CPX - Frequently Asked Questions

 

(1)   What is CPX?

CPX stands for Cardiopulmonary Exercise Testing and is used in clinical medicine to assess

the capacity of the heart and lungs.

 

(2)   What exercise is involved?

CPX uses an upright bicycle which looks like a standard exercise bike. It is linked to a computer. At the start of exercise,minimal effort is required to turn the pedals. The computer slowly increases the effort required in a gentle manner.

 

(3)   How much exercise is needed?

The computer is looking for a target amount of exercise sufficient to decide if your heart and lungs have enough capacity for the proposed operation. The amount of exercise is modest.

It does not require you to exert yourself to maximum effort.

 

(4)   How does the computer measure fitness?

As you cycle you will be attached to a mouthpiece which measures the amount of oxygen your body is using and how much carbon dioxide your body is getting rid of. As exercise continues there comes a time when you produce more carbon dioxide than oxygen. This happens because the body’s metabolism changes and becomes ‘anaerobic’. This point is called the anaerobic threshold (AT).

 

(5)   Why do we measure AT?

In the past AT has been used in the assessment of patients before surgery. When a patient’s AT is greater than 15ml/kg/min, fitness for surgery is generally adequate and very few patients have serious postoperative problems.

 

(6)   What happens if my AT is low?

The postoperative risk after surgery increases when a patient’s AT is low. However, treatment before surgery to make the heart and lungs as good as possible can reduce the risk to a minimum. Identifying who has a low AT and doing something about it offers the best

treatment currently available for patients undergoing surgery. 

 

(7)   Do all operations carry the same risk?

No. For example many operations that are performed on the body’s surface have a low risk when compared to more invasive operations. This is because during ‘surface operations’, the stress placed on the body’s heart and lungs is lower when compared to more invasive procedures. Your doctor will know which type of surgery would benefit from CPX testing.

 

(8)   How long will CPX testing take?

Please allow 1 hour for your appointment. The cycling portion of the testing only takes approximately 10 minutes. The rest of the allocated time is used for test explanation,

taking your medical history and vital signs, lung  function testing and recovery time.

 

(9)   Will I break into a sweat?

Not always. For many patients the amount of effort that is required is low.  However there are showering facilities should you require them.

 

(10)   What facilities will be available for me?

We have change rooms for changing pre and post testing. There is a shower if required. Tea and coffee making facilities are also available.

 

(11)   Are there any risks?  

The risk for CPX is the same as for mild exercise. The number of patients that develop symptoms is low (1:1000), and it is the same as for exercise testing in cardiology. We will be monitoring you closely during the test, with continuous ECG, blood pressure and oxygen measurements. If you develop significant symptoms, the trained staff will stop the testing.

 

(12)   When will I know the result?

Your referring doctor will discuss the test results with you. Your results will be reported on

by the CPX Medical Consultant promptly after your test and your referring doctor will receive

the report in a timely manner. We suggest you allow 48 hours. Urgent reporting can be arranged with advanced warning.

            

(13)   What do I need to wear for the test?

Cool, comfortable clothing and walking shoes. Clothing that is suitable for the gym.

 

(14)   Can I eat before the test?

Yes. However it is not advised to have a large meal immediately prior to your test. It is recommended to have a light meal a few hours prior. Diabetic patients are also advised to bring ‘snacks’ to consume after the test. We also request that diabetic patients

bring their blood sugar machine so that blood sugar levels can be tested prior to exercise.  

 

(15)   Should I take my usual medications prior to the test?

The doctor who referred you for CPX testing will advise you if you need to make any

changes to your usual medication regime. However the majority of patients will not need to make any changes.

 

(16)   Who will be present during the test?

A minimum of 2 staff will be present.

 

(17)   How is my test paid for?

All of the major insurance companies recognise CPX testing as a valid pre-operative assessment test. It is advised that you check with your insurance company prior to your appointment. We are also happy to facilitate those patients who wish to self pay or

those who are sponsored.