PFT, also known as the pulmonary function test, is used to measure how well your lungs are working. This test examines the size of the lungs, its functioning, the rate of air flow, and gas exchange. This information could be used by your physician for the evaluation and treatment of some lung disorders.
Multiple types of PFT tests are available for the diagnosis of the suspected condition. Your doctor will advise you on how to get ready for the test and inform you about any risks that you need to be aware of.
Two conditions affect how oxygen enters and leave the lungs:
Restrictive breathing happens whenever the lungs or chest muscles are unable to sufficiently expand. This causes airflow problems, mainly due to decreased lung capacity.
Obstructive breathing occurs when there is difficulty exhaling because of airway resistance. Airflow is reduced as a consequence of this.
Why is PFT done?
PFTs are safe examinations. A physician might prescribe them for the below-mentioned conditions:
- If you’re exhibiting lung disease symptoms
- If you are often in contact with specific chemicals at your place of work or surroundings
- To evaluate the progression of a chronic lung condition like chronic obstructive pulmonary disease, also known as (COPD) or asthma
- Before having surgery, to determine how effectively your lungs are functioning.
PFT can be used to evaluate the following:
VT or tidal volume – This is the volume of oxygen that is normally breathed in or out.
MV or minute volume – This represents the overall oxygen exhaled each minute.
VC or Vital capacity – This is the total amount of oxygen that may be exhaled after taking in as much oxygen as possible.
FRC or functional residual capacity – This is the amount of oxygen that remains in your lungs following a normal exhalation.
Residual volume – This is the amount of oxygen that remains in your lungs after you’ve exhaled as effectively as you can.
Total lung volume – This is the overall volume that occupies the lungs when they are fully inflated with oxygen.
Forced vital capacity (FVC) – This is the volume of oxygen that is exhaled fast and strongly after inhaling as much oxygen as possible.
Forced expiratory volume (FEV) – This represents how much oxygen is released in each of the 1st, 2nd, and 3rd seconds of the FVC examination.
PEFR (peak expiratory flow rate) – This is the quickest rate at which you can expel oxygen from your lungs.
Different people have different normal ranges of PFT. Your test findings of air intake and output are compared with the normal ranges available for people of similar height, age, sex, and race. The findings are also compared with any previous test results you may have. You might require additional testing if your PFT readings are abnormal or if the findings have altered.
Uses of PFT Test
If you experience signs associated with the lungs or airways conditions, such as coughing or loss of breath, have undergone a relevant surgery, or are using tobacco-containing products, your doctor may request pulmonary function testing.
Some of the signs which may necessitate PFT may include:
- Tightness and discomfort in the chest region
- Coughing, particularly if you expel phlegm or mucus
- Taking deep breaths or breathing difficulty
- Dyspnea (shortness of breath)
- Wheezing.
Your doctor may request the PFT test as a part of the normal physical exam even though you are symptom free.
Your physician can use PFTs to:
- Look for airway constriction in your lungs
- Evaluate early alterations in your lungs’ capacity to deliver oxygen into the bloodstream
- Analyse how smoking continues to affect chronic pulmonary conditions
- Determine whether certain medications could make breathing easy
- Determine whether your lungs have been impacted by environmental substance contact
- Evaluate whether you can withstand surgeries or additional medical treatments.
PFT tests can help diagnose disorders such as:
- Asthma
- Chronic obstructive pulmonary disease (COPD)
- Breathing muscle weakness
- Constriction of the trachea
- Pulmonary fibrosis
Types of the PFT Test
PFT tests are of several types. Depending on the type of health issue doctors are trying to diagnose, they could request you to undergo one or more of these examinations. They include:
Spirometry
Spirometry is a harmless test that might be performed in a physician’s office, hospital, or specialised PFT lab as a part of your PFT test. Spirometry is very useful for identifying COPD and asthma. This is because it can be used to measure how quickly and a certain amount of oxygen you can exhale after taking a deep breath. Your doctor will perform this test while you are seated in a straight position in front of a spirometry device connected to a mouthpiece. To ensure that all the oxygen that you inhale enters the device, the mouthpiece must fit properly. To prevent you from exhaling air through your nose, the doctor will put a nasal clip on your nose.
Plethysmography
The lung volume, often known as the amount of oxygen in your lungs, is measured during a plethysmography examination. You’ll stand or sit in a tiny room for this exam while breathing in a mouthpiece. By monitoring the airflow inside the booth, your physician can determine the size of your lungs.
Cardiopulmonary exercise test (CPET)
A cardiopulmonary exercise test (CPET) is a specialised exercise stress exam used to determine your abilities for exercise and identify any potential causes of limitations in exercise. It is often carried out in a physician’s office or PFT laboratory on a treadmill.
When exercising, the following are evaluated according to CPET:
- Heart
- Lungs
- Muscles
- Blood vessels
The amount of oxygen your body can consume while exercising is also measured by CPET. A technician will attach electrodes to the patient’s body before the test, such as:
- EKG leads, which are used to evaluate the rhythm of the heart
- A mouthpiece, which is connected by a tube with a flow metre that measures how deeply and fast you breathe as well as the amount of carbon dioxide and oxygen that pass into and out the lungs
- A cuff for blood pressure
- A pulse oximeter to detect the amount of oxygen in the bloodstream.
Preparation for the PFT Test
You might be required to prepare for the PFT test because it is an important test and aims to determine how accurate your lung function is. For instance, you may be required to stop consuming medicines that widen your airways used in disorders including long-term bronchitis or asthma. Any modifications to your medication plan should be explained by your doctor in advance because medicines can interfere with test findings. As a result, you might have to stop taking painkillers, both prescribed and non-prescribed. Contact your physician with any queries you may have before the appointment.
These are the things you should avoid on the day of your test:
- Consuming a heavy meal
- Drinking tea, coffee, or other caffeinated beverages
- Eating chocolate
You also should not engage in vigorous exercise at least one hour before the exam.
Other preparation
- Make sure to dress comfortably for the exam, especially if you plan to use an exercise bike or a treadmill. Even if you only sit throughout the exam, wearing tight clothes may prevent you from breathing properly.
- Avoid wearing any jewellery that could interfere with your breathing.
- To make sure that your mouth can fit comfortably on a mouthpiece used during the examination, you can use dentures or detachable dental items.
- After an exercise that involves physical activity or repeated exhalations, try to relax since you might feel dizzy or exhausted.
- If you have recently had a cardiac arrest, stomach, chest, or eye surgery, you might need to postpone the PFT test.
Risks associated with the PFT Test
For the most part, PFT tests are harmless. However, you might feel lightheaded or have trouble breathing since the PFT test could require you to breathe rapidly in and out of your lungs. Additionally, you pose a risk of fainting. Inform your doctor if you have dizziness. Additionally, you might want to make plans for someone to drive you home following the PFT test.
If you already have asthma, the examination could trigger a severe flare-up. PFTs can very rarely result in lung collapse. There will be a team of medical experts available to assist if difficulties arise following the test.
A PFT may be problematic if you:
- Have experienced a cardiac attack recently
- Have a serious respiratory condition
- Have recently undergone an abdomen surgery
- Have recently undergone cataract surgery
- Have recently undergone chest surgery
- Are experiencing an unstable heart disorder.
