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Handbook of Clinical Neurology 2018General anesthesia is the induction and maintenance of a state of unconsciousness with the absence of pain sensation. General anesthesia is accomplished by the... (Review)
Review
General anesthesia is the induction and maintenance of a state of unconsciousness with the absence of pain sensation. General anesthesia is accomplished by the administration of a combination of inhaled anesthetic gases and intravenous drugs. These medications eliminate behavioral thermoregulatory compensations, leaving only autonomic defenses to offset environmental perturbations. Anesthetics inhibit thermoregulatory control in a dose-dependent fashion over the entire clinical range. Impairment of thermoregulatory control is observed by a change in thermoregulatory thresholds with the vasoconstriction threshold being affected about three times as much as the sweating threshold. Consequently, the zone between sweating and vasoconstriction thresholds, called interthreshold range, is widened dose-dependently. Impairment of thermoregulation, triggered by general anesthesia, typically causes inadvertent hypothermia. In febrile patients, general anesthesia reduces the magnitude of perioperative fever.
Topics: Anesthesia, General; Animals; Body Temperature Regulation; Humans; Hypothermia; Sensory Thresholds; Vasoconstriction
PubMed: 30459029
DOI: 10.1016/B978-0-444-64074-1.00037-9 -
Clinical Orthopaedics and Related... Mar 2020Blood flow restriction (BFR) is a process of using inflatable cuffs to create vascular occlusion within a limb during exercise. The technique can stimulate muscle...
BACKGROUND
Blood flow restriction (BFR) is a process of using inflatable cuffs to create vascular occlusion within a limb during exercise. The technique can stimulate muscle hypertrophy and improve physical function; however, most of these studies have enrolled healthy, young men with a focus on athletic performance. Furthermore, much of the information on BFR comes from studies with small samples sizes, limited follow-up time, and varied research designs resulting in greater design, selection, and sampling bias. Despite these limitations, BFR's popularity is increasing as a clinical rehabilitation tool for aging patients. It is important for practitioners to have a clear understanding of the reported effects of BFR specifically in older adults while simultaneously critically evaluating the available literature before deciding to employ the technique.
QUESTIONS/PURPOSES
(1) Does BFR induce skeletal muscle hypertrophy in adults older than 50 years of age? (2) Does BFR improve muscle strength and/or physical function in adults older than 50 years?
METHODS
Using PubMed, Google Scholar, Web of Science, and Science Direct, we conducted a systematic review of articles using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to assess the reported effects of BFR on skeletal muscle in older adults. Included articles enrolled participants 50 years of age or older and used BFR in conjunction with exercise to study the effects of BFR on musculoskeletal outcomes and functionality. The following search terms were used: "blood flow restriction" OR "KAATSU" OR "ischemic training" AND "clinical" AND "elderly." After duplicates were removed, 1574 articles were reviewed for eligibility, and 30 articles were retained with interventions duration ranging from cross-sectional to 16 weeks. Sample sizes ranged from 6 to 56 participants, and exercise tasks included passive mobilization or electrical stimulation; walking; resistance training using machines, free weights, body weight, or elastic bands; and water-based activities. Furthermore, healthy participants and those with cardiovascular disease, osteoarthritis, osteoporosis, sporadic inclusion body myositis, spinal cord injuries, and current coma patients were studied. Lastly, retained articles were assigned a risk of bias score using aspects of the Risk of Bias in Nonrandomized Studies of Interventions and the Cochrane Collaboration's tool for assessing the risk of bias in randomized trials.
RESULTS
BFR, in combination with a variety of exercises, was found to result in muscle hypertrophy as measured by muscle cross-sectional area, thickness, volume, mass, or circumference. Effect sizes for BFR's ability to induce muscle hypertrophy were calculated for 16 of the 30 papers and averaged 0.75. BFR was also shown to improve muscle strength and functional performance. Effect sizes were calculated for 21 of the 30 papers averaging 1.15.
CONCLUSIONS
Available evidence suggests BFR may demonstrate utility in aiding rehabilitation efforts in adults older than 50 years of age, especially for inducing muscle hypertrophy, combating muscle atrophy, increasing muscle strength, and improving muscle function. However, most studies in this systematic review were at moderate or high risk of bias; that being so, the findings in this systematic review should be confirmed, ideally using greater sample sizes, randomization of participants, and extended follow-up durations.
LEVEL OF EVIDENCE
Level II, systematic review.
Topics: Aged; Exercise Therapy; Female; Humans; Hypertrophy; Male; Middle Aged; Muscle Strength; Muscle, Skeletal; Orthopedic Procedures; Regional Blood Flow; Vasoconstriction
PubMed: 31860546
DOI: 10.1097/CORR.0000000000001090 -
Journal of Neurology Feb 2023Reversible cerebral vasoconstriction syndrome may be underdiagnosed. It can be accompanied by various complications, mainly intracerebral hemorrhage and ischemic stroke.... (Review)
Review
BACKGROUND/OBJECTIVE
Reversible cerebral vasoconstriction syndrome may be underdiagnosed. It can be accompanied by various complications, mainly intracerebral hemorrhage and ischemic stroke. The clinical presentation of this condition varies according to its localization. The aims of this review are to raise awareness of the disease, especially in the presence of corresponding risk factors; to connect its precipitating factors, pathophysiology, and complications; and to compare various differential diagnoses of vasoconstriction.
METHODS
A review of the literature in PubMed/MEDLINE and Google Scholar was conducted from May 1997 until May 2022.
RESULTS
Reversible cerebral vasoconstriction syndrome, which is a clinical-radiological syndrome, is mainly characterized by the occurrence of thunderclap headache and widespread vasoconstriction. The most common precipitating factors are the use of vasoactive substances and postpartum status. The pathophysiology is currently assumed to include two mechanisms: sympathetic overactivity and endothelial dysfunction. From these mechanisms, it is possible to derive potential complications as well as the most important differential diagnoses: posterior reversible encephalopathy syndrome, convexity subarachnoid hemorrhage, ischemic and hemorrhagic stroke, and primary angiitis of the central nervous system.
CONCLUSION
In general, the outcome of reversible cerebral vasoconstriction syndrome is very good. Vasospasm as well as thunderclap headache attacks can be fully reversible, and > 90% of patients are functionally independent at discharge.
Topics: Female; Humans; Vasospasm, Intracranial; Posterior Leukoencephalopathy Syndrome; Cerebrovascular Disorders; Headache Disorders, Primary; Vasoconstriction
PubMed: 36305970
DOI: 10.1007/s00415-022-11425-z -
British Journal of Anaesthesia Aug 2019
Topics: Anesthesia; Hemodynamics; Humans; Perioperative Care; Regional Blood Flow; Vasoconstriction; Vasoconstrictor Agents
PubMed: 31153629
DOI: 10.1016/j.bja.2019.04.052 -
CMAJ : Canadian Medical Association... Jan 2021
Topics: Cerebrum; Computed Tomography Angiography; Defecation; Female; Headache Disorders, Primary; Humans; Middle Aged; Vasoconstriction
PubMed: 33667187
DOI: 10.1503/cmaj.201234-f -
Emergency Medicine Clinics of North... Nov 2014To effectively treat an aging and increasingly complex patient population, emergency physicians and other acute-care providers must be comfortable with the use of... (Review)
Review
To effectively treat an aging and increasingly complex patient population, emergency physicians and other acute-care providers must be comfortable with the use of vasopressors, inotropes, and chronotropes. These medicines are used to augment the cardiovascular function of critically ill patients. Each class of medication produces a different hemodynamic effect. Some agents produce only one of these actions, whereas others have multiple effects. For the emergency physician, these agents are used with the explicit goal of preserving vital organ perfusion during acute and severe illness. This article reviews the physiologic receptors targeted by such drugs, common agents used, and specific clinical indications for their use.
Topics: Cardiotonic Agents; Dopamine; Epinephrine; Heart Arrest; Heart Failure; Heart Rate; Humans; Myocardial Infarction; Shock, Cardiogenic; Shock, Septic; Vasoconstriction; Vasoconstrictor Agents
PubMed: 25441037
DOI: 10.1016/j.emc.2014.07.006 -
Current Vascular Pharmacology 2016Purinergic signalling is involved in the control of vascular tone and remodelling. Endothelial cells release purines and pyrimidines in response to changes in blood flow... (Review)
Review
Purinergic signalling is involved in the control of vascular tone and remodelling. Endothelial cells release purines and pyrimidines in response to changes in blood flow (evoking shear stress) and hypoxia. They then act on P2Y, P2X and P1 receptors on endothelial cells leading to release of EDRF mediated by nitric oxide and prostaglandins and EDHF, resulting in vasodilatation. The therapeutic potential of purinergic compounds for the treatment of vascular diseases, including hypertension, ischaemia, atherosclerosis, migraine and coronary artery and diabetic vascular disease as well as vasospasm is discussed.
Topics: Animals; Endothelium, Vascular; Humans; Hypertension; Ischemia; Purines; Receptors, Purinergic; Signal Transduction; Vasoconstriction; Vasodilation
PubMed: 26638799
DOI: 10.2174/1570161114666151202204948 -
Handbook of Clinical Neurology 2018Cold exposure stimulates heat production and conservation to protect internal temperature. Heat conservation is brought about via reductions in skin blood flow. The... (Review)
Review
Cold exposure stimulates heat production and conservation to protect internal temperature. Heat conservation is brought about via reductions in skin blood flow. The focus, here, is an exploration of the mechanisms, particularly in humans, leading to that cutaneous vasoconstriction. Local skin cooling has several effects: (1) reduction of tonic nitric oxide formation by inhibiting nitric oxide synthase and element(s) downstream of the enzyme, which removes tonic vasodilator effects, yielding a relative vasoconstriction; (2) translocation of intracellular alpha-2c adrenoceptors to the vascular smooth-muscle cell membrane, enhancing adrenergic vasoconstriction; (3) increased norepinephrine release from vasoconstrictor nerves; and (4) cold-induced vasodilation, seen more clearly in anastomoses-rich glabrous skin. Cold-induced vasodilation occurs in nonglabrous skin when nitric oxide synthase or sympathetic function is blocked. Reflex responses to general body cooling complement these local effects. Sympathetic excitation leads to the increased release of norepinephrine and its cotransmitter neuropeptide Y, each of which contributes significantly to the vasoconstriction. The contributions of these two transmitters vary with aging, disease and, in women, reproductive hormone status. Interaction between local and reflex mechanisms is in part through effects on baseline and in part through removal of the inhibitory effects of nitric oxide on adrenergic vasoconstriction.
Topics: Body Temperature Regulation; Humans; Skin; Skin Temperature; Vasoconstriction
PubMed: 30454589
DOI: 10.1016/B978-0-444-63912-7.00011-4 -
Autonomic Neuroscience : Basic &... Mar 2015Sympathetic vasoconstriction is normally attenuated in exercising muscle by local changes in muscle metabolites and other substances that reduce vascular responsiveness... (Review)
Review
Sympathetic vasoconstriction is normally attenuated in exercising muscle by local changes in muscle metabolites and other substances that reduce vascular responsiveness to α-adrenergic receptor activation. Termed functional sympatholysis, this protective mechanism is thought to optimize muscle blood flow distribution to match perfusion with metabolic demand. Emerging evidence from both animal and human studies indicate that functional sympatholysis is impaired in hypertension and may constitute an important underlying cause of skeletal muscle malperfusion during exercise in this common cardiovascular condition. Findings from studies of animal models of hypertension and patients with essential hypertension will be integrated in this review to provide insight into the underlying mechanisms responsible for inappropriate sympathetic vasoconstriction in exercising muscle and the treatment options that may restore functional sympatholysis and improve muscle perfusion during exercise.
Topics: Animals; Exercise; Humans; Hypertension; Muscle, Skeletal; Sympathetic Nervous System; Vasoconstriction
PubMed: 25458424
DOI: 10.1016/j.autneu.2014.10.019 -
Interventional Cardiology Clinics Jul 2020Passing contrast media through the renal vascular bed leads to vasoconstriction. The perfusion decrease leads to ischemia of tubular cells. Through ischemia and direct... (Review)
Review
Passing contrast media through the renal vascular bed leads to vasoconstriction. The perfusion decrease leads to ischemia of tubular cells. Through ischemia and direct toxicity to renal tubular cells, reactive oxygen species formation is increased, enhancing the effect of vasoconstrictive mediators and decreasing the bioavailability of vasodilative mediators. Reactive oxygen species formation leads to oxidative damage to tubular cells. These interacting pathways lead to tubular necrosis. In the pathophysiology of contrast-induced acute kidney injury, low osmolar and iso-osmolar agents have theoretic advantages and disadvantages; however, clinically the difference in incidence of contrast-induced acute kidney injury has not changed.
Topics: Acute Kidney Injury; Contrast Media; Drug-Related Side Effects and Adverse Reactions; Humans; Incidence; Kidney; Kidney Tubules; Necrosis; Osmolar Concentration; Reactive Oxygen Species; Vasoconstriction
PubMed: 32471670
DOI: 10.1016/j.iccl.2020.03.001