Anaesthesia and Intensive Care Medicine最新文献

Nausea and vomiting are both very unpleasant experiences. The physiology is poorly understood; however, understanding what we do know is key to tailoring a preventative or therapeutic anti-emetic regime. There are two key sites in the central nervous system implicated in the organization of the vomiting reflex: the vomiting centre and the chemoreceptor trigger zone. There are five key neurotransmitters involved in afferent feedback to these areas. These are histamine (H₁ receptors), dopamine (D₂), serotonin (5-HT₃), acetyl-choline (muscarinic) and neurokinin (substance P). Postoperative nausea and vomiting will occur in around one-third of elective patients who have no prophylaxis. This can result in many detrimental effects including patient dissatisfaction, unplanned admission and prolonged recovery. It is therefore essential that clinicians understand how they can prevent and treat nausea and vomiting using either a single agent or a combination of anti-emetics to target relevant receptors. Commonly used drugs include antihistamines, dopamine antagonists, serotonin antagonists and steroids. More novel agents are being developed such as aprepitant, a neurokinin receptor antagonist, palonosetron, a 5HT₃ receptor antagonist, and nabilone, a synthetic cannabinoid.

The delivery of anaesthesia to children and young people provides unique challenges. A careful, systematic approach to assessment and preparation can deliver a positive experience for the child, carers and staff while mitigating potential complications. Preparation for anaesthesia should encompass information-gathering, assessment and planning for anatomical, physiological, social and behavioural elements specific to the child and the surgery. Delivery of appropriate information, consent and fasting are also key elements of ensuring positive perioperative outcomes. We consider the common components of preparation for the delivery of safe paediatric anaesthesia.

Airway management is undertaken to deliver oxygen, remove carbon dioxide and protect against pulmonary aspiration. This article describes the equipment utilized by airway providers in order to achieve these aims, aided by their relevant knowledge, skills and experience. The use of this equipment forms the basis of core airway management techniques, including facemask ventilation, use of supraglottic airway devices, laryngoscopy, awake tracheal intubation and front-of-neck access.

General anaesthesia is a state of controlled unconsciousness utilized to perform a therapeutic procedure. The aims of anaesthesia have traditionally been summarized by the triad of hypnosis, analgesia and muscle relaxation. The process begins with preoperative assessment of the patient before ensuring equipment and drugs are available and safe to use. Anaesthesia commences with administration of induction agents, delivered via inhalational or intravenous routes. Consideration of airway management is an essential component of the induction phase of anaesthesia. The choice and dose of induction agent is multifactorial and can include: co-morbidity; type of surgery, age and patient physiology. Following induction of anaesthesia, the maintenance phase of anaesthesia can be delivered via an inhalation or intravenous route. The administration of anaesthetic drugs is generally associated with rapid loss of airway reflexes and cardiorespiratory changes. Complications of general anaesthesia can include awareness, aspiration, anaphylaxis, airway loss, laryngospasm, cardiovascular instability, malignant hyperpyrexia and dental damage. Meticulous attention to detail is vital to minimize the risk of these potential complications.

Humidification is concerned with the addition of water vapour to a gas and can be measured as either absolute or relative. Adequate humidification is a vital consideration in anaesthesia given that the anatomical source of natural gas humidification (the nasopharynx) is generally bypassed, which can lead to complications including hypothermia, thickening of respiratory secretions, mucus plugging and airway keratinization. Humidification may be passive or active. Equipment involved in passive humidification includes heat and moisture exchanger (HME) filters, soda lime and cold water baths, with these devices able to achieve varying efficiencies without extrinsic energy input. Active humidification devices (including hot water baths) are capable of delivering a higher relative humidity but are associated with higher cost and potential hazards. While not strictly classed as true humidification devices, nebulizers are considered in this article as they add water droplets into a gas flow using a Venturi system, spinning discs or ultrasound vibration technology.

A diagnosis of congenital heart disease increases perioperative risk for children having surgical procedures. Some will require anaesthesia at a specialist cardiac centre, while for others it is safe and appropriate to have their procedure in a local district general hospital. Children with complex congenital heart disease and poor physiological status carry the highest risk of cardiac arrest and mortality. Clinical features of cardiomyopathy, cyanosis, pulmonary hypertension, arrhythmia and cardiac failure are most likely to require specialist input and tertiary referral, whereas those with a preoperative stay of less than 10 days undergoing elective, minor surgery, who are older than 2 years of age and physiologically well may be safely anaesthetized in a district general hospital. In order to maximize safety, the anaesthetist must carry out a thorough preoperative assessment, have an understanding of the patient’s individual physiology and be prepared for the potential effects of general anaesthesia. Systemic vascular resistance is reduced by most induction agents and volatile anaesthetics; pulmonary vascular resistance is affected by changes in ventilation and gas exchange. The anaesthetist should also be alert to particular potential complications, such as arrhythmias, hypoxia, bleeding and cardiac arrest.

Safeguarding is an action that promotes the welfare of children and adults and aims to protect them from harm and maltreatment. This article will focus on children and the role of the anaesthetist. As an anaesthetist, you may not see signs of abuse often, but you will see children in different settings and should be able to clearly communicate any worrying concerns. Reading this article will increase your knowledge of laws and statutory advice for safeguarding.

Growth and maturation characterize the transition of neonates to adults. The physiological changes that children undergo present numerous pharmacological conundrums for the anaesthetist. Extensive changes in drug absorption, protein binding, metabolism and excretion during development result in wide variability in drug disposition. Pharmacodynamic differences and genetic polymorphisms further exacerbate these pharmacokinetic disparities. These changes directly affect drug efficacy and toxicity, and an awareness of this is crucial for clinicians involved in paediatric anaesthesia. Population-based pharmacokinetic–pharmacodynamic modelling provides a novel prospect in paediatric pharmacology research. Modelling has the potential to improve safety in clinical trials and enhance our understanding of drug disposition in vulnerable populations like preterm neonates. Although progress is occurring in developmental pharmacology, gaps remain, and a lot yet remains to be elucidated.

Children with acute and chronic associated medical conditions often present for surgical and radiological procedures. An understanding of the implications of these conditions for anaesthesia is important for preventing perioperative adverse events. In this article, we outline the relevant clinical features of some of the commonly encountered associated medical conditions and provide guidance on the current evidence for the perioperative anaesthetic management of these children.

Advances in paediatric anaesthetic equipment and monitoring continue to be made. While the mainstay of airway intubating equipment currently is the direct laryngoscope, videolaryngoscopes and endoscopes are increasing in their use. These continue to evolve, generating better quality pictures, with more sophisticated yet easier to use equipment. Vascular access in paediatric anaesthesia can be challenging. Ultrasound has become an integral piece of equipment in the management of these children with difficult access. As the population increases in weight, so the management of the obese child is now a reality. This requires thought and careful planning of their perioperative care. Newer techniques such as high flow nasal oxygen are useful both to prevent hypoxia at induction, but also to facilitate surgery. Total intravenous anaesthesia will be discussed with reference to paediatric algorithms and equipment. Neurological monitoring in the form of near-infrared spectroscopy and depth of anaesthesia monitoring are discussed with evidence relevant to paediatric practice.