OSCE Station #13 for the Primary

Last updated on Jul 29, 2024

Practical skills station

You are the anaesthetic registrar on call for the evening.

Your CT1 colleague has called you for assistance, having independently anaesthetised an ASA1 patient for an appendicectomy.

It was a grade 1 intubation and they have just transferred the patient to the operating table, and connected to the machine.

Please assess and manage the situation as you would in your day to day practice.

All of the equipment required will be provided for you.

Station set up

This is a practical skills station of moderate fidelity. The manikin may be of variable completeness but the only requirement is that it can be intubated.

Manikin intubated attached to anaesthetic machine
Endotracheal tube tied at 26cm at teeth
Sevoflurane running with O2/Air mix
Drapes over patient
Equipment available to candidate - laryngoscope, IGEL, LMA, BVM and facemask, stethoscope

Monitor set up

Low tidal volumes
High pressure alarm
SPO2 to decrease from 95% to 85% over the first minute of the station*
Airway pressure 40
FiO2 0.4

*As soon as the candidate finds and manages the problem, the sats rapidly increase. If the candidate does not solve the issue, or only applies 100% oxygen, the sats continue to drop.

Mark scheme

Notes abnormal observations - 2 marks
Switches to 100% oxygen and increases flow rate - 2 marks
Uses stethoscope to listen to the chest - 2 marks
Assesses tube position at the teeth - 2 marks
Deflates cuff and withdraws the tube - 2 marks
Re-assesses the chest with stethoscope - 2 marks
Reduces the FiO2, flow and adjusts sevoflurane appropriately - 2 marks

What other therapeutic manoeuvres may be required?

Increasing PEEP
Recruitment manoeuvre
Hand bagging

Any 2 for 2 marks

What was your differential diagnosis for this clinical picture?

Pneumothorax
Airway obstruction
Accept any cause of significant shunt

Any 2 for 2 marks

Why did the patient not respond to 100% oxygen?

Large shunt due to endobronchial intubation - 2 marks

Tips and Tricks

If bad stuff is happening quickly in a practical skills scenario, there's a good chance it's an A problem, because A is the examiners' favourite letter to assess*.

*Well, it's definitely in the top three.

If you get into the habit of immediately:

Applying 100% oxygen
Increasing flow
Assessing the tube position at the teeth and checking the breathing system tubing back to the machine
Listening to the chest

Then you'll quickly pick up on pretty much any airway problem they can throw at you.

(e.g. the examiner deliberately standing on the tubing)

Signs of Endobronchial intubation

A tube that's rather too many cm at the teeth (more than 25cm should be raising an eyebrow)
High pressure alarms
Poor sats despite a raised FiO2
Poor tidal volumes
A generally angry ventilator
You might also see unilateral chest rise and hear unequal breath sounds

💡

If the tip of the tube is in the right main bronchus, the murphy's eye will often still provide a little ventilation to the other lung, so hearing breath sounds on both sides doesn't rule out endobronchial intubation.

Key times to think about endobronchial intubation

When you have a short patient
When you have an obese patient
When you position the patient head down
In little kids where any head movement can move the tube in the trachea quite substantially

ChatGPT wrote us a poem about endobronchial intubation

In the depths of the airway's gentle curve,
Where breaths should flow with quiet verve,
A tube misplaced, a path astray,
Brings forth a challenge, come what may.

Endobronchial, the word so vast,
An intubation's shadow cast,
A breath intended for both lungs,
Now whispers where a song's unsung.

One lung's breath, the other's still,
A silent chest, an urgent thrill,
The signs arise, uneven chest,
A gasping call for urgent quest.

The patient stirs, discomfort clear,
A wheeze, a drop, a rising fear,
A prompt review, a careful ear,
To guide the tube where lungs adhere.

First, check the tube, confirm its place,
A stethoscope to lead the chase,
A chest rise missed, a capnograph,
These tools will guide, avoid the gaffe.

Adjust the depth, a measured slide,
Until the breath is not denied,
Withdraw, recheck, ensure the flow,
In both lungs now, a steady glow.

If signs persist, a different sight,
A chest X-ray to shed the light,
A picture clear, a view precise,
To see the tube in airway's slice.

Correct the course, return to norm,
Restore the breath, a vital storm,
A team at hand, with skill and grace,
To set the tube in proper place.

Through careful checks, the path aligned,
The breath restored, the patient fine,
A lesson learned, a skill refined,
In airways’ depths, we are defined.

Here's a highly useful page from Deranged Physiology

(Shared with permission - click the image to go to the full page on pathalogical capnography waveforms)