For many years, physicians’ approach to the transfusion of allogeneic red blood cells (RBC) was not individualized. It was accepted that a hemoglobin concentration (Hb) of less than 10 g/dL was a general transfusion threshold and the majority of patients were transfused immediately. In recent years, there has been increasing evidence that even significantly lower hemoglobin concentrations can be survived in the short term without sequelae. This somehow contradicts the observation that moderate or mild anemia is associated with relevant long-term morbidity and mortality. To resolve this apparent contradiction, it must be recognized that we have to avoid acute anemia or treat it by alternative methods. The aim of this article is to describe the physiological limits of acute anemia, match these considerations with clinical realities, and then present “patient blood management” (PBM) as the therapeutic concept that can prevent both anemia and unnecessary transfusion of RBC concentrates in a clinical context, especially in Intensive Care Units (ICU). This treatment concept may prove to be the key to high-quality patient care in the ICU setting in the future.
Die Mikrozirkulation umfasst alle Blut-und Lymphgef äße mit einem Durchmesser < 100 µm. Störungen der Mikrozirkulation finden sich bei kritisch kranken Patienten häufig und weisen einen engen Zusammenhang mit dem Schweregrad der (Multi-) Organdysfunktion sowie der Sterblichkeit auf. Dieser Beitrag bietet eine Übersicht über die Pathophysiologie, das Monitoring und die Therapie der Mikrozirkulationsstörung beim kritisch kranken Patienten.
Purpose of review Despite restoration of adequate systemic blood flow in patients with shock, single organs may remain hypoperfused. In this review, we summarize the results of a literature research on methods to monitor single organ perfusion in shock. We focused on methods to measure heart, brain, kidney, and/or visceral organ perfusion. Furthermore, only methods that can be used in real-time and at the bedside were included. Recent findings We identified studies on physical examination techniques, electrocardiography, echocardiography, contrast-enhanced ultrasound, near-infrared spectroscopy, and Doppler sonography to assess single organ perfusion. Summary Physical examination techniques have a reasonable negative predictive value to exclude single organ hypoperfusion but are nonspecific to detect it. Technical methods to indirectly measure myocardial perfusion include ECG and echocardiography. Contrast-enhanced ultrasound can quantify myocardial perfusion but has so far only been used to detect regional myocardial hypoperfusion. Near-infrared spectroscopy and transcranial Doppler sonography can be used to assess cerebral perfusion and determine autoregulation thresholds of the brain. Both Doppler and contrast-enhanced ultrasound techniques are novel methods to evaluate renal and visceral organ perfusion. A key limitation of most techniques is the inability to determine adequacy of organ blood flow to meet the organs’ metabolic demands.
Review question / Objective: The objective of this review is to identify the current scientific evidence on the value of clinical signs to indicate systemic tissue hypoperfusion or shock. Condition being studied: In the literature and clinical studies, shock has traditionally been defined by a drop in arterial blood pressure under a critical threshold, e.g., a systolic blood pressure of 90 mmHg, a mean arterial blood pressure <65 mmHg or a relative drop in systolic blood pressure of ≥40 mmHg. From a pathophysiologic point of view, shock relates to an imbalance between tissue oxygen delivery as well as cellular oxygen consumption and utilization. In most cases, shock results from systemic tissue hypoperfusion with consequent decreased tissue oxygen delivery (commonly referred to as circulatory shock). Impaired cellular oxygen consumption and utilization appear to play contributory roles in specific disease states (e.g., sepsis) or conditions (e.g., intoxications).
Background: Bleeding events are frequent complications during extracorporeal membrane oxygenation therapy (ECMO). Objective: To determine the rate of acquired factor XIII deficiency and its association with major bleeding events and transfusion requirements in adults undergoing ECMO therapy. Materials and Methods: A retrospective single centre cohort study. Adult patients receiving veno-venous or veno-arterial ECMO therapy during a 2-year period were analysed and screened for factor XIII activity measurements. Factor XIII deficiency was defined based on the lowest factor XIII activity measured during ECMO therapy. Results: Among 84 subjects included into the analysis, factor XIII deficiency occurred in 69% during ECMO therapy. There were more major bleeding events (OR, 3.37; 95% CI, 1.16–10.56; p = 0.02) and higher transfusion requirements (red blood cells, 20 vs. 12, p < 0.001; platelets, 4 vs. 2, p = 0.006) in patients with factor XIII deficiency compared to patients with normal factor XIII activity. In a multivariate regression model, factor XIII deficiency was independently associated with bleeding severity (p = 0.03). Conclusions: In this retrospective single centre study, acquired factor XIII deficiency was observed in 69% of adult ECMO patients with a high bleeding risk. Factor XIII deficiency was associated with higher rates of major bleeding events and transfusion requirements.
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