First aid: Airway, choking and asphyxia

In the second part of our series, Samena Chaudhry and colleagues guide you through management and problems associated with airway obstruction

When a person has collapsed or is unconscious, they risk an obstruction of their airway. Airway compromise can be sudden and complete, insidious or partial, and progressive or recurrent. Inadequate delivery of oxygenated blood to the brain and other vital structures is the fastest killer of trauma patients.1 Hypoxaemia, inadequate oxygen supply in arterial blood, can be prevented by a protected unobstructed airway and adequate ventilation.

Airway management

A man was in a motorcycle crash and has arrived in the emergency department. He was lying about 8 m from his bike and still has his full face helmet on. Upon initial assessment, you hear gurgling from his airway. The ambulance driver tells you that his respiratory rate is 7 breaths/min and irregular with a weak, rapid heart rate of 140 beats/min. He is unconscious. As you glance at his body for obvious bleeding, you note pinkish fluid draining from his nose.

Ensuring a patent airway

You need to do several things to ensure a patent airway in this man. The full face helmet is hampering your ability to effectively manage the patients airway, so it must be removed. Firstly, you must immobilise the cervical spine until a complete clinical and radiological evaluation has excluded injury. The potential for cervical spine injury makes airway management more complex in trauma patients, and you should consider it in all injuries involving blunt trauma.

At this point, it is worth stressing that treatment is best done by a well organised and trained team made up of staff competent in assessing and managing life threatening injuries. An experienced emergency medicine doctor or anaesthetist, possessing airway and resuscitation skills, who is confident in dealing with unconscious patients, is a vital member of the team and in many hospitals is the team leader.

STEWART COOK/REX

Heimlich inventing his manoeuvre

Compromised ventilation often results from upper airway obstruction by the tongue, substances retained in the mouth, or laryngospasm (adductor spasm of the vocal cords). In people with decreased levels of consciousness, relaxation of the tongue and jaw leads to a reduction in the space between the base of the tongue and the posterior pharyngeal wall. This is the commonest cause of either partial or complete upper airway obstruction.^234 Complete obstruction is characterised by a total lack of air exchange, whereas partial obstruction results in inspiratory stridor and retraction of the neck and intercostal muscles. Stridor is an inspiratory musical wheeze heard loudest over the trachea during inspiration. This suggests an obstructed trachea or larynx and constitutes a medical emergency that requires immediate attention. To correct the soft tissue obstruction of the airway, you should perform the chin lift or jaw thrust manoeuvre. In people with suspected cervical spine injuries, the jaw thrust manoeuvre should be used as it involves less movement of the cervical spine.

Laryngospasm, which is a primitive reflex resulting from stimuli to or the presence of foreign matter in the oral and laryngopharynx, can then be treated by maintaining positive airway pressure using a face mask and bag valve device.⁴

You should always be aware of the risk of contamination of the unprotected airway by regurgitation or vomiting. Gurgling respirations indicate the presence of fluid, probably blood or vomit, in the patients mouth which will need to be sucked out using a suction catheter. Because the man is unconscious and has an irregular respiratory rate of 7 breaths/min, you should insert an oropharyngeal airway. This is functionally dependent upon getting the right size and is sized on the distance from the angle of the patients mouth to the ear. It is inserted upside down until the tip is beyond the end of the tongue and then rotated 180 into position.²

The patient can then be ventilated with a bag valve mask. Self refilling manual resuscitation bags attach to a mask and facilate bag valve mask ventilation with air and supplementary oxygen via an oxygen reservoir bag. This can ensure inspired oxygen levels of 80-95%.

Does the man need a definitive airway?

Yes, the man needs a definitive airway. The man has a Glasgow coma score of less than 8 and is unable to protect or maintain his own airway. A definitive airway requires a tube present in the trachea with the cuff inflated, the tube connected to oxygen rich ventilation and the airway secured in place with tape. The three types of tube are orotracheal, nasotracheal, and surgical cricothyroidotomy.

Orotracheal tube--Tracheal intubation with a cuffed tube is best for airway protection. Using a laryngoscope to lift the jaw and base of tongue forward, the glottis is exposed and the larynx is visible. A curved tube is then inserted into the trachea through the vocal cords. Inflation of the tracheal cuff isolates the airway allowing safe ventilation. This is a skill requiring considerable experience and is more difficult in a trauma patient.⁴

Nasotracheal tube--Nasotracheal tubes are less commonly used in resuscitation situations, usually if orotracheal intubation is impossible. It is contraindicated in patients with facial or basal skull fractures.

Surgical cricothyroidotomy--Surgical cricothyroidotomy is necessary when other means of securing an airway fail. A transverse incision is made over the cricothyroid membrane. After the incision is expanded with dilators, a cuffed tracheostomy tube can be inserted into the trachea.

Minimal chest wall movement

The most common problem encountered when using a bag valve mask device is difficulty in maintaining an airtight seal. To avoid this, you must re-evaluate the mask to ensure that it is the correct size. The best method for placing the mask on the patients face is to lock the mask under the patients chin, and secure the bridge of the mask over the bridge of the patients nose. It may need one person to manipulate the bag and another to hold the mask in position to ventilate the patient effectively.

Would a nasopharyngeal airway be suitable?

No. Nasopharyngeal airways are contraindicated when there is obvious nasal trauma or if there is drainage from the nose. The pinkish fluid is most likely cerebrospinal fluid, which indicates a skull fracture. If you put in a nasal airway, you risk placing the airway directly into the cranium. As the man is unconscious, you should use an oropharyngeal airway. After 10 minutes of good chest wall movement with each breath, you notice the patient becoming cyanotic, despite that fact that you are assisting ventilations.

Why would he suddenly become cyanotic?

If a patient suddenly becomes cyanotic during assisted ventilation, you must determine why. In many cases, you will find that the oxygen tubing has become disconnected from the oxygen source or that the oxygen tank is depleted. You must correct this immediately. Critical patients need high flow oxygen to survive and prevent secondary brain injury.

Other causes for cyanosis include airway obstruction by blood or vomit; or the patients airway needs to be re-evaluated to make sure that it is still in the correct position as the tongue is the commonest obstruction.

When providing assisted ventilation, signs that the patient may be improving include:

• Improvement in heart rate (remember that children respond to hypoxia with bradycardia)
• Improvement in colour (if previously cyanotic)
• Improvement in level of consciousness (not likely in this man due to his injuries)
• Pulse oximeter reading. Pulse oximetry is a simple non-invasive method of monitoring the percentage of haemoglobin that is saturated with oxygen and is helpful in monitoring oxygenation.

Asphyxia

Asphyxia is a condition in which an extreme decrease in the concentration of oxygen in the body accompanied by an increase in the concentration of carbon dioxide leads to loss of consciousness or death. This may be due to a physical blockage in the airway (choking), drowning, obstruction around the neck (hanging), lack of oxygen in the air itself, or inability of the blood to carry the oxygen (for example, carbon monoxide poisoning).³

Choking

A persons airway can become obstructed by a foreign object. Choking is often caused by food or other foreign body lodged in the throat and can result in unconsciousness and cardiopulmonary arrest. Being familiar with a few simple steps could save someones life.

If the person can speak, cough, or breathe, it is best to encourage coughing. If the flow of air is obstructed and the patient is struggling to breathe, try to remove the foreign body from the mouth. If this is not possible using the heel of your palm, give them back blows (hit them firmly and sharply between the shoulder blades) to dislodge the blockage (use a more gentle tap for small children). This may dislodge the obstruction by compressing the air that remains in the lungs and providing an upward force behind it.^{4 5}

If choking continues, try the abdominal thrust--the Heimlich procedure. Stand behind the patients waist and clenching your fist, place it just below the patients xiphisternum (bottom tip of the sternum). Grasp it with your other hand then pull sharply inwards and upwards. Then alternate this with back slaps.

If the person becomes unconscious open the airway by tilting the head backwards and lifting the chin. Open their mouth and look inside. If an obstruction is clearly visible, attempt to remove it. Be careful not to push it in further. Check for breathing. Attempt two rescue breaths if the person is not breathing.

If you cannot give two effective breaths within five attempts, start chest compressions immediately to relieve the obstruction. After 15 compressions, check the mouth for any obstruction then attempt further rescue breaths. In this situation chest compressions are given to relieve airway obstruction rather than to circulate the blood as in a cardiac arrest.⁵ Continue to give cycles of 15 compressions followed by attempts at rescue breaths. If at any time, you can give effective breaths, check for signs of circulation and continue chest compressions or rescue breaths as appropriate. It is strongly advised that a course in first aid of cardiopulmonary resuscitation be completed before attempting these procedures (see www.resus.org.uk and www.frca.co.uk).

Samena Chaudhry, senior house officer in cardiothoracic surgery,
Email: sxc602@doctors.org.uk

Magnus Harrison, consultant in emergency medicine, University Hospital North Staffordshire

Martin S Roth, first year anaesthesia resident, Hospital Italiano de Buenos Aires, Argentina
Email: martinsroth2828@hotmail.com


studentBMJ 2005;13:89-132 March ISSN 0966-6494

1. American College of Surgeons Committee on Trauma. Advanced trauma life support manual. 6th ed. Chicago: ACoS, 1997.
2. Criswell JC, Parr MJ, Nolan JP: Emergency airway management in patients with cervical spine injuries. Anaesthesia 1994;49:900-3.
3. Asphyxia: a medical dictionary, bibliography, and annotated research guide to internet references. Milton Keynes: Lightning Source, 2004.
4. Colquhoun MC, Handley AJ, Evans TR. ABC of resuscitation. 5th ed. London: BMJ Books, 2004.
5. Handley AJ, Monsieurs KG, Bossaert LL. European resuscitation council guidelines 2000 for adult basic life support. Resuscitation 2001;48:199-205.