Obstructive ventilatory defect

Medically reviewed by A Ras MD.  Last updated March 30, 2022

 Obstructive ventilatory defect (OVD) is typically described by a lower ratio between the first forced expiratory volume as well as the “forced/slow” vital capacity [FEV 1/(F)VC]

Obstructive ventilatory defect
Obstructive ventilatory defect curve

The test is usually performed via the lung function test. It assists in diagnosing chronic lung diseases based on the presence of a trapping obstruction, as well as decreased compliance and restriction.

What are Pulmonary Function Tests?

  • To determine if you have asthma/COPD or another lung disease,  Your doctor will look over your symptoms, medical history, and family history, and may also conduct tests for lung functions (also known as tests to determine pulmonary function). Your doctor will also be looking into any breathing issues you may have suffered from in the past, and also an asthma-related family history or other lung diseases as well as allergies or skin diseases such as eczema. It is essential to identify your asthma symptoms in full detail (coughing or wheezing, breathlessness, and chest tightness) along with the time and how often they occur.


  • Your doctor will also conduct a physical examination and take listen to your heartbeat and lung. Alongside asthma pulmonary function tests The doctor could also perform allergy tests as well as blood tests and sinus and chest X-rays. They may recommend you to a pulmonologist or a specialist in lung health to conduct further tests for asthma, as well as other conditions that could be affecting the condition.

What are the various Lung Function Tests?

Obstructive ventilatory defectThere are many lung function tests that can be used to diagnose asthma. The most commonly used tests include:

  • Spirometry The test for breathing tests the quantity of air you take in and how fast the air can be blown out. It will show the amount of obstruction to your airway that you have. Take an exhale and take a deep breath through a hose connected to a device known as the nanometer. It tracks how much air you exhale (FVC or forced vital capacity) and how fast you blow it out (FEV, also known as forced expiratory volume). It is possible to measure spirometry prior to and after inhaling the short-acting drug known as a bronchodilator. It is similar to albuterol. The bronchodilator helps your airways expand, which allows air to move through without restriction. The test also helps the doctor monitor your progress and determine if and how to modify the treatment regimen.
  • Peak flow test for meter: These tests measure how efficiently your lungs push out air. While less precise than Spirometry, they’re an excellent method of assessing the function of your lungs in the comfort of your home and before you experience any signs. A peak flow monitor can aid in determining what causes the asthma condition to worse. It can also tell you if treatment is working, and also when you need urgent care.
  • Challenge tests: The doctor may refer them to provocation tests. There are three kinds:
    • Test for exercise challenge: This test helps determine whether you suffer from exercise-inducing bronchoconstriction (EIB) which is a sign that exercising can trigger asthma symptoms. The doctor will observe your oxygen level and cardiovascular rate when you exercise on the treadmill. This will tell the doctor that exercising causes your symptoms.
    • Irritant challenge Doctors expose your body to triggers for asthma for example, such as perfume, smoke, or chemical. You then take a breath test to determine how your lungs react. This can help determine the cause of your asthma.
    • Methacholine test challenge: It is most commonly performed for adults than for children. You could get it when your symptoms and screening spirometry do not clearly indicate an asthma diagnosis. If you suffer from asthma, and breathe in methacholine airways contract (contract due to an impulse) as well as narrow. In this test, you breathe in methacholine-infused mists prior to and after the spirometry. If your lung function decreases by 20 percent then you are suffering from asthma. The doctor will prescribe medication at the conclusion of this test, to counteract the effect of methacholine.
  • FeNO Test: You might hear it being called the exhaled nicotine oxide test. If you suffer from allergies or eosinophilic asthma could help you determine the amount of inflammation you suffer and how well your inhaled steroids are keeping it under control. Then, you blow into an instrument that can measure how much nitric oxide is present in the air you breathe.

Obstructive ventilatory defect classification

The year 2014 saw the introduction of a brand new alternate classification (GLI classification) to grade severity of the OVD severity was suggested to replace the classification of 2005.

the purpose of this class was to evaluate the functional capability of patient-based OVD against two other classifications.

Following OVD classifications were used to determine severity:

  • (FEV 1%pred) (FEV 1%pred) (>70 percent),
  • moderate (60-69 moderate (60-69),
  • moderately severe (50-59 50-59 %),
  • severe (35-49 severe (35-49 %) severe (35-49%)
  • extremely severe (<35 very severe (35)

The reason behind the revised method of diagnosing OVD and classifying the spirometric deficit was fascinating. The purpose behind the brand new class was intended to fill in the gap among the population diagnosed with COPD using the older classification.

Additional details

Always consult your doctor to confirm that the information provided on this site is appropriate to your specific situation.

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