Patients requiring resuscitation may have an obstructed airway, either as the cause or as result of their loss of consciousness. Prompt assessment, control of the airway and establishment of ventilation are essential throughout resuscitation in order to prevent secondary hypoxia damage of vital organs, particularly the brain. Therefore, in both basic life support and advanced life support, management of the airway is the first priority – the “A” of “ABC”.
Obstruction of the airway may be partial or complete and occur at any level. In the unconscious patient, the commonest site of obstruction is the pharynx, which most commonly is occluded by the tongue but sometimes by other structures in the neck such as the epiglottis or soft palate. Obstruction may also caused by vomit, blood or foreign material because of trauma. Laryngeal obstruction may occur as of a result of oedema “spasm” or an inhaled foreign body. Obstruction of the airway below the larynx is less common but may occur because of excessive bronchial secretions, mucosal oedema, bronchospasm, and pulmonary oedema, aspiration of gastric contents or pulmonary haemorrhage and pneumothorax secondary to thoracic trauma.
This is best achieved by the “look, listen and feel” approach –
Look – for chest and abdominal movement.
Listen/Feel – for airway flow at the mouth and nose.
In partial obstruction, air movement is diminished and usually noisy. Inspiratory stridor is caused by upper airway obstruction whereas expiratory noises suggest obstruction of the lower airways, which tend to collapse and obstruct during expiration. Other characteristic sounds which may be heard are:
“Gurgling” – suggests the presence of liquid or semi-solid foreign material;
“Snoring” – common when the pharynx is partially occluded by the tongue;
“Crowing” – which accompanies laryngeal spasm.
The above characteristic sounds are commonly grouped together and called “stridor”
Complete airway obstruction in a patient who is making respiratory efforts, results in paradoxical chest and abdominal (‘seesaw’) movement, often exaggerated by use of accessory muscles.
This may mimic normal respiratory effort so that looking at the chest and abdomen alone is not a satisfactory method of assessing complete obstruction of the airway, which should be confirmed by the absence of breath sounds.
Obstruction in the airway should be confirmed by listening for breath sounds (or the absence) with a stethoscope.
Once any degree of airway obstruction is recognized, immediate measures must be taken to create and maintain a clear airway, initially using techniques of head tilt and chin lift, or jaw thrust.
Head Tilt and Chin Lift
Gravity alone does not explain why the airway becomes occluded by the base of the tongue, Obstruction may occur when a patient is lying supine, prone or in a lateral position.
Even holding the tongue forward using an oropharyngeal airway may not be sufficient to prevent obstruction.
In the unconscious patient, abnormal activity in various muscles of the tongue, pharynx, neck and larynx results in failure to maintain airway patency when the head is in the neutral or flexed position.
This may be overcome in most patients by the simple manoeuvre of head tilt; stretching the anterior neck muscles lifts the base of the tongue from the posterior pharyngeal wall and the epiglottis from the laryngeal inlet. Lifting the chin stretches these structures further and pulls the mandible (and thus the tongue) forward. The procedure is as follows:-
* If possible, support the head on a small pillow.
* Extend the head on the neck by pushing backwards with the palm on the forehead.
* Simultaneously place two fingers under the tip of the mandible and lift the chin, displacing the tongue anteriorly.
If a neck injury is suspected, do not tilt the head unless other methods of opening the airway have failed. To reduce the risk of exacerbating an injury, keep neck movements to an absolute minimum with in-line stabilization, but remember:
Death from hypoxic airway obstruction is more common than tetraplegia arising as a result of emergency airway manipulation.
Jaw Thrust
If head tilt/chin lift fails, jaw thrust is an alternative manoeuvre for relieving obstruction by the tongue. It can also be used when there is nasal obstruction and the mouth has to be opened to provide an airway. It is the technique of choice in patients in whom there is a strong suspicion of an injury to the cervical spine. The procedure is as follows:
* Hold the patient’s mouth slightly open by downward displacement of the chin with the thumbs
* Place the fingers behind the angles of the mandible (lower jaw) and apply steady upward and forward pressure to lift the jaw forward
These positional methods are successful in most cases when airway obstruction results from relaxation of soft tissues. After each manoeuvre, check for success by using the; “look, listen and feel” sequence. If a clear airway cannot be achieved other causes must be sought. Obvious solid foreign material in the mouth should be removed using a finger sweep and broken or displaced dentures should be removed; well fitting may be left in place as they help to maintain a seal around the mouth during ventilation.
Pharyngeal Airways
Simple airway adjuncts are often helpful and sometimes essential to maintain airway patency, particularly when resuscitation is prolonged. The position of the head and neck must be maintained to keep the airway aligned. Oropharyngeal and nasopharyngeal tubes for maintenance of the airway are designed to overcome backward tongue displacement in the comatose patient, but head tilt and additional jaw thrust are usually required as well.
Oropharyngeal Airways
Oropharyngeal (Guedel) airways are curved plastic tubes, flanged and reinforced at the oral end, with a flattened shape to ensure that they fit neatly between the tongue and the hard palate. They are available in sizes suitable for newborn babies to large adults; an estimate of the size required can be obtained by selecting an airway that corresponds in length to the distance between the corner of the patient’s mouth and the angle of the jaw. The most common sizes are 2, 3 and 4, for small, medium and large adults respectively.
During insertion of an oropharyngeal airway, the tongue may be pushed backwards exacerbating obstruction instead of relieving it. Vomiting or laryngeal spasm may occur if glossopharyngeal and laryngeal reflexes are present; hence insertion should only be attempted in comatosed patients. The procedure for insertion is as follows:
* Open the patient’s mouth and ensure that there is no material present likely to be pushed into the larynx.
* Introduce the airway into the oral cavity in the inverted position and rotate it through 180o as it passes below the palate and into the oropharynx.
Incorrect placement can push the tongue further back into the pharynx and thus produce airway obstruction.
If there is evidence of active laryngeal reflexes, such as retching or coughing, the airway should be removed to avoid the risk of stimulating vomiting or severe laryngospasm.
After insertion, check the patency of the airway and ventilation by “looking, listening and feeling” whilst maintaining correct alignment of the head and neck with chin lift or jaw thrust.
Nasopharyngeal Airways
These are made from malleable plastic, bevelled at one end and with a flange at the other. They are often better tolerated that oropharyngeal airways and may be life-saving in patients with clenched jaws, trismus, or maxillary injuries. They should not, however, be used in patients with evidence of a fractured base of skull. These tubes are sized in millimetres according to their internal diameter, the length increasing with diameter. The sizes used in adults are 6 – 8 mm (approximately the same diameter as the patients little finger). Insertion can cause bleeding from the nose or nasopharynx and if the tube is too long, laryngospasm and vomiting. The procedure for insertion is as follows:
* Check the patency of the right nostril
* Insert a safety-pin through the flange to prevent the airway being inhaled
* Lubricate the airway thoroughly
* Insert the airway, bevel end first, vertically along floor of the nose with a twisting action
* The tip should eventually lie in the pharynx
* When fully inserted, the flange should lie at the nostrils
If obstruction is met, remove the tube and try using the left nostril once in place, check patency of the airway and adequacy of ventilation by “look, listen and feel”, and maintain correct alignment of the head and neck.
If opening the airway using basic techniques, or following the insertion of a pharyngeal airway, results in the return of spontaneous ventilation, the patient should be placed in a stable lateral position (the recovery position). This reduces the risk of further obstruction and allows any vomit or blood to drain from the upper airway. If available, oxygen should be administered. A Venturi mask (the design of the Venturi mask allows air entrainment) will deliver 24% – 60% depending upon the mask chosen and a Standard concentration mask (the Standard mask does not allow air entrainment) will deliver up to 60% provided the flow of oxygen is high enough (12-15L/min). The most effective system is a Hudson mask with reservoir which can provide an inspired concentration of 85%.
Artificial ventilation must be commenced in any patient in whom spontaneous ventilation is inadequate or absent. Expired air (mouth to mouth) ventilation provides 16% inspired oxygen concentration and can be started without the need for any equipment. Some rescuers however find the technique unhygienic, particularly when vomit or blood is present. Simple adjuncts are available which can be used to avoid person to person contact, and such devices may also reduce the risk of cross infection between patient and rescuer. One such common device is a plastic film with a hole in the middle that fits over the face of the victim.
The most common device is the resuscitation mask (e.g. Laerdal pocket mask). This is similar to an anaesthetic face mask and allows mouth to mouth ventilation. It has a uni-directectional valve so that the patients expired air is directed away from the rescuer, thereby isolating the two airways. The masks are transparent to allow the direction of vomit or blood and some masks have an additional attachment which allows oxygen supplementation of the rescuers breath
Self – inflating bag, this is the most common device used to ventilate patients and explained more fully later in this handout.
Technique using facemask ventilation
* Place patient supine with head supported on a small pillow
* Apply the mask to the patients face using the thumbs of both hands
* `Lift` the jaw into the mask with the remaining fingers by exerting pressure behind the angles of the jaw (as for the jaw thrust). At the same time press the mask onto the face with the thumbs to make a tight seal.
* Blow through the Inspiratory valve and watch to ensure the chest rises and falls
* Any leaks between the face and the mask can be reduced or abolished by adjusting the contact pressure, the position of the fingers and thumbs, or altering the jaw thrust manoeuvre.
* If oxygen is available, add it via the nipple at 10 L/min.
Tracheal intubation
This is the best method of providing and maintaining a clear and secure airway. The most obvious indication for this manoeuvre is failure of all other methods of providing an airway. In addition to securing the airway it allows suction and clearance of inhaled debris from the lower respiratory tract and eliminates the risk of aspiration by regurgitated gastric contents, and blood etc. Ventilation can be achieved without leaks even when airway resistance is high (e.g. Pulmonary oedema, broncospasm) and once the tracheal tube is in place this route can be used to administer drugs.
In certain cases laryngoscopy and attempted intubation may prove either impossible or cause a life threatening deterioration in the patient’s condition (e.g. Epiglottitis, laryngeal pathology, head injury, cervical spine injury) In these circumstances, specialist skills including the use of anaesthetic drugs or fibreoptic laryngoscopy may be required.
These techniques are not for the inexperienced
Considerable training and practice is required in order to acquire and maintain the skill of intubation and repeated attempts by the inexperienced are likely to be unsuccessful, traumatic and to compromise oxygenation. Furthermore a range of equipment in good working order is required to achieve successful intubation.
A brief description of orotracheal intubation follows but this is not intended as a substitute for practice on a mannequin or, betters still, an anaesthetized patient under the direction of a skilled anaesthetist.
Ultimately when ventilation and intubation are impossible, it may be necessary to create a surgical airway using the technique of needle Cricothyroidotomy.