Respiratory failure in pregnancy poses unique challenges, as you are ventilating two circulatory systems using only one set of diseased lungs. Gas exchange will be complex. It is hard enough ventilating and oxygenating the mother, but then you need to take into account the fact that the foetus is in there, with its own brand of haemoglobin. On top of that, there is the various drug selection and position limitations on the patient (i.e. good luck turning her prone). In short, everything becomes more difficult, includng the social scenario (particularly if the family are then expected to help with decisionmaking regarding ongoing foetal or maternal survival).
This topic has come up a couple of times in the SAQs. Question 26 from the second paper of 2010 presented a (then-topical but 12 months late) scenario of a pregnant patient with H1N1 influenza, and Question 12 from the second paper of 2006 asked more broadly about the possible causes of respiratory failure in of the pregnant woman. Specifically, sudden respiratory failure was being asked about. Clinical features which discriminate between these different causes were sought.
A good thorough resource for this topic can be found in UpToDate. For those cursed with poverty, one can recommend this 2015 review article by Stephen Lapinsky. Management strategies and caveats are well-explored by Jain et al, 2015.
This list could be super long, seeing as pregnant human beings remain susceptible to the causes of respiratory failure which affect the normal non-pregnant population. Thus, here is an abbreviated list of respiratory disorders which are somehow (at least loosely) associated with pregnancy, and which have a sudden (or at least subacute onset. As such, this table makes a suitable answer for Question 12 from the second paper of 2006.
|Cardinal features and brief discussion
|High epidural/spinal block
|Amniotic fluid embolism
|Pre-eclampsia leading to pulmonary oedema
|Tocolytic-associated pulmonary oedema
(also known as Hamman's syndrome)
|Accidental magnesium overdose
|Causes which are not unique to pregnancy, but which commonly co-exist with pregnancy
|Peripartum opiate use
Major pregnancy-related limiting factors which complicate the management of ARDS are as follows:
Thus, a management strategy mentioning all the important points would resemble the following list: