Anaesthesia and Intensive Care Medicine最新文献

The concept of brain and brainstem death developed from the observation of apnoeic comatose patients. In the UK, the diagnosis of brainstem death is made by clinically testing brainstem function once specific pre-conditions have been met. The exact definition of brain death and some details regarding the tests required to make this diagnosis vary across the globe. However, the majority of tests carried out are similar to those in the UK. In this review we define brainstem death and the clinical tests used to confirm it. The use of ancillary testing can have a role in patients where clinical tests are not possible and this is also discussed.

This article provides a brief historical overview, description of types of donation, determination of death by circulatory and neurological criteria, dead donor rule, conduct of donation and retrieval and the ethical challenges that arise in this sphere.

Solid organ transplantation has progressed dramatically over the last 50 years; however, rejection still remains one of the barriers to successful transplantation. Immunological processes underlying the mechanisms of rejection are well described and numerous pharmacological agents exist to help suppress a recipient's immune system in order to prolong graft survival. Furthermore, clinician decisions and actions during both the work-up of a potential transplant recipient and in the perioperative phase can impact upon the immunological status of an individual and the likelihood of successful solid organ transplantation. In this article we aim to describe the key processes involved in solid organ immunology and their relevance in anaesthetic practice.

Injury or foreign invasion will instigate a cascade of events directed at eliminating the intruder and augmenting the healing process. This involves the unification of two separate processes (inflammatory and immune processes) to provide an effective host defence. Chemical mediators converge on the site of tissue damage and exert local and distant effects. The immune response is divided into innate and acquired immunity. The immediate, non-specific innate response, combined with the specifically targeted acquired response, provide our major defence mechanisms. Lymphocytes and immunoglobulins are the hallmark of acquired immunity. Regulation of these interlinked systems provide cohesion and a group of soluble proteins called cytokines have a major role. Protective immune mechanisms can sometimes cause detrimental effects to the host. We discuss and classify allergic reactions, in particular, the most severe and potentially life-threatening form – anaphylaxis.

Organ donation provides a treatment for patients with severe organ dysfunction that is both life-saving, and life-enhancing. Most organs in the UK are transplanted after deceased donation; clinical staff working in the intensive care unit must be familiar with the principles of deceased organ donation and be able to support both the donor and their family through this process. The pathophysiological response to neurological injury after Death by Neurological Criteria requires optimization to preserve organ function and allow donation of healthy organs to proceed. Recent advances in in-vivo and ex-vivo perfusion techniques have revolutionized some aspects of organ retrieval practice. Donation after Circulatory Death now accounts for one-third of cardiac transplants, which were recently exclusively obtained from Donation after Brainstem Death. Accordingly, an up-to-date knowledge base of this rapidly evolving field is vital. This article will focus on deceased organ donation, specifically the processes of Donation after Brainstem Death and Donation after Circulatory Death, and the physiological support of the potential organ donor in the intensive care unit.

Solid organ transplant is increasing globally. According to Kidney Research UK, around 5000 people in the UK are on the waiting list for a kidney and this is only increasing. Improved immunosuppression therapy and general management of transplanted patients mean their survival has improved. It will get more common for these patients to require input from a non-transplant centres. There are nuances of transplant patients which non-transplant anaesthetists and intensivists may not be aware of. A good understanding of some of these complexities are crucial to optimizing perioperative care and outcome.

Cross-matching of blood components to the patient's blood is mandatory to ensure the safe transfusion of suitable blood components in a timely manner and avoid serious harm to the recipient. This article will outline the validated methods of cross-matching in the laboratory setting. We will also discuss transfusion reactions and consequences of transfusion of inappropriate or mismatched blood components, alongside the principles of patient blood management and preoperative anaemia.

Disorders of fluid balance and electrolyte homeostasis are commonly observed in critically ill patients and in those who require emergency anaesthesia. Consequently, anaesthetists and intensive care physicians must understand the physiological principles that govern fluid balance. This article discusses the compartmentalization of total body water and describes methods by which the volume of the fluid compartments may be measured. The novel concept of the endothelial glycocalyx is discussed in addition to the conventional and contemporary models of capillary filtration dynamics. The core elements of fluid balance and cardiovascular homeostasis are also explored.

The immune system is vital to the body's defence against bacterial, viral and fungal pathogens. An initial defence is provided by the innate immune system. The body's physical barriers are the first line of defence. If these barriers are breached a complex series of chemical, molecular and cellular interactions come into play to protect the body from further assault and tissue damage. Further mechanisms provide future protection through the development of acquired immunity.

Disruption of these intricate pathways results in a significant risk to the individual and is a common therapeutic challenge for clinicians. The immune system is a constant interplay of pathways that without balance can also lead to clinical compromise and morbidity, for example, through the extremes of overstimulation and development of an anaphylactic reaction or the failure to respond in an immunocompromised patient.

Recognition and appropriate management of over- and under-activity of the immune system are essential in reducing the risk of harm to patients.