Basic Airway Assessment: It’s as easy as… 1-2-3?

In Medical Concepts by Rob Woods8 Comments

In medical school, many multiple-choice questions in the setting of an acutely ill patient have an option of “managing the ABC’s” and it is always the correct answer.  Unfortunately, saying “I would manage the ABCs as my first priority” is very different from actually knowing how to assess an airway, let alone managing abnormalities during a trauma resuscitation.

If you think this is going to be some crazy airway blog post, think again.  This isn’t a sexy topic on cool, cutting-edge airway interventions…. It’s a bread and butter BoringEM topic that deserves attention. Read on for an approach to basic airway assessment.

Misconceptions about the “A” of ABC

The biggest misunderstanding is around the A of the ABC’s: Airway. In the trauma room I regularly hear the statement, ‘They are talking, so their airway is patent’.  This is inaccurate.  Patency is our primary concern in airway assessment, but the patient who can talk does not necessarily have a PATENT airway.  Think about a patient with bad airway edema from a laryngeal fracture, or a patient with an inhalational injury.  They can talk, but their airway may be closing nonetheless.  The ability to talk usually implies a PROTECTED airway, not a patent airway.  Lack of airway protection is a less urgent matter than patency.

PATENCY is assessed through the presence/absence of obstructive symptoms (stridor, secretions, snoring, etc.), or findings suggesting an airway that may become obstructed (singed nasal/facial hair, carbonaceous sputum, stab to neck with risk of expanding hematoma).

Managing the Airway

The next issue is that the indications for definitive airway management involve both airway and breathing, so just because the airway is patent and protected, it doesn’t mean the patient won’t need to be intubated.

In general, the indications for intubation are (Walls et al., 2012):

  1. Failure to oxygenate
  2. Failure to ventilate
  3. Failure to maintain airway patency
  4. Anticipated clinical course: going for imaging/OR (airway or breathing)

1 and 2 relate to breathing issues, 3 is about airway patency, and 4 is about airway protection.

Look before you Leap:  Assess the airway for difficulty of potential interventions

From here, there is confusion about assessing the airway for PATHOLOGY (patency and protection issues) versus INTERVENTIONS such as: Bag-Valve Mask ventilation (BONES or BOOTS), difficult Laryngoscopy & Endotracheal Intubation (LEMON), difficult Laryngeal Mask Airway (RODS) and difficult Surgical Airway (SHORT).

Deciding that something is wrong with the airway SHOULD be the easy part, and simple interventions will deal with the most immediate airway issue of obstruction. (These simple interventions being:  suction, jaw thrust, oral-pharyngeal airway, supplemental O2).

Deciding if a definitive intervention (i.e. intubation) is required and how to go about that takes a lot more experience and training. The table below contains mnemonics for assessing a patient for intubation, bag-malve-vask ventilation, LMA placement, and cricothyrotomy.

Airway mnemonics modified from the STARSTM Manual & Walls et al. (4th edition)

Difficulty Endotracheal Intubation Difficult Bag-Mask-Valve (BMV)
L   Look externally
E   Evaluate 3-3-2
M  Mallampati*
O  Obstruction/Obesity
N  Neck Mobility**
B Beard
O Obstructed/Obese/OSA
N Neck Stiffness / Neck Mass
E Expecting (Pregnant)
S Stridor / Snores (OSA)**
Difficult Laryngeal Mask Airway (LMA) Difficult Cricothyrotomy
R  Restricted Mouth Opening
O  Obstruction
D  Distorted airway anatomy
S  Stiff Lungs / Neck
S  Surgery
H  Hematoma, Have Infection (Abscess)
O  Obesity
R  Radiation
T  Trauma, Tumor

* this is of limited use in non-elective intubations (e.g. Trauma)
** technically, can add an extra “S” behind all these mnemonics, since Stiff Lungs always makes any positive pressure ventilation strategy more difficult.

A suggested approach to basic airway assessment

My approach to airway assessment for PATHOLOGY is to assess the “S’s” in 3 steps:

The S’s of Airway Pathology

Step 1: Is there evidence of airway OBSTRUCTION now – is it complete or partial?

Complete Obstruction:
Silence without chest rise or
See-Saw Chest movement (chest down, abdo up with attempted respiration – resulting from diaphragmatic excursion with a closed glottis/obstructed tongue)

*Complete airway obstruction needs immediate intervention – cardiac arrest is likely within seconds to minutes of complete airway obstruction.

Partial Obstruction
Stridor – airway swelling/compression by hematoma
Secretions – saliva, blood
Snoring – tongue relaxation
Smash – risk of teeth/blood in the airway

Interventions:
SIMPLE = jaw thrust, suction, OPA, supplemental Oxygen, BVM
ADVANCED = Definitive airway management

Step 2: Is there a risk of ANTICIPATED airway obstruction?

Singe or Sputum (carbonaceous) – risk of delayed airway swelling from inhalational burn
Stab or Swelling neck – risk of delayed airway compression from expanding hematoma or neck mass

Interventions:
Frequent re-assessment, early intervention (if skilled), early consultation with experts

Step 3: Is there a risk of Aspiration from failure to PROTECT their airway?

Sleepy (low GCS)

Interventions:
Definitive airway management if decreased LOC (impaired gag reflex) is going to be prolonged, is not easily reversible, is deteriorating, or if intubation will facilitate further investigations (ie CT Scan).

The level of consciousness can always change and along with it the ability to protect the airway from aspiration, however aspiration is not an immediate event the second your GCS hits 8 or less.  GCS < 8 is not an absolute indication for intubation.  Many intoxicated patients and post-ictal patients live with a GCS or 5 or 6 and wake up a few hours later.  They don’t usually aspirate, and can be managed without definitive airway protection. Alternatively the head-injured trauma patient with a GCS of 12 at presentation that is a 10 now probably needs definitive airway management.

Conclusion

Always assess the S’s of the Airway.  If they are all normal, you can be confident that you are NOT dealing with an immediate or impending airway issue of patency or protection.  If there are abnormalities in the S’s, simple airway interventions will temporize the situation until more experienced providers can assist with definitive airway interventions. The table below summarizes the three steps and nine S’s. This approach is illustrated in 3 cases below.

  Step 1: Is there evidence of airway obstruction now? Step 2: Is there a risk of anticipated airway obstruction? Step 3:Is there a risk of Aspiration from failure to PROTECT their airway?
Signs Symptoms Complete Obstruction
Silence without chest rise
or
See-Saw Chest movementPartial Obstruction
Stridor – airway swelling/compression by hematoma
Secretions – saliva, blood
Snoring – tongue relaxation
Smash – risk of teeth/blood in the airway
Singe or Sputum (carbonaceous) – risk of delayed airway swelling from inhalational burnStab or Swelling neck – risk of delayed airway compression from expanding hematoma or neck mass  Sleepy (low GCS)

Cases

Case 1

44 y o male, assaulted to head/face with baseball bat.  Brought to ED in sitting position in c-spine precautions, normal Vital Sign, GCS 15.

Airway Assessment for Pathology:
Deformed nose bleeding into pharynx, difficulty opening mouth/sore jaw, spitting up blood continuously.  No trauma to neck, no stridor, no singed hairs or carbonaceous sputum, no see-saw respirations.

Q: What is going on with this patient’s airway?  What should you do immediately?
A: Partial airway obstruction from blood.  Awake and protecting airway.  Manage this airway with suction +/- supplemental O2, upright positioning.

Airway Assessment for Intervention:
History of Sleep Apnea, Obese, Beard, Unable to open mouth (likely from mandible fracture), and no neck mobility (c-spine collar).

Q: How should you proceed?
A: This person is a predicted difficult BVM, Laryngoscopy, LMA and Surgical Airway!  If you do need to intervene for a drop in GCS or loss of patency you would need additional airway experts to definitively manage this airway safely. 

Case 2

36 y o female single vehicle rollover on highway, brought in c-spine precautions.  GCS initially 15/15 by EMS, no signs of external head injury/trauma, complaining of abdominal pain.  Initial Vitals: HR 115, BP 92/68, RR/O2 sats normal.  On arrival to hospital, GCS now 11, HR 130, BP 68/40 with a distended abdomen (not pregnant).

Airway Assessment for Pathology:
Snoring respirations. No secretions, stridor, see-saw resps, singe or stab/swelling to neck.

Q: What is going on with this patient’s airway?  What should you do immediately?
A: This patient has a partial obstruction from her tongue due to decreased LOC and should be treated with jaw thrust/OPA/supplemental O2. Additionally, she may fail to protect her airway due to a low GCS secondary to hypovolemic shock.  Her ability to protect her airway is likely to correct with blood transfusion.

Airway Assessment for Intervention:
This patient has no predictors of difficult airway intervention except for a c-spine collar.

Q: How will you proceed?
A: Don’t just do something… Stand there!  Intubation comes with a significant risk of hypotension, both from the drugs given as well as the effect of positive pressure ventilation on pre-load.  You would NOT want to intubate this patient until their BP improved, or you might end up running a code.  If their BP improves, it is likely that their LOC will as well, so you probably won’t need to intubate at all.

Case 3

14 y o male flipped his quad, with quad landing on his head, brought in c-spine precautions.  EMS reports the helmet to be split in two.  GCS 12 (E4, V3, M3) with blood draining from both ears.  No visible trauma to chest/abdo or extremities.  HR 55, BP 177/94, RR/O2 sats normal.

Airway Assessment for Pathology:
Low and declining GCS. No see-saw resps, snoring, secretions, stridor, smash, stab, singe.

Q: What is going on with this patient’s airway?  What should you do immediately?
A:  This patient is at risk of failing to protect airway and has obvious signs of skull fracture for which they will need a CT scan.  Although the GCS is more than 8, it is deteriorating.  Also, the most predictive aspect of the GCS is the motor score.  As this patient is demonstrating flexor posturing and early Cushing’s response (hypertension/bradycardia), there is a high likelihood of intra-cranial injury.  This patient will likely need to be intubated.

Airway Assessment for Intervention:
There are no predictors of difficult airway intervention in this patient except for c-spine collar.

Q: How will you proceed?
A:  You need to get definitive control of this patient’s airway.  Hypoxemia and hypotension contribute to secondary brain injury, so management of this airway should pay close attention to these issues.  You would want to use apneic oxygenation as part of your RSI to mitigate the risk of hypoxemia, and choose a sedative agent that will maintain their blood pressure.

Case 4

56 yo female trapped in a housefire, no traumatic injuries.  Wheezy and SOB on scene once extricated from hospital, treated with Salbutamol nebulizer en route to hospital by EMS.  Wheeze/SOB settled upon ED arrival. Normal vital signs, GSC 15.

Airway Assessment for Pathology:
Black soot at the back of the throat, singed eyebrows.  No stridor, secretions, snoring, see-saw respirations, stab.

Q: What is going on with this patient’s airway?  What should you do immediately?
A: There is an impending loss of airway patency from airway edema.  Consider early intubation before airway before the swelling makes passing an Endotracheal tube difficult or impossible.

Airway Assessment for Intervention:
No predictors of difficulty for airway intervention.

Q: How will you proceed?
A:  Early definite airway management under the auspices of impending airway loss.  It’s impossible to know if she will swell in her airway or not, but if she does it could be life threatening.  Early management is the usual approach if there is reasonable suspicion for inhalational burn, although at times it is an unnecessary intervention.

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  • George Farjou

    Dr. Woods – amazing article that provides an easy approach for clerks and residents. Often we mindlessly say “assess the ABCs” with nobody actually questioning if we actually know HOW to assess them. Great start and can’t wait to read more on Breathing and Circulation!

    • Rob Woods

      Thanks George. I’d be happy to add B and C down the road. I don’t find as many misconceptions about them as Airway, so I haven’t been as motivated to post about it. In general, I believe the primary survey in trauma should be a series of questions you try to answer for yourself. Airway has three questions, as seen in the post. Breathing has 2: Does this patient need a needle decompression for tension pneumo AND does this patient intubation for respiratory failure? Circulation has 2 questions: Does this patient display signs of shock AND where is the source of the bleeding? Disability has 2 questions: Does this patient need acute therapy for high ICP/herniation AND does this patient have signs of a spinal cord injury? Exposure has 2 questions: Is my patient hypothermic AND do they have any hidden injuries (log roll, skin folds)? If you approach it from a goal for each area, you are more purposeful with your data collection, and you don’t miss important information.

      • Chris Bond

        Hey Rob,

        Great post. If you have time in your hectic schedule, you should post all the questions for B-E together as one second post. There is a lot of great teaching in this comment alone.

        Cheers,

        Chris

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  • Anonymous

    I don’t understand – the definition of patent that I know of essentially means “open, not obstructed”. If the person is talking, the airway has to be open. If it is blocked, sound cannot be generated. Or perhaps molecules moving may create sound, but voice/words will not be generated against a closed off tube.

    You give an example of laryngeal fracture and an airway closing from oedema….would it not then be correct to say the airway is patent? It’s not yet closed off. Might not be protected due to anticipated clinical course, but for now at least, it is still patent, even if partially.

    Am I missing something big here? Could you please further explain?

    • Rob Woods

      Hi Anonymous,

      Yes the definition of patent means ‘open, not obstructed’. Practically you should NOT consider partial obstruction and impending obstruction as patent. Just because it is not completely obstructed, it does not mean that patency is not an issue. Complete airway obstruction is a fatal event within seconds to minutes, so as a result, you will likely not deal with it in the hospital very often. Partial airway obstruction or impending airway obstruction are the airway concerns you will see and need to recognize. By the time patients develop stridor or other signs of advanced airway obstruction, more than 50% of their airway lumen is either collapsed or swollen. Definitively managing the airway at that point is challenging, and as a result, waiting until that happens could be catastrophic for the patient.

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  • Rye

    What about the edentulous patient? Is that under SMASH?