mechanical power
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Umělá plicní ventilace (UPV) patří mezi zavedené metody orgánové podpory na jednotkách intenzivní péče. U pacientů s plicním postižením, zejména pak s jejich těžšími formami, může UPV působit takovými silami, že mohou vést k dalšímu poškození nemocných plic. Mechanická energie (ME) je parametr představující celkovou energii, kterou UPV působí na plíce (případně na plíce, dýchací cesty a hrudník). Vyšší hodnoty ME jsou spojené s vyšším rizikem plicního postižení indukovaného ventilátorem (VILI). ME je možné vypočítat z ventilačních parametrů pomocí rovnic, z nichž některé umožňují výpočet přímo u lůžka nemocného na běžné kalkulačce. Úpravou jednotlivých parametrů, pak můžeme ME snížit ve snaze snížení rizika VILI. Ze vzorců lze rovněž odvodit jak se jednotlivé parametry podílejí na celkové ME a můžeme se tak rozhodnout, který parametr je vhodné upravit. Tento přehledový článek přináší ucelený pohled na současné postavení ME jako ventilačního parametru asociovaného s rizikem VILI. Jsou zde uvedeny rovnice pro výpočet ME pro jednotlivé ventilační režimy s kritickým hodnocením přesnosti jednotlivých možností výpočtu a využití konceptu ME v běžné denní praxi u lůžka pacienta na UPV.
Mechanical ventilation (MV) is one of the established methods of organ support in intensive care units. In patients with lung disease, especially in its more severe forms, MV can act with such forces that it can lead to further damage to the diseased lungs. Mechanical energy (ME) is a parameter representing the total energy that the MV exerts on the lungs (or lungs, airways, and chest). Higher ME values are associated with a higher risk of ventilator-induced lung injury (VILI). ME can be calculated from ventilation parameters using equations, some of which allow calculation directly at the patient's bedside on a regular calculator. By adjusting individual parameters, we can then reduce the ME to reduce the risk of VILI. From the formulas, it is also possible to derive how the individual parameters contribute to the overall ME, and we can thus decide which parameter should be adjusted. This review article provides a comprehensive view of the current knowledge of ME as a ventilatory parameter associated with the risk of VILI. Equations for calculating ME for individual ventilation modes are presented here, with a critical assessment of the accuracy of individual calculation options and the use of the ME concept in routine daily practice at the patient's bed on MV.
- Klíčová slova
- mechanická energie,
- MeSH
- lidé MeSH
- mechanické ventilátory škodlivé účinky MeSH
- poškození plic mechanickou ventilací prevence a kontrola MeSH
- přenos energie MeSH
- syndrom dechové tísně etiologie terapie MeSH
- umělé dýchání * metody škodlivé účinky MeSH
- ventilace umělá s výdechovým přetlakem metody MeSH
- Check Tag
- lidé MeSH
Understanding the mechanics of the respiratory system is crucial for optimizing ventilator settings and ensuring patient safety. While simple models of the respiratory system typically consider only flow resistance and lung compliance, lung tissue resistance is usually neglected. This study investigated the effect of lung tissue viscoelasticity on delivered mechanical power in a physical model of the respiratory system and the possibility of distinguishing tissue resistance from airway resistance using proximal pressure measured at the airway opening. Three different configurations of a passive physical model of the respiratory system representing different mechanical properties (Tissue resistance model, Airway resistance model, and No-resistance model) were tested. The same volume-controlled ventilation and parameters were set for each configuration, with only the inspiratory flow rates being adjusted. Pressure and flow were measured with a Datex-Ohmeda S/5 vital signs monitor (Datex-Ohmeda, Madison, WI, USA). Tissue resistance was intentionally tuned so that peak pressures and delivered mechanical energy measured at airway opening were similar in Tissue and Airway Resistance models. However, measurements inside the artificial lung revealed significant differences, with Tissue resistance model yielding up to 20% higher values for delivered mechanical energy. The results indicate the need to revise current methods of calculating mechanical power delivery, which do not distinguish between tissue resistance and airway flow resistance, making it difficult to evaluate and interpret the significance of mechanical power delivery in terms of lung ventilation protectivity.
The purpose of this study was to determine the optimal load for the maximal power output during the acceleration phase of a power movement in bench press (BP) exercises of highly trained soccer players at the beginning of a competition period. Fifteen professional male soccer players with an average age of 26.1 ± 3.9 years, an average height of 183.3 ± 6.7 cm, an average body mass of 78.8 ± 7.2 kg, and an average 1 repetition maximum (1RM) of 83.3 ± 11.2 kg were employed as subjects in this study. Maximal mean power output during a BP at 0, 10, 30, 50, 70, and 90% of their 1RM was measured to determine whether an optimal load exists that allows for the attainment of maximal power output. Three-dimensional upper extremity kinematic data were collected. Two force plates embedded in the floor and positioned below the bench were used to measure contact forces between the bench and ground during the lift. A repeated-measures analysis of variance was performed to determine power output differences at different percentages of the 1RM. The results of this study indicated that loads of 50% of the 1RM resulted in greater mean power output during the complete positive power movement. Loads at 30 and 50% of the 1RM resulted in greater mean power output computed from the acceleration phase of the lift than did all loads and were not statistically different from each other. However, individual soccer players did not reach the maximum power output with the same relative load. In conclusion, when soccer players develop muscular power toward the end of when the most important competitions are scheduled, dynamic effort strength training with the range of load from 30 to 50% of 1RM BP should be used. During the competition period, a load of 50% of a 1RM should be used in a BP to maintain muscular power over a wide load range.
- MeSH
- biomechanika MeSH
- cvičení fyziologie MeSH
- dospělí MeSH
- fotbal fyziologie MeSH
- fyzická vytrvalost fyziologie MeSH
- horní končetina fyziologie MeSH
- kosterní svaly fyziologie MeSH
- lidé MeSH
- mladý dospělý MeSH
- sportovci MeSH
- svalová síla fyziologie MeSH
- vzpírání fyziologie MeSH
- zatížení muskuloskeletálního systému MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The present study was carried out to search whether organophosphate pesticides affect the mechanical properties of the thoracic aorta. Wistar female rats (aged 6-8 weeks) were assigned randomly to a control group and groups treated with either dichlorvos or chlorpyriphos for 90 days at a dose of 5 mg/kg/day. After that period, animals were killed and thoracic aorta strips in longitudinal direction were isolated. The stress, strain and elastic modulus were obtained from the strips. Our results showed that chronic administration of chlorpyriphos and dichlorvos caused downward shift of the stress-strain relations compared to the control curve. The elastic modulus-stress curve revealed distinct characteristics in the low and high stress regions. A power function was used to simulate the low stress region while a line was fit to the high stress region. Curve fitting procedure illustrated that both pesticides influenced mainly the high stress region, but they had diverse effects at the low stress region. The results also imply that chlorpyriphos and dichlorvos decrease the strength of the aorta and therefore might influence the response of the aorta to mechanical loading induced by blood pressure.
- MeSH
- aorta thoracica účinky léků MeSH
- dichlorvos farmakologie MeSH
- dursban farmakologie MeSH
- financování organizované MeSH
- insekticidy farmakologie MeSH
- krevní tlak účinky léků MeSH
- krysa rodu rattus MeSH
- mechanický stres MeSH
- pevnost v tahu MeSH
- potkani Wistar MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
n this work, a commercial flexible thermoelectric generator (f-TEG) was used to harvest the body thermal energy during the execution of activities of daily living (ADL). The f-TEG was placed at the level of the ankle, and the performed activities were sitting at the desk and walking. In the first stage of measurements, tests were performed to choose the value of the resistor load that maximizes the power output. Then, while performing ADL, the values of generated power were in the range from 100 to 450 μW. Moreover, while users are walking, the pattern of the output signal of f-TEG is compatible to a sine function with frequency close to that one of human gait. This preliminary result may represent a new way to study the movement of human body to recognize ADL.
BACKGROUND AND OBJECTIVE: Despite the fact that the molecular mechanism of low-level laser therapy (LLLT) is not yet known, the exploitation of phototherapy in clinical medicine and surgery is of great interest. The present study investigates the effects of LLLT on open skin wound healing in normal and diabetic rats. MATERIALS AND METHODS: Four round full-thickness skin wounds on dorsum were performed in male adult nondiabetic (n = 24) and diabetic (n = 24) Sprague-Dawley rats. AlGaInP (635 nm, wavelength; 5 J/cm(2), daily dose) was used to deliver power densities of 1, 5, and 15 mW/cm(2) three times daily until euthanasia. RESULTS: PMNL infiltration was lower in the irradiated groups (15 mW/cm(2)). The synthesis and organisation of collagen fibres were consecutively enhanced in the 5 mW/cm(2) and 15 mW/cm(2) groups compared to the others in nondiabetic rats. In the diabetic group the only significant difference was recorded in the ratio PMNL/Ma at 15 mW/cm(2). A significant difference in the number of newly formed capillaries in the irradiated group (5, 15 mW/cm(2)) was recorded on day six after injury compared to the control group. CONCLUSION: LLLT confers a protective effect against excessive inflammatory tissue response; it stimulates neovascularization and the early formation of collagen fibres.
- MeSH
- dávka záření MeSH
- experimentální diabetes mellitus patologie terapie MeSH
- fototerapie * MeSH
- hojení ran účinky záření MeSH
- krysa rodu rattus MeSH
- kůže zranění účinky záření MeSH
- laserová terapie s nízkou intenzitou světla * MeSH
- lidé MeSH
- nemoci imunitního systému MeSH
- poruchy leukocytů MeSH
- zánět patologie terapie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Mechanical ventilation (MV) provides basic organ support for patients who have acute hypoxemic respiratory failure, with acute respiratory distress syndrome as the most severe form. The use of excessive ventilation forces can exacerbate the lung condition and lead to ventilator-induced lung injury (VILI); mechanical energy (ME) or power can characterize such forces applied during MV. The ME metric combines all MV parameters affecting the respiratory system (ie, lungs, chest, and airways) into a single value. Besides evaluating the overall ME, this parameter can be also related to patient-specific characteristics, such as lung compliance or patient weight, which can further improve the value of ME for characterizing the aggressiveness of lung ventilation. High ME is associated with poor outcomes and could be used as a prognostic parameter and indicator of the risk of VILI. ME is rarely determined in everyday practice because the calculations are complicated and based on multiple equations. Although low ME does not conclusively prevent the possibility of VILI (eg, due to the lung inhomogeneity and preexisting damage), individualization of MV settings considering ME appears to improve outcomes. This article aims to review the roles of bedside assessment of mechanical power, its relevance in mechanical ventilation, and its associations with treatment outcomes. In addition, we discuss methods for ME determination, aiming to propose the most suitable method for bedside application of the ME concept in everyday practice.
- MeSH
- agrese MeSH
- dýchání MeSH
- hrudník MeSH
- lidé MeSH
- poškození plic mechanickou ventilací * MeSH
- syndrom dechové tísně * MeSH
- umělé dýchání MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s(-1)) to maximal velocity (m•s(-1)). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.
- Publikační typ
- časopisecké články MeSH
... Jungwirth (Czech Republic) 3 -- Advances in industrial high power lasers -- H. ... ... Widen (USA) 19 -- Compact, high-power ceramic slab laser -- A. Lapucci, M. ... ... Thornton (USA) 88 -- SESSION 15 -- High Power Laser Applications / -- Trends in high power laser applications ... ... Bohn (Germany) 103 -- Propulsion by laser power -- W. O. ... ... Fujioka (Japan) 157 -- High-efficiency mixing in high-power COIL. ...
1st ed. 209 s. ; 30 cm
Rheological Maxwell-type model is used to obtain a relation between energy input to a muscle and the work produced by it. The key role in the relation plays the muscle activity 1/η which describes how much energy is converted to work in unit volume element at unit time. The activity is the muscle material value describing how much actin-myosin pairs are engaged in a given place to maintain the work production of the whole muscle system. The modelling of the system has been done and it is now possible to calculate the energy input in special muscle system activities by mechanical means.
- Klíčová slova
- aktino-myozinové dvojice, tvorba energie, viskoelasticita,
- MeSH
- aktomyosin fyziologie metabolismus MeSH
- biomechanika fyziologie MeSH
- energetický metabolismus fyziologie MeSH
- experimenty na lidech MeSH
- financování organizované MeSH
- lidé MeSH
- reologie metody MeSH
- statistika jako téma MeSH
- svalová kontrakce fyziologie MeSH
- svalová síla fyziologie MeSH
- teoretické modely MeSH
- Check Tag
- lidé MeSH
