SciCombinator

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Concept: Hypovolemia

169

Various hydroxyethyl starch (HES) preparations have been used for decades to augment blood volume. There has been concern recently regarding possible adverse outcomes when using HES in the intensive care setting, especially in patients with septic shock. However, the pharmacokinetic and pharmacodynamic properties of HES preparations depend on their chemical composition and source material. Thus, different clinical conditions could result in differing effectiveness and safety for these preparations. Consequently, we assessed the safety of tetrastarches when used during surgery, using a formal search, that yielded 59 primary full publications of studies that met a priori inclusion criteria and randomly allocated 4529 patients with 2139 patients treated with tetrastarch compared with 2390 patients treated with a comparator. There were no indications that the use of tetrastarches during surgery induces adverse renal effects as assessed by change or absolute concentrations of serum creatinine or need for renal replacement therapy (39 trials, 3389 patients), increased blood loss (38 trials, 3280 patients), allogeneic erythrocyte transfusion (20 trials, 2151 patients; odds ratio for HES transfusion 0.73 [95% confidence interval = 0.61-0.87], P = 0.0005), or increased mortality (odds ratio for HES mortality = 0.51 [0.24-1.05], P = 0.079).

Concepts: Blood, Intensive care medicine, Renal physiology, Starch, Septic shock, Hypovolemia, Blood transfusion, 3rd millennium

166

Background/Aims: This study investigates the use of blood volume monitoring (BVM) markers for the assessment of fluid status. Methods: Predialysis fluid overload (FO) and BVM data were collected in 55 chronic hemodialysis patients in 317 treatments. Predialysis FO was measured using bioimpedance spectroscopy. The slope of the intravascular volume decrease over time normalized by ultrafiltration rate (Slope4h) was used as the primary BVM marker and compared against FO. Results: Average relative blood volume curves were well separated in different FO groups between 0 and 5 liters. Receiver-operating characteristics analysis revealed that the sensitivity of BVM was moderate in median FO ranges between 1 and 3 liters (AUC 0.60-0.65), slightly higher for volume depletion of FO <1 liter (AUC 0.7) and highest for excess fluid of FO >3 liters (AUC 0.85). Conclusion : Devices that monitor blood volume are well suited to detect high FO, but are not as sensitive at moderate or low levels of fluid status.

Concepts: Dialysis, Blood, Hemodialysis, Litre, Cubic metre, Hypovolemia, Aquapheresis, Hypervolemia

160

The Nuss procedure, which is a minimally invasive approach for treating pectus excavatum, has better functional and cosmetic outcomes than other invasive procedures. Cardiac perforation is the most serious complication and several methods for the prevention of intraoperative events has been developed. Although most cardiac injuries are detected in the operating room, in the case described herein the patient experienced sudden hypovolemic shock during the postoperative recovery period. This indicates that special caution is mandatory even after successful execution of the Nuss procedure.

Concepts: Blood, Surgery, Pectus excavatum, Chest, Sternum, Shock, Minimally invasive, Hypovolemia

34

Echocardiography is pivotal in the diagnosis and management of the shocked patient. Important characteristics in the setting of shock are that it is non-invasive and can be rapidly applied.In the acute situation a basic study often yields immediate results allowing for the initiation of therapy, while a follow-up advanced study brings the advantage of further refining the diagnosis and providing an in-depth hemodynamic assessment. Competency in basic critical care echocardiography is now regarded as a mandatory part of critical care training with clear guidelines available. The majority of pathologies found in shocked patients are readily identified using basic level 2D and M-mode echocardiography. A more comprehensive diagnosis can be achieved with advanced levels of competency, for which practice guidelines are also now available. Hemodynamic evaluation and ongoing monitoring are possible with advanced levels of competency, which includes the use of colour Doppler, spectral Doppler, and tissue Doppler imaging and occasionally the use of more recent technological advances such as 3D or speckled tracking.The four core types of shock-cardiogenic, hypovolemic, obstructive, and vasoplegic-can readily be identified by echocardiography. Even within each of the main headings contained in the shock classification, a variety of pathologies may be the cause and echocardiography will differentiate which of these is responsible. Increasingly, as a result of more complex and elderly patients, the shock may be multifactorial, such as a combination of cardiogenic and septic shock or hypovolemia and ventricular outflow obstruction.The diagnostic benefit of echocardiography in the shocked patient is obvious. The increasing prevalence of critical care physicians experienced in advanced techniques means echocardiography often supplants the need for more invasive hemodynamic assessment and monitoring in shock.

Concepts: Doppler echocardiography, Echocardiography, Medical ultrasound, Shock, Physician, Septic shock, Hypovolemia

29

Inadequate resuscitation of major haemorrhage is an important cause of avoidable death in severely injured patients. Early recognition of blood loss, control of bleeding and restoration of circulating volume are critical to the management of trauma shock, and transfusion of blood components is a key intervention. Vital signs may be inadequate to determine the need for transfusion, and resuscitation regimens targeting vital signs may be harmful in the context of uncontrolled bleeding. This article addresses current concepts in haemostatic resuscitation. Recent guidelines on the diagnosis and treatment of coagulopathy in major trauma, and the role of component and adjuvant therapies, are considered. Finally, the potential role of thromboelastography and rotational thromboelastometry are discussed.

Concepts: Blood, Hospital, Hemostasis, Bleeding, Hypovolemia, Physical trauma, Blood transfusion, Exsanguination

28

Several changes in the way patients with hemorrhagic shock are resuscitated have occurred over the past decades, including permissive hypotension, minimal crystalloid resuscitation, earlier blood transfusion, and higher plasma and platelet-to-red cell ratios. Hemostatic adjuncts, such as tranexamic acid and prothrombin complex, and the use of new methods of assessing coagulopathy are also being incorporated into resuscitation of the bleeding patient. These ideas have been incorporated by many trauma centers into institutional massive transfusion protocols, and adoption of these protocols has resulted in improvements in mortality and morbidity. This article discusses each of these new resuscitation strategies and the evidence supporting their use.

Concepts: Blood, Hospital, Medical emergencies, Shock, Bleeding, Hypovolemia, Physical trauma, Exsanguination

28

INTRODUCTION: The hemorrhagic shock (HS) model is commonly used to initiate a systemic post-traumatic inflammatory response. Numerous experimental protocols exist and it is unclear how differences in these models affect the immune response making it difficult to compare results between studies. The aim of this study was to compare the inflammatory response of different established protocols for volume-controlled shock in a murine model. METHODS: Male C57/BL6 mice 6-10weeks and weighing 20-25g were subjected to volume-controlled or pressure-controlled hemorrhagic shock. In the volume-controlled group 300μl, 500μl, or 700μl blood was collected over 15min and mean arterial pressure was continuously monitored during the period of shock. In the pressure-controlled hemorrhagic shock group, blood volume was depleted with a goal mean arterial pressure of 35mmHg for 90min. Following hemorrhage, mice from all groups were resuscitated with the extracted blood and an equal volume of lactated ringer solution. Six hours from the initiation of hemorrhagic shock, serum IL-6, KC, MCP-1 and MPO activity within the lung and liver tissue were assessed. RESULTS: In the volume-controlled group, the mice were able to compensate the initial blood loss within 30min. Approximately 800μl of blood volume was removed to achieve a MAP of 35mmHg (p<0.001). No difference in the pro-inflammatory cytokine (IL-6 and KC) profile was measured between the volume-controlled groups (300μl, 500μl, or 700μl). The pressure-controlled group demonstrated significantly higher cytokine levels (IL-6 and KC) than all volume-controlled groups. Pulmonary MPO activity increased with the severity of the HS (p<0.05). This relationship could not be observed in the liver. CONCLUSION: Volume-controlled hemorrhagic shock performed following current literature recommendations may be insufficient to produce a profound post-traumatic inflammatory response. A decrease in the MAP following blood withdrawal (300μl, 500μl or 700μl) was usually compensated within 30min. Pressure-controlled hemorrhagic shock is a more reliable for induction of a systemic inflammatory response.

Concepts: Immune system, Blood, Blood pressure, Artery, Bleeding, Vein, Lactated Ringer's solution, Hypovolemia

27

Shock index [SI = the ratio of heart rate (HR) to systolic arterial pressure (SAP)] is a metric used to diagnose patients at risk of impending hemorrhagic shock. We hypothesized that a metric called the compensatory reserve index (CRI), derived using computer modeling with continuous feature extraction from arterial waveforms, would provide an earlier indicator of cardiovascular instability than SI during progressive central hypovolemia.

Concepts: Blood, Heart, Blood pressure, Shock, Artery, Ratio, Bleeding, Hypovolemia

27

Acute decompensated heart failure (ADHF) with associated volume overload is the most common cause of hospitalization in heart failure patients. When accompanied by worsening renal function, it is described as a cardiorenal syndrome and is a therapeutic challenge. Initial treatment commonly encompasses intravenous diuretics however, suboptimal results and high rehospitalization rates have led experts to search for alternative therapeutic strategies. Recent technological advances in extracorporeal therapies have made ultrafiltration a feasible option for treatment of hypervolemia in ADHF. Recent large randomized trials have compared the efficacy and safety of ultrafiltration with diuretics. Additionally, the benefits of novel pharmacologic approaches, including combining hypertonic saline with diuretics, have recently been studied. The aim of this review is to discuss the developments in both pharmacologic and extracorporeal methods for treating hypervolemia in ADHF and acute cardiorenal syndrome.

Concepts: Medicine, Heart failure, Randomized controlled trial, Hemodialysis, Hypovolemia, Cardiovascular diseases, Acute decompensated heart failure, Aquapheresis

26

Recent findings showed advantages of a novel pyruvate-enriched oral rehydration solution (Pyr-ORS) in resuscitation of burns. This study focused on effects of Pyr-ORS on the visceral blood perfusion (VBP), gastrointestinal function, and survival rate, compared with the bicarbonate-based World Health Organization-guided oral rehydration solution (WHO-ORS), during intragastric rehydration of lethal hemorrhagic shock in rats.

Concepts: Blood, Shock, Perfusion, Hypovolemia, Oral rehydration therapy