Spirometry is a medical procedure used to measure lung functions, specifically the volume and speed of the air one breathes in and out. It is one of pulmonary function tests and it is also referred to as measuring of breath. Spirometry is performed using pieces of equipment called spirometers. There are many version and models of these apparatus in the market, giving a buyer a wide range of options to choose from.

The function of this apparatus is determining abnormalities in ventilation patterns and air movements out and into the lungs. The devices detect two forms of abnormalities in ventilation pattern. The two abnormalities in ventilation pattern are restrictive and obstructive. Various models employ different measurement techniques to accomplish their task. Some of those methods are, use of water gauges, pressure or ultrasonic transducers.

These gadgets continue getting better as technology improves. At the present time several makes are in utilization in different around the globe. Among the key models are windmill-type, incentive, whole body plethymograph, pneumotachometer, peak flow type, fully electronic, and tilt compensated model. Of all the models body plethymograph has the highest accuracy with high precision in values taken. The great precision is partially because patients get enclosed in small spaces during the process.

The pneumotachometer gauges the flow rate of air by employing a fine mesh. The pressure of inhaled or exhaled gases is detected as they flow over the fine mesh, allowing measurement of their rate of flow. Patients are allowed to breathe in fresh air as the process continues. That is an advantage that lacks in most other models.

Fully electronic model is a complete improvement of other models because it does not have fine meshes or moving components. Rate of air flow is measured using methods such as pressure difference and ultrasonic transudcers. Lack of moving components improves the accuracy of these models because there is no friction or resistance. The hygiene is also improved since air flow channels used are disposable after use.

The incentive model is the most widely employed kind. These models are meant to improve air exchange in lungs when utilized for long a period. In health centers they are placed on tables or benches adjacent to beds when in use. Health officers instruct patients to breathe into the mouthpiece for a certain number of times every day. An improvement the patient observes in their inhalation and exhalation is seen on the calibrated sides of the apparatus.

Windmill-type model can measure forced vital capacity without use of water. In comparison to the water-tank type, it is more portable and lighter. Measurements recorded are broad and range from 1000ml to 7000ml. When taking measurements, the apparatus must be maintained in horizontal position because it contains rotating discs. Tilt-compensated model contains 3D sensing mechanics, which allow backward or forward positions when in use.

The success of the testing is determined by cooperation given to the doctor by the patient. Normally values acquired from one test contain errors and are therefore not used as final results. Three repetitions must be done obtain final figures. Little children cannot understand directions cannot be tested because they cannot give correct figures.