Asthma and surgery: Why asthma people need special care during surgery?

What is asthma? 

Asthma is reversible narrowing of the airways due to oedema of airway, increased airway secretions and due to constriction of the smooth muscle cells of bronchial walls.

What happens in asthma?

The respiratory tract of the people with asthma is very sensitive. Their airway gets narrowed as soon as it gets encounters with a noxious stimulus. In general the bronchioles of the respiratory tracts are composed of a mucosa, a smooth muscle layer and other types of connective tissue which contain secretary glands. These glands produce mucous which help in keeping the respiratory tract moist.

In asthma, as the noxious stimulus enters the respiratory tract following changes occur.

• The mucosa gets inflamed
• The smooth muscles constrict
• The glands start secreting more and more secretions

As a result of above effects the airways get narrowed.  As a result the person feels difficulty in breathing and a wheezing sound is produced when he/she breaths. 

What happens in surgery?

To many people surgery means a fearful experience. In one hand it is true, because it involves a lot of interventions that put the body in to a dangerous position. But, now as the Medical technology has advanced so much, the fear is minimal. To a normal healthy person it can be said that the risk is close to nothing. 

But people with other cormobidities, like asthma,   face an additional risk as their respiratory system is already compromised. Surgeries are done under local or regional anaesthesia. Out of these two, general anaesthesia cause profound changes in the respiratory system. Even some of the people with no respiratory tract disease start having respiratory problems after surgery.  Therefore, the risks for people with asthma are even higher.  

So, what will the doctor do about it?

If you present with asthma before surgery, he/she will make an assessment regarding your condition. In this case, he/she will assess the severity of the disease. This is usually done by clinical examination, because the clinical assessment is considered very important. 

There are other ways besides clinical assessment to assess the severity. It is done by doing some tests. They are listed below.

• Spirometry – This done by using a small device called the spirometer. This requires high Patient Corporation. 

 

A reduction in following values is seen in asthma.

• FEV1 (Normal value for women = >2L, for men = >3L)
• FEV1/FVC
• FEF 25-75%

• The Spirometry is also used to evaluate the response of the respiratory tract to bronchodilators.

• PEFR is measured at bedside by Wright peak flow meter. It is normally >200L/min

• An FEV1 or PEFR <50% of normal indicate moderate to severe asthma. 

• Apart from the above tests, the doctor will also do an arterial blood gases to find out any hypoxaemia and hypercapnia.

• Chest X-ray is often done to look for flattened diaphragm and hyperluscent lung fields indicating air trapping and hyperinflation.

• Sputum culture may also be done.

How the asthmatics are managed during surgery?

Elective surgeries will be postponed in patients presenting with exercebations of asthma. Other patients who undergo emergency surgeries are provided with intensive treatment. The treatment involves,

• Bronchodilators – Beta 2 agonists like salbutamol

• Steroids – Prednisolone

• Antibiotics are given in the presence of infections.

Regional analgesia is mostly preferred in asthmatic patients, since it does not involve any airway manipulation, but still high spinal or epidural can restrict respiration and produce an ineffective cough.