John Hutchinson, a surgeon by profession, invented spirometer. He noted that air that can be exhaled from a fully inflated lung is a powerful indicator of longevity. His basic spirometer measured vital capacity or capacity to live. Much later modern parameter like FEV1 (forced vital capacity in one second) were invented.
Spirometer measures airflow from fully inflated lungs over time in liters. The two most important measurements are Forced vital capacity (FVC) and FEV1. FVC is maximum amount of air which can be forcefully exhaled from a fully inflated lung.
Indications for spirometry:
Spirometer is an integral part of the evaluation, diagnosis and management of patients with respiratory disorders. The main indications are:
Evaluation a case with respiratory symptoms.
Assessment of severity of respiratory disorder.
Assessment of response to therapy.
Per-operative evaluation of respiratory system.
Detection of pulmonary functional abnormality in predisposed individuals, e.g. occupational exposure, neuromuscular, chest wall or upper airway disorders.
Spirometer are gold standard in the diagnosis and management of asthma and COPD.
Types of spirometer:
Spirometer is basically of two types:
Volume displacement spirometer, are the earlier versions.
Flow-sensing spirometer.
All the latest spirometer are flow-sensing type. Flow-sensing spirometer are either turbine based or pneumotach based.
Contraindications for spirometry:
Absolute contraindication for spirometry include recent myocardial infarction ie less than one month old.
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.
Hazards and complications:
Hazards of spirometry though rare include:
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.