Exam Intelligence

To everyone who is doing the exam….

We’ve had a couple of requests for articles which have been published in journals such as Anaesthesia and the BJA.  Unfortunately for copyright reasons we can’t really repost those articles, however, you should be able to access almost all of those articles online.

If you are a member of the AAGBI you have access to Anaesthesia articles through the AAGBI website.  If you follow this link you will be taken to the page where you can find out how to get your login details, or if you already have them, you can then login, and follow the link to the Anaesthesia website.

For the BJA you will have to follow this link, where you will find an explanation of how to register with the website so you can access online content.  The same access details apply for CEACCP articles. As a member of the college you automatically have a subscription to this journal.

If you are having problems, then both sites have email addresses on them for support and help!

I think that if you keep the basic principles in mind this is quite simple to understand.

Firstly decide on what side of tube you need, a left or a right. i.e. do you want the left or the right bronchus to be intubated. So in exam speak;

“This will depend on patient factors and surgical factors.”

A right sided tube will generally pass into the right bronchus more easily due the more direct angle the right main bronchus branches from the trachea. So for many procedures on either the right or the left lung or pleura a right sided tube is often selected.

Sometimes the tube could get in the way of the surgeon for example, if a right pneumonectomy needs to be performed, for example, the right bronchus may need to be resected which means you can’t put a right sided tube in there!

Another indication for a specific sided tube may be to protect a lung from an infected lung on the other side.

There is some interesting physiology which occurs when ventilating only one lung, and http://ourworld.cs.com/_ht_a/doschk/onelung.htm contains some useful descriptions of the physiological changes.

It is worth remembering the following points though:

1. As always consider the West Zones creating a starling resistor in the upper zones of the dependant lung. Here the flow of blood through the pulmonary capillaries is reduced due to the effects of gravity and can be occluded completely if the alveolar pressure is higher than the hydrostatic pressure in the capillary. Remember also that in the horizontal position the West zones become horizontal.
2. When inflating the upper lung after the operation, the clamp is often switched to the dependant lung for the first few breaths to direct all the pressure to the collapsed upper lung. The reason is that otherwise, the collapsed upper lung will offer a higher resistance to the air flow than the already inflated dependant lung (LaPlaces’ Law). In other words the already inflated balloon (the lower lung) will be much easier to blow up than the fully deflated balloon (the upper lung). So, with the dependant lung clamped, all the ventilation pressure is directed to inflating the collapsed lung. Obviously don’t forget to unclamp the dependant lung after a few breaths!

From SuneilR