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Sedation and Restraint for Standing Procedures
Published in Michele Barletta, Jane Quandt, Rachel Reed, Equine Anesthesia and Pain Management, 2023
Mechanism of action. Agonism of alpha-2 adrenoreceptors in the central nervous system (CNS). Inhibition of norepinephrine and dopamine storage and release.Decrease in firing rate of central and peripheral neurons.Decrease in CNS sympathetic output and peripheral sympathetic tone; increase in parasympathetic tone.Alpha-1 effects functionally antagonize the hypnotic effects of alpha-2 antagonism.
Naturopathic Medicine and the Prevention and Treatment of Cardiovascular Disease
Published in Stephen T. Sinatra, Mark C. Houston, Nutritional and Integrative Strategies in Cardiovascular Medicine, 2022
One method to calm an overactive sympathetic nervous system is to increase parasympathetic tone. Many mind-body therapies including Tai chi, Qi gong, Yoga, biofeedback, and meditation and/or slow belly breathing help reduce stress by activating parasympathetic pathways. When practiced regularly, these therapies can have a profound impact on the quality of life, and can reduce blood pressure as well. These mind-body therapies have a common denominator: meditation through habitual breathing. Learning how to breathe, and building awareness around breathing exercises, is likely why these therapies are beneficial for lowering blood pressure; breathing encourages parasympathetic tone in the body which in turn supports heart rate variability. Increasing heart rate variability is a major prognosticator in protecting cardiovascular health.73
Psychosocial Aspects of Diabetes
Published in Jahangir Moini, Matthew Adams, Anthony LoGalbo, Complications of Diabetes Mellitus, 2022
Jahangir Moini, Matthew Adams, Anthony LoGalbo
Delirium may involve reversible impairment of cerebral oxidative metabolism, generation of cytokines, and multiple neurotransmitter abnormalities. Any type of stress causes upregulating of the sympathetic tone while downregulating the parasympathetic tone. This impairs cholinergic function, which contributes to the condition. The elderly have a higher vulnerability to reduced cholinergic transmission, increasing risks. No matter what the cause, there is impairment of the cerebral hemispheres, or the arousal mechanisms of the thalamus and brainstem reticular activating system. Neurologists often use the words “delirium” and “toxic metabolic encephalopathy” interchangeably.
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].
Shift working and cardiovascular health
Published in Chronobiology International, 2023
Amir Gohari, Darrin Wiebe, Najib Ayas
Due to dysfunction of the autonomic nervous system (ANS), shift work-induced circadian misalignment may potentiate cardiometabolic risk in OSA (Santos et al. 2020). The interplay between sympathetic and parasympathetic tone is integral to cardiovascular regulation. In healthy individuals, sleep stages can have a demonstrated impact on sympathetic nervous activity, whereas parasympathetic activity has been shown to be largely driven by circadian rhythm (Kufoy et al. 2012). Autonomic tone, and specifically increased sympathetic activity, has been shown to predict the metabolic syndrome and is increasingly being explored as a mediator in the cardiovascular risk profile associated with disordered sleep states (Miglis 2016). This interaction is broadly thought of as the balance between the sympathetic and parasympathetic systems. The balance of these two opposing systems is generally measured using indirect methods, with testing of the autonomic nervous system to physiologic challenges including assessments of heart rate, blood pressure, as well as sweat production (Santos et al. 2020).
Short-term transcutaneous non-invasive vagus nerve stimulation may reduce disease activity and pro-inflammatory cytokines in rheumatoid arthritis: results of a pilot study
Published in Scandinavian Journal of Rheumatology, 2021
AM Drewes, C Brock, SE Rasmussen, HJ Møller, B Brock, BW Deleuran, AD Farmer, M Pfeiffer-Jensen
To the best of our knowledge, this is the first exploratory report examining the short-term effect of n-VNS directed at therapeutically manipulating the cholinergic anti-inflammatory pathway in RA. We demonstrated a small but significant reduction in disease activity in participants with active disease, which was associated with a reduction in IFN-γ. The reduction in disease activity was mediated by a decrease in the number of swollen and tender joints, as well as in CRP. Such effects were not seen in those participants with low disease activity, suggesting that this effect was specific to those RA patients with marked inflammation. This may be due to the fact that they already had a very low inflammation level and therefore a decrease in disease severity was more difficult to obtain. In addition, disease activity was negatively associated with baseline CVT. The observed decrease in systolic BP is a physiological response to increased parasympathetic tone. Given the lack of standardized VNS paradigms (long term vs short term and invasive, aural vagal stimulation and n-VNS), an obvious limitation exists since there is no consensus on the best cardiovascular outcome parameter. It has been shown that n-VNS has limited effects on C-fibres. Consequently, there is expectedly constrained stimulation of the Bezold–Jarisch reflex following n-VNS, which would have inhibited sympathetic activity, leading to bradycardia, vasodilatation, and hypotension (25). In contrast to previous studies where no effect on HR and BP is reported, we saw a reduction in systolic BP following n-VNS.