Early Symptoms of Idiopathic Pulmonary Fibrosis
Idiopathic pulmonary fibrosis (IPF) mainly affects people who are over the age of 50. IPF is rare, affecting fewer than 5 people out of every 10,000 people.1 It often starts with vague, annoying symptoms that do not seem very serious. People with early IPF may become breathless when walking upstairs, or climbing a hill. They may develop a nagging, dry cough. They may feel tired, even after a full night’s sleep. Many people with early symptoms think that their symptoms are just a normal part of aging.
It is important to take these early symptoms of IPF seriously. Feeling breathless or having a nagging cough are not a normal part of aging. Although IPF has no cure, treatments are available that can slow down lung damage, improve symptoms, and improve quality of life. These treatments work best when the condition is diagnosed early.
Three Main Early Symptoms
There are three main early symptoms of idiopathic pulmonary fibrosis (IPF). These are2:
- Breathlessness – a feeling of being short of breath or out of breath. This is often more noticeable during exercise, such as walking upstairs or uphill. In early IPF, breathlessness may only happen during exercise. Later, patients may feel breathless even while resting.
- Cough – usually dry and nagging. Coughing often comes in episodes for people with IPF. Coughing episodes can be triggered by exercise, hot weather, talking, laughing, or crying. They can also be triggered by breathing in smoke, strong smells, fumes, or dust.
- Fatigue – a feeling of tiredness or weariness that is not relieved by sleeping. It may feel physical, emotional, or both. Fatigue may be worse after coughing episodes. For people with IPF, fatigue seems to worsen over time.
Other symptoms include a rounding of the ends of the fingers and toes (clubbing), heartburn (acid reflux), and pain (headache, body aches, pain in the fingers and toes).
Symptoms Start Years Before Diagnosis
Breathlessness and a nagging, dry cough can start years before a person is diagnosed with IPF. A research study from the United Kingdom looked at medical records for 1,671 patients who were eventually diagnosed with IPF. The study found that patients with IPF were telling their primary care doctors about their troubles with breathlessness and cough for up to five years before they were actually diagnosed with IPF.3
Why Does IPF Cause Breathlessness?
During breathing, air enters through the main windpipe (trachea) and flows down branches (bronchi) to the left and right lungs. As the air flows deeper into the lungs, the airways become smaller, with more and more branches (bronchioles). This can be visualized like an upside-down tree, where the trunk is the main windpipe and the branches become smaller and smaller as they move father away from the trunk.
At the end of the smallest branches are clusters of air sacs called alveoli. These look like clusters of grapes. Inside the tiny air sacs, fresh oxygen passes into tiny blood vessels, and carbon dioxide passes out of those blood vessels. This movement of oxygen and carbon dioxide is called gas exchange.
In healthy lungs, the air sacs are flexible and gas exchange happens easily and quickly. In a person with IPF, scar tissue builds up around the air sacs. The sacs become stiff instead of flexible, and some sacs completely collapse and cannot be used. Gas exchange becomes slow and difficult.
One way to visualize this is to imagine healthy lungs as a balloon. When a person blows into the mouth of the balloon, the rubber walls of the balloon push back a little. Still, the pushback is not so hard that the person cannot blow air in and blow up the balloon. The walls of the balloon move in and out easily as air enters and leaves. Lungs with IPF are like a balloon with very stiff, very thick rubber walls. It takes a great deal of force to push air into the balloon because the walls do not stretch easily. Air does not move in or out easily.
People with IPF breath more deeply than healthy people do.4 Even at rest, a person with IPF will breathe in a bigger volume of air than a healthy person does. They breathe in more air to try to make up for the slow and difficult gas exchange. They need more oxygen to be available to move into their blood vessels, so they draw in more air. Breathing more air into lungs that are stiff takes quite a bit of work, even if the person is not fully aware of it. The muscles in the chest that the body uses to draw in air must work harder. The diaphragm, the muscle at the bottom of the chest that contracts hard when a person inhales, also works extra hard in IPF.
The combination of slow and difficult gas exchange and harder working muscles creates the feeling in the brain that we know as breathlessness. Breathlessness is a neurological response in the brain that happens when the brain senses that breathing is hard work, and even with all that hard work not enough oxygen is getting into the bloodstream.
Why Does IPF Cause Cough?
Researchers are still studying this question. There is no proven answer at this time. This is a complicated question because coughing is actually very complex process controlled by nerves.5 There are nerves that dial down the coughing reflex, and there are other nerves that dial up the coughing reflex. Among the nerves that dial up the coughing reflex, there are many types. Some respond to heat or cold in the air. Some respond to dust, smoke, or fumes. Others respond to mucus in the airways. Still others respond to how flexible the lungs are during breathing (the less flexible, the greater the urge to cough).
One theory of the IPF cough states that the coughing is caused by the disease affecting the nerves.6 There is some evidence that the scar tissue (fibrotic tissue) in the lungs of patients with IPF may actually destroy some of the nerves that dial down the coughing reflex. At the same time as these calming nerves are being destroyed, the other types of nerves that ramp up coughing get very hyperactive. This may be a response to the deeper and harder breathing that IPF patients must do in order to draw in enough air to keep oxygen flowing into the bloodstream.
Because of the loss of the calming nerves, and the hyperactivity of the nerves that dial up the cough reflex, patients with IPF often feel strong urges to cough. Unfortunately, coughing does not eliminate or reduce the urge to cough for people with IPF, because the nerves are still not functioning properly.
References and Further Reading
- Raghu G, Weycker D, Edelsberg J, Bradford WZ, Oster G. Incidence and prevalence of idiopathic pulmonary fibrosis. Am J Respir Crit Care Med. 2006;174(7):810-816.
- The U.S. Food and Drug Administration (FDA). The voice of the patient: idiopathic pulmonary fibrosis. March 2015.
- Hewson T, McKeever TM, Gibson JE, Navaratnam V, Hubbard RB, Hutchinson JP. Timing of onset of symptoms in people with idiopathic pulmonary fibrosis. Thorax. 2018;73(7):683-685.
- Olukogbon KL, Thomas P, Colasanti R, Hope-Gill B, Williams EM. Breathing pattern and breathlessness in idiopathic pulmonary fibrosis: An observational study. Respirology. 2016;21(2):344-349.
- Satia I, Badri H, Al-Sheklly B, Smith JA, Woodcock AA. Towards understanding and managing chronic cough. Clin Med (Lond). 2016;16(Suppl 6):s92-s97.
- an Manen MJ, Birring SS, Vancheri C, Cottin V, Renzoni EA, Russell AM, Wijsenbeek MS. Cough in idiopathic pulmonary fibrosis. Eur Respir Rev. 2016;25(141):278-286.