Essential notes: the anaesthetic management of an inhaled foreign body in a child

Inhaled foreign bodies are a common surgical emergency in young children and may need management outside of a specialised paediatric hospital. These cases are usually managed with a rigid bronchoscopy. This is a challenging case for the ‘occasional’ paediatric anaesthetist, with a significant risk of mortality and morbidity.1, 2 Particular problems include maintenance of a patent airway and avoidance of airway obstruction; induction and maintenance of satisfactory anaesthesia for a very stimulating procedure; a high risk of hypoxaemia during the ‘shared airway’; and the prevention and management of possible postoperative airway problems.

Preoperative assessment

During preoperative assessment, ensure that the anxiety of the child is minimised by trying to develop a rapport with the patient, parental presence at induction, and premedication with midazolam or clonidine if needed. Take an ‘AMPLE’ history (allergies, medications, past medical/anaesthesia history, last meal, events leading up to the presentation), and ask about family history of problems with anaesthesia. Examine the child with a focus on the airway. Look at neck and chest radiographs for the position of any radio-opaque foreign body.

Anaesthesia

A key goal is usually to keep the child breathing spontaneously, although there is little evidence to support this.³ Theoretically, positive pressure may push the foreign body further down the airway; maintaining spontaneous ventilation is a safe option when you do not know if positive pressure ventilation will be suboptimal.

Induction

Induction of anaesthesia can be either inhalational or intravenous. A safe approach is to induce anaesthesia with sevoflurane in oxygen. An alternative is i.v. induction with fentanyl 0.5 μg kg⁻¹ followed by incremental boluses of propofol (initial dose 1 mg kg⁻¹, then increments of 0.5 mg kg⁻¹ or less) until the child loses consciousness. Another option is to start with i.v. dexmedetomidine 1 μg kg⁻¹.

Maintenance

Maintenance of anaesthesia can be with volatile anaesthetic agents, insufflated through the ventilating bronchoscope. I prefer to use an intravenous maintenance, as it avoids needing to use the airway to administer anaesthesia when the airway is shared, and there is less exposure of the operating theatre team to waste anaesthetic gases. During the initial maintenance phase, deepen the plane of anaesthesia until you think that the patient is deep enough to tolerate the application of topical local anaesthetic to the airway—then wait a few minutes more. Proceed slowly, because if anaesthesia is too deep the patient will often stop breathing. Some anaesthetists place a supraglottic airway device (SAD) at this point for convenient maintenance of a patent airway. Titrate the dose of opiate to the ventilatory frequency; a rule of thumb is to aim for half the preoperative rate.⁴ Titrate propofol to the respiratory pattern, muscle tone, and heart rate. Children under 3 yrs tolerate higher doses of propofol and remifentanil than older children,⁵ and maintain spontaneous ventilation. I typically start with propofol 250 mcg kg⁻¹ min⁻¹ and remifentanil 0.2 mcg kg⁻¹ min⁻¹. At this point dexamethasone 0.25–0.5 mg kg⁻¹ can be given to prevent airway swelling.

For local anaesthesia of the airway, perform a direct laryngoscopy and spray with lidocaine (up to 4 mg kg⁻¹) at and through the vocal cords with a mucosal atomisation device or with a small gauge i.v. cannula.⁶ If the child coughs, oxygenate the patient's lungs with a facemask until spontaneous ventilation resumes, and then continue to topicalise the airway. If the child continues to cough with the local anaesthetic, then the patient is not ready for surgery. Concentrated lidocaine works better than 1%.

It is essential to maintain a deep plane of anaesthesia during the case, as coughing and bucking on the rigid bronchoscope risks trauma and bronchial or tracheal perforation. Removal of the foreign body through the larynx is a high-risk time: some anaesthetists give a bolus of propofol to ensure adequate depth of anaesthesia.⁷

Maintaining oxygenation

A key challenge is oxygenation during the procedure. If the surgeon has passed a ventilating bronchoscopy through the vocal cords you can attach a breathing circuit to the 22 mm connector on the bronchoscope.⁸ If the surgeon is working at the level of the larynx, then you can attach oxygen tubing to most surgical laryngoscopes or insufflate oxygen through a tracheal tube passed through the nares into the nasopharynx just above the vocal cords (Fig. 1). Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) may be useful to maintain oxygenation.⁹

Fig 1.

(Left) anaesthesia breathing circuit attached to the Stortz ventilating bronchoscope via a standard 22mm connection, used for a foreign body in the trachea or bronchi; (right) oxygen tubing attached to the side port of a Parson's laryngoscope, used for direct laryngoscopy by the surgeon for a foreign body at or immediately below the larynx.

Reliable capnography will not be possible, even when using the ventilating bronchoscope. As a rule of thumb, ventilation and oxygenation will often remain adequate if: (i) you are administering oxygen to the airway; (ii) you can see the airway is open on the surgeon's screen or the surgeon can confirm the airway is open; and (iii) you can identify reasonable respiratory effort. However, hypoxia is common during rigid bronchoscopy, especially if there is significant comorbidity or obstruction to ventilation from the foreign body. Some patients arrive at the operating theatre with profound hypoxia, and these patients have a higher risk of morbidity and mortality.

Case management

A vital leadership role is to control the room and stand at the head of the bed until you are happy that the child is ready for the surgeon to begin the rigid bronchoscopy. Make it clear that the airway is ‘owned’ by anaesthesia until the ENT (ear, nose, and throat) surgeon is invited to take over. Communication with the ENT team is essential throughout the case to prevent hypoxia caused by periods of poor oxygenation, including advising the ENT surgeons when to remove the bronchoscope if profound hypoxia occurs during the procedure.¹⁰

Postoperative management

After the foreign body has been removed, there are several options for airway management until the patient is fully recovered. Many children can breathe spontaneously with simple airway support until emergence from anaesthesia. Some anaesthetists wake the child up with a SAD in situ for convenience. If there is significant airway swelling or trauma, or ongoing airway obstruction after removal of the foreign body, tracheal intubation may be necessary before emergence from anaesthesia. In rare cases, transfer to ICU may be needed, before extubation when the airway swelling has improved.

You should anticipate a prolonged stay in the PACU and plan to review the child before discharge to the ward. If the child has postoperative croup whilst in PACU, nebulised racemic adrenaline (epinephrine) 1–5 mg should be given and ENT colleagues consulted early. Intubation is rarely required at this point.

Declaration of interest

The author declares that they have no conflict of interest.

MCQs

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Biography

Dylan Bould FRCA MEd is a consultant at the Children's Hospital of Eastern Ontario and an associate professor at the University of Ottawa. He is an editor and editorial board member of BJA Education.

Matrix codes: 1A02, 2D02, 3D00