Complications and emergencies: paradoxical air embolism: practice question

A Anaesthesia question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

Anaesthesia · Complications and emergencies: paradoxical air embolism

Sample item

A patient has a venous air embolism during a sitting-position posterior fossa craniotomy and wakes with a new right hemiparesis, although the chest is clear. Which mechanism best explains the stroke?

AParadoxical embolism across a patent foramen ovaleBFat embolism from the marrow cavity of long bonesCCardiac thrombus embolising from atrial fibrillationDWatershed infarction from prolonged intra-operative hypotension

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Paradoxical embolism across a patent foramen ovale

In the sitting position, venous pressure in the head is subatmospheric, so air is entrained into veins. If a probe-patent foramen ovale is present, a rise in right atrial pressure can push air into the left heart and the cerebral circulation, producing a stroke. Screening echocardiography is therefore done for sitting craniotomies.

Option by option

A. Paradoxical embolism across a patent foramen ovale (correct)
Correct. Air that crosses a patent foramen ovale reaches the arterial circulation and lodges in the brain.
B. Fat embolism from the marrow cavity of long bones
Fat embolism follows long bone fractures or reaming and causes respiratory, skin and neurological signs together.
C. Cardiac thrombus embolising from atrial fibrillation
Nothing in the history suggests atrial fibrillation or a cardiac source of thrombus.
D. Watershed infarction from prolonged intra-operative hypotension
Watershed infarcts are bilateral border-zone lesions and are not attributed to a documented air embolism.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is A, Paradoxical embolism across a patent foramen ovale. In the sitting position, venous pressure in the head is subatmospheric, so air is entrained into veins.

Why is "Fat embolism from the marrow cavity of long bones" not the answer?

Fat embolism follows long bone fractures or reaming and causes respiratory, skin and neurological signs together.

Why is "Cardiac thrombus embolising from atrial fibrillation" not the answer?

Nothing in the history suggests atrial fibrillation or a cardiac source of thrombus.

Why is "Watershed infarction from prolonged intra-operative hypotension" not the answer?

Watershed infarcts are bilateral border-zone lesions and are not attributed to a documented air embolism.

What concept does this question test?

It tests Complications and emergencies: paradoxical air embolism in Anaesthesia. If a probe-patent foramen ovale is present, a rise in right atrial pressure can push air into the left heart and the cerebral circulation, producing a stroke. Screening echocardiography is therefore done for sitting craniotomies.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Complications and emergencies: paradoxical air embolism?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.