Minerva anestesiologica
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Minerva anestesiologica · Jun 2006
ReviewMetabolic treatment of critically ill patients: energy balance and substrate disposal.
Oxidation of substrates is the main biochemical process used by the human body to produce energy. Different substrates (carbohydrates, lipids, and proteins) have different effects on oxygen consumption and carbon dioxide production: during the critical phase of pathologies it could be relevant pay attention to the use of various nutrients, that have some altered effect respect to the normal subjects metabolism, and during the length of metabolic treatment, too. ⋯ Adequate amount of energy intake in carbohydrates determine an increase of RQ, that means a shift from a more lipid-based to a more glucose-based oxidation. Composition of dietary intake can be usefully different for each pathology, and also for different periods of the same pathology, because critically ill patients have a variety of metabolic needs during their stay in ICU.
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Minerva anestesiologica · Jun 2006
ReviewUsing the nerve stimulator for peripheral or plexus nerve blocks.
Conventional methodology for nerve location utilizes anatomical landmarks followed by invasive exploration with a needle to a suitable endpoint. An appropriate endpoint can be either anatomical in nature (e.g. transaterial technique) or functional (paresthesia or motor response to electrical stimulation). Ability to electrically stimulate a peripheral nerve or plexus depends upon many variables, including; 1) conductive area at the electrode, 2) electrical impedance, 3) electrode-to-nerve distance, 4) current flow (amperage), and 5) pulse duration. ⋯ The above parameters can be varied optimally to enhance successful nerve location and subsequent blockade. Unlike imaging modalities such as ultrasonography, electrical nerve stimulation depends upon nerve conduction. Similarly, percutaneous electrode guidance (PEG) makes use of the above variables to allow prelocation of the nerve by transcutaneous stimulation.
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Minerva anestesiologica · Jun 2006
ReviewMeaning of arterio-venous PCO2 difference in circulatory shock.
The arterovenous difference in carbon dioxide tension (DeltaPCO2) can be calculated after simultaneous sampling of arterial blood (PaCO2) and of mixed venous blood from the distal of a pulmonary artery catheter (PvCO2). Under physiological conditions, DeltaPCO2 ranges from 2 to 5 mmHg. The DeltaPCO2 depends on carbon dioxide and cardiac output by a complex fashion. ⋯ We bring evidence that DeltaPCO2 cannot serve as a marker of tissue hypoxia contrary to what was initially thought. However, DeltaPCO2 can be considered as a marker of the adequacy of venous blood flow (i.e. cardiac output) to remove the total CO2 produced by the peripheral tissues. In this regard, the knowledge of DeltaPCO2 should help the clinicians for the decision of giving therapy aimed at increasing cardiac output.
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Minerva anestesiologica · Jun 2006
Review Comparative StudyLow vs high positive end-expiratory pressure in the ventilatory management of acute lung injury.
Positive end-expiratory pressure (PEEP) has become an essential component of the care of many critically ill patients who require ventilatory support. The application of PEEP is expected to improve lung mechanics and gas exchange as it recruits lung volume. ⋯ Although the data from those animal studies and clinical trials could be seen as very convincing, there are insufficient data to propose an universal approach for the use of PEEP in patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). In this article I will review the basic mechanisms of PEEP and the current knowledge of the effects of PEEP on the evolution and outcome of ALI/ARDS.
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Minerva anestesiologica · Jun 2006
ReviewMetabolic treatment of critically ill patients: energy expenditure and energy supply.
Nutrition in critically ill patients should be considered as therapy: assessing the energy expenditure and the termogenic effect of food, and knowing the differences among composition and amount of given substrates, it is possible restore, maintain, or at least limit the derangement of energy equilibrium. Energy metabolism comprehends assumption, storage and oxidation of nutrients: all these factors could be discriminant in critical clinical conditions, particularly cardiac and respiratory failure. Then, this review would lead the decision making process beginning from biochemistry and bioenergetics, until the metabolic strategy practically usable at the bedside of patients during the whole critical phase of their pathology.