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%)
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• 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 guidelines).1 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
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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 for • Pain and opioid analgesics lead to any deterioration in his/her condition in this specific group of delayed gastric emptying. (especially during the first 2 hours post patients it will lead to • Err on the safe side and use muscle event) until the discharge criteria are met morbidity and mortality. relaxants, rapid sequence induction and in a stable patient. secure the airway with an endotracheal tube when in doubt. Criteria for monitored discharge of patients The diagnosis of partial or complete who have aspirated to a general ward are: 7 laryngeal obstruction by looking and Aspiration may be obvious macro-aspiration • Clinical stability listening for signs and symptoms of of regurgitated content or it may consist of • Oxygen saturation (SpO2) 95% on FiO2 laryngeal spasm are important. You should micro-aspirates. 50% recognise suprasternal and supraclavicular • Heart rate <100 beats/min retraction, a tracheal tug and paradoxical Diagnosis of macro-aspiration is usually • Respiratory rate <20/min movement of the abdomen and chest obvious and the most important priority • Temperature normal during obstructive breathing. Inspiratory is early intervention to prevent further • Minimal bronchodilation needed. aspiration. Particulate matter can cause immediate airway obstruction and should be Laryngospasm treated as such if it happens. Regurgitation Laryngospasm is a protective reflex closure of non-particulate matter/fluids is usually of the upper airway from spasm of the glottic noticed once the airway device or oral musculature as the result of an abnormal cavity is soiled by them. The regurgitation stimulus.8 Laryngospasm is mediated by and aspiration can go unnoticed and the the superior laryngeal nerve.9 It occurs first sign might be laryngospasm, airway more commonly in paediatric anaesthesia obstruction, desaturation, bronchospasm, and after certain procedures. Predisposing hypoventilation or even cardiac arrest.7 factors, including respiratory tract infections, must be elucidated in your pre- Management operative history taking and examination. Management consists of: Inexperienced anaesthetists will experience • Early diagnosis – tell the rest of theatre this complication more frequently than team and call for help. their more experienced colleagues. • Position the patient head down in the left lateral decubitus position, if feasible. Airway instrumentation or intravenous • Open the airway and keep it patent. cannulation (any patient stimulation) • Apply cricoid pressure (relief of cricoid should only be attempted after a sufficiently pressure if patient vomits). deep level of anaesthesia has been reached. • Clear the oro-, naso- and hypopharynx Only sevoflurane and halothane must within direct vision from aspirate, if possible. be used for inhalational induction. The • Oxygenate and ventilate patient, use pulse use of muscle relaxant at the correct oximetry to guide fractional inspired dose before attempting intubation will
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Diagnosis of laryngospasm
Identification and removal of the stimulus (secretions, blood, nociceptive stimulus)
Chin lift and jaw thrust Oropharyngeal airway
CPAP and FiO2 100%
No Assess air entry Yes Bag movement?
Complete laryngospasm Partial laryngospasm
Call for help Positive pressure ventilation with face Deepen anaesthesia with small doses of mask propofol or inhalational agent
No improvement Reassess air entry with CPAP
Improvement IV access No IV access
IV suxamethonium IM (1.5 - 4 mg/kg) 0.5 - 2 mg/kg after or intraosseous IV atropine 0.02 mg/kg or 0.5 - 1 mg/kg IV propofol 1 mg/kg suxamethonium
Positive pressure ventilation with Improvement
FiO2 100% Followed by tracheal intubation Surgery or PACU No improvement
Cardiopulmonary resuscitation
10 Fig. 1. Management of laryngospasm in paediatric patients. CPAP = continuous positive airway pressure; FiO2 = fractional inspired oxygen tension; IV = intravenous; IM = intramuscular; PACU =post-anaesthesia care unit.
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stridor with incomplete laryngospasm or Table 2. Clinical manifestations of Miller notes that ‘Pregnant patients no air movement with complete obstruction complete spinal block develop more extensive spinal blocks than should be followed by prompt manoeuvres nonpregnant patients. This is related to to treat the laryngospasm. Cardiorespiratory increased sensitivity to local anesthetics as Hypotension* well as the mechanical effects of epidural Bradycardia secondary to hypoxia should vein engorgement.’12 Bradycardia* never be treated by atropine. Administration Respiratory compromise* of suxamethonium may lead to severe High spinal blocks (above T4) result bradycardia and even to cardiac arrest Apnoea* because of excessively high spread of the in a hypoxic patient. Therefore, giving Reduced oxygen saturation local anaesthetic and can be diagnosed intravenous atropine before an intravenous Difficulty speaking/coughing by the following signs and symptoms: injection of suxamethonium to treat Cardiac arrest (asystole) nausea, vomiting, development of weakness laryngospasm is mandatory.10 of the upper extremities, breathing Neurological difficulty, feeling of impending doom and Treatment Nausea and anxiety* haemodynamic instability (bradycardia and The treatment of laryngospasm consists of: Arm/hand dysaethesia or paralysis* hypotension). Haemodynamic instability • Removal (e.g. suctioning away of blood, High sensory level block is secondary to sympathetic blockade, secretions, surgical debris) of the blockade of the accelerator fibres to the Cranial nerve involvement offending trigger heart (T1 - T4) or hypoperfusion of the vital • Administration of 100% oxygen by tight- Loss of consciousness centres in the brainstem. fitting face mask, continuous positive * Commonly reported or ‘classic’. airway pressure (CPAP) with gentle Miller offers the following good advice. positive pressure ventilation with a chin ‘Intraoperatively, during high spinal lift and jaw thrust manoeuvre (painful The incidence of complications resulting anesthesia, patients occasionally complain stimuli in this position help to prevent from laryngospasm can vary as follows: 8 excessively about dyspnea. This is not a and relieve laryngospasm)11 • Cardiac arrest 0.5% result of significantly decreased inspiratory • If the abovementioned measures • Pulmonary aspiration 3% capacity but most often seems to be related to are ineffective, more aggressive• Obstructive negative pressure pulmonary loss of chest wall sensation, which does not pharmacological therapy is needed oedema 4% (succinylcholine, rocuronium – if there is • Bradycardia 6% a contraindication to succinylcholine’s use • Oxygen desaturation 61%. and no difficult airway is anticipated, use propofol etc.). Succinylcholine in a dose According to Donlan et al., ‘In addition to not less than 0.5 mg/kg should be used. If hypoxemia some patients who are able to intravenous access is not secured at this generate very large negative inspiratory stage, the best alternative option is to use pressures when attempting to breathe the intramuscular route (intraosseous against the obstruction may succumb to or intralingual are other alternatives) of “negative-pressure pulmonary edema”.’9 administration at a dose of 1.5 mg/kg to 4 mg/kg. (Delayed onset of action is a High or total (complete) real problem, but in this case there is no spinal blocks during caesarean alternative available.) 10 section Neuroaxial blockade by spinal anaesthesia Fig. 1 details the management of is the choice of anaesthesia for caesarean laryngospasm in paediatric patients.10 section if no contraindications exist. A high or total (complete) spinal block is an General anaesthesia conducted with a anaesthetic emergency and prompt and facemask (and harness) is a technique now definitive treatment and management not frequently used by practitioners, but should proceed before the airway protective is less likely to cause laryngospasm than reflexes are lost, ventilation becomes using either supraglottic airway devices compromised or haemodynamic collapse (e.g. LMAs) or endotracheal intubation. happens (asystole or pulseless electrical However, this is also controversial.8 activity).
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allow patients to experience the reassurance patient will be unconscious and her pupils High and total spinals resolve within a period of a deep breath. This impediment to patient will be fixed and dilated to mid-stance; of time and the support for a good outcome acceptance can often be overcome by the patient will appear to be dead. Table 2 needs to be instituted immediately and instructing the patient to raise a hand near lists the clinical manifestations of complete effectively and continued until the event the mouth and exhale forcefully. The tactile spinal block. resolves. Misdiagnosis or late diagnosis appreciation of the deep breath seems to leads to morbidity and mortality. provide reassurance.’12 Immediate diagnosis of a total spinal block is essential, followed by prompt treatment. Conclusion During spinal anaesthesia frequent monitoring Protection of the airway (to prevent Acute incidents happen during the peri- (every minute) of the haemodynamic aspiration and asphyxia) and ventilation, operative care of patients. Paediatric, parameters should continue till the newborn together with haemodynamic support with geriatric and pregnant patients are more has been delivered and the mother is adrenaline and intravenous fluid boluses, are prone to develop acute incidents and are haemodynamically stable, then blood pressure the cornerstones of treatment. The patient more vulnerable to complications once and other vital signs (heart rate) can be must be placed in the left lateral tilt position these events have taken place. The prompt monitored and recorded less frequently. during resuscitation, if not already in this diagnosis and effective treatment and position, to prevent aortocaval compression. management of these incidents prevent A total (complete) spinal can be diagnosed if morbidity and mortality. If an acute incident the patient loses consciousness not because CPR must be started immediately when occurs, it must be documented meticulously. of hypotension and hypoperfusion of the cardiac arrest is diagnosed. Cardiac The event should be discussed with the vital centres, but when the spread of local compressions should be started at 100 patient and all other interested parties at a anaesthetic is so high that the spinal block compressions per minute. The immediate convenient time after the incident. reaches the cervical spine, vital centres in delivery of the newborn is part of the the brainstem and cranial nerves. A total resuscitation attempt. Intravenous adrenaline spinal will then lead to unconsciousness and at a dose of 1 mg of a 1:1 000 solution is cardiovascular collapse/cardiac arrest. The indicated during a cardiac arrest.1 References available at www.cmej.org.za. IN A NUTSHELL • Anaesthesia is uneventful in the majority of cases but in a small percentage acute incidents do take place. • All anaesthesia providers must be able to perform basic and advanced cardiopulmonary resuscitation. • Acute incidents can occur during induction, maintenance and emergence of anaesthesia. • Diagnosis of anaphylaxis is difficult during general anaesthesia and a high index of suspicion is needed. • The first step in treating anaphylaxis is to stop all possible suspected agents. • The top three risk factors for aspiration are emergency surgery, anaesthesia that is too light, and gastrointestinal pathology. • The inexperienced anaesthetist experiences the complication of laryngospasm more often. • Laryngospasm is more common in paediatric anaesthesia. • During spinal anaesthesia haemo-dynamic parameters should initially be monitored every minute. • Cardiopulmonary resuscitation must be initiated immediately when cardiac arrest is diagnosed.
SINGLE SUTURE ‘Kangaroo’ care could save thousands of babies As many as 450 000 lives could be saved each year by taking a cue from marsupials. If parents of premature babies in poor countries were to continuously carry infants against the skin in ‘kangaroo pouches’ and increase breastfeeding and regular medical monitoring, we might save more of the 15 million babies born too soon each year. That is the message from the most comprehensive global survey of premature births yet. Most premature births are in poor countries – two-thirds in south Asia and sub-Saharan Africa alone. Yet only 10% of premature newborns survive there, compared with 90% in rich nations. Research has shown that the Kangaroo Mother Care technique could save almost half of the 1.1 million babies that die after premature birth each year. ‘It’s about keeping the babies warm, breastfeeding, and treating any new infections with antibiotics,’ says Joy Lawn, lead author of the report published this week by a group including the World Health Organization. Already used in South Africa and Malawi, a scale-up of the technique is under way in Tanzania, Rwanda and Ghana. The report found that premature births are increasing in rich countries because of obesity, smoking, IVF and older women having babies, and in poor countries owing to malnutrition, teen pregnancy and lack of contraception, which means women tend to have babies closer together, increasing the chances of premature births. New Scientist online 2 May 2012.
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