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This chapter discusses the different types of scoring systems that include specific, generic, anatomical and functional scoring systems. The measurement of outcome is important as considerable resources are expended in providing intensive care. Outcome in intensive care can be measured with respect to mortality, morbidity, disability and quality of life. There are many influences on outcome which can be broadly grouped into patient factors, disease factors and intensive care factors. The process by which a scoring system becomes an outcome probability model is through multiple logistic regression. The scoring systems in common use in critical care include the Acute Physiology and Chronic Health Evaluation (APACHE), Simplified Acute Physiology Score (SAPS), Mortality Probability Model (MPM), Sequential Organ Failure Assessment (SOFA), Trauma and Injury Severity Score (TRISS), and the ASCOT. These scores can also be used on trauma patients in all settings.
The inflammatory response is a central component of sepsis as it drives the physiological alterations that are recognized as systemic inflammatory response syndrome (SIRS). In contrast to the hypothesis of exuberant inflammatory response in sepsis is the finding that septic patients may have a relative anti-inflammatory environment. Cellular death may be a key factor in sepsis and its related mortality. Cells that are destined to die can do so by two mechanisms: apoptosis and necrosis. In sepsis, cytokine-induced coagulopathy triggers increased activity of tissue factor (TF) and plasminogen activator inhibitor-1 (PAI-1) and decreased levels of the natural anticoagulant protein C on mononuclear and endothelial cells. Critical illness related corticosteroid insufficiency (CIRCI) occurs as a result of either a decrease in adrenal steroid production. In patients with severe sepsis, a strategy of glycaemic control using intravenous insulin should include a nutritional protocol with preferential use of the enteral route.
This chapter discusses the cell-based model of coagulation, regulation of coagulation, and bleeding disorders. The disorders include congenital disorders and acquired disorders such as thrombocytopenia, disseminated intravascular coagulation (DIC) and microangiopathic haemolytic anaemia. Thrombocytopenia may occur because of impaired production, sequestration, increased consumption, and enhanced degradation. Activated protein C has been shown to reduce mortality in sepsis especially in patients with DIC and multi-organ failure. During the resuscitation of patients who have suffered a major haemorrhage, factors that can contribute to associated coagulopathy are: hypothermia, metabolic acidosis, and consumption of clotting products. Heparin-induced thrombocytopenia (HIT) usually occurs 5-10 days following exposure to heparin. It is a pro-thrombotic disorder and can lead to significant venous and arterial thrombosis. HIT usually resolves following the discontinuation of heparin over a few days. Management includes the prompt removal of all heparin containing medication and the substitution of a direct thrombin inhibitor to control clotting.
Cardiac arrhythmias can be broadly classified based on the heart rate as bradyarrhythmia (<60 bpm) and tachyarrhythmia (>100 bpm). Physiological bradycardia can often be found in athletes whilst pathological bradycardia signifies sinus node or conduction pathway abnormalities, which may or may not be associated with drugs, autonomic or endocrine dysfunction. Acute management of arrhythmias depends on the haemodynamic status of the patient and the type of arrhythmia. Patients who exhibit adverse features will require urgent treatment to resolve the arrhythmia. Narrow complex and broad complex tachyarrhythmias without adverse signs are managed differently in the acute setting. Most sinus tachycardias are related to underlying causes and will resolve once the cause is rectified. Broad complex tachycardias are due to a number of underlying rhythms. In the long term, implantable cardiovertordefibrillator (ICD) insertion is beneficial for patients who have structurally abnormal hearts with ventricular arrhythmias.
The initial assessment of the critically ill patient should begin with a brief, targeted history and an appraisal of the patient's vital signs to identify life threatening abnormalities that merit immediate attention. The goals of resuscitation are usually achieved by the use of supplemental oxygen, fluid or red blood cell transfusion, inotropic support or antibiotics as needed. Physiological Scoring Systems (PSS) developed from the recognition that critically ill patients, and in particular patients who suffered cardiac arrests, often had long periods of deterioration before the crisis or medical emergency occurred. Medical emergency teams (METs) and critical care outreach (CCO) teams aim to provide critical care skills rapidly to critically ill patients. Referrals to the critical care services may happen from any level, but the final decision to admit a patient to a critical care bed should be made by an experienced critical care physician.
Antibiotics should only be administered after microbiological specimens are taken, except in emergencies. Most antibiotics are removed from the body via the kidneys. Renal failure may cause the accumulation of a drug, or its metabolites. This is a particular problem with glycopeptides and aminoglycosides where toxic levels are associated with severe and permanent side effects such as ototoxicity and renal impairment. Organisms resistant to multiple antibiotics such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) have emerged in healthcare environments and have proved difficult to control in many countries. Prophylaxis is recommended where a bacteraemia is expected, and the resultant infection may result in significant morbidity or mortality. The commonly used antibiotics on intensive care unit are: beta-lactams, carbapenems, aminoglycosides, glycopeptides, quinolones, macrolides, rifampicin, oxazolidinone and nitroimidazoles. The three major classes of anti-fungal drug are: azoles, polyenes, and echinocandins.
The critical care unit manages patients with a vast range of disease and injuries affecting every organ system. The unit can initially be a daunting environment, with complex monitoring equipment producing large volumes of clinical data. Core Topics in Critical Care Medicine is a practical, comprehensive, introductory-level text for any clinician in their first few months in the critical care unit. It guides clinicians in both the initial assessment and the clinical management of all CCU patients, demystifying the critical care unit and providing key knowledge in a concise and accessible manner. The full spectrum of disorders likely to be encountered in critical care are discussed, with additional chapters on transfer and admission, imaging in the CCU, structure and organisation of the unit, and ethical and legal issues. Written by Critical Care experts, Core Topics in Critical Care Medicine provides comprehensive, concise and easily accessible information for all trainees.
The passing of a postgraduate examination in intensive care medicine (ICM) identifies the successful individual to all as someone who has been trained to a high standard in ICM. The knowledge required to thrive in clinical practice as well as examinations in ICM is broad based involving most hospital speciality areas. This chapter focuses on two examinations, namely, the Intercollegiate Diploma in Intensive Care Medicine (DICM), and European Diploma in Intensive Care Medicine (EDIC). Success in professional examinations requires a substantial investment of time. Candidates preparing for examinations must avail themselves of all the educational opportunities at local, regional and national levels in ICM. In the UK, there are many specialist society ICM meetings such as the Intensive Care Society. The internet offers a wealth of useful websites relating to ICM and all can be used to prepare for diploma examinations. Preparation for diploma examinations extends ICM knowledge.
This chapter outlines the indications for admissions to the critical care unit (CrCU), and role of scoring systems to aid admission. The admission criteria should be based on need of the patient rather than bed availability. A number of steps could be taken if a critically ill patient presents in the absence of an available bed in the unit. The choice is often determined by the severity of illness, haemodynamic stability, ease of oxygenation, necessity of advanced interventions, time of the day and availability of medical staff. Patients who are deemed to have irreversible or severe organ system damage which is likely to prevent reasonable recovery should have treatment limits in place. All admitted patients should be handed over to one of the critical care doctors. A timely discharge from the CrCU is just as important as timely admission.
Deliberate self-poisoning is usually an intentional oral ingestion of a variety of drugs by previously well adults and makes up 95% of cases. This chapter explains airway and breathing, and circulation in the initial assessment and resuscitation phase. In the clinical examination the patient's symptoms and signs elicited on physical examination provide clues to the most likely drugs involved and guide early therapy especially when the cause is unidentified. The chapter lists out various investigations that include electrocardiogram, arterial blood gases, radiology and drug screening. The importance of maintaining physiological stability whilst minimizing the toxic effects of drug ingestion is paramount. The toxicity can be diminished by preventing drug absorption, inhibition of toxic metabolite formation, and augmentation of drug elimination. The general care of the unconscious patient includes regular monitoring of vital signs and organ support. The chapter lists out management of specific drugs that include salicylates (aspirin).
This chapter focuses on invasive blood pressure monitoring, and components of the invasive blood pressure monitoring system. It explains the complications of invasive blood pressure monitoring, central venous pressure monitoring and cardiac output monitoring. Central venous pressure monitoring measures pressure in the great veins of the thorax usually the superior vena cava and the right atrium. It involves introducing a catheter into a vein so that the tip of the catheter lies at the junction of the superior vena cava and the right atrium. Haemodynamic monitoring is most informative when it is used to supplement clinical judgement. Clinical parameters may be used to determine cardiac output. Poor cerebral perfusion leads to agitation and confusion. A reduction in renal perfusion leads to decreased urine output and subsequently to anuria. Skin perfusion is a clinically useful sign and can be determined using the capillary refill time.
The three parts of the respiratory control system are: sensors, central control and respiratory muscles. The different disorders of ventilation include hypoventilation syndromes and hyperventilation syndromes. The three main types of hypoventilation syndromes are: obesity hypoventilation syndrome, respiratory neuromuscular disorders and primary alveolar hypoventilation. Alveolar hyperventilation exists when PaCO2 decreases below 4.5 kPa. It is not the same as hyperpnoea which is increased minute ventilation with a normal PaCO2. Detailed history and clinical examination along with knowledge of coexistent disorders can provide clues to the cause of hyperventilation. An elevated pH is suggestive of a primary respiratory alkalosis; a low pH will show a metabolic acidosis. Widened A-a gradient suggests presence of a primary pulmonary disorder. Low bicarbonate suggests a chronic nature of the disorder and implies an organic cause. Transcutaneous PCO2 or arterial PCO2 during sleep studies can help to exclude psychogenic hyperventilation.