Best practice & research. Clinical anaesthesiology
-
Over the last decade, there has been an increased interest in the use of goal-directed therapy (GDT) in patients undergoing high-risk surgery, and various haemodynamic monitoring tools have been developed to guide perioperative care. Both the complexity of the patient and surgical procedure need to be considered when deciding whether GDT will be beneficial. ⋯ Although global haemodynamic parameters may be optimised with the use of GDT, microvascular impairment can still persist. This review will provide an overview of both haemodynamic optimisation and microvascular assessment in the perioperative period.
-
In case of haemorrhage, a combination of low volume fluid resuscitation and permissive hypotension is used to avoid the adverse effects of early aggressive fluid resuscitation. During this phase, occult microvascular hypoperfusion can possibly develop over time. After controlling the bleeding, it is expected that optimization of macrocirculation will result in an improvement in microcirculation. ⋯ However, haemorrhagic shock, reperfusion, traumatic injury and inflammation can damage microcirculation and thus lead to a loss of haemodynamic coherence. In these cases, a systemic haemodynamic-driven resuscitation would not be effective in restoring microcirculation and tissue oxygenation. A real-time technique enabling microcirculation monitoring can create an opportunity for microcirculatory haemodynamic-driven resuscitation to become the gold standard in the future.
-
Best Pract Res Clin Anaesthesiol · Dec 2016
ReviewHaemodynamic coherence - The relevance of fluid therapy.
The ultimate goal of fluid therapy is to improve the oxygenation of cells by improving the cardiac output, thus improving microcirculation by optimizing macrocirculation. This haemodynamic coherence is often altered in patients with haemorrhagic shock and sepsis. The loss of haemodynamic coherence is associated with adverse outcomes. ⋯ Monitoring microcirculation and haemodynamic coherence may be an additional tool to predict the response to fluid administration. In addition, microcirculatory analysis may support the clinician in his decision to not administer fluids when microcirculatory blood flow is preserved. In future, the indication, guidance and termination of fluid therapy may be assessed by bedside microvascular analysis in combination with standard haemodynamic monitoring.
-
Microvascular alterations are a hallmark of sepsis and play a crucial role in its pathophysiology. Such alterations are the result of overwhelming inflammation, which negatively affects all the components of the microcirculation. ⋯ Other therapeutic interventions are still being investigated. In this review, we discuss the pathophysiology of septic microcirculatory dysfunction and its implications for possible treatments.
-
Best Pract Res Clin Anaesthesiol · Dec 2016
ReviewRed blood cell transfusion and its effect on microvascular dysfunction in shock states.
Among critically ill patients, red blood cell (RBC) transfusion is often prescribed for anemia in the absence of active or recent bleeding. The failure of RBC transfusion to improve physiological parameters and clinical outcomes in this setting may be explained by current understanding of the relationship between the RBCs and the microcirculation. It is now evident that the circulating RBCs contribute to microcirculatory hypoxic vasodilation by regulated nitric oxide (NO)-dependent vasodilation, thereby facilitating delivery of oxygen to oxygen-deprived tissue. ⋯ In recent years, there has been a significant focus on the dysfunctional interaction between stored RBCs and the microcirculation, with emphasis on understanding the mechanisms that drive erythrocyte NO-mediated vasodilation. The development of technology that allows noninvasive observation of the microcirculation in humans has allowed for direct observation of the microcirculation immediately before and after RBC transfusion. The current understanding of RBC NO-mediated vasodilation and the results of direct observation of the microcirculation in the setting of RBC transfusion are reviewed.