Difficult Mask Ventilation

Question 1

Define difficult mask ventilation

Answer 1

It is not possible for the unassisted anaesthetist to maintain SpO2 >90%, using 100% oxygen and positive pressure mask ventilation in a patient whose SpO2 was >90% before anaesthetic intervention

Question 2

How common is difficult BVM?

Answer 2

Estimates vary, accepted at <1 in 10000

Question 3

What are some common factors that would make you suspect difficulties with BVM?

Answer 3

BOOTS

1. Beards
2. Obese
3. Old
4. Toothless
5. Snore

Question 4

Outline steps to try and improve BVM conditions

Answer 4

1. Optimize position - neck flexion, head extension (not pillow under shoulders)
2. Appropriately sized facemask and oropharyngeal/nasopharyngeal airway
3. Two-handed mask hold with assistant squeezing bag
4. Close APL valve and increase FGF
5. Maximal jaw thrust applied with 3rd person if available
6. OPA + x2 NPAs
7. Dry perioral area, trim beard, or apply defib pad over perioral area
8. Give more anaesthetic if safe to do so

Question 5

What other factors should be considered when encountering difficult BVM?

Answer 5

Is this my technique, or some other factor?

If the reservoir bag has poor refilling, there is low circuit pressure, palpable/audible facemask leak - then it’s you

If the bag is filling well, there is good seal, or high circuit pressure - consider laryngeal spasm or factors that elevate airway pressure (see other cards)

Question 6

Despite all the best efforts, BVM remains difficult - what now?

Answer 6

1. If anticipated - consider waking the patient and adjusting the plan (eg gas induction or gradual TIVA)
2. If unanticipated and patient has received full intubating dose +/- relaxant -> ensure adequate anaesthesia and attempt LMA insertion x2
3. If LMA insertion fails - progress to RSI
4. If RSI fails - move onto CICV

Question 7

Time management is vital to prevent complications. What can assist with time management during difficult airway management?

Answer 7

Ensure enough people are available to help

Ensure all equipment is readily available

Certain drugs have faster onset times

Don’t become fixated on one thing - avoid tunnel vision

Delegate a staff member to call out elapsed time, SpO2 or EtCO2 readings