scholarly journals Evaluation of cushions using dynamic pressure measurement

1991 ◽  
Vol 15 (3) ◽  
pp. 232-240 ◽  
Author(s):  
C. A. Bar
Keyword(s):  
Dynamic Pressure ◽  
Pressure Sores ◽  
Patient Assessment ◽  
Pressure Monitoring ◽  
Time Profiles ◽  
Pressure Time ◽  
Subject Variability ◽  
Dynamic Pressure Measurement ◽  
Ischial Tuberosities ◽  
Spinal Cord Injured

Reduction of pressures generated in the tissues overlying the ischial tuberosities is an important measure for predicting a cushion's effectiveness. In particular, the pressure-time relationship is significant in the prevention of pressure sores. In this study a dynamic pressure monitoring system was used to obtain pressure-time profiles for 25 spinal cord injured subjects. Each subject tested three types of cushion (Foam, Gel (Aberdeen) and Roho) for periods of two hours each during which routine activities were performed. Results obtained were broadly comparable with previous studies. Average pressures were: Foam 87.6mmHg (11.6kPa); Gel 68.6mmHg (9kPa) and Roho 54.6mmHg (6.7kPa). Pressure-time histograms are presented for three subjects for each cushion. These show inter-subject variability on the same cushion as well as intra-subject variability on different cushions. Therefore individual patient assessment is important in providing the most appropriate cushion. Dynamic pressure monitoring allows the pattern of pressure variation to be determined and hence the potential effectiveness of the cushion.

Experimental Investigation of Combustion Dynamics in a Turbulent Syngas Combustor

2017 ◽  
Author(s):  
Nikhil Ashokbhai Baraiya ◽  
Baladandayuthapani Nagarajan ◽  
Satynarayanan R. Chakravarthy
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Bluff Body ◽  
Dynamic Pressure ◽  
Fuel Mixture ◽  
High Amplitude ◽  
Acoustic Oscillations ◽  
Combustion Dynamics ◽  
Dynamic Pressure Measurement ◽  
Body Location

In the present work, the proportion of carbon monoxide to hydrogen is widely varied to simulate different compositions of synthesis gas and the potential of the fuel mixture to excite combustion oscillations in a laboratory-scale turbulent bluff body combustor is investigated. The effect of parameters such as the bluff body location and equivalence ratio on the self-excited acoustic oscillations of the combustor is studied. The flame oscillations are mapped by means of simultaneous high-speed CH* and OH* chemiluminescence imaging along with dynamic pressure measurement. Mode shifts are observed as the bluff body location or the air flow Reynolds number/overall equivalence ratio are varied for different fuel compositions. It is observed that the fuel mixtures that are hydrogen-rich excite high amplitude pressure oscillations as compared to other fuel composition cases. Higher H2 content in the mixture is also capable of exciting significantly higher natural acoustic modes of the combustor so long as CO is present, but not without the latter. The interchangeability factor Wobbe Index is not entirely sufficient to understand the unsteady flame response to the chemical composition.

Sustainable inspiratory pressures over varying flows, volumes, and duty cycles

1990 ◽  
Vol 69 (5) ◽  
pp. 1875-1882 ◽  
Author(s):  
T. L. Clanton ◽  
B. T. Ameredes ◽  
D. B. Thomson ◽  
M. W. Julian
Keyword(s):  
Tidal Volume ◽  
Duty Cycle ◽  
Dynamic Pressure ◽  
Breathing Patterns ◽  
Transdiaphragmatic Pressure ◽  
Lung Inflation ◽  
Duty Cycles ◽  
Pressure Time ◽  
Endurance Tests ◽  
Normal Humans

This study identifies the influence of flow (0.5-2.0 l/s), duty cycle (0.29-0.57), and tidal volume (1.08-2.16 liters) on sustainable inspiratory muscle pressure (Pmus) and transdiaphragmatic pressure (Pdi) development. Six normal humans performed endurance tests using an isoflow method, which allowed for measurements of maximum dynamic Pmus and Pdi, with controlled lung inflation. The subjects repeated maximum dynamic voluntary inspirations for 10 min. Pressures dropped exponentially from initial measurements at rest (Pmusi or Pdi) to sustainable values (Pmus or Pdis). As flow and tidal volume increased, maximum initial and sustainable pressures decreased significantly. However, at a constant duty cycle, the sustainable dynamic pressures remained predictable fractions of initial dynamic pressures (i.e., Pmuss/Pmusi or Pdis/Pdii), regardless of changes in flow and tidal volume. In contrast, as duty cycle increased, the sustainable fractions significantly decreased for both Pdi and Pmus. For example, at a duty cycle of 0.29, Pmuss/Pmusi was approximately 0.71, and at a duty cycle of 0.57, Pmuss/Pmusi was approximately 0.62. Calculated sustainable pressure-time indexes varied significantly between 0.16 to 0.32 for Pmus and 0.11 to 0.22 for Pdi over the breathing patterns studied. We conclude that 1) the maximum dynamic pressure that can be sustained at a given duty cycle is a predictable fraction of the maximum dynamic pressure that can be generated at rest when measured under the same conditions of inspiration and 2) the sustainable fraction of initial dynamic pressure significantly decreases with increasing duty cycle.

Numerical Simulation of Multi-Field Coupling in Aqueous Humor Under the Condition of Dynamic Pressure

2019 ◽  
Vol 16 (03) ◽  
pp. 1842001 ◽  
Author(s):  
Hongfang Song ◽  
Lin Li ◽  
Wenjia Wang ◽  
Qi Li ◽  
Zhicheng Liu
Keyword(s):  
Numerical Simulation ◽  
Aqueous Humor ◽  
Dynamic Pressure ◽  
Field Coupling ◽  
Rabbit Eye ◽  
Aqueous Humor Flow ◽  
Simulation Based ◽  
Dynamic Pressure Measurement ◽  
Ocular Pressure ◽  
Fluid Solid Interaction

In order to investigate the aqueous humor flow based on the coupling effects of fluid–solid–heat under different ocular pressure, four models of rabbit eye were constructed and multi-field coupling vs. fluid–solid interaction was compared in these models. ADINA software was applied to mimic the aqueous humor flow. The contour of temperature demonstrates multiple peaks with larger value near the pupil. The flow pattern is influenced mainly by the variation of ocular pressure. It is necessary to perform multi-field coupling simulation based on dynamic pressure measurement when studying the aqueous humor flow in eyes.

scholarly journals Spinal cord injured patients’ knowledge of pressure sores

2001 ◽  
Vol 57 (4) ◽  
pp. 9-13
Author(s):  
W. Mudzi ◽  
A. Steward ◽  
C. Eales
Keyword(s):  
Spinal Cord ◽  
Occupational Therapists ◽  
Pressure Sore ◽  
Test Method ◽  
Knowledge Gain ◽  
Pressure Sores ◽  
Post Test ◽  
Discharge Pressure ◽  
Injured Patients ◽  
Spinal Cord Injured

Despite much effort being put into educating spinal cord injured patients on pressure sore prevention, pressure sores remain a major cause of morbidity and mortality. This study sought to establish: i) paraplegics’ knowledge on pressure sore prevention prior to discharge; ii) the influence of knowledge on pressure sore occurrence during hospitalization; iii) sources of paraplegics’ knowledge on pressure sore prevention. A total of twenty-six men and two women with paraplegia aged between 18 and 45 years participated in the study. A rospective pre-test post-test method using a structured questionnaire was used to test paraplegics’ knowledge on pressure sore prevention. The first interview was done within one week of mobilising in a wheelchair and the second one after two months or a few days before discharge. Pressure sore occurrence and the source of knowledge were also recorded. The results showed that paraplegics’ knowledge on pressure sore prevention at discharge is incomplete. Knowledge gain does not seem to determine whether one will develop pressure sores or not. Physiotherapists (89%), nurses (82%) and occupational therapists (68%) are the main educators of paraplegics on pressure sore prevention in rehabilitation hospitals.

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