Common Medical Tests

• Bruce Protocol
• Coronary Angiography
• Endoscopic Examination of the GI Tract
• Peak Flow Meters
• Spirometry Tests

Bruce Protocol (Treadmill Exercise) Test

Formal exercise testing is undertaken when the diagnosis of angina needs to be confirmed in suspected individuals and indeed the severity of the coronary disease.

A standard treadmill or, more rarely, a bicycle ergometer is used and a formal exercise test (ETT) is performed. It is carried out according to a standard protocol.

The patient walks on the treadmill, which has a varying speed (which can be altered, i.e. made faster or slower) and a variable gradient (slope), which can mimic going uphill or upstairs. (The Bruce Protocol is a description of the protocol for the increments in speed and gradient in the treadmill test).

During the time of testing, continual monitoring of the patient’s general condition, ECG and blood pressure take place.

A specialist must supervise and full resuscitation facilities must be available. The patient stops when chest pain or discomfort occurs, or when advised to, by the Specialist.

For the Full (Standard) Bruce Protocol, each stage lasts 3 minutes and the speed and gradient are increased at each stage.

For the modified Bruce Protocol, the gradient, but not the speed, is increased at each stage (see table).

Specific ECG changes indicate myocardial ischaemia.

The modified test is used in cases where standard testing would be too strenuous for the patient. The patient may not be able to participate in exercise testing because of co-existing problems (i.e. severe OA of the hip, or severe chronic obstructive airways disease).

Modified Bruce Protocol

If the patient can complete Stage 1 of the test they are able to walk 138 metres on the flat.

Coronary Angiography

Coronary angiography is performed in order to demonstrate the exact anatomy of the coronary arteries, usually with a view to progression to PTCA (percutaneous transluminal coronary angioplasty) with or without stents, or CABG (coronary artery bypass graft).

Indications for angiography are:

• Where the diagnosis is not clear,
• Angina not responding to medical therapy,
• Strongly positive exercise test according to the Bruce Protocol,
• Moderate or severe angina,
• Unstable angina (very severe angina),
• After an infarct (M.I), if well enough.

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Endoscopic examination of the GI Tract

Sigmoidoscopy

Sigmoidoscopy is a special internal investigation of the lower third of the large bowel (colon). An instrument called a sigmoidoscope is inserted via the anus and allows direct visual examination of back passage (rectum) and the sigmoid and descending colon (the last part of the colon).

The sigmoidoscope is a small camera attached to a flexible tube about twenty centimetres long (flexible sigmoidoscope). In some circumstances a rigid tube is used (rigid sigmoidoscope). The sigmoidoscope allows the operator to see any bleeding, inflammation, abnormal growths or ulcers in the colon and rectum. During the procedure the operator is also able to remove small samples of any abnormal tissue identified (biopsy) for more detailed examination under the microscope to confirm diagnosis.

Colonoscopy

Colonoscopy is a special investigation that permits internal examination of the entire large bowel (colon). A long flexible fibro-optic tube, the colonoscope, is inserted via the anus and slowly guided through the large bowel under sedation. The colonoscope transmits pictures of the inside of the bowel on to a video screen.

The operator is able to visualize any bleeding, inflammation, abnormal growths or ulcers in the colon. Abnormal growths arising from the inner surface of the bowel, such as polyps, can be removed via the colonoscope. In addition small samples of any abnormal tissue identified (biopsy) may be removed for more detailed examination under the microscope to confirm diagnosis.

Gastroscopy

Gastroscopy is a special investigation that permits internal examination of the upper parts of the gastrointestinal tract. It allows direct examination of the oesophagus, stomach and duodenum. The gastroscope is a long flexible fibro-optic tube that transmits pictures of the inside of the gut on to a video screen. It is passed from the mouth, via the throat, into the oesophagus and then on to the stomach and duodenum. The fibro-optic tube is also referred to as an endoscope and the examination as endoscopy.

The operator is able to identify any abnormal inflammation, bleeding or growths, and to locate stomach or duodenal ulcers. Small samples of any abnormal tissues identified (biopsy) may be removed via the gastro scope for more detailed examination under the microscope to confirm diagnosis.

Gastroscopy is commonly used investigate symptoms of dyspepsia and locate peptic ulcers in the stomach and duodenum. It also used to investigate inflammation in the oesophagus and to diagnose oesophageal and stomach tumours.

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Peak Expiratory Flow (PEF)

This is usually used for asthma.

It is the maximum rate of air breathed out as hard as possible through a measuring device called a peak flow meter, (after a full breath taken in). The reading is measured in litres/minute (l/min). Three readings are taken and the best of three is recorded.

A measured peak flow of less than 80% predicted indicates that airways obstruction is present but the diagnosis of asthma cannot be made on a single peak flow measurement as PFR may vary throughout the day as well as on a day-to-day basis, a series of sets of readings should be considered. Also, having a normal one-off peak flow reading does not exclude asthma.

Peak flow measurement is done very commonly, and many patients test their peak flows on a daily basis, having their own peak flow meters. They then may record the reading in a graph form, which then easily highlights any change especially morning and evening. It is a very easy test to do. GPs and Specialist Asthma nurses can do an on-the-spot reading to quickly check a patient’s status.

EU Standard for Peak flow Meters

Background

Studies have identified that existing scales on hand held mini-Peak Flow Meters are accurate in the mid range but at the high and low ends of the range they are less accurate, with a result that asthma may be under-diagnosed and treatment may not be optimal.

As a consequence, a new EU standard has been introduced for mini peak flow meters, which is now in force. Any PF meter purchased or prescribed in the UK will from now on be EU standard compliant.

Peak flow meters, which are well maintained, and in good condition can still, be used, since it is possible to apply an algorithm, which converts old to new readings.

It is important to determine the type of meter with which the reading was taken.

Therefore, when documenting Peak Flow, it should be recorded whether an existing “Wright” or new “EU” meter has been used, like this:

PFR 450l/min (Wright) or PFR 450 (EU)

Examples of comparable peak flow values are:

The average range for an adult for peak flow lies between PFR 450 (EU) and PFR 600 (EU), but because the peak flow depends on age, gender, race and height, the measured result is compared to that predicted for a person’s age, gender, and height, using special charts and the measurement is compared with what would be expected.

Below are some approximate result ranges indicating the level of peak flow reduction.

With the new EU values, a new Nomogram has been provided, which should be used to determine whether the claimant has mild, moderate or severe asthma.

“In men, readings up to100 litres/minute lower than predicted are within normal limits.

For women, the equivalent figure is 85 litres / minute.

Values are derived from Caucasian populations”.

Special Peak Flow Monitoring

The patient is asked to measure their peak flow on a peak flow meter, every morning and evening for 1 to 2 weeks, to measure variability.

A variation between the morning and evening readings of more than 15% is diagnostic of asthma.

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Spirometry Test

A Spirometry Test measures the volume of air blown out against time and gives more specific information about lung function. This is done by a special technician or specialist using a machine into, which the patient’s age, gender, and height have been entered, so that a predicted value has already been made. The patient blows out into a mouthpiece connected to the machine, as fully and as long as possible, after a deep breath in. Various readings can then be taken and compared with the predicted values.

It is the single best diagnostic test for patients with airflow limitation. All new diagnoses of COPD have to be tested to fulfil scores in the new GP General Medical Services contract. Most GPs are now becoming familiar with this and have nurses who perform spirometry and reversibility testing.

A value is calculated for the amount of air blown out in one second (this is known as the “Forced Expiratory Volume” or FEV1). This is divided by the total amount of air blown out until all air is expired (known as Forced Vital Capacity or FVC). This is expressed as a percentage value and a value of less than 70% indicates COPD.

In asthma, the readings will be reduced, returning to normal between episodes, and again, the recorded result would be compared with what is predicted (according to age, height and gender, by the machine) and the results are then printed out.

Below are some approximate result ranges indicating the level of reduced FEV1.  These can only be considered approximate as factors such as height, age and weight are not considered.

Amended April 2009