Anaesthesia and Intensive Care Medicine最新文献

Presented is an approach to a chest radiograph, paying particular attention to features commonly seen in the intensive care unit (ICU) with regards to iatrogenic lines and tubes, together with common pathologies that may be encountered. This is accompanied by helpful images to use as an aide memoire when reviewing ICU chest X-rays. Pitfalls in interpreting these often complex X-rays are also discussed.

The neuromuscular junction is a complex structure consisting of the muscle cell, the nerve terminal of a motor neuron and the synaptic cleft. It is the site of action for neuromuscular blocking drugs, which are a cornerstone of anaesthetic practice. These drugs can be divided into depolarizing and non-depolarizing drugs; the latter can be further subdivided into benzylisoquinolinium and aminosteroid compounds. Reversal agents are also discussed. The pharmacology of neuromuscular blocking drugs and reversal agents is discussed including mechanism of action, metabolism, factors influencing choice of drug as well as adverse effect profile.

A comprehensive preoperative assessment is imperative for patients undergoing lung surgery, ideally by way of a multidisciplinary team approach. This not only allows for clinicians to risk stratify patients and gain informed consent, but also to explore avenues in optimizing patients prior to surgery and plan for the delivery of the most appropriate postoperative care. A tripartite risk assessment combining risks of operative mortality, perioperative adverse cardiac events and postoperative dyspnoea should be assessed and discussed with patients. Those patients who continue towards surgical management may then be optimized with patient education addressing nutritional status, smoking cessation and alcohol dependency as well as the management of anaemia and physiological prehabilitation. This article aims to review existing guidelines for preoperative assessment in thoracic surgery as well as the latest preoperative guidance for enhanced recovery specific to thoracic surgery.

Applied respiratory physiology is crucial for perioperative patient management. This article reviews respiratory mechanics, gas exchange, and ventilation regulation, focusing on their practical applications from preoperative assessment to postoperative recovery. Cardiopulmonary exercise testing (CPET) is emphasized for predicting perioperative risk, with metabolic equivalents (METs) highlighted as indicators of cardiovascular fitness. The significance of oxygen delivery (DO₂) components and types of hypoxia are detailed. Anaesthesia's effects on respiratory physiology, including the suppression of ventilatory response and impact on upper airway muscles, are analysed. Postoperative strategies to prevent atelectasis, such as positive end-expiratory pressure (PEEP) and recruitment manoeuvres, are discussed.

Assessment of emergency surgical patients aims to stratify risks of intended operation based on patient's condition and planned surgery, direct preoperative optimization and construct an anaesthetic plan accordingly. Compared to elective patients, emergency patients are susceptible to greater challenges including high aspiration risks, dehydration, electrolyte disturbances and impaired consciousness. Although only limited time is allowed, early recognition of these conditions allow appropriate intervention to minimize perioperative complications. In trauma patients, relevant history of injury regarding the type, mechanism and sites of injury is especially essential. They may present with difficult airway, ongoing bleeding and haemodynamic instability. This further complicates perioperative management where anaesthetic assessment is crucial to guide anaesthetic plans.

The physiology of fluid balance in humans should be understood and applied in clinical practice. Fluid balance, when managed accurately and safely, can prevent significant morbidity and mortality. Anaesthesia and critical care patients are often fasted and under physiological stress. Therefore, homeostatic regulation of fluid balance is impaired. A disturbance in normal fluid balance induces a physiological ‘stress’ response via metabolic, neuroendocrine and immune-mediated systems. Critically unwell patients may suffer morbidity secondary to high-volume fluid losses or oedema. There are three fluid compartments discussed in relation to human fluid balance. The intracellular space is surrounded by extracellular fluid, separated by a water permeable cell membrane. Extracellular fluid (ECF) compartment volume and electrolyte concentration, majorly sodium, must be tightly regulated to avoid osmosis and cell damage. The renal system maintains ECF volume by regulating sodium and osmotic concentration by retaining or excreting water.

Pulmonary aspiration is an important complication of airway management that can result in serious morbidity and mortality. Inhalation of foreign substances can cause airway obstruction, chemical injury or secondary infections. Proper assessment of aspiration risk identifies patients at risk, allowing proper precautions to be performed. Point-of-care ultrasound can help with risk stratification. Premedication and rapid sequence induction should be considered in high-risk patients. Caution should be extended to the postoperative period.

Inappropriate fluid therapy can lead to significant morbidity and mortality. The maintenance of normal cellular and organ function relies on body fluid homeostasis. The concept of total body water compartmentalization, and the essential principles behind fluid physiology such as osmolarity and osmolality, osmosis and tonicity will be discussed. Factors that can influence body fluid distribution across different compartments and capillary fluid dynamics, such as the Starling forces and the role of endothelial glycocalyx layer will be discussed. Sodium, which plays a major role in plasma osmolality and compartment volume, requires tight regulation through various neuroendocrine mechanisms including the renin–angiotensin–aldosterone system (RAAS) and vasopressin. In addition to the regulation of the extracellular environment, cells have a number of specialized transmembrane transporters such as the sodium–potassium pump and the aquaporin channels to modulate water movement in response to osmotic stress.

Emergence and extubation are critical transitional phases in the perioperative period. Evidence has shown that complications occur more at extubation than intubation and induction. A comprehensive understanding of the various factors influencing emergence and extubation, potential complications, essential steps and different techniques employed can maximize patient outcomes and satisfaction. Vigilant monitoring and assessment of the patient's readiness for extubation are required at emergence. Reasons for delay and delirium in emergence must be screened and investigated so that corresponding treatment can be pursued. Haemodynamic stability, continued oxygen delivery, adequate analgesia and anti-emesis are the general objectives. Extubation is an elective procedure with the potential for unanticipated challenges and mortalities. Should extubation be determined appropriate, individualized planning and methodical preparation must precede the performance of extubation to avoid complications and failures. Risk stratification, airway assessment and optimization of physiological parameters are some of the necessary processes. Different extubation techniques are selected and performed to address specific physiological consequences and airway concerns. Guidelines and systematic approaches regarding emergence and extubation should be followed.