Spirometry FAQ

A spirometry is a medical test to asses if your lungs are working well. It is a simple and harmless test, but it requires an active effort to perform it well. A spirometry test is typically performed by a general practitioner, an occupational medicine specialist, a lung specialist or in a hospital.

A spirometry is performed to assess the respiratory function. This test should be done routinely by General Practitioners as it is the most sensitive test to detect Chronic Obstructive Pulmonary Disease (COPD), a very common and possibly lethal disease caused mainly by smoking.

The most important test is the "forced vital capacity" (FVC), which gives some very important parameters of the lung function, like the "forced expiratory volume during the first second" (FEV1), the Peak (Expiratory) Flow (PEF) and the FEF25-75and other "forced expiratory flow"- measurements like FEF75%, FEF50%, FEF25%, FIF50% and PIF.
During the FVC-manoeuvre, the physician should be able to see the flow-volume curve on a screen.
Other tests that can be done with a spirometer are the "maximum voluntary ventilation" (MVV) and the "(slow) Vital Capacity" (VC).

The indications for spirometry include the need to

• detect the presence or absence of lung dysfunction suggested by history or physical signs and symptoms (eg, age, smoking history, family history of lung disease, cough, dyspnea, wheezing) and/or the presence of other abnormal diagnostic tests (eg, chest radiograph, arterial blood gas analysis);
• quantify the severity of known lung disease;
• assess the change in lung function over time or following administration of or change in therapy;
• assess the potential effects or response to environmental or occupational exposure;
• assess the risk for surgical procedures known to affect lung function;
• assess impairment and/or disability (eg, for rehabilitation, legal reasons, military).

AARC Clinical Practice Guideline - Spirometry, 1996 Update

The requesting physician should be made aware that the circumstances listed in this section could affect the reliability of spirometry measurements. In addition, forced expiratory maneuvers may aggravate these conditions, which may make test postponement necessary until the medical condition(s) resolve(s).

Relative contraindications to performing spirometry are

• hemoptysis of unknown origin (forced expiratory maneuver may aggravate the underlying condition);
  pneumothorax;
• unstable cardiovascular status (forced expiratory maneuver may worsen angina or cause changes in blood pressure) or recent myocardial infarction or pulmonary embolus;
• thoracic, abdominal, or cerebral aneurysms (danger of rupture due to increased thoracic pressure);
  recent eye surgery (eg, cataract);
• presence of an acute disease process that might interfere with test performance (eg, nausea, vomiting);
• recent surgery of thorax or abdomen.

AARC Clinical Practice Guideline - Spirometry, 1996 Update

Although spirometry is a safe procedure, untoward reactions may occur, and the value of the information anticipated from spirometry should be weighed against potential hazards. The following have been reported anecdotally:

• pneumothorax;
• increased intracranial pressure;
• syncope, dizziness, light-headedness;
• chest pain;
• paroxysmal coughing;
• contraction of nosocomial infections;
• oxygen desaturation due to interruption of oxygen therapy;
• bronchospasm.

AARC Clinical Practice Guideline - Spirometry, 1996 Update

Patients can be examined sitting or standing up. Occasionally, a patient may feel syncope or dizziness while performing a forced expiratory maneuver. Therefore, the sitting position can be safer. If such a patient is standing, a suitable chair (eg with armrests and without wheels) should be placed behind him in case the patient needs to be able to sit down quickly. If the maneuver is performed from a seated position, the patient should sit upright with both feet on the floor and positioned correctly in relation to the device. The test position should be noted on the report.

AARC Clinical Practice Guideline - Spirometry, 1996 Update

The "Exercise Challenge Test" identifiesa patient with Exercise Induced Bronchospasm.

Procedure:

• Spirometry
• 6-8 min practise at 70-80% of maximum pulsrate
• 2nd spirometry

A decline of 15% or more is diagnostic for EIB

You can find more on spirometry on spirometry guru.