breathing frequency and stride rate were calculated for the last minute of each stage from real-time playback of the videotapes. The breathing frequency breakpoint was determined in six subjects only for Test 2 and in five subjects only for Test 3. For Test 2, there were no differences between the breakpoint in breathing frequency (14.7 +/- 0.9 km . h - 1), the lactate threshold (14.7 +/- 0.9 km . h -1 ) and the ventilatory threshold (14.7 +/- 1.1 km . h -1 ). For Test 3, the breakpoint in breathing frequency (14.0 +/- 1.0 km . h -1 ) was not appreciably different from the lactate threshold (14.7 +/- 1.2 km . h -1 ). Hey plots showed marked interindividual differences in the responses of breathing frequency and tidal volume to exercise. In four subjects, the ventilatory threshold was mediated by a non-linear increase in tidal volume, with breathing frequency either increasing in a linear manner (n = 1) or remaining constant owing to entrainment of breathing frequency to cadence (n = 3). We conclude that the breakpoint in breathing frequency does not provide a valid method for the field-based assessment of the lactate or ventilatory thresholds in most subjects for running exercise.

Esophageal Pressure Measurements in Cardiopulmonary Exercise Testing

We sought to determine the adaptability and effectiveness of a new esophageal balloon technique to measure changes in esophageal pressure (Pes) as a reflection of pleural pressure with progressive incremental exercise testing in normal subjects. An 8F (0.9 cm) esophageal balloon catheter (Smart Cath; Allied Health Products; Riverside, Calif), a CP-100 pulmonary monitor (BiCore Monitoring Systems PC-100; Irvine, Calif), and a flow transducer (Var flex; Allied Health Products; Riverside, Calif) were connected to a breathing valve (model 2700; Hans-Rudolph Inc; Kansas City, Mo). This apparatus was then used to measure Pes during a graded cardiopulmonary exercise test (CPX) to symptom limitation. University-affiliated Veterans Affairs Hospital. Eight nonsmoking volunteers with normal results of pulmonary function tests. Plots of deltaPes against pressure time product (PTP), minute ventilation (VE), and oxygen consumption (VO2) were obtained. Pes at baseline, anaerobic threshold (AT), and maximum oxygen consumption (VO2max) were obtained by comparing the Pes measurements from the computer printout to the corresponding breath-by-breath measurements on the CPX. The flow transducer (Varflex) connection added only 20 mL of dead space to the standard mouthpiece apparatus. The mean maximum work performance was 203+/-32 W. The mean VO2max was 29+/-9 mL/kg/min. The Pes at AT was 16+/-3 cm H2O. The Pes at maximal exercise was 42+/-16 cm H2O. The small esophageal balloon was well tolerated by all subjects. Plots of deltaPes vs PTP, VE, and VO2 demonstrated a linear correlation. This apparatus could be added to the standard CPX to assess the contribution of the diaphragm and respiratory muscles in patients with dyspnea.