Conventional Cushions Research Articles

On the Design of Energy Absorbing Crash Buffers for High Speed Roadways

The aim of this paper is to design and analyze cost-effective and high energy absorbing buffer systems for high speed roadways. Unlike conventional crash cushions, the proposed buffer design is based on the assembly of a series of cylindrical hollow tubes (cells) with thorough slots around the cells. The idea is that during the collisions, the kinetic energy of the errant vehicles will be absorbed by the progressive deformation of the cells, hence minimizing damage to the vehicle and allowing a comfortable ride down deceleration of the vehicle’s occupants. As the cell was the fundamental unit of the buffer design, three cells with different geometry were studied to understand the underlying deformation of the individual cells. Nonlinear quasi-static tests using three-dimensional (3D) finite element (FE) simulation and experimental techniques were performed to evaluate the deformation and energy absorption capacity of the cells. Simulation results matched closely with experimental ones with relatively small errors. Based on the experimental results of single cells, a number of potential buffer systems were designed for 80 and 100 km/h speed roadways. Results indicate that the buffers with larger diameter cells are favorable to be used in high speed zones as they reduce the overall size of buffers and contain less number of cells, while being able to absorb the required amount of impact energy. Consequently, they are found to result in a reduced cost associated with materials and fabrication. All the buffer designs were relatively shorter than commercially available buffers used in roadways. In addition, due to their reduced and compact size, the designed buffers can potentially be used in a space limited and hazardous road environment to reduce the vehicle crash with the fixed objects.

Development of a method for manufacturing customized nasal mask cushion for CPAP therapy.

A continuous positive airway pressure (CPAP) device is considered one of the most effective treatments for obstructive sleep apnea (OSA). However, many patients receiving this treatment complain of mask discomfort and other issues. Therefore, this study aimed to develop a customized nasal mask cushion to reduce the discomfort associated with conventional masks. First, a 3D face scanner was used to obtain 3D facial data of participants. Second, a model of the face was created by reverse-engineering and then used for the computer-aided design (CAD) of the cushion. Finally, computer numerical control (CNC) was used to manufacture the mold, into which silicone was then injected slowly. A perceived comfort questionnaire was used to compare the customized and conventional cushions. 40 patients were randomly divided into two groups: 20 patients in the control group used a conventional cushion, and the remaining 20 patients used the customized cushion. The customized cushion was found to be superior to the conventional cushion. There are clear differences in the headgear force of the two cushion types (P = 0.001). The customized cushion applied less force to a patient’s face than a conventional cushion. Furthermore, there were obvious differences in the fit of the cushions (P = 0.001). Patients using the customized cushions experienced a better fit than those using the conventional cushions. This study has developed a new method for manufacturing customized cushions with better cushion fit through rapid tooling.

2P1-I02 荷重分散・底付き防止を目的としたじょくそう予防クッションの開発

Conventional cushions to prevent pressure ulcer have not completely realized the objective. For example, cushions filled with air do not sink enough to disperse the load. On the other hand, cushions filled with liquid sink excessively, and thus buttocks may hit on the bottom of the cushions. In this paper, we develop a cushion to solve these problems. Our developed cushion consists of multiple balls named "cell structures," each of which has air in the core and liquid around the core. We confirm that the cushion can realize both load dispersion and prevention of bottoming by experiments.

Clinical verification of patients with obstructive sleep apnea provided with a customized cushion for continuous positive airway pressure

Statement of problemPatients with obstructive sleep apnea may stop breathing momentarily during sleep because of a narrow upper respiratory tract. One of the main treatments for obstructive sleep apnea is continuous positive airway pressure. However, after long-term treatment, patients tend to complain about the leakage, inconvenience, and discomfort of the nasal mask. PurposeThe purpose of the study was to develop customized cushions and compare the clinical performance of the customized cushion with the conventional one. Material and methodsEach participant's face was replicated by using a 3-dimensional scanner and reverse-engineering technology, and computer numerical control techniques were used to design and manufacture customized cushions. Forty participants were randomly divided into 2 groups, a control group with conventional cushions and an experimental group with customized cushions. The saturation level of peripheral oxygen, apnea-hypopnea index, leakage data, and answers to a comfort questionnaire were examined. ResultsCustomized and conventional cushions were compared with independent sampling t tests and relational analyses. A significant difference was found in the apnea-hypopnea index (P=.001) of participants with the customized cushion and those with the conventional cushion. Participants with the conventional cushion had a lower apnea-hypopnea index. The customized cushion applied less headgear force and fit better than the conventional cushion. The leakage volume, saturation of peripheral oxygen (SpO2), treatment compliance, and degree of comfort were not significantly different between the groups. ConclusionsCustomized nasal mask cushions fit better and reduce the force applied by the headgear. Participants using a customized cushion showed an improved apnea-hypopnea index.

Transpedicular screw fixation on the thoracolumbar spine.

Pedicular fixation has found great acceptance as a modality for spinal fusions. Being a "blind technique" it is associated with a potential high risk of neural and vascular morbidity. In an attempt to evaluate and/or establish a uniformly accepted concept of surgical management we designed a questionaire composed of seventeen questions dealing with different pre-, intra- and postoperative procedures in transpedicular fixation. This was sent to 31 experienced surgeons organized in the working group "spine" of the german trauma association. Half of the answers to each question were similar. The other half however, showed a wide variation of thought. It is thus deduced that although some concepts are frequently applied there is no general agreement to an optimal method of surgical handling. Most surgeons use conventional operative cushions for positioning the patients (22/31). Access is usually proceeded by sharp dissection of the lumbodorsal fascia using a scalpell instead of cauterisation (21/31), consciously avoiding traumatisation of paravertebral muscle insertion to the transverse processes (22/31), as well as sparing the dorsal branch of segmental arteries (25/31). Intraoperative orientation is attained by inspection coronarly and fluoroscopy sagittaly (15/31). Most surgeons remove cortical bone using a Rongeur (22/31), transpedicular drill hole is prepared by means of a k-wire (11/31), for orientation again the fluoroscop is made use of (15/31). On perforating the medial boundry of the pedicle thirteen operators correct the direction on drilling, on perforating the lateral boundry twelve medialise the screws on fixation, and eleven surgeons would leave the screws in place if firm holding is warranted. Half of the questioned surgeons simply lateralise the screws if cerebrospinal fluid leaked from the drill holes. If a malposition of the pedicle screws is not suspected no control computer tomography is performed (21/31). Regarding these facts a comparative evaluation of the different techniques used in transpedicular fixation is lacking. In our opinion further multicenter evaluation is neccessary to establish a unified method and thus optimize postoperative results.

Seating pressures with conventional and dynamic wheelchair cushions in tetraplegia

Objective: To compare pressure relief from a dynamic wheelchair cushion to a tilt-in-space wheelchair with conventional cushions. Study Design: Repeated measures analysis. Setting and Subjects: Spinal cord injury unit; 16 tilt-in-space wheelchair users with motor-complete tetraplegia. Main Outcome Measures: Interface pressure at ischial tuberosities. Results: Mean ischial pressure with subjects seated upright on the dynamic cushion during the low ischial pressure phase was lower than tilted pressure on the gel cushion, but it was not significantly different from tilted pressure on the dry-flotation cushion (dynamic/upright, 71mmHg; gel/tilted, 86mmHg; dryflotation/tilted, 74mmHg; p < .05 dynamic vs gel). Mean ischial pressure with subjects upright on the dynamic cushion during the high ischial pressure phase was significantly greater than the gel/upright and dry-flotation/upright conditions (dynamic/upright, 157mmHg; gel/upright, 128mmHg; dry-flotation/ upright, 111mmHg; p < .001). Conclusion: The dynamic cushion produces similar pressure relief over the ischial tuberosities during the low pressure phase to a tilt-in-space wheelchair and conventional cushions. The dynamic cushion may be an alternative to a tilt-in-space wheelchair for some individuals.

Transpedicular implantation of screws in the thoracolumbar spine. Results of a survey of methods, frequency and complications

Pedicular fixation has found great acceptance as a modality for spinal fusions. Being a "blind technique" it is associated with a potential high risk of neural and vascular morbidity. In an attempt to evaluate and/or establish a uniformly accepted concept of surgical management we designed a questionnaire composed of seventeen questions dealing with different pre-, intra- and postoperative procedures in transpedicular fixation. This was sent to 31 experienced surgeons organized in the working group "spine" of the german trauma association. Half of the answers to each question were similar. The other half however, showed a wide variation of thought. It is thus deduced that although some concepts are frequently applied there is no general agreement to an optimal method of surgical handling. Most surgeons use conventional operative cushions for positioning the patients (22/31). Access is usually proceeded by sharp dissection of the lumbodorsal fascia using a scalpel instead of catheterization (21/31), consciously avoiding traumatisation of paravertebral muscle insertion to the transverse processes (22/31), as well as sparing the dorsal branch of segmental arteries (25/31). Intraoperative orientation is attained by inspection coronary and fluoroscopy sagittal (15/31). Most surgeons remove cortical bone using a Rongeur (22/31), transpedicular drill hole is prepared by means of a k-wire (11/31), for orientation again the fluoroscope is made use of (15/31). On perforating the medial boundary of the pedicle thirteen operators correct the direction on drilling, on perforating the lateral boundary twelve medialise the screws on fixation, and eleven surgeons would leave the screws in place if firm holding is warranted. Half of the questioned surgeons simply lateralise the screws if cerebrospinal fluid leaked from the drill holes. If a malposition of the pedicle screws is not suspected no control computer tomography is performed (21/31). Regarding these facts a comparative evaluation of the different techniques used in transpedicular fixation is lacking. In our opinion further multicenter evaluation is necessary to establish a unified method and thus optimize postoperative results.

The Glenn Face Down Pillow

The ease of performing computed tomography (CT)-guided radiologic procedures with the patient in the prone position can be compromised by patient discomfort. This is especially true during transthoracic needle aspiration biopsy when sedation or analgesia may interfere with the patient's ability to cooperate. The Glenn Face Down Pillow, a foam cushion with air vents that allows unimpeded respiration with the patient entirely prone, was tested in 34 such biopsies over a 1-year period. Patient compliance was better than with conventional cushions and padding, and procedural problems related to motion from cramping and stiffness were reduced.