Acute Incidents During Anaesthesia a Small Percentage of Apparently Routine Anaesthetics Will End in an Anticipated Or Unforeseen Acute Incident
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Acute incidents during anaesthesia A small percentage of apparently routine anaesthetics will end in an anticipated or unforeseen acute incident. Edwin W Turton, MB ChB, Dip Pec (SA), DA (SA), MMed Anes, FCA (SA) Head of Cardiothoracic Anaesthesia, Bloemfontein Hospitals Complex, Department of Anaesthesiology, University of the Free State, Bloemfontein Dr Edwin Turton worked as a clinical fellow in cardiac anaesthesia at Glenfield Hospital, Leicester, UK, in 2009. His current fields of interest are adult and paediatric cardiac anaesthesia and peri-operative echocardiography, and focussed assessment through echocardiography in emergency care. Correspondence to: E W Turton ([email protected]) Anaesthesia is uneventful in the majority Although anaesthesia is a very well- • Antibiotics (2.6%) of cases but in a small percentage of controlled and governed discipline, acute • Benzodiazepines (2%) routine and emergency cases there will incidents do occur. Incidents can occur • Opioids (1.7%) be an anticipated or an unforeseen acute during induction, maintenance and • Other agents (e.g. radio contrast media) incident. These incidents need immediate emergence from anaesthesia. (2.5%). theoretical knowledge and clinical skills to be managed effectively and to The following acute critical incidents are Treatment and management prevent further morbidity and mortality. discussed in this article: • Stop administration of all suspected Therefore all providers of anaesthesia, • Anaphylaxis agents. at different levels of experience, should • Aspiration • Call for help. be able to provide basic and advanced • Laryngospasm • Airway must be secured and 100% cardiopulmonary resuscitation (CPR).1 • High or total (complete) spinal blocks in oxygen given, and ensure adequate obstetric anaesthesia. ventilation. The first death associated with an anaesthetic • Intravenous or intramuscular adrenaline was reported in 1848 in the USA. Hannah Anaphylaxis must be administered, the dose Greener was due to have an ingrown toenail The prompt diagnosis and correct treatment depending on the cardiovascular status. removed. She aspirated after induction of of an anaphylatic reaction is paramount CPR guidelines must be adhered to if anaesthesia with chloroform by her surgeon to avoid deleterious outcomes after these cardiac arrest or near arrest is diagnosed. and died.2 events. The estimated mortality once a reaction has started is approximately 5%.3 Anticipation, prediction Diagnosis of anaphylaxis is more challenging and recognition will all during general anaesthetic and a high index lead to the early and of suspicion is needed. The three most effective management of common initial presenting features during anaesthesia are: 4 acute incidents and the • No pulse detected or hypotension (28%) prevention of adverse • Difficulty in inflating the lungs (26%) outcomes. • Flushing (21%). Other presenting features are coughing, rash, Anticipation, prediction and recognition desaturation, cyanosis, electrocardiograph will all lead to the early and effective (ECG) changes, wheezing, urticaria and management of acute incidents and angio-oedema. the prevention of adverse outcomes. Identification of the predisposing factors Causes of anaphylactic reactions during that have led to the acute incident should anaesthesia include (the agents implicated be addressed by the peri-operative team are listed in order of most to least to prevent similar future incidents. responsible): 3 The entire peri-operative team should • Neuromuscular blocking agents (70%) be involved in the post-event analysis • Latex (12.6%) and the event should be reported to the • Colloid solutions (4.7%) authorities. • Induction agents (3.6%) Carvetrend Island CME May2011.indd 1 5/12/11 9:13 AM 197 CME June 2012 Vol.30 No.6 Acute incidents • Adequate amounts of the correct resuscitation of anaphylaxis, can cause Mendelson’s landmark paper, the aspiration crystalloid solution should be given; in anaphylactic reactions themselves.3 of solid regurgitate had a much worse adult patients up to 2 - 4 litres might be outcome than aspiration of fluids.5 The needed (additionally both the legs can be After the resuscitation and resolution of the increased use of supraglottic airway devices raised to centrally pool the blood volume event a causative agent should be identified (e.g. laryngeal mask airways (LMAs)) and to improve the preload of the heart). and mast-cell tryptase (enzyme) should be has increased the incidence of aspiration. • CPR should start when cardiac arrest measured at three intervals: Micro-aspiration will go unnoticed until is diagnosed (2010 South African • Immediately after the reaction has been it occurs in the debilitated patient with 1 guidelines). treated co-morbidities, and in this specific group • Additionally, antihistamines (H1-receptor • About 1 hour after the event of patients it will lead to morbidity and blocking agents, e.g. promethazine 25 mg • 6 - 24 hours after the suspected mortality. intravenously (0.5 mg/kg in children), anaphylaxis (tests not readily performed glucocorticosteroids (hydrocortisone 100 in South Africa) to confirm the diagnosis. The top three risk factors for aspiration are: 5 - 200 mg intravenously (4 - 5 mg/kg in • Emergency surgery children)) and bronchodilators must be The samples should be separated and • Light anaesthesia or unexpected administered if bronchospasm is severe stored at 4°C if they can be analysed within response to stimulation or persistent. 48 hours or at -20°C if sent for analysis • Upper or lower gastrointestinal • Catecholamine infusion (adrenaline later than 48 hours. The rise in tryptase pathology. 0.05 - 0.10 µg/kg/min) should be started, is transient so timing of sample taking is because cardiovascular instability may important.3 Patients should be sent for Possible risk factors for regurgitation and last for hours. further allergy testing and be informed pulmonary aspiration according to Engelhardt • Follow-up/step up in post-incident care is about the anaphylaxis. and Webster are shown in Table 1.6 necessary, because a biphasic event may occur. The cause must be determined if The prompt diagnosis possible, education given and the use of a Table 1. Possible risk factors for MedicAlert disc advised. and correct treatment of regurgitation and pulmonary an anaphylactic reaction regurgitation Colloid solutions, and especially the gelatine is paramount to avoid Increased gastric content solutions used for volume expansion post Delayed gastric emptying deleterious outcomes Gastric hypersecretion after these events. Overfeeding Lack of fasting Increased tendency to regurgitate Advise the patient to wear a form of Decreased lower oesophageal sphincter tone identification to indicate the fact that he Gastro-oesophageal reflux or she has had an anaphylactic response or Oesophageal strictures/carcinomas previous anaphylaxis to a specific agent (e.g. Zenker’s diverticulum anaesthetic hazard card or MedicAlert disc). Achalasia Be aware of and take the necessary Extremes of age Diabetic autonomic neuropathy precautions when patients present with a history of previous allergic reactions – do Laryngeal incompetence not ignore the patient’s history. General anaesthesia Emergency surgery Inexperienced anaesthetist Anaphylactoid reactions are indis- Night-time surgery tinguishable from anaphylaxis and for Head injury all practical purposes are treated in a Cerebral infarct/haemorrhage similar way. The most common cause of Neuromuscular disorders anaphylactoid reactions is exposure to Multiple sclerosis contrast mediums. Parkinson’s disease Guillain-Barré syndrome Aspiration Muscular dystrophies Cerebral palsy Aspiration has a higher incidence in specific Cranial neuropathies cases (upper and lower gastrointestinal Trauma/burns pathology) but is unexpected in others. In Carvetrend Island CME May2011.indd 1 5/12/11 9:13 AM 198 CME June 2012 Vol.30 No.6 Acute incidents The following are good measures to prevent oxygen tension (FiO2) delivery, and secure prevent laryngospasm. Extubating the regurgitation and pulmonary aspiration: the airway by rapid sequence induction patient fully awake or at a sufficiently • Keep to nil by mouth protocol and do and endotracheal intubation. deep level of anaesthesia is advised to not compromise. • Suction the trachea and accessible bronchi prevent laryngospasm on extubation and • Keep a suctioning catheter/device at the through the endotracheal tube. emergence. Laryngospasm usually ceases head end of the operating theatre table • Take a chest X-ray if aspiration suspected. spontaneously as hypoxia and hypercapnia during the peri-operative period. • Take a decision to continue or to postpone develop, but it is a dangerous practice to • If in any doubt suction the stomach the case. wait for this to develop before you start to of the patient suspected of having a • Further management includes actively intervene. full stomach. Empty in three different bronchoscopy (to clear aspirate from the positions before induction of anaesthesia. lower airways) and – more controversially Micro-aspiration will go • Contraindications to the use of LMAs – steroids/antibiotics. should be adhered to. • Step up postoperative care and use unnoticed until it occurs • Patients in labour have delayed stomach intermittent positive pressure ventilation in the debilitated patient emptying and the airway must be (IPPV) and bronchodilators if needed. with co-morbidities, and secured with an endotracheal tube. • Be vigilant and monitor the patient