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Regulation of Arterial Blood Pressure
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
The arterial baroreceptor reflex is the most important mechanism of the short-term regulation of blood pressure. The mean arterial blood pressure is determined by the amount of blood in the arterial system at any point in time. The volume of blood in the arteries is determined by the amount of blood entering the aorta as cardiac output and the blood volume leaving the arteries as peripheral runoff into the capillaries. The cardiac output is the product of heart rate and stroke volume, and the peripheral runoff is determined by the mean arterial blood pressure acting across the total peripheral resistance of the arterioles. The main determinants of mean arterial blood pressure are therefore the cardiac output and the total peripheral resistance acting via changes in the arterial blood volume. The negative feedback arterial baroreceptor reflex influences many factors controlling cardiac output, peripheral resistance and arterial blood pressure (Figure 31.4).
Anesthesia for Thyroid Surgery
Published in Madan Laxman Kapre, Thyroid Surgery, 2020
Vidula Kapre, Shubhada Deshmukh, Pratibha Deshmukh, Meghna Sarode, Rajashree Chaudhary
In hypothyroidism there is bradycardia, decreased cardiac output, and reduced blood volume, which may get further aggravated by cardiac depressant effects of anesthetic drugs and blood loss during surgery. Abnormal baroreceptor function poses problems because if there is a fall in cardiac output, the normal tachycardic response is blunted so the blood pressure cannot be restored and there may be catastrophic hypotension.
Resetting of the Arterial Baroreflex: Peripheral and Central Mechanisms
Published in Irving H. Zucker, Joseph P. Gilmore, Reflex Control of the Circulation, 2020
Mark W. Chapleau, George Hajduczok, Francois M. Abboud
Several studies have demonstrated impaired baroreceptor function prior to the development of hypertension when vascular compliance is normal in spontaneously hypertensive rats (SHR) and Dahl salt-sensitive rats (Andresen et al., 1980; Gordon and Mark, 1984). The results suggest a genetic alteration in receptor function unrelated to structural changes in the vasculature. Thus, impaired baroreceptor function may not only result from the elevated pressure but may contribute to the initiation of the hypertension.
Novel approaches: targeting sympathetic outflow in the carotid sinus
Published in Blood Pressure, 2023
Dagmara Hering, Krzysztof Narkiewicz
Tonic sympathetic activation and tonic arterial BP control depend on central integrative structures in the brain stem, the rostral ventrolateral medulla (RVLM) [3]. Descending projections to the RVLM arise among others from the neurons in the peri-aqueductal grey and hypothalamic paraventricular nucleus (PVN). The RVLM integrates reflex neural mechanisms from arterial baroreceptors, chemoreceptors and various afferent sensory visceral receptors via direct connection with the upper part of the medulla through the NTS and PVN which modulate vasomotor sympathetic nerve discharge and BP. Under physiological conditions, arterial baroreceptors play a fundamental role in preventing excessive variability in BP. Afferent signals from baroreceptors stimulate the NTS in the upper part of the medulla in response to the distension of the vessel wall caused by transmural pressure. A signal arising from the NTS exerts a parasympathetic vagal effect resulting in slowing HR and reducing tonic sympathetic activity generated in the RVLM (Figure 2).
Baroreflex control model for cardiovascular system subjected to postural changes under normal and orthostatic conditions
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
V. L. Resmi, R. G. Sriya, N. Selvaganesan
An integrated mathematical model is proposed which consist of baroreflex control along with the cardiovascular system. The proposed model determines the dynamical interaction among blood pressure, parameters that control it and the baroreflex mechanism. This model consists of:Cardiovascular system that utilizes a simple resistance-compliance model to replicate the flow of blood in the vasculature and a heart model proposed by Mulier (Ottesen 1997). Both pulsatile and non pulsatile models are considered for the simulation of the proposed integrated model.Baroreceptor reflex consisting of (i) Baroreceptors modeled as mechanoreceptors using stress strain based voigt model (ii) Central nervous system modeled using Hodgkin-Huxley model and (iii) Efferent pathways modeled using dynamics of chemical reactions that control HR, stroke volume, venous compliance and contractility (Ottesen 1997; Samaan and Stella 1935).
The role of serial cardiac biomarkers in prognostication and risk prediction of chronic heart failure: additional scientific insights with hemodynamic feedback
Published in Expert Review of Cardiovascular Therapy, 2023
Youssra Allach, Jasper J. Brugts
The pathophysiology of HF is greatly influenced by the activation of the neurohormonal system. In order to keep the cardiovascular system in a state of homeostasis, the regulation of the blood volume in circulation is closely controlled by the neurohormonal system. The aorta and carotid sinus contain what are known as baroreceptors, which are able to detect changes in the arterial blood volume of the peripheral circulation. While the carotid sinus’s baroreceptors detect high pressure, those in the aortic arch operate as low-pressure cardiopulmonary mechanoreceptors. When engaged, the baroreceptors have an inhibitory impact on the central nervous system and suppress systemic circulation and outflow to the heart. Changes in the heart’s ability to pump blood, the amount of blood circulating in the body, or both cause a drop-in baroreceptor activity. Parasympathetic tone decreases as a result, and sympathetic tone is reflexively enhanced [18,19]. This causes an increase in heart rate and contractility as well as peripheral vasoconstriction. Additionally, neurohormonal stimulation can result in renal salt retention, which can result in hypervolemia. The effects of diuretics are exacerbated, and their effectiveness is decreased when renal impairment is present [20]. Therefore, the extent of neurohormonal activity in HF has been found to be correlated with the severity of the condition and the clinical prognosis [21].