Minerva anestesiologica
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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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Hypercapnia has traditionally been avoided in the quest to keep parameters normal. Recent understanding of the role of excessive tidal stretch has prompted clinicians to avoid high tidal volumes or plateau pressures, and the resulting permissive hypercapnia has been increasingly tolerated by clinicians. Newer data point to the potential for elevated CO2 to be protective, and in some experimental situations, to cause harm. The protective effects of so called therapeutic hypercapnia' remain experimental at present, but promising laboratory studies suggest potential roles for the eventual selective application at the bedside.
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Metabolically critical illness can be divided in two phases, acute and prolonged. Whereas the acute or hypermetabolic phase is characterized by elevated circulating concentration of catabolic hormones and substrate utilization to provide energy to vital organs, the prolonged or catabolic phase of critical illness is marked by reduced endocrine stimulation and severe loss of body cell mass. The most common analgesic and sedative agents used in the intensive care unit, if used in small or moderate doses, do not interfere significantly with the metabolic milieu; however, prolonged infusions, and in high doses, without adequate monitoring of level of sedation and quality of analgesia, can precipitate morbid events. Further research is needed in the metabolic aspects of analgesia and sedation in the intensive care unit, particularly if a multimodal pharmacologic strategy is used whereby multiple interventions aim at minimizing the risk of overdosing and contributing to attenuation of the stress response associated with critical illness.
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Massive haemorrhage after trauma is a big challenge for care-givers, being a leading cause of early in-hospital mortality. Surgical bleeding may be easily controlled with several techniques. Otherwise, consumptive coagulopathy is often extremely difficult to stop. An adjunctive strategy to treat traumatic coagulopathic bleeding is recombinant activated factor VII (rFVIIa) (NovoSeven, Novo Nordisk A/S, Bagsvaerd, Denmark). ⋯ Off-label administration of rFVIIa was able to reverse life-threatening bleeding not manageable with standard strategies in our series of major trauma patients without systemic adverse effects.
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Minerva anestesiologica · Jun 2006
ReviewThe effect of alcohol abuse on ARDS and multiple organ dysfunction.
A history of alcohol abuse is very common and many times unrecognized in critically ill patients. The consequences of alcohol abuse are multifactorial, and it is associated with excessive morbidity and increased mortality. Alcohol causes acute and chronic dysfunction in multiple organ systems, and the underlying mechanisms responsible for organ injury are complex. ⋯ This increased susceptibility to developing acute lung injury has been evaluated by many investigators, and the common variable appears to be oxidative stress. In this article, we review the epidemiology of alcohol abuse and its association with ARDS. In addition, we provide an overview of the mechanisms thought to contribute to ARDS and multiple organ dysfunction.