Airway Flashcards
Describe the gross anatomy of the upper airway.
The upper airway consists of the oral cavity, nose, and pharynx. The pharynx itself is sub-divided into the nasopharynx, oropharynx, and laryngopharynx. NB/ the lower respiratory system refers to everything below the vocal cords (tracheobronchial tree).
What are the functions of the upper airway?
Conduct, humidify and warm air. Prevent foreign materials from entering the lower airway. Contribute to speech, swallowing and smell.
What are the signs of airway obstruction (partial and complete)?
LOOK/LISTEN/FEEL!
LOOK:
- Are they conscious?
- See-saw movements/paradoxical breathing
- Accessory muscles?
- Central cyanosis
LISTEN:
Partial = coughing, gagging, stridor, dysphonia, noisy Complete = drooling, gagging, aphonia, silent
FEEL:
- Air movements at mouth?
> Yes = partial
> No = complete
List the causes of airway obstruction.
- CNS depression (GCS <8)
- Foreign body
- PNS disorder (recurrent laryngeal n. palsy/hypocalcaemia)
- Neuromuscular disorder (laryngospasm/myasthaenia gravis)
- Infection (epiglottis/bacterial tracheitis)
- Haemorrhage
- Laryngeal oedema (anaphylaxis/hereditary angiodaema)
- Trauma
- Burns
- Neoplasm (upper airway malignancy/polyp)
What is the easiest way to determine an airway is patent?
The patient is speaking to you.
How does the airway “collapse” in an unconscious patient?
Patients who are sedated, anaesthetised or unconscious, the commonest cause is the loss of airway muscle tone. The usual site of obstruction is the soft palate > epiglottis > tongue.
How do you approach an obstructed airway?
ABCDE –> A = Head tilt, chin lift OR jaw thrust (cannot perform head tilt chin lift in C-spine injury/rheumatoid arthritis as risk of atlanto-axial subluxation.
Explain the benefit of basic airway manouevres (head-tilt chin lift/jaw thrust).
Tenses the muscles at the floor of the mouth causing the hyoid and larynx to be lifted away from the posterior pharyngeal wall.
What is the commonmost cause of airway obstruction?
Loss of airway muscle tone.
What is the indication for a guedel/oropharyngeal airway?
UNCONSCIOUS patient with obstructed airway (prevents tongue from obstructing airway).
What is the contraindication for a guedel/oropharyngeal airway?
Stimulates a powerful gag reflex in conscious or partially conscious patients (if you try to insert one and a patient gags - remove the airway adjunct and replace with a nasopharyngeal airway).
How is a guedel/oropharyngeal airway inserted?
Insert the airway upside down until contact is made with the soft palate - then rotate 180 degrees.
How do you size a guedel/oropharyngeal airway?
HARD TO HARD –> Place the guedel airway from the lateral incisor to the angle of the mandible.
What is the advantage of a nasopharyngeal airway?
Prevents the stimulation of a gag reflex and therefore is indicated in the use in patients with in-tact airways (partially conscious patients).
How do you size a nasopharyngeal airway?
SOFT TO SOFT –> Measure from the nostrils to the tragus of the ear.
What are the contraindications of a nasopharngeal airway?
- Active nose bleeds.
- Nasal polyps.
- Known or suspected basal skull fracture.
What is an iGel?
iGels are the newest generation of laryngeal mask airways - a supraglottic airway. They do not need to be inflated like previous models.
What are the main benefits of laryngeal mask airways (LMAs)/iGels?
These airways free the hands of the clinician and produce less gastric distension.
What are the contraindications of LMAs/iGels?
- Non-fasted patients (risk of aspiration)
- Morbidly obese/pregnancy (risk of aspiration due to increase in intra-abdominal pressure)
- Obstructive or abnormal orophaynx.
How are LMAs sized?
LMAs are sized based on the weight of the patient. The size/weight in kg’s will be on the LMA (good tip for OSCEs).
How can you tell a patient is ventilating after LMA/iGel insertion?
Look at capnograph for end-tidal CO2 trace. No trace means the LMA is not placed correctly.
What are the disadvantages of an LMA over endotracheal tube?
- Aspiration more likely (NOT a protected airway as supraglottic)
- Air leak more likely
- Cause of laryngospasm (emergency)
Why are endotracheal tubes considered the only “protected” or “secure” airway?
Endotracheal tubes transverse through the vocal cords to sit a few centimetres above the bronchial carina - a cuff is then inflated and thereby the lungs are protected from gastric contents aspiration/other secretions.
What are the advantages of an endotracheal airway?
- Only protected airway
- Access to tracheo-bronchial tree for suctioning of secretions
- Does not cause gastric distension
