Anaesthesia & Intensive Care Medicine

Therapeutic hypothermia and acute brain injury Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Jagdish Sokhi, Ugan Reddy Abstract Secondary brain injury has devastating effects on morbidity, mortality and good functional outcomes. Neuroprotection is multimodal, with decades of preclinical and small clinical studies showing the benefits of therapeutic hypothermia. The basic scientific principles have merit, yet large randomized controlled trials fail to show a clear benefit. This article will review the basic science the practical aspects of delivering targeted temperature management and evaluate the evidence behind its use for acute brain injuries. With a lack of high-quality evidence for hypothermia, recent consensus statements are shifting the paradigm away from hypothermia to the maintenance of normothermia and prevention of pyrexia.

Applied cerebral physiology Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Pranoy Das, Astri Luoma Abstract This article reviews cerebral metabolism and blood flow, and the pressure dynamics within the cranial cavity. The brain functions within the confines of the cranial cavity and it is important to understand the dynamics of the parenchyma, cerebrospinal fluid and blood in relation to intracranial pressure (ICP) and metabolic needs. It requires an uninterrupted supply of oxygen and glucose to maintain its basal energy requirements and these are increased during periods of enhanced activity. Cerebral blood flow (CBF) is therefore critical for normal cerebral function. Its control is dictated by local intrinsic metabolic needs as well as extraneous factors such as arterial blood pressure, arterial carbon dioxide and oxygen tension, temperature and neural factors; all of which can be measured to guide therapy.

Anaesthesia for interventional neuroradiology Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Sarah J. Muldoon, Ian Appleby Abstract The volume and range of procedures undertaken by interventional neuroradiologists continues to expand. They are now treating many conditions previously considered untreatable or only amenable to open surgical techniques. To facilitate the close cooperation required between radiologists and anaesthetists necessary for the successful outcome of these complex and lengthy procedures, it is important for the anaesthetist to have an appreciation of the pathophysiology, potential multisystem effects of the underlying disease, cerebral protection strategies and the potential pitfalls of each procedural technique. Maintaining vigilance during the post-procedural monitoring phase is essential for the early recognition of potential complications, such as bleeding or vessel occlusion, which may warrant further emergency radiological or neurosurgical interventions.

Principles of intraoperative neurophysiological monitoring and anaesthetic considerations Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Brett Sanders, Santiago Catania, Astri MV. Luoma Abstract Surgery to the nervous system poses risks to neural structures be that mechanical, haemodynamical, chemical or thermal. The role of intraoperative neurophysiological monitoring (IONM) is to facilitate the assessment of the functional integrity of neural structures and provide a real time alerting system when changes caused by surgically induced insults are detected, with the goal of reducing the risk of postoperative neurological deficits. Furthermore, it is also used as a guidance system to map eloquent areas within the cortex and to identify specific neuronal structures, particularly when landmarks cannot be easily recognized. In this article, we focus on the various neurophysiological modalities used in intraoperative monitoring, their basic principles, indications and the information that they provide. We also examine the anaesthetic considerations and the checklist for the multidisciplinary team should an intraoperative alert be issued.

The management of spontaneous primary intracerebral haemorrhage Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Christopher J. Taylor Abstract Intracerebral haemorrhage (ICH) accounts for around 10–20% of all strokes and results from a variety of disorders. ICH is more likely to result in death or major disability than ischaemic stroke or subarachnoid haemorrhage. Rapid imaging allows early diagnosis and characterization of the localization and severity of the haemorrhage. Patients with significant acute ICH should be managed in a critical care unit. Treatment entails general supportive care, control of blood pressure and intracranial pressure, prevention of haematoma expansion and, where indicated, neurosurgical intervention. In those patients whose bleed extends into the ventricular system or who have infratentorial bleeds are at increased risk of associated hydrocephalus, rapidly increasing intracranial pressure requiring urgent CSF drainage. The 30-day mortality from intracerebral haemorrhage ranges from 35–52%. Among survivors, the prognosis for functional recovery depends upon the location of haemorrhage, size of the haematoma, level of consciousness, the patient's age, and overall medical condition.

Cerebrospinal fluid and its physiology Publication date: Available online 12 December 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Rosie May, Ugan Reddy Abstract This article describes the anatomy and physiology of CSF, and how abnormalities can result in hydrocephalus.

Perioperative anaphylaxis Publication date: Available online 29 November 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Nina Hjelde, Abdul G. Lalkhen Abstract Anaphylaxis is defined as a ‘severe life-threatening generalized or systemic hypersensitivity reaction’. Anaphylactic shock is characterized by generalized vasodilation and increased capillary permeability, leading to reduction in cardiac output. The pathophysiology of anaphylaxis can be described as immunologic and non-immunologic. The National Audit Project 6 (NAP 6) has recently investigated perioperative anaphylaxis and this article will outline some key updates from their report. Common triggers include antibiotics, followed by neuromuscular blocking agents, chlorhexidine and patent blue dye. Invasive lines impregnated with chlorhexidine are frequently missed as a cause of anaphylaxis. Patients at high risk of adverse outcomes include the elderly and those with pre-existing cardiopulmonary disease. The diagnosis is clinical and can be confounded by physiological changes commonly experienced after induction or airway manipulation. Key management principles include early administration of intravenous adrenaline, CPR if the systolic blood pressure is <50 mmHg and fluid resuscitation. Follow-up investigations are essential to guide future patient care and this is the responsibility of the anaesthetist.

Tracheal intubation Publication date: Available online 29 November 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Barry McGuire, Kimberley Hodge Abstract Tracheal intubation is the act of placing a tube into the trachea. The tube enables oxygen delivery and removal of carbon dioxide, while also allowing for the administration of pharmacological agents. Intubation is the most reliable method of maintaining an airway under anaesthesia, and for protection against aspiration of stomach contents. Traditionally, intubation is achieved by direct visualization of the glottis, but now indirect laryngoscopy (via a videolaryngoscope) is a common alternative. Prior to embarking upon intubation, a thorough patient history and examination must be undertaken by the laryngoscopist; equipment must be prepared and checked; a trained assistant present; and an experienced anaesthetist available in case assistance is required. Once the endotracheal tube has been placed, correct positioning must be confirmed via both clinical examination and monitoring, including capnography. Tracheal intubation is a procedure that should only be undertaken by trained operators and is not without risk. It is important to note that it is failure to oxygenate patients rather than failure to intubate that ultimately leads to serious morbidity and mortality. The Difficult Airway Society has produced guidelines on how to manage unanticipated difficulty in tracheal intubation; it is essential that every practitioner trained to intubate patients is familiar with these algorithms and the key principles of safe airway management.

Pathophysiology of respiratory disease and its significance to anaesthesia Publication date: Available online 26 November 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): S Kimber Craig Abstract Significant changes occur in the respiratory physiology of healthy patients during anaesthesia. In patients with underlying respiratory pathology, the changes in respiratory physiology may lead to additional clinical problems during the conduct of anaesthesia and in the perioperative period. An understanding of the disease processes that can affect the lungs and pleura allows the anaesthetist to account for the potential complications of these conditions and manage the anaesthetic accordingly.

Anaesthesia for eye surgery in paediatrics Publication date: Available online 26 November 2019 Source: Anaesthesia & Intensive Care Medicine Author(s): Tom Y. Pettigrew, Sarah J. Smith Abstract Children are rarely able to tolerate being awake for any type of surgery under local anaesthesia, therefore the majority of paediatric eye surgery is performed under general anaesthesia. Most patients presenting on a paediatric ophthalmology operating list will be otherwise healthy children who are suitable for day surgery. However, some children may have eye abnormalities as part of a congenital disorder. The perioperative plan should be formulated after assessment of the child's behaviour, co-existing medical issues and the surgical conditions required for the specific procedure. Factors influencing Intraocular pressure may require to be controlled, and anaesthetists should be vigilant for the oculocardiac reflex. Postoperative nausea and vomiting (PONV) is increased in ocular surgery, particularly with strabismus correction. Pain and opioid analgesics can both increase the risk of PONV. In most cases, simple analgesia and the intraoperative use of topical local anaesthesia will provide effective postoperative pain relief.