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Craig Sims, Dana Weber and Chris Johnson (eds.) A Guide to Pediatric Anesthesiahttps://doi.org/10.1007/978-3-030-19246-4_11

11. Respiratory Illnesses and Their Influence on Anesthesia in Children

Britta von Ungern-Sternberg^{1, 2} and David Sommerfield¹

(1)

Department of Anaesthesia and Pain Management, Perth Children’s Hospital, Nedlands, WA, Australia

(2)

Medical School, The University of Western Australia, Perth, WA, Australia

Britta von Ungern-Sternberg (Corresponding author)

Email: Britta.Regli-VonUngern@health.wa.gov.au

David Sommerfield

Email: David.Sommerfield@health.wa.gov.au

Keywords

Asthma and anesthesiaBronchospasm during anesthesia childrenUpper respiratory tract infection and anesthesia childrenAnesthesia for cystic fibrosisAirway irritability during anesthesia

Respiratory disease is a frequent co-morbidity in children, and is the commonest reason for hospital admission in children aged 4 years and younger. Illnesses of the upper airway and respiratory tract are often the cause of adverse events during pediatric anesthesia. Approximately two thirds of critical incidents and one third of cardiac arrests in pediatric anesthesia have a respiratory cause. Whilst arrests due to a cardiovascular problem occur mainly in children with known cardiac disease, critical incidents or cardiac arrests with an underlying respiratory cause are seen in children who were previously healthy. This is particularly important in younger children since the risk for respiratory events decreases by about 10% for each year older the child becomes. Many of the risk factors for respiratory events are associated with airway inflammation and subsequent hyper-reactivity of the airway and bronchi, such as asthma, recent upper respiratory tract infection (URTI) or passive smoke exposure. These risk factors are common in the pediatric population and easily detectable by thorough history taking. They are cumulative and the risk of adverse events correlates with the number of risk factors better than with tests of airway inflammation such as blood markers of allergy or exhaled nitric oxide.

11.1 Bronchial Hyper-Reactivity

Recent upper respiratory tract infection (URTI), passive smoke exposure, chronic lung diseases such as asthma or cystic fibrosis, and atopy are associated with bronchial hyper-reactivity and increased airway reflexes (an ‘irritable’ airway). Mechanical stimuli during procedures such as laryngoscopy, intubation and suctioning of the airway can lead to bronchospasm or laryngospasm, particularly in those with increased reactivity. These reflex responses are mainly under vagal control and are more active in younger children. Thus, induction and extubation are the commonest periods for these problems to occur. This section highlights how to identify and manage at risk children.

Atopy, a general tendency to allergic hypersensitivity, may be present in children with eczema, hay fever, asthma or environmental allergies. Eczema, and to a lesser extent hay fever, are early risk factors for development of recurrent wheeze and asthma. These conditions or even a family history of them, is associated with a higher risk of respiratory events during anesthesia. A history of eczema is of importance in the younger child as symptoms of bronchial hyper-reactivity might not yet have become apparent. Additionally, about 10–15% of parents report respiratory symptoms such as nocturnal cough, wheezing, or wheezing with exercise even when asthma has not been diagnosed. These symptoms usually reflect underlying bronchial hyper-reactivity and increased risk (Table 11.1).

Table 11.1

Risk factors for respiratory events during anesthesia

Key points from history associated with risk of respiratory events during anesthesia
Young age
History of prematurity, chronic lung diseases including asthma or cystic fibrosis
Recent upper respiratory tract infection
Symptoms associated with bronchial hyper-reactivity: wheeze, nocturnal cough, purulent nasal discharge, fever
Symptoms of sleep disordered breathing: snoring, apnea, mouth breathing
Personal or family history (>1 first degree relative) of atopy (asthma, eczema, hay fever)
Exposure to passive (parental) smoking

11.2 Asthma

For unknown reasons, the incidence of both allergy and asthma have increased in recent decades, with the prevalence of asthma around 20% in western societies. The rise appears to be levelling off.

11.2.1 Background

Asthma is a chronic inflammatory disorder of the airway associated with variable airflow obstruction and airway re-modelling. Wheezing is the main symptom, but there is underlying airway inflammation and increased airway reactivity. Children without a history of allergy tend to outgrow their asthma, making asthma more common in children than adults. Of children aged 3 years who wheeze, 60% will stop wheezing by school age, and even more by adolescence.

Treatment is directed at the airway inflammation and resulting bronchospasm (Table 11.2). All children should use metered dose inhalers (MDI) via a spacer device and facemask, rather than the inhaler directly. The spacer is a tubular container placed between the inhaler and mask. The inhaler dose mixes with air in the spacer, and is then inhaled over several breaths. The combination of an MDI with a spacer gives better deposition of the inhaled drug into the bronchioles compared to a nebulizer. If no spacer is available, a nebulizer is better than an MDI with no spacer. Although the dose in the nebulizer bowl is much larger than an MDI dose, only a tiny proportion of the nebulizer dose is inhaled, and most is lost to the atmosphere. Nebulizers are also noisy and may frighten young children.

Table 11.2

Commonly used medications for treatment of asthma in children

Group	Agent	Example product	Route	Role
Beta-2 agonists:
– Short acting	Salbutamol	Ventolin	Inhal/Neb	Treatment of bronchospasm Pre-op optimization
– Long acting	Salmeterol	Serevent
Inhaled steroids	Fluticasone Budesonide	Flixotide Pulmicort	Inhal	Treatment of airway inflammation Prevention of bronchospasm
Leukotriene modifiers	Montelukast	Singulair	Oral	Anti-inflammatory and b/dilator effects. Reduce frequency exacerbations
Cromolyns	Cromolyn, Nedocromil	Intal, Tilade	Inhal	Prevention of bronchospasm
Prednisolone			Oral/IV	Rescue therapy for acute exacerbation

Oral steroids are only used in short courses to control an acute flare in symptoms, as long-term systemic steroids affect growth. Most children have mild asthma that is well controlled and characterized by infrequent episodes, perhaps only related to URTIs in the winter months. Children particularly at risk are those with recent hospital admissions, escalating therapy or use of oral steroids, and those who have had episodes of sudden, severe asthma requiring intensive care.

Note

Although asthma causes wheezing, the underlying chronic airway inflammation is the focus for long-term treatment. This is why bronchospasm may occur from a stimulus that would not normally cause bronchospasm.

11.2.2 Anesthesia and Asthma

Airway instrumentation during anesthesia is a potent stimulus that can trigger bronchospasm. Perioperative management of asthmatic children aims to optimize asthma treatment and minimize the effects of increased airway reactivity. Although asthmatic children have an increased risk of respiratory events, the risk of bronchospasm and morbidity is low in the child with stable asthma.

Keypoint

Audible wheeze at the time of preoperative assessment indicates a high risk of intraoperative respiratory adverse events. The child should be wheeze-free at induction.

11.2.2.1 Preoperative Treatment for Asthmatic Patients

Children with stable asthma should continue their regular medications. Children who have had recent symptoms or are undergoing tonsillectomy benefit from preoperative salbutamol. Children who are wheezing at the time of the preoperative assessment are at high risk for respiratory complications and should therefore always be given inhaled salbutamol preoperatively. If the child’s symptoms are poorly controlled, a short course of oral steroids could be discussed with the child’s physician. Steroids need to be given at least 24 h before surgery because their effect on airway reactivity begins after 6–8 h and is maximal after 12–36 h. Children taking long-term inhaled steroids do not have suppression of the hypothalamic-pituitary axis and do not need perioperative steroid supplementation, unlike the rare child taking long-term oral steroids.

Note

An inhaler used with a spacer is the best way to give salbutamol to young children. If this combination is not available, use a nebulizer. The nebulizer dose for salbutamol in children is 0.05 mg/kg (minimum 1.25 mg, maximum 2.5 mg) in 3 mL saline.

11.2.2.2 Intraoperative Management of Asthmatic Children

Bronchospasm can be avoided by choosing appropriate anesthetic techniques (Table 11.3). It is most likely to occur with airway manipulation such as the insertion or removal of an airway device, and particularly an endotracheal tube. A bolus dose of propofol 1–3 mg/kg suppresses airway reflexes and should be considered in the absence of contraindications. Although there is little difference between the effect of sevoflurane and isoflurane on the airway, desflurane increases airway resistance in all children and should be avoided. IV induction with propofol is also protective compared with an inhalational induction with sevoflurane—although inhalational agents are bronchodilators, airway obstruction and other respiratory events are common during the slower induction with them. Agents that may blunt reflex bronchoconstriction or cause bronchodilation such as clonidine, ketamine or propofol are preferred. Atracurium and morphine and are associated with histamine release, although usually only cutaneous histamine release occurs in children and these drugs are often used in asthmatic children. Non-steroidal anti-inflammatory drugs can worsen bronchospasm by increasing leukotrienes. However apart from children with nasal polyps or severe, uncontrolled asthma, the risk from NSAIDs is low (2% compared to 7% in adults) and generally easily treated.

Table 11.3

List of factors during anesthesia that may contribute to incidence of bronchospasm in children with bronchial hyper-reactivity

Less likely to trigger	More likely to trigger
Preoperative inhaled salbutamol
α2 agonists, clonidine IV induction with propofol	Inhalational induction with sevoflurane
Ketamine Fentanyl Maintenance with Propofol, sevoflurane or isoflurane	Desflurane Morphine Atracurium and neostigmine
Face mask or LMA	Endotracheal intubation
Deep removal of airway device	Awake removal of airway device
Specialist pediatric anesthetist

Tip

A bolus of propofol 1–3 mg/kg reduces the risk of airway and respiratory events during insertion or deep removal of any airway device.

Tip

Deepening anesthesia is an important step because infants and young children often cough, breath hold, develop rigidity of the chest and abdominal muscles and become very difficult to ventilate as anesthesia is lightened. This is often confused with severe bronchospasm.

11.2.2.3 Treatment of Bronchospasm During Anesthesia

As soon as a bronchospasm is suspected, 100% oxygen is given and anesthesia deepened. Deepening anesthesia is an important step because infants and young children often cough, breath hold, and develop rigidity of the chest and abdominal muscles as anesthesia is lightened. Repeated doses of salbutamol are given until bronchospasm is relieved. Less than 3% of aerosolized drug given through a supraglottic airway or endotracheal tube reaches the patient. Many factors reduce the delivery of the drug, and the disease itself will favor delivery to areas of the lung that are already better ventilated. Only very limited drug delivery is achieved with ‘home made’ devices such as a 50 mL syringe delivering into the angle piece or trachea, and the devices are not without risk. The most effective method during anesthesia is to use an MDIs with an inline spacer (Fig. 11.1). Second best is directly connecting the outlet of the aerosol canister to the airway device. If repeated doses of salbutamol from an MDI are insufficient, then give IV salbutamol 10–15 μg/kg IV bolus over 10 min and consider infusion 1–5 μg/kg/min. In severe resistant cases ketamine, magnesium sulfate (40 mg/kg/IV over 20 min) and adrenaline (epinephrine) (0.01 mg/kg IV) can be considered. Neuromuscular blockade may also help.

../images/467929_2_En_11_Chapter/467929_2_En_11_Fig1_HTML.png — Fig. 11.1

An inline inhaler as close as possible to the ETT or LMA is the best method to deliver salbutamol into the anesthetic circuit

Consider that suctioning of airway secretions via the ETT is a powerful stimulus that may worsen bronchoconstriction. Ventilation with slow breaths, a long expiratory time and plateau pressures less than 30 cm–35 cmH₂O all aim to allow full expiration and reduce air trapping. Flow-time loops can be monitored to ensure expiratory flow has finished and avoid raising intrinsic PEEP.

11.3 Upper Respiratory Tract Infection (URTI)

Over 200 viruses are associated with the common cold, or URTI, and there is often superimposed bacterial infection. Rhinoviruses account for about 80% of URTIs and have a predilection for the nasal mucosa and upper respiratory tract. Respiratory syncytial virus (RSV) can cause cold-like symptoms but causes a more severe infection particularly affecting the bronchi. The viral infections causing URTIs also cause airway inflammation, increased secretions and hyper-reactivity of the airway and bronchi, much like asthma. It can be difficult to decide whether or not to proceed with elective surgery in a child with a recent URTI. Between a third and a half of children presenting for surgery have had an URTI in the preceding 6 weeks. Preschool-aged children undergoing ENT surgery have an average of six to eight URTIs per year, potentially leaving only a few weeks of the year when the child is well and not recently had an URTI.

Note

Although called upper respiratory tract infections, the lower respiratory tract is often affected, causing bronchial hyper-reactivity and a susceptibility to atelectasis.

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Illnesses and Their Influence on Anesthesia in Children