Airway Support

Original article by Tom Leach | Last updated on 28/1/2015
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Airway management is an important skill in Emergency Medicine, Critical care (including Intensive care and High Dependency (HDU)) as well as in anaesthetics.

There are many methods and adjuncts tomanaging a patient's airway.
In any situation where the patient is not able to maintain their own airway you should follow a systematic approach, and begin with the least invasive methods, in the order outlined below. Remember that these methods only provide ventilation and thus should only be used when the patient still has a pulse. If they have no pulse, and they are not breathing, then start the ALS protocol.
Also note that many of these methods are often used in conjunction with CPR as part of ALS.
 

Airway Assessment

  1. Open the patient's mouth, do head tilt and chin lift (or jaw thrust – whichever is appropriate) and check for any obstructions. If you can remove any obstruction manually with your finger, then do so.
  2. If there appears to be fluid or secretion in the mouth, use suction to remove them. Get a suction tube, tell the patient what you are going to do, and that it might be unpleasant. Put the plastic nozzle part on the end of the tube. You can squeeze the tube (put a kink in it and squeeze it) to control the flow of air. Try to be gentle!

Upper Airway Adjuncts

e.g. The patient is still having trouble breathing. They may be gasping, but they are still conscious and attempting to take their own breaths

  1. Try using a non re-breathing mask. Connect it to 15L O2
  2. Remember you may still need to open the airway by performing a head tilt / chin lift or a jaw thrust – don’t forget to keep doing this if the patient keeps moving!
  3. If the tongue keeps getting in the way, or they keep biting their mouth closed,then you should use a Guedel airway (aka oropharyngeal tube) – this is a short plastic tube that sits in the Guedel Tubemouth and prevents the tongue from falling backwards and obstructing the airway. Once inserted, don't forget to put the re-breathing mask over the mouth.
  4. Inserting the Guedel tube – choose the correct size. To do this, measure it up against the patient’s cheek – a correctly sized tube should reach from the corner of the mouth to the angle of the jaw. Once you are happy you have the right size, put it in upside down (with it curling up to roof of mouth) then once you are past the back of the tongue rotate it through 180'. 
  5. An alternative is the nasopharyngeal airway – this is a little rubber tube that you pass into the nostril. Before you insert it, have a good look around the nostril – is there trauma? Is one occluded? Are there big blisters/sores, scars, polyps? Obviously use common sense and go for a nostril that looks normal – don’t insert it if it looks like there is trauma. Normally the right nostril is slightly bigger than the left due to the natural shape of the septum.
    1. Put KY jelly on it! KY jelly is water soluble, and thus absorbed by the body when it has done its job of lubricating. Insert it slowly and carefully. Inserting it too aggressively can shear the mucous membrane, and this may cause a lot of bleeding. Rotate it gently as you pass the tube.
    2. There may be a safety pin on the end – this is just to prevent the tube being snorted up the nostril by mistake.
    3. DO NOT USE when there is head trauma – if there is a fractured base of skull there is a risk of up pushing it all the way into the brain.

Face Mask / Bag and Mask

  1. Remember to attach it to oxygen at the wall and turn it on to 15L/min. Then, standing at the head of the bed, seal the mask around the mouth with both hands, and give breaths by sequeezing the bag.
  2. It is possible to operate the bag and mask with one person, but it is probably better to have two – you need one person to make sure the mask is making a good seal, and another person to squeeze the bag. The person who is holding on the mask should also do the head tilt & chin lift / jaw thrust as necessary; lift the patient’s jaw up and into the mask – don’t push the mask down onto the patient’s face!
  3. Be careful when you squeeze the bag – if you squeeze too hard you’ll end up forcing air into the stomach. Also, bear in mind the 'bag' is usually around 2L in size, and a normal tidal volume is around 500mls. A small gentle squeeze of the bag will usually deliver enough oxygen.

Laryngeal Mask Airway

  1. Laryngeal mask airway (LMA) – these are sometimes usedas an alternative to intubation in a non-critical care setting - e.g. in theatre in patients that are expected to be straight forward. The mask is placed over the entrance to the trachea, thus alleviating any problems higher up the airway. You then ventilate the patient using a bag and 15/L O2 (or ventilator). The mask slides down through the mouth, along the hard palate, with the mask deflated. Slide it in with the mask facing the posterior pharyngeal wall – no need to do it the wrong way like with a Guedel tube. Don’t forget to use lube – although in reality, the region is often lubricated enough by natural means. Once you're happy it's in place, inflate the cuff with air using the valve. Only use about 30ml. Then check it's working by filling with air and watching the chest rise. You might also want to listen over the lungs for air flow, and over the epigastrium to check no air is going into the stomach.
  2. They are not used in emergency medicine because they do not produce a perfect seal around the airway, thus there is still a risk of aspiration. They are preferred in anaesthetics because in elective surgery, the patients are starved, thus less risk of aspiration, and there is less trauma to the airway than an ET tube.

Endotracheal Intubation

Endotracheal intubation –is THE definitive management in a patient with severe breathing difficulties. However, the patient needs to be unconscious to tolerate the tube. This often means the patient has to be sedated before they are intubated . In general, any patient with a GCS <8 is at risk of losing their airway and should be considered for intubation.

  • Ensure the patient has received adequate ventilation before attempting the procedure – this is sometimes called pre-oxygenation.  This usually means the patient has been adequately ventilated with a bag & mask for several minutes. .
  • Check that the equipment is in date
  • Check that the balloon is inflated properly – sometimes this has perished
  • Get the right size – this is roughly size 7-8 for men and size 6-7 for women. If you are unsure, then size 8 is a good all round fit.
  • Collect the rest of your equipment; syringe (for air), KY jelly, stethoscope, McGill forceps, introducer, laryngoscope.
  • Note that the laryngoscope is a left-handed tool – you hold this with your left hand and the slide the tube in with your right.
  • Get the laryngoscope – and slide it slowly and gently into the mouth. You should stand behind the patient’s head. You want to get the largnscope in as far as the epiglottic vallecula. This is the region just behind the tongue, but just in front of the epiglottis. Once you are happy the laryngoscope is here, lift up and lever the tongue out of the way – do NOT use the teeth as a pivot – you will break them. You have to lift and push the laryngoscope away from you, which can be quite heavy and difficult. At the same time, bend down and look, you need to be looking for the vocal cords. You may need to press on the patient’s forehead at this stage to keep the head still.
  • Seeing the vocal cords – once you can see these, slide the tube in. Put lube on beforehand if you think this is necessary. You should watch as the tube goes into the larynx. Push it a reasonable way in – there is a rough guide on the side of the tube to tell you where to stop
  • If you go too far you will end up in the right main bronchus. Only the right lung will inflate, and eventually the left lung may collapse.
  • Fill up the balloon – one you are happy you are in, fill up the balloon with no more than 10ml of air – as soon as you see the front of the trachea move on the surface of the neck, then stop. Usually you should put about 5ml in.
  • Check you are in – get a colleague to do the bag on the end of the tube – this should be filling up the lungs. Whilst they are doing this, you should listen on the lungs (approx 3 places on each) to check they are filling with air, and also listen of the epigastrium to check that this is not filling with air.
  • Finishing off – you might want to stick a Guedel tube in the mouth to stop them biting down on your nice endotracheal tube. Also you need to tie the tube in place – to do this use a slipknot around the tube itself, then tie the two ends around the patient’s neck.
 

Ventilation vs oxygenation

Oxygenation is just the process by which you provide the patient with a higher percentage of oxygen than is present in normal room air. Ventilation is the process by which you provide gas at a pressure, and thus do some of the ‘work’ of expanding the lungs for the patient.
Flow rates of oxygen above 5L/min will require humidification – this involves a container of water stuck to the wall where the gas comes out – helps prevent soreness and infection to the respiratory tract (particularly upper tract).
 

Invasive and non-invasive ventilation

Invasive ventilation
This involves either laryngeal mask airways, or endotracheal intubation.
Non-invasive ventilation
This is any technique that provides at least some of the effort required for ventilation, so for example, we have already looked at pocket masks, and bag & masks. Other important examples include BiPAP and CPAP.
 

CPAP

CPAP – Continuous positive airways pressure – this is a technique that was first developed for sleep apnoea. It is now most commonly used for type I respiratory failure patients (low O2, low or normal CO2).The patient is hooked up to a ventilator connected to a mask that provides oxygen. The mask is tightly sealed around the patients face.  It provides a constant flow of air – which increases the pressure, in the lungs, particularly the PEEP (Positive end expiratory pressure). This higher pressure helps to keep the airways open at the end of respiration, that would otherwise collapse. This works by:
  • Moving the dynamic closure point of the airway further distally, in a similar way to pursed lip breathing, thus recruiting more airways, and allowing for a greater gaseous exchange, and thus increasing the PaO2.
  • It can also literally force alveoli to have a larger surface area (stretch the alveoli) which can be useful in conditions where there is fluid in the alveoli, as the fluid becomes spread more thinly, and thus better gaseous exchange can occur across it
  • The pressure at which air is delivered is determined on an individual basis. The pressure is measured in cm H2O. A typical value is 4-16cm H2O.

BIPAP

BiPAP – Bi-level positive airways pressure is similar to CPAP. The equipment used is often the same, however, the ventilator used in this instance is able to detect inspiration, and adjusts to give a higher pressure during inspiration. Thus, two pressure levels are provided - one on inspiration, and one on expiration. The pressure on inspiration (IPAP) is much greater than the pressure on expiration (EPAP). The IPAP will always be higher than the EPAP!
BiPAP allows you to use higher pressures than CPAP without exposing the patient to prolonged periods of high pressure, which can cause barotrauma. 
The longer a patient receives positive airway pressure (PAP), the greater the risk of trauma.

BiPAP is used to treat type II respiratory failure (low O2, high CO2).

 
Note – that for both BiPAP and CPAP, the mask has to be held on very tightly, and create a good seal around the mouth and nose for this reason, it often has to be worn with a head strap.
 
Type I respiratory failure
Type II respiratory failure
Signs
Low O2
(<8)
Low O2
(<8)
Normal/Low CO2
(<6)
High CO2
(>6)
 
 
Causes
Respiratory depression (drugs, obesity)
 
Note: often patients progress initially from type I to type II – especially COPD patients as their disease progresses