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Tags: respiratory, Paed
asthma
Children with a history of reactive airway disease and atopy are at increased risk of perioperative bronchospasm. The periods of highest risk are during intubation and extubation
History should focus on the frequency and severity of symptoms, activity level, current medication including steroids, emergency attendances, hospital and intensive care admissions, recent URTIs and previous issues during anaesthesia.
Up to 15% of asthma sufferers have nasal polyps and this should be considered when nasal intubation may be required. Chronic sinusitis and polyps are associated with increased airway reactivity after non-steroidal anti-inflammatory drug (NSAID) administration
→ Samter triad
Assessing asthma control in last 4 wks
- Daytime asthma symptoms > twice a week?
- Nocturnal waking due to asthma?
- Reliever need for symptoms > twice a week?
- Any activity limitation due to asthma?
Routine peak expiratory flow rate (PEFR) testing in children with well-controlled asthma is unnecessary, difficult to perform in children under 5 and does not correlate with severity of illness or degree of hypoxia. PEFR has also been shown to underestimate the degree of airflow obstruction in severe disease.
Premedication with oral midazolam 0.5 mg/kg (maximum 20 mg) reduces anxiety-related bronchospasm
Preoperative inhaled or nebulized bronchodilator 1–2 hours before surgery improves lung function and attenuates airway resistance associated with tracheal intubation
Where surgery is urgent and asthma is considered poorly controlled, consideration should be given to pulsed perioperative steroid therapy
Anaesthetic Mx
In patients with severe asthma, avoid histamine-releasing drugs such as atracurium, mivacurium, thiopentone and suxamethonium. Some include morphine in this group but evidence of adverse airway effects is scant. Propofol, ketamine, pancuronium, vecuronium, rocuronium and fentanyl are preferable.
Poorly controlled asthmatics should be treated by an experienced paediatric anaesthetist, this reduces the risk of perioperative respiratory adverse events (PRAE). Poor disease control is the biggest risk factor for respiratory complications.
Intubation should be avoided if possible. If necessary, ensure adequate depth of anaesthesia, and ensure the ETT is not close to the carina; this is a potent trigger of bronchospasm.
During controlled ventilation aim to avoid hyperinflation, air trapping and barotrauma, adjust inspiratory:expiratory (I:E) ratio to prevent breath stacking, keep respiratory rate (RR) near or below physiologic range, and use positive end-expiratory pressure (PEEP) 3–5 cmH2O.
Suctioning, if necessary, should be performed in a deep plane of anaesthesia
Topical lignocaine increases the risk of perioperative respiratory events. IV lignocaine can be used to attenuate response to airway instrumentation.
Desflurane increases airway resistance during induction and should be avoided. Sevoflurane is preferred
Reversal agents such as neostigmine increase bronchial secretions and airway reactivity, but this is attenuated if administered with glycopyrrolate. Sugammadex is not associated with increased adverse events compared with neostigmine, although there may be a small increase in bronchospasm.
If the child has been on regular oral steroids or on high-dose inhaled steroids within the past 2 months, supplementary intravenous steroids need to be administered perioperatively.
Deep extubation is a strategy to be considered, although evidence to support superiority of this technique is lacking.
NSAIDS should only be avoided in children with severe or brittle asthma, nasal polyps, and in those with history of previous adverse reactions to NSAIDs.
Nebulized bronchodilators should be prescribed post-operatively if children unable to use metered-dose inhalers.
Other causes of airway obstruction and wheeze, in particular anaphylaxis, pneumothorax and mucus plugging must be excluded with acute deterioration of oxygenation during anaesthesia in asthmatic children