A 35-year-old female is admitted to your ICU with community acquired pneumonia requiring 60% inspired oxygen via facemask. She is previously quite fit and well, and is currently 32 weeks pregnant.
Forty-eight hours later, she suffers a pulseless electrical activity (PEA) arrest.
a) What is your differential diagnosis? (30% marks)
b) Outline factors that may make successful resuscitation of this woman more challenging.(40% marks)
c) What specific alterations would you make to the standard ALS algorithm in this woman? Justify your answer. (30% marks)
Pulmonary Embolism (must state this to gain any marks in this section)
Severe Hypoxaemia (airway obstruction/lung collapse/aspiration/AFE [see below])
Amniotic Fluid Embolism
Tension pneumothorax / Tamponade (potentially post CVC etc., spontaneous unlikely)
‘Iatrogenic’ catastrophe/other: air embolism, drug error, anaphylaxis etc.
Hypovolemia (unlikely unless massive concealed bleed but possible), placental abruption
Factors relate to the underlying cause of arrest, the woman’s state pre-arrest, the physiological changes of pregnancy and the presence of a gravid uterus/unborn fetus.
Underlying cause of arrest
Lack of a rapidly reversible cause such as pneumothorax /airway obstruction.
Woman’s state pre-arrest
Severe pre-existing/worsening hypoxaemia
Physiological Changes of Pregnancy
Airway oedema and increased incidence of difficult airway and airway bleeding, high oxygen consumption and increased minute ventilation, reduced FRC, increased risk of aspiration, supine hypotensive syndrome [aortocaval syndrome], procoagulant state, chest compressions may be challenging with obesity/breast enlargement
Presence of gravid uterus/unborn fetus
Prevention of supine hypotensive syndrome [aortocaval syndrome] requires lateral tilt but chest compressions should be performed supine with manual displacement of uterus [AHA rec: see below], reduced diaphragmatic excursion due to presence of uterus with reduced FRC, poor ECHO windows especially subcostal, need for resuscitative hysterotomy and potential simultaneous neonatal resuscitation, potential for delay/hesitation in delivering indicated treatment e.g. antiarrhythmics, thrombolysis, extracorporeal support due to concerns regarding pregnancy.
Main differences are
10-15 degrees of lateral tilt during chest compressions to avoid aortocaval compression or continuous lateral uterine displacement (LUD).
Early perimortem caesarean section
Candidates often gave a routine list for cardiac arrest causes (Hs and Ts) without much specific consideration of situation. Almost no consideration given to underlying cause and pre-arrest condition of patient as factors making successful resuscitation challenging. Often no justification given for alterations to ALS algorithm
To counter the examiners' comments, one might present them with a "routine list of cardiac arrest causes" which relates the 4 Hs and 4 Ts to the specific scenario. Thus:
The "factors that may make successful resuscitation of this woman more challenging" is a strangely worded question, as it could be interpreted as almost anything. The examiner's comments about how disappointing it was that the trainees didn't give enough attention to "underlying cause and pre-arrest condition of patient" are rendered all the more bizarre given that the presented pre-arrest history of the scenario was hardly sufficient to make any judgments about the challenging aspects of the specific situation. We know that she is very pregnant, hypoxic, and previously healthy. Almost everything else is left up to the imagination (eg. are we resuscitating her in a narrow corridor? Has the registrar had enough sleep? Is this a small regional hospital with a single GP anaesthetist? Are you the baby's father?). As such, one must reinterpret the question as "what features of third trimester pregnancy make it more difficult to successfully resuscitate a pregnant patient from cardiac arrest?"
These features can be separated into categories:
The main differences to the ALS algorithm are:
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