Airway management: hypoxaemia during one-lung ventilation: 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 · Airway management: hypoxaemia during one-lung ventilation

Sample item

During right thoracotomy with left lung ventilation, saturation falls to 85% and the double-lumen tube position has been confirmed by bronchoscope on 100% oxygen. What should be done next?

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

The answer and the reasoning

D. Apply low-level CPAP to the collapsed operative lung

After correcting tube position and giving 100% oxygen, CPAP to the operative lung provides oxygen to the shunting lung, and PEEP can be added to the dependent lung. Large tidal volumes raise pulmonary vascular resistance in the ventilated lung and divert blood to the collapsed lung.

Option by option

  • A. Lower the inspired oxygen concentration to 40%

    Lowering oxygen worsens hypoxaemia.

  • B. Add nitrous oxide to the mixture

    Nitrous oxide displaces oxygen and is unhelpful.

  • C. Increase the tidal volume to 12 mL/kg

    Large tidal volumes increase resistance in the dependent lung and increase shunt.

  • D. Apply low-level CPAP to the collapsed operative lung (correct)

    Correct. CPAP oxygenates blood passing through the non-ventilated lung.

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.

More Anaesthesia questions

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is D, Apply low-level CPAP to the collapsed operative lung. After correcting tube position and giving 100% oxygen, CPAP to the operative lung provides oxygen to the shunting lung, and PEEP can be added to the dependent lung.

Why is "Lower the inspired oxygen concentration to 40%" not the answer?

Lowering oxygen worsens hypoxaemia.

Why is "Add nitrous oxide to the mixture" not the answer?

Nitrous oxide displaces oxygen and is unhelpful.

Why is "Increase the tidal volume to 12 mL/kg" not the answer?

Large tidal volumes increase resistance in the dependent lung and increase shunt.

What concept does this question test?

It tests Airway management: hypoxaemia during one-lung ventilation in Anaesthesia. Large tidal volumes raise pulmonary vascular resistance in the ventilated lung and divert blood to the collapsed lung.

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 Airway management: hypoxaemia during one-lung ventilation?

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.