What Is Bibasilar Atelectasis?

Bibasilar atelectasis is the collapse of the lower parts of both lungs. It most often affects people who have undergone major surgery with general anesthesia but can also be due to an obstruction, tumor, blood clot, or pressure change in the lungs.

Bibasilar atelectasis is one of several types of atelectasis in which parts of one or both lungs collapse. When a lung completely collapses, it is called pneumothorax.

Symptoms of bibasilar atelectasis include difficulty breathing and coughing with mucus (phlegm). The treatment depends on the underlying cause but may involve breathing exercises, breathing devices, and medications to re-expand the lungs.

This article describes the symptom and causes of bibasilar atelectasis, including how it is diagnosed, treated, and prevented.

Symptoms of Bibasilar Atelectasis

Atelectasis occurs when the airways collapse and air can't reach the tiny sacs called alveoli where oxygen and carbon dioxide are exchanged. This causes a condition called hypoxia in which organs and tissues don't get enough oxygen.

Bibasilar atelectasis occurs when the lower lobe of the right lung (which has three lobes) and the lower lobe of the left lung (which has two lobes) collapses.

Symptoms tend to develop suddenly and involve:

• Dyspnea (shortness of breath)
• Wheezing
• Rapid, shallow breathing
• A persistent, productive cough with phlegm

As the condition progresses, symptoms can worsen as oxygen levels plummet. If left untreated, this can lead to a severe drop in blood pressure, tachycardia (rapid heart rate), and shock.

What Causes Bibasilar Atelectasis?

There are obstructive and non-obstructive causes of basilar atelectasis. Obstructive causes are those that physically block the airways, while non-obstructive causes place pressure on the lungs that makes airways harder to fill.

Obstructive causes of bibasilar atelectasis include:

• Postoperative mucus plug: This occurs when mucus accumulates in the lower lungs, a common occurrence during and after surgery because you cannot cough. The resulting mucus plug causes the collapse.
• Cystic fibrosis: This is a genetic disorder that causes the overproduction of mucus in the lungs.
• Severe asthma: This is a chronic condition in which the airways become narrow and produce excess mucus.
• Chronic obstructive pulmonary disease (COPD): This is a group of lung diseases that block airflow and cause excess mucus.
  
• Foreign body aspiration: This occurs when a small object gets inhaled into the airways, causing an obstruction.
• Pulmonary embolism: This is the development of a blood clot in the lungs.
• Lung infections: Examples include severe pneumonia and tuberculosis.
• Tumors: These include benign (non-cancerous) tumors like adenomas and lung cancers like squamous cell carcinoma that develop in the airways.

Non-operative causes of bibasilar atelectasis include:

• General anesthesia: Used for major surgery, this form of anesthesia changes a person’s regular breathing pattern as well as the normal gas exchange, causing airways to collapse.
• Pleural effusion: Excess fluid accumulates in the space between the lungs and chest wall, altering the pressure within the lungs.
• Chest trauma: A blunt force injury can cause chest compression and alter the pressure in the lungs.
• Pneumothorax: The collapse of one lung alters the pressure within the other lung.
• Pulmonary fibrosis: This is the scarring of lung tissues caused by radiation, toxins (like asbestos), drugs (like chemotherapy), autoimmune diseases (like lupus), and other causes.
• Drug reactions: Opioid drugs and sedatives can over-relax respiratory muscles and slow breathing, both of which alter blood gases and internal lung pressure.
• Tumors: These include benign tumors like hamartomas and lung cancers like adenocarcinoma that develop in the tissues surrounding the airways.
• Ascites: This is a complication of liver failure in which the accumulation of fluids in the abdomen places pressure on the diaphragm and lungs.

Risk Factors

The risk of bibasilar atelectasis increase with age. The risk is the same whether you are assigned male at birth or female at birth.

Other factors that can contribute to bibasilar atelectasis include:

• Obesity, which exerts pressure on the diaphragm and lungs
• Pregnancy, which also exerts pressure on the diaphragm and lungs
• Smoking, which increases the risk of lung disease
• Prolonged bed confinement
• Longer surgeries (due in part to the prolonged use of anesthesia)

How Bibasilar Atelectasis Is Diagnosed

If your healthcare provider suspects you have atelectasis, they will perform a physical exam. If there is a collapse, your breathing sounds may be quiet or absent in the lower areas of your lung.

Your healthcare provider will also perform percussion by gently tapping your chest. The sound of the tapping will be different over areas of atelectasis than over healthy areas of the lung.

Additional tests may be ordered to confirm the diagnosis, including:

• Chest X-ray: This standard imaging test can visualize abnormalities in the lungs and chest.
• Ultrasound: This non-invasive imaging test can detect changes in lung tissues and airways using reflected sound waves.
• Computed tomography (CT scan): This imaging test can detect smaller obstructions by compositing multiple X-ray images of the airways.
• Bronchoscopy: This indirect imaging technique involves the insertion of a flexible scope into the trachea (windpipe) to view the lungs.
• Positron emission tomography (PET): This imaging test looks at changes in cell metabolism that are suggestive of lung cancer.
  

Treatment of Bibasilar Atelectasis

The treatment of bibasilar atelectasis varies by the underlying cause. Irrespective of the cause, the ultimate goal is to re-expand the lung to its normal size. A combination of approaches may be needed.

Non-drug intervention may include:

• Breathing exercises: This includes huffing with coughing (also known as controlled coughing).
• Chest percussion: This involves gentle thumping of the chest and back to break up mucus.
  
• Postural drainage: This involves sitting or lying in different positions to move mucus out of the lungs.
• Positive-end expiratory pressure; This device uses gentle air pressure against breathing to help cough up mucus.
• Airway suctioning: This uses gentle vacuum pressure to clear mucus from the lungs.
  

Medications can improve the clearance of mucus, including:

• Bronchodilators: These are inhaled or oral drugs that help open airway passages.
• Mucolytic agents: These are medications that break up and thin mucus in the airways.

The underlying cause of atelectasis needs to be treated to prevent further collapse. This may involve surgery and chemotherapy for lung cancer, fluid drainage for pleural effusion, and antibiotics to treat lung infections or complications of cystic fibrosis.

Complications of Bibasilar Atelectasis

Bibasilar atelectasis can cause severe complications if left untreated, including:

• Bronchiectasis: This is the abnormal, permanent widening of the airways that causes the pooling of mucus in the airways.
• Bacterial pneumonia: This is a severe respiratory infection that causes alveoli to fill with pus and fluid.
• Respiratory failure: This is a potentially life-threatening condition in which the lungs cannot get enough oxygen into the bloodstream.
• Sepsis: This is a potentially life-threatening reaction to a secondary lung infection that spreads into the bloodstream.

Prognosis

The outlook for bibasilar atelectasis is generally good, mostly because it usually occurs in the hospital and can be immediately treated. When treated early, atelectasis can be resolved without any long-term harm to the lungs.

If not treated early, bibasilar atelectasis can cause scarring of lung tissues. This contraction of these tissues can lead to another form of atelectasis, called cicatrization atelectasis.

Cicatrization atelectasis is a form of the disease in which severe scarring of the lungs (pulmonary fibrosis) reduces their ability to expand. The outlook is far less favorable because the loss of lung volume is permanent and sometimes progressive.

How to Prevent Bibasilar Atelectasis

Major surgery with general anesthesia is the most common cause of bibasilar atelectasis. To prevent postoperative atelectasis, your healthcare providers will advise you to stop smoking before your surgery if you are a smoker.

After surgery, there are four things you should do to prevent atelectasis:

• Use an incentive spirometer: This is a simple device that measures the amount of air that you breathe in and out. By keeping your breathing at the optimal range, you can avoid lung collapse.
• Deep breathing: To perform deep breathing exercises, focus on long inhalations and controlled exhalations. Pursed-lip breathing is one example.
• Clear phlegm: Make a concerted effort to cough to clear any mucus from your lungs.
• Move around: It is important to walk, move about, and change your position regularly as directed by your healthcare provider.

Summary

Bibasilar atelectasis is the collapse of the lower lobes of both lungs, most often in people who have undergone surgery with general anesthesia. Symptoms include wheezing, shortness of breath, a wet cough, and rapid, shallow breathing.

Bibasilar atelectasis can be diagnosed with a physical exam, imaging tests, and occasionally a minimally invasive procedure called bronchoscopy. The treatment may involve breathing exercises, airway clearance, and medications that help open the airways and thin mucus. The outlook is generally good with the appropriate treatment.