Asthma is very severe and difficult to treat? Why not try this method?

Author: Lin Jiangtao, Chief Physician of China-Japan Friendship Hospital

Reviewer: He Quanying, Chief Physician, Peking University People's Hospital

Do you have any asthma patients like this around you?

They need to rely on large doses of inhaled hormones for a long time, or even oral hormones (hormone-dependent asthma)...

When they have an asthma attack, they may suffer from severe respiratory failure and hypercapnia, and if they are not rescued in time, they will die (fatal asthma)...

They usually have no symptoms, and their lung function tests are normal. But once an asthma attack occurs, it is very serious, even fatal (brittle asthma)...

Clinically, we can call these types of asthma refractory asthma or severe asthma.

1. What are the causes of refractory asthma?

At present, the causes of refractory asthma include both internal and external factors.

Intrinsic factors are related to the patient's own genetic susceptibility.

In clinical practice, we have seen some patients with refractory asthma who have had severe and difficult-to-treat asthma since the day they became ill. It is not because of lack of timely diagnosis or failure to cooperate well with treatment. The condition turns from mild to severe or difficult to treat. This situation is caused by genetic factors.

External factors include many aspects, which can turn mild asthma into severe or refractory asthma.

For example, in the example we just mentioned, he was not diagnosed and treated in time. At first, he had mild to moderate asthma, which later gradually became severe asthma. There are many external factors that can cause the disease to develop further, such as smoking, repeated respiratory infections, and the continuous presence of allergens in the environment, which cause continuous inflammation of the airway and changes in the airway structure.

Figure 1 Original copyright image, no permission to reprint

In short, from a mechanistic point of view, why do all the links and factors cause mild asthma to develop into severe or refractory asthma? It is because the inflammation of the airways persists, and it has a special airway inflammation mechanism, which makes the current drugs unable to effectively control it.

For such patients, we can consider treatment with bronchial thermoplasty.

2. How does bronchial thermoplasty treat refractory asthma?

To understand how bronchial thermoplasty treats refractory asthma, we must first understand the most basic pathological changes in asthma, that is, why asthma patients have attacks.

Asthma attacks are caused by the contraction of smooth muscles. The bronchial smooth muscles of asthma patients are particularly susceptible to irritation. When they encounter various external stimuli, such as physical, chemical, allergic, and infectious stimuli, the smooth muscles will contract, and then the patients will experience symptoms of dyspnea and wheezing. Therefore, smooth muscles play a very important role in the occurrence and development of asthma.

Figure 2 Original copyright image, no permission to reprint

Our previous research has found that after an asthma patient died, an autopsy was performed and it was discovered that his bronchial smooth muscles had obvious hyperplasia. This means that due to repeated asthma, his smooth muscles had become muscle masses similar to those of a weightlifter, that is, the smooth muscles were particularly developed.

The smooth muscles of healthy people do not contract normally, and only contract when coughing to expel harmful substances. However, due to airway hyperresponsiveness, airway remodeling, structural changes, etc., the bronchial smooth muscles of asthma patients will contract repeatedly after being stimulated by various stimuli. So everyone thought of a way to reduce the role of smooth muscles, reduce their contraction ability, and prevent them from contracting excessively.

This method is bronchial thermoplasty. How is bronchial thermoplasty performed?

Simply put, it is to place a catheter under the bronchoscope. There is an electrode at the front end of the catheter. When the electrode is opened, it can fully contact the tracheal wall. Then we convert the heat energy of radio frequency to the smooth muscle cells. Due to the increase in temperature, the protein of the smooth muscle coagulates and necrotizes, so that the smooth muscle loses its ability to contract and reduces its responsiveness to external stimuli.

Therefore, when asthma patients encounter various external stimuli, the bronchus will not have a contraction reaction, which means that asthma will not occur again.

3. Can bronchial thermoplasty be performed once to treat refractory asthma?

This operation is usually completed in three times. Why is it divided into three times? There is a certain reason. If it is completed in one time, the operation time will be very long. Splitting it in three times can shorten the time of each operation. The shorter the operation time, the lower the risk during the operation.

If one operation is used to solve all the problems, the damage to the bronchi and mucosa will be very large. The risk of postoperative infection and aggravation of the disease will also increase, and the patient's recovery time will be longer. Therefore, it is now advocated to complete the operation in three times.

The first operation was done on the right lower lobe, and the second was done on the left lower lobe. All lobar bronchi, segmental bronchi, and subsegmental bronchi, that is, bronchi larger than 3 mm, had to be operated on. Each of these two operations took about 30 to 40 minutes.

The third time, we operated on the upper lobes of both lungs. Because the upper lobes of both lungs were operated on together, there were more bronchial openings. This operation took about an hour, or even more than an hour.

Additionally, there needs to be about three weeks between each surgery to allow the patient to fully recover.

Bronchial thermoplasty, as a supplement to drug therapy, can bring great benefits to patients with severe and refractory asthma.