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Minerva Anestesiologica Apr 2004Diastolic function is essential for efficient systolic performance. A normal diastole allows left ventricle (LV) filling to occur under normal intracavitary pressure. It... (Review)
Review
Diastolic function is essential for efficient systolic performance. A normal diastole allows left ventricle (LV) filling to occur under normal intracavitary pressure. It is an energy dependent process, as such affected by ischemia. Several factors influence diastolic function of the LV: the mitral valve area, the gradient between atrium and ventricle, LV relaxation and compliance, atrial compliance, the presence of sinus rhythm, the end-systolic volume. Echocardiography is the principal diagnostic tool to assess LV diastolic function noninvasively in clinical practice. Doppler evaluation allows to analyse each phase of LV diastole through measurement of transmitral and pulmonary veins flows velocities. Tissue Doppler echocardiography and color M-mode Doppler have also been introduced in the study of diastole. The use of echocardiography in the setting of diastolic dysfunction in ICU and operatory room has relevant implications in the management of haemodynamic instability, in vasoactive d rugs titration, in the detection of myocardial ischemia, and in performing prognostic stratification. These information can guide the management of cardiac patients undergoing cardiac and non cardiac surgery, in the perioperative phase, as well as in the management of critical ICU patients. On this basis evaluating the LV filling properties can contribute to improve the quality of treatments in such challenging situations.
Topics: Compliance; Diastole; Heart; Heart Ventricles; Humans; Laser-Doppler Flowmetry; Ventricular Dysfunction, Left
PubMed: 15173700
DOI: No ID Found -
British Journal of Clinical Pharmacology Sep 19941. Venous resistance contributes very little to total peripheral resistance; more than half of the total blood volume, however, is contained in the extrathoracic veins.... (Review)
Review
1. Venous resistance contributes very little to total peripheral resistance; more than half of the total blood volume, however, is contained in the extrathoracic veins. Owing to marked differences between venous and arterial anatomy and physiology, studies on veins and arteries usually require different methodological approaches. Whereas for arteries the most relevant parameters are resistance, pressure and flow, for veins volume and compliance are most important. For studies of general aspects of the peripheral circulatory system, venous occlusion plethysmography is probably the most useful method. The determination of both the rate of rise in limb volume and the total volume rise after inflating a proximally applied occlusion cuff to a subdiastolic pressure permits the concomitant estimation of both arterial flow and venous compliance. 2. Studies of direct pharmacological or physiological effects on veins, interactions of various pharmacological or physiological stimuli, or pathophysiological changes in venous responsiveness have been facilitated by the development of investigational techniques relying on direct measurements of the compliance of single human veins in vivo. One of these, relying on the use of a linear variable differential transformer (LVDT) for determining changes in the compliance of superficial veins at a standardized congestion pressure, has been found very suitable for the practical application in both patients and healthy subjects. 3. Physiological studies were carried out on the effect of age, exercise, temperature, and the menstrual cycle on venous compliance and venous responsiveness to various stimuli. In addition, interindividual variability in venous responsiveness in monozygotic and dizygotic twins and in unrelated subjects was investigated, and studies on the function of the endothelium were carried out in man in vivo. 4. Pathophysiological studies using this technique were reported from patients with hypertension, orthostatic hypotension, myocardial infarction, varicosis, cystic fibrosis, asthma, diabetes, systemic sclerosis, and cluster headache. 5. Clinical pharmacological studies represent a most important field for the use of this method. Studies were carried out on the effects of a large number of constrictor and dilator agents, and also on drug interactions on human veins in vivo. Venoconstriction was observed after local administration of alpha-adrenoceptor and 5-HT-receptor agonists, ergot derivatives, angiotensinogen, angiotensin I and II, and several prostaglandins. 6. Owing to the low venous tone present under effects can usually be quantified only on veins e.g. noradrenaline or 5-hydroxytryptamine. Under these conditions dilatation was observed after the administration of beta-adrenoceptor agonists, cholinergic (muscarinic) agonists, nitrates, calcium antagonists, bradykinin, substance P and several prostaglandins.
Topics: Aging; Animals; Blood Pressure; Cardiovascular Diseases; Compliance; Diabetes Complications; Diabetes Mellitus; Endothelium, Vascular; Exercise; Female; Humans; Hypertension; Hypotension, Orthostatic; Plethysmography; Raynaud Disease; Vascular Resistance; Veins
PubMed: 7826819
DOI: 10.1111/j.1365-2125.1994.tb04341.x -
International Journal of Law and... 2019A person's capacity to process advice is an important aspect of decision making in the real world. For example, in decisions about treatment, the way patients respond to... (Review)
Review
A person's capacity to process advice is an important aspect of decision making in the real world. For example, in decisions about treatment, the way patients respond to the advice of family, friends and medical professionals may be used (intentionally or otherwise) as a marker of the "use or weigh" requirement of decision-making capacity. Here we explore neuroscientific research on decision-making to identify features of advice-taking that help conceptualize this requirement. We focus on studies of the neural and computational basis of decision-making in laboratory settings. These studies originally investigated simple perceptual decisions about ambiguous stimuli, but have more recently been extended to more complex "value-based" decisions involving the comparison of subjective preferences. Value-based decisions are a useful model system for capacity-related decision-making as they do not have an objectively 'correct' answer and are instead based on subjective preferences. In this context, advice-taking can be seen as a process in which new evidence for one or other option is integrated, leading to altered behaviour or choices. We use this framework to distinguish between different types of advice-taking: private compliance consists of updating one's privately held beliefs based on new evidence, whereas in the case of public compliance, people change their behaviour at a surface level without shifting their privately-held beliefs. Importantly, both types of advice-taking may lead to similar outcomes but rely on different decision processes. We suggest that understanding how multiple mechanisms drive advice-taking holds promise for targeting decision-making support and improving our understanding of the use and weigh requirement in cases of contested capacity.
Topics: Choice Behavior; Cognitive Neuroscience; Compliance; Decision Making; Humans; Judgment; Mental Competency; Metacognition
PubMed: 31785723
DOI: 10.1016/j.ijlp.2019.101504 -
Exercise and Sport Sciences Reviews Apr 2017The deterioration in arterial and cardiac function with aging impairs arterial ventricular coupling, an important determinant of cardiovascular performance. However,... (Review)
Review
The deterioration in arterial and cardiac function with aging impairs arterial ventricular coupling, an important determinant of cardiovascular performance. However, exercise training improves arterial ventricular coupling especially during exercise during the age and disease process. This review examines the concept of arterial-ventricular coupling, and how age, and disease uncouples but exercise training recouples the heart and arterial system.
Topics: Aging; Arteries; Blood Pressure; Cardiovascular Diseases; Compliance; Exercise; Heart; Humans
PubMed: 28072585
DOI: 10.1249/JES.0000000000000100 -
American Journal of Physiology. Heart... Aug 2021In a progressively aging population, it is of utmost importance to develop reliable, noninvasive, and cost-effective tools to estimate biomarkers that can be indicative...
In a progressively aging population, it is of utmost importance to develop reliable, noninvasive, and cost-effective tools to estimate biomarkers that can be indicative of cardiovascular risk. Various pathophysiological conditions are associated to changes in the total arterial compliance (C), and thus, its estimation via an accurate and simple method is valuable. Direct noninvasive measurement of C is not feasible in the clinical practice. Previous methods exist for indirect estimation of C, which, however, require noninvasive, yet complex and expensive, recordings of the central pressure and flow. Here, we introduce a novel, noninvasive method for estimating C from a single carotid waveform measurement using regression analysis. Features were extracted from the carotid wave and were combined with demographic data. A prediction pipeline was adopted for estimating C using, first, a feature-based regression analysis and, second, the raw carotid pulse wave. The proposed methodology was appraised using the large human cohort ( = 2,256) of the Asklepios study. Accurate estimates of C were yielded for both prediction schemes, namely, = 0.83 and normalized root mean square error (nRMSE) = 9.58% for the feature-based model, and = 0.83 and nRSME = 9.67% for the model that used the raw signal. The major advantage of this method pertains to the simplification of the technique offering easily applicable and convenient C monitoring. Such an approach could offer promising applications, ranging from fast and cost-efficient hemodynamical monitoring by the physician to integration in wearable technologies. This article introduces a novel artificial intelligence method to estimate total arterial compliance (C) via exploiting the information provided by an uncalibrated carotid blood pressure waveform as well as typical clinical variables. The major finding of this study is that C, which is usually acquired using both pressure and flow waveforms, can be accurately derived by the use of the pressure wave alone. This method could potentially facilitate easily applicable and convenient monitoring of C.
Topics: Adult; Aorta; Carotid Arteries; Compliance; Female; Humans; Male; Middle Aged; Pulse Wave Analysis; Vascular Stiffness
PubMed: 34213389
DOI: 10.1152/ajpheart.00241.2021 -
Journal of Psychiatric Research Jul 2009Ecological momentary assessment (EMA) gathers respondent data on affective, behavioral, and contextual experiences as close in time to those experiences as possible.... (Review)
Review
Ecological momentary assessment (EMA) gathers respondent data on affective, behavioral, and contextual experiences as close in time to those experiences as possible. Potential advantages of EMA in aging research include reducing memory biases and gathering intra-individual data, yet there is little understanding about implementation. The goal of this critical review was to assess the feasibility and applications of EMA in psychological and behavioral research on aging. Through a comprehensive search of the online electronic databases, Psycinfo and Pubmed, for English-language peer-reviewed journals published between 1990 and 2007, we identified 40 articles using EMA methods in older adults. Studies sampled participants between five times per day over one day to once a week for 210 days. Samples were generally not cognitively impaired, evenly split between healthy and clinical populations, and only 6 of 40 studies focused on psychiatric diagnoses. The most common assessment content solicited ratings on affect (n=15), activities of daily living (n=12), physical activities (n=10), and social exchanges (n=8). A total of 90% of the studies that reported compliance reported rates over 80%. Uses of EMA varied widely, with research goals including validation of global measures, detection of subtle treatment effects, and for testing hypotheses about causal intra-individual relationships. Although these measures appear feasible and useful in aging research, recommendations for future studies include adapting measures to enable data collection among older participants with cognitive impairments and/or psychopathology, along with greater use of electronic data capture to improve compliance and increase ease of implementation.
Topics: Aged; Aging; Compliance; Databases, Bibliographic; Ecology; Geriatric Assessment; Humans; Reproducibility of Results; Research; Time Factors
PubMed: 19272611
DOI: 10.1016/j.jpsychires.2009.01.014 -
European Journal of Vascular and... Nov 2020Abdominal aortic aneurysm (AAA) is associated with morphological and functional changes in both aneurysmal and non-aneurysmal arteries. However, it remains uncertain...
OBJECTIVE
Abdominal aortic aneurysm (AAA) is associated with morphological and functional changes in both aneurysmal and non-aneurysmal arteries. However, it remains uncertain whether similar changes also exist in the venous vasculature. The aim of this study was to evaluate global venous function in patients with AAA and controls.
METHODS
This experimental study comprised 31 men with AAA (mean ± standard deviation age 70.0 ± 2.8 years) and 29 male controls (aged 70.6 ± 3.4 years). Venous occlusion plethysmography (VOP) was used to evaluate arm venous compliance at venous pressures between 10 and 60 mmHg in steps of 5 mmHg. Compensatory mobilisation of venous capacitance blood (capacitance response) was measured with a volumetric technique during experimental hypovolaemia induced by lower body negative pressure (LBNP).
RESULTS
The VOP induced pressure-volume curve was significantly less steep in patients with AAA (interaction, p < .001), indicating lower venous compliance. Accordingly, the corresponding pressure-compliance curves displayed reduced venous compliance at lower venous pressures in patients with AAA vs. controls (interaction, p < .001; AAA vs. control, p = .018). After adjusting for arterial hypertension, diabetes mellitus, hyperlipidaemia, chronic obstructive pulmonary disease, and smoking, VOP detected differences in venous compliance remained significant at low venous pressures, that is, at 10 mmHg (p = .008), 15 mmHg (p = .013), and 20 mmHg (p = .026). Mean venous compliance was negatively correlated with aortic diameter (r = -.332, p = .010). Mobilisation of venous capacitance response during LBNP was reduced by approximately 25% in patients with AAA (p = .030), and the redistribution of venous blood during LBNP was negatively correlated with aortic diameter (r = -.417, p = .007).
CONCLUSION
Men with AAA demonstrated reduced venous compliance and, as a result, a lesser capacity to mobilise peripheral venous blood to the central circulation during hypovolaemic stress. These findings imply that the AAA disease may be accompanied by functional changes in the venous vascular wall.
Topics: Aged; Aorta, Abdominal; Aortic Aneurysm, Abdominal; Arm; Case-Control Studies; Compliance; Female; Humans; Hypovolemia; Male; Plethysmography; Ultrasonography; Veins; Venous Pressure
PubMed: 32778487
DOI: 10.1016/j.ejvs.2020.07.009 -
Journal of Applied Physiology... Jan 2008We model the action of muscle-tendon system(s) about a given joint as a serial actuator and spring. By this technique, the experimental joint moment is imposed while the...
We model the action of muscle-tendon system(s) about a given joint as a serial actuator and spring. By this technique, the experimental joint moment is imposed while the combined angular deflection of the actuator and spring are constrained to match the experimental joint angle throughout the stance duration. The same technique is applied to the radial leg (i.e., shoulder/hip-to-foot). The spring constant that minimizes total actuator work is considered optimal, and this minimum work is expressed as a fraction of total joint/radial leg work, yielding an actuation ratio (AR; 1 = pure actuation and 0 = pure compliance). To address work modulation, we determined the specific net work (SNW), the absolute value of net divided by total work. This ratio is unity when only positive or negative work is done and zero when equal energy is absorbed and returned. Our proximodistal predictions of joint function are supported during level and 15 degrees grade running. The greatest AR and SNW are found in the proximal leg joints (elbow and knee). The ankle joint is the principal spring of the hindleg and shows no significant change in SNW with grade, reflecting the true compliance of the common calcaneal tendon. The principal foreleg spring is the metacarpophalangeal joint. The observed pattern of proximal actuation and distal compliance, as well as the substantial SNW at proximal joints, minimal SNW at intermediate joints, and variable energy absorption at distal joints, may emerge as general principles in quadruped limb mechanics and help to inform the leg designs of highly capable running robots.
Topics: Animals; Biomechanical Phenomena; Compliance; Female; Forelimb; Goats; Hindlimb; Joints; Models, Biological; Muscle, Skeletal; Physical Exertion; Range of Motion, Articular; Running; Tendons; Weight-Bearing
PubMed: 17947498
DOI: 10.1152/japplphysiol.01090.2006 -
The Journal of Thoracic and... Aug 2016
Topics: Compliance; Hemodynamics
PubMed: 27234021
DOI: 10.1016/j.jtcvs.2016.04.065 -
Journal of Orthopaedic Surgery and... Apr 2016Flexor retinaculum transection is a routine surgical treatment for carpal tunnel syndrome, yet the biomechanical and clinical sequelae of the procedure remain unclear....
BACKGROUND
Flexor retinaculum transection is a routine surgical treatment for carpal tunnel syndrome, yet the biomechanical and clinical sequelae of the procedure remain unclear. We investigated the effects of flexor retinaculum release on carpal tunnel structural compliance using cadaveric hands.
METHODS
The flexor retinaculum was incrementally and sequentially released with transections of 25, 50, 75, and 100 % of the transverse carpal ligament, followed by the distal aponeurosis and then the antebrachial fascia. Paired outward 10 N forces were applied to the insertion sites of the transverse carpal ligament at the distal (hamate-trapezium) and proximal (pisiform-scaphoid) levels of the carpal tunnel. Carpal tunnel compliance was defined as the change in carpal arch width normalized to the constant 10 N force.
RESULTS
With the flexor retinaculum intact, carpal tunnel compliance at the proximal level, 0.696 ± 0.128 mm/N, was 13.6 times greater than that at the distal level, 0.056 ± 0.020 mm/N. Complete release of the transverse carpal ligament was required to achieve a significant gain in compliance at the distal level (p < 0.05). Subsequent release of the distal aponeurosis resulted in an appreciable additional increase in compliance (43.0 %, p = 0.052) at the distal level, but a minimal increase (1.7 %, p = 0.987) at the proximal level. Complete flexor retinaculum release provided a significant gain in compliance relative to transverse carpal ligament release alone at both proximal and distal levels (p < 0.05).
CONCLUSIONS
Overall, complete flexor retinaculum release increased proximal compliance by 52 % and distal compliance by 332 %. The increase in carpal tunnel compliance with complete flexor retinaculum release helps explain the benefit of carpal tunnel release surgery for patients with carpal tunnel syndrome.
Topics: Adult; Biomechanical Phenomena; Cadaver; Carpal Bones; Carpal Tunnel Syndrome; Compliance; Decompression, Surgical; Fasciotomy; Female; Humans; Ligaments, Articular; Male; Middle Aged; Radiography
PubMed: 27074707
DOI: 10.1186/s13018-016-0380-3