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There is a wide variety of equipment that can be used to support a patient’s airway and at first glance, it can seem a little overwhelming. This article aims to provide a basic overview of the most common airway equipment you may come across on the wards and in theatre.


Introduction

Airway management aims

  • Ensure airway patency
  • Ensure ventilation of the lungs
  • Protect the lungs from soiling

Nasal cannula

  • Used for mild hypoxia and in non-acute situations
  • Delivers 24-30% O2 (maximum flow rate of 4L/min)
  • Tubing is placed around patient’s face with prongs positioned at nostrils
  • Tubing can be secured behind the patient’s head or around their ears
  • Caution – high flows will dry and irritate nasal passages
  • Caution – does not allow close control of FiO2

Nasal cannula 1


 Hudson mask

  • Used in mild hypoxia and non-acute situations
  • Delivers 30-40% O2 (flow rate 5-10L/min)
  • Mask is positioned over the patient’s nose and mouth with the elastic strap behind their head
  • Caution – does not allow close control of FiO2

 


Reservoir mask

  • Used for acutely unwell patients
  • Aims to provide high FiO2 concentrations as the oxygen is inhaled from the reservoir alongside the oxygen source
  • Delivers approximately 70% O2 when used with a 15L flow rate
  • Mask fits over the patient’s nose and mouth and can be secured to the face using elastic straps
  • Ensure the reservoir bag has filled by temporarily obstructing the valve before positioning on the patient
  • Caution – the mask is not tightly sealed so some entraining of surrounding air is unavoidable. It is therefore not a true fixed performance device.

 


Venturi mask

  • Designed to deliver constant FiO2 regardless of patient’s respiratory rate and flow pattern
  • Often used in patients with chronic obstructive pulmonary disease (COPD)
  • Fits over the patient’s nose and mouth like a Hudson mask
  • Details of required flow rate and percentage oxygen delivery are detailed on the coloured fittings (see below)
Flow rate required (L/min FiO2 delivered
Blue 2-4 24%
White 4-6 28%
Yellow 8-10 35%
Red 10-12 40%
Green 12-15 60%

 

Venturi masks


Humidified oxygen

  • Standard oxygen gases have a drying effect on the mucous membranes that can result in airway damage, heat and fluid loss. Humidified oxygen reduces this effect and can assist in breaking down a patient’s respiratory secretions, making them easier to clear.
  • Most effective when the gas reaching the alveoli is at body temperature (37ºC) with a relative humidity of 100%
  • Oxygen is passed through a humidifying device producing sterile vapour before travelling in “Elephant” tubing to a face mask covering the patient’s nose and mouth
  • Caution – water can pool in oxygen tubing. This needs to be drained regularly.

Airway intervention overview

Table of airway interventions

Airway intervention Is the airway protected?
Airway manoeuvres No
Oropharyngeal (Guedel) Airway No
Nasopharyngeal airway No
iGel No
Laryngeal Mask No
Proseal laryngeal mask No
Endotracheal tube Yes
Fibreoptic intubation Yes
Cricothyroidotomy Yes

Airway manoeuvres

The overall aim is to lift the tongue and soft tissues of the pharynx anteriorly in order to open the airway.

 

Head-tilt, chin-lift

  • Place one hand on the patient’s forehead and the other under the chin
  • Tilt the forehead back whilst lifting the chin forwards to extend the neck

 

 

Jaw thrust

  • Use both hands to apply force behind the ramus of the mandible, displacing the lower jaw forwards and upwards

Jaw thrust 2

 


Oropharyngeal (Guedel) airway

  • An oropharyngeal airway can help prevent the tongue and soft tissues of the pharynx from obstructing the airway.
  • There are a variety of sizes available for children and adults
  • Size airway by measuring it against a patient’s face – when the tip is placed at the angle of the jaw the flange should align with the centre of the top teeth (hard airway = measure “hard to hard”)
  • Insert into the patient’s mouth upside down, pass to the back of the throat and rotate 180 degrees to fit behind the tongue base. In children, insert the right way up.
  • Caution – poorly tolerated in semi-/conscious patients as it induces a gag reflex. Can cause trauma to teeth or oral mucous membranes.


Nasopharyngeal airway (NPA)

  • Used to bypass obstructions in the mouth, nose, nasopharynx or base of tongue
  • Size the NPA by measuring from the tip of patient’s nose to the tragus of the ear (soft airway = measure “soft to soft”). The diameter should not exceed that of the patient’s little finger.
  • Lubricate the tip of NPA, insert it into the right nostril and aim perpendicular to the face to pass along the nasal passage and down into the pharynx.
  • The NPA tip should sit just above the epiglottis and the flange should be at the tip of the nose.
  • Caution – should not be used in patients with suspected base of skull fracture. Also can cause trauma to the nostril.

Nasopharyngeal airway


Supraglottic airways

  • A group of airway devices that sit abutting the larynx, above the vocal cords
  • Used as alternatives to endotracheal airways in short or low-risk anaesthetic cases
  • Can also be used in prehospital and cardiac arrest settings to achieve more secure airway without endotracheal intubation
  • If placed in cardiac arrest, cardiac compressions do not need to be interrupted as ventilation can be delivered simultaneously
  • Different types of supraglottic airways are described below with varying advantages/disadvantages

 

Complications/contraindications:

  • Supraglottic airways do not protect against aspiration and therefore do not provide a definitive airway.
  • Other complications include gastric insufflation, laryngospasm and partial airway obstruction.
  • Supraglottic airways should not be used if there is poor mouth opening, pharyngeal pathology or obstruction at/below the level of the larynx.

 

Insertion method:

  • The patient is positioned supine, with the neck flexed and head extended at the atlanto-occipital joint.
  • The tube is inserted blind into the patient’s mouth and guided over the tongue until resistance is encountered.
  • The tube can then be connected to a ventilation device and airway patency confirmed with chest movement, fogging of the tube and a CO2 trace.
  • If there is no CO2 trace present, the airway is not patent and must be removed or adjusted.

Laryngeal Mask Airway (LMA)

  • Reusable supraglottic device
  • Silicone rubber tube ending in elliptical, spoon-shaped mask designed to fit over the larynx
  • Inflatable mask rim forms a low-pressure seal over the laryngeal inlet
  • Reinforced laryngeal masks are available to prevent kinking
  • “Proseal” is a type of LMA that has an additional inflatable segment that allows greater seal within the larynx and a gastric port for drainage of gastric secretions

Proseal LMA (on left) // Standard LMA (on right)

 

iGel

  • A single-use supraglottic airway device
  • Non-inflatable thermoplastic elastomer that has been designed to create an anatomical seal around the larynx and peri-laryngeal structures when warmed to body temperature
  • Inserted as above and does not require inflating to form a seal

iGel in plastic case


Self-inflating bag valve resuscitator

  • Otherwise known as an Ambu Bag, Bag Valve Mask (BVM), self-inflating bag or manual resuscitator
  • The ability to use a BVM is an essential skill for airway management
  • Typically used to provide oxygenation and ventilation prior to placement of a definitive airway
  • The device consists of a face mask (variable size based on the patient) attached via a shutter valve to a flexible air chamber. The tubing connects the BVM to flowmeter or oxygen cylinder.
  • When the face mask is placed firmly over the patient’s face to create a seal, air entrainment is reduced and high oxygen concentrations can be delivered. If a reservoir bag is also used, it is possible to achieve an FiO2 of 100%.
  • Patients can breathe spontaneously through the system or can be ventilated by squeezing the bag provided there is a firm seal between the mask and the patient’s face.
  • Typically one person performs the airway opening manoeuvres and holds mask onto the patient’s face with an effective seal and a second person squeezes the bag. If practised, one person can both hold the airway open and ventilate using the bag.
  • The shutter valve and bag can also be connected to airway devices such as LMA, iGEL or ETT.

Bag valve mask (BVM)


 Suction

  • In emergency situations, unprotected airways are at risk of soiling from secretions, saliva, gastric contents, blood or other debris. Suction is therefore essential to clear the airway as well as improve the view during laryngoscopy.
  • Suction devices should be available in all hospital bed spaces. Portable devices are also available for patient transfers.
  • Yankaur Suction refers to a firm plastic tube with a large opening that is used to clear the oropharynx.
  • Suction catheters are long, flexible tubes that can be inserted into an ETT or tracheostomy tube to clear secretions from within the airway.

Suction


Laryngoscopes

  • Laryngoscopy refers to the process of visualising the larynx and can be direct or indirect. It is performed when attempting to pass an endotracheal tube through the vocal cords in order to achieve a definitive, protected airway.
  • Laryngoscopes are used to facilitate endotracheal intubation as part of Rapid Sequence Induction (RSI) or modified induction of anaesthesia. This should only be performed by trained clinicians. Specific guidelines and checklists for advanced airway management are available.
  • Macintosh Laryngoscopes consist of a handle (with battery inside) and attachable blades of different sizes. Each blade has a light that allows visualisation of the vocal cords. It is essential to check the connection and light before use.
  • Laryngoscopes are held in the left hand. The blade is inserted along the right side of the tongue and positioned in the groove between the tongue and epiglottis. Soft tissues are lifted in the direction of the handle to reveal the vocal cords.
  • Video laryngoscopy refers to a laryngoscope blade with a camera that allows the larynx and vocal cords to be seen on-screen beside the patient’s bed. Video laryngoscopy is used in airways where direct visualisation of the airway may be difficult. This is often not useful in patients with blood or secretions in the airway as the camera becomes obscured.

Laryngoscopes


Endotracheal tubes

  • Endotracheal tubes (ETT) vary in length and diameter.
  • The general sizing rule is 7.0 for women and 8.0 for men. Guidelines are available to calculate appropriate tube size for children based on weight.
  • One end of the tube has a universal plastic connector that fits bag valve masks or a variety of ventilator tubing types. The distal end is shaped to ensure ventilation of both right and left bronchi and has a small hole (known as Murphy’s eye) which can be used for ventilation should the end of the tube become obstructed.
  • Centimetre markings indicate the depth to which tube has been inserted. In normal adults, a tube should sit 20-24cm at the teeth.
  • An inflatable cuff seals the trachea to protect against airway contamination and gas leaks. The cuff and pilot balloon should be tested before the tube is used.
  • Variations include tubes with additional suction ports to remove secretions above the cuff, reinforced tubes with metal rings to reduce kinking and nasal endotracheal tubes for intubation of the trachea through the nose.

Endotracheal tubes


Gum elastic Bougie

  • Slender, flexible instrument that can be moulded into a curved shape
  • Placed into the airway under direct/indirect guidance before an ETT is railroaded over the top
  • Used for potentially difficult airways

Bougie


Tracheostomy tube

  • Used to bypass the upper airway, allowing a patient’s trachea to be ventilated through the front of the neck.
  • Different insertion techniques are used based on the urgency of the situation:
    • Cricothyroidotomy is performed in emergencies such as airway obstruction using needle or scalpel dissection to insert airway through the membrane between the cricoid and thyroid cartilage.
    • Surgical tracheostomy refers to an airway inserted directly through trachea below the cricoid cartilage. It is performed by trained ENT surgeons in a controlled operating theatre environment.
  • A variety of specialised tracheostomy airway devices can be used based on the patient requirements.

Tracheostomy


Monitoring

Pulse oximetry

  • Pulse oximetry is placed peripherally on the fingers, toes or ears.
  • The pulse oximeter estimates arterial saturation of oxygen. Based on oxyhaemoglobin dissociation curve, when saturations are below approx. 90% any fall in arterial partial pressure of oxygen will give a sharp fall in recorded oxygen saturations.
  • Pulse oximetry is affected by the poor perfusion of the peripheries, false nails/nail varnish, excessive motion and carboxyhaemoglobin

Pulse oximetry 3

 

Capnography

  • Capnography is essential in determining patency of the airway.
  • CO2 is only produced in the lungs and therefore the presence of CO2 in expired gas confirms that the patient is being ventilated.
  • Capnography is used to confirm the position of an ETT in the trachea. If there is no CO2 trace following intubation, the ETT must be removed and/or replaced.
  • The shape of a CO2 curve can give an indication of the efficacy of ventilation.

 

Capnography


References

1. Nasal cannula: By BruceBlaus (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

2. Jaw thrust: By Randhillon (Own work) [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons

3. Pulse oximeter: By Thinkpaul (Own work) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons