The airway becomes more difficult to manage, for numerous reasons.

Bag-mask ventilation becomes more difficult:

  • The nasal mucosa is engorged, which means there is greater resistance to flow
  • The upper airway mucosa is oedematous
  • There has been weight gain

Laryngoscopy becomes more difficult:

  • Upper airway oedema
  • Breast enlargement
  • The Mallampatti grade changes during pregnancy, largely because of oedema of the pharynx, and due to weight gain. It gets even worse with labour.

Less time is available for intubation:

  • Decreased FRC, less time to intubate
  • Increased oxygen consumption, less time to intubate

Intubation is more risky

  • Increased risk of aspiration, decreased stomach emptying

References

Oh's Intensive Care manual:

Chapter 64   (pp. 684) General  obstetric  emergencies by Winnie  TP  Wan  and  Tony  Gin

Chapter 65   (pp. 692) Severe  pre-existing  disease  in  pregnancy by Jeremy  P  Campbell  and  Steve  M  Yentis

Munnur, Uma, Ben de Boisblanc, and Maya S. Suresh. "Airway problems in pregnancy." Critical care medicine 33.10 (2005): S259-S268.

Jeejeebhoy, Farida M., et al. "Management of cardiac arrest in pregnancy: a systematic review." Resuscitation 82.7 (2011): 801-809.

Kodali, Bhavani-Shankar, et al. "Airway changes during labor and delivery."Anesthesiology 108.3 (2008): 357-362.