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Signa Vitae

A Journal In Intensive Care And Emergency Medicine

Category: Reviews (Page 1 of 16)

How I use skeletal muscle Near Infrared Spectroscopy to non-invasively assess hemodynamic status of the critically ill

Abstract

The major goal of hemodynamic treatment is to reach adequate flow. Near infrared spectroscopy (NIRS) allows non-invasive assessment of skeletal muscle tissue oxygenation during rest and also during vascular occlusion test (VOT). VOT allows estimation of tissue oxygen extraction capability, which could be preserved (i.e. hypovolemic, obstructive and cardiogenic shock) or inappropriate (i.e. sepsis/septic shock). By using ultrasound to estimate cardiac output, arterial hemoglobin oxygen saturation, skeletal muscle NIRS, arterial lactate and hemoglobin, therapeutic goals in critically ill patients with preserved oxygen extraction capability can easily be targeted. Current controversies of NIRS technology and approach to patients with impaired oxygen extraction are discussed as well.

Key words: shock, skeletal muscle, near-infrared spectroscopy, critically ill

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Assesment of hemodynamics by basic ultrasound

Abstract

Basic ultrasound can provide important information about the main parts of the circulatory system, the heart, and the main vessels. At the bedside, only by brief visual impression of the heart function and inferior vena cava diameter, and without any measurements, the attending physician can get important information which can influence the clinical opinion-making process and the management of the hemodynamically unstable patient. No less important is to obtain information about the lungs, particularly to estimate if extravascular lung water is present in excess or not. Ultrasound can help in the detection of the potentially reversible causes of hemodynamic instability or arrest and can guide the treatment. Examples are pneumothorax, cardiac tamponade, thromboembolism, the detection of blood in the pleural, pericardial or abdominal space after trauma and the detection and treatment of the source of the infection.

Key words: ultrasound, hemodynamic monitoring, shock

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Inotropes and vasopressors

Abstract

Inotropic agents are used to increase myocardial contraction while vasopressors are used to increase vascular tone. They are often used for treatment of patients whose tissue perfusion is insufficient to meet metabolic requirements. Therefore, these agents are usually administered in intensive care units where continuous and invasive monitoring of cardiac function can be applied.

Inotropic agents can be divided into those that increase cAMP levels and those that do not. Adrenergic receptor agonists and phosphodiesterase inhibitors (PDEi) increase cAMP levels and are currently the mainstay of positive inotropic therapy. Levosimendan acts as calcium sensitizer and increases myocardial contraction force without increasing intracellular calcium levels. In addition to existing inotropic agents, new promising inotropes are being developed. These include sarcoplasmic reticulum calcium pump (istaroxime), cardiac myosin activators (omecamtivmecarbil), gene therapy, nitroxyl donors and ryanodine receptor stabilizers.

Current treatments of heart failure are aimed at prolonging survival and not just alleviating symptoms. This review provides a short description of the physiology of myocardial contraction and adrenergic receptors. We also provide a short description of commonly used inotropic agents and vasopressor drugs as well as a short review of agents that are expected are in use in the future.

Inotropes are agents used to increase myocardial contractility, while vasopressors are administered to increase vascular tone(1).Their use ismostly confined to critically ill patients whose hemodynamic impairment is such that tissue perfusion is insufficient to meet metabolic requirements(2). Patients in need of inotropic or vasopressor support are often presented with septic or cardiogenic shock and severe heart failure, and are victims of major trauma or undergoing major surgery.These drugs are therefore administered usually to patients treated in intensive care settings where continuous monitoring of cardiac rhythm, arterial oxygenation, urine output and other invasive hemodynamic monitoring can be applied.Inotropic and vasopressor drugs should be administered through a central venous catheter via infusion pumps that can deliver precise flow rates. These agents are mostly short acting with rapid onset and offset of action. Therefore, they can be used without an initial bolus and can be titrated frequently. Abrupt discontinuation should be avoided because of possible hypotension.

Key words: Inotropes, Vasopressor Agents, Intensive Care, Heart Failure

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Evolving from Past to Future: Facilitating SMART research

Abstract

In clinical research, there has been an increasing need to titrate ethical, legal and insurance requirements to the type of study, so that higher-risk research receives necessary and appropriate detailed attention, while low-risk studies can proceed more rapidly.

Spontaneous Medically Advantageous Research Trials (SMART) are non-profit studies that carry minimal or no risk to patients. This type of investigation, however, is currently hampered by the fact that, in many hospitals and jurisdictions it has to undergo the same bureaucratic procedures and safety assessments as high-risk, for-profit studies. We strongly believe that such practice of scientific research assessment should be radically modified. We advocate a new, specific research category for SMART investigations that grants them a preferential route from conception to ethics assessment to execution. In addition, we argue that such low risk studies assessing common, often not evidence-based applied treatments or investigations should in fact be a mandatory component of modern medicine. All clinicians, scientists, patients, patient associations, politicians, scientific associations and common citizens should be involved in this process, as they all play a crucial role in its evolution and success.

We contend that modern medical research and entire health systems should transition to a novel model of healthcare system where SMART execution is embedded into daily practice, in order to minimize anecdotal practice and maximize evidence-based practice.

Key-words: no profit study, medical research, ethical committee, progress

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Lung replacement therapies for acute respiratory failure

Abstract

Acute respiratory failure is one of the critical conditions with an increased mortality. In order to reverse lung injury and reduce the mortality rate, several lung replacement therapies have been developed, including the extracorporeal membrane oxygenation, the intravascular oxygenator and carbon dioxide removal device, the intravenous membrane oxygenator and the thoracic artificial lung. This article aims to present the properties, indications and advantages of these devices.

Key words: artificial organs, extracorporeal membrane oxygenation, respiratory insufficiency

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