How to Diagnose Acute Respiratory Distress Syndrome

Before going into details on how to efficiently diagnose acute respiratory distress syndrome (ARDS), we’ll have a quick overview and some signs and symptoms.


Acute respiratory distress syndrome (ARDS) develops due to the building up of fluids inside the alveoli or the microscopic, elastic sacs of air inside the lungs. This build-up of fluid will prevent or make it difficult for the lungs to be filled in with air, resulting in limited oxygen reaching the bloodstream. Decreased oxygen in the body compromises the entire system from working properly.


ARDS usually happens to people who are severely ill or those who have experienced critical injuries. As for those who already have ARDS, most of them do not survive, and the risk of mortality increases with the illness’ severity and age. As for those who do survive, they either have irreversible lung damage or will recover completely.

Signs and Symptoms

The manifestations of ARDS change with intensity, and will significantly depend on the illness’ severity and cause; not to mention the presence of an underlying lung or heart disease. Some of the common signs and symptoms of ARDS are:

  • Shortness of breath (SOB)
  • Decreased blood pressure
  • Extreme fatigue
  • Confusion
  • Rapid and labored breathing


How do we diagnose ARDS? How does one say that the client needs to be taken to the ICU as soon as possible? Here are the main criteria to accurately diagnose ARDS in a client:

  1. Erroneous breathing

One of the main criteria for diagnosing ARDS is the inconsistency in breathing patterns since the lungs are primarily affected.

  1. Oxygen saturation (SaO2)

If a post-operative client’s oxygen saturation has been steadily below 90% Sa02, it is one of the main indicators for ARDS.

  1. Partial pressure of oxygen (PaO2)

The doctor will also order out an ABG test to see how much PaO2 or oxygen is going back to the pulmonary artery. If the result is anything less than 60%, that’s another criterion for ARDS.

  1. Power of hydrogen (pH)

If the pH result is less than 7.30, this means that the blood’s acidity is high and will immediately affect the lungs.

To summarize, here are the things that healthcare practitioners should watch out for when trying to diagnose ARDS:

  • SaO2 – less than 90%
  • PaO2 – less than 60%
  • pH – less than 7.3


Aside from distressed breathing, if the results show the indicators mentioned above, all it means is that the lungs are filling up with carbon di-acid or carbon dioxide, which makes it hard for the client to breathe.

While oxygen is not going inside the lungs and to the rest of the body, carbon dioxide is building up. Therefore, it is expected that carbon dioxide can go as high as 50mEq/L. This will cause the blood to become very acidic.

So, now that we are well aware of how acute respiratory distress syndrome is diagnosed, we will now proceed to the stages based on the severity of the illness; all this and more in our next article.

For more topics related to nursing, drop by Simple Nursing’s website and YouTube channel.

Tuberculosis Pathology and Assessment

Tuberculosis (TB) is a bacterial infection that resides inside the lungs caused by Mycobacterium tuberculosis. While books and nursing lectures would insist that tuberculosis is a droplet precaution, the Centers for Disease Control (CDC) and Prevention would say otherwise.

According to the CDC, tuberculosis is an airborne precaution that can spread by breathing in the same air that an infected person breathes in, especially when the person coughs, sneezes, laughs, sings, and even speaks.

Airborne Diseases

Airborne diseases can be categorized with MTV, which can be translated as:

  • MMR (measles, mumps, and rubella)
  • Tuberculosis
  • Varicella (chicken pox)

Varicella and mumps are also under the category of contact precautions. Take note that MTV diseases are required to be placed inside a negative pressure room so that air is taken out, minimizing the risk of spreading the diseases.

Breathing In the Same Air

Regarding pathology, what happens when you breathe in the same air as someone who has tuberculosis? This scary occurrence can happen especially when you’re in a crowded place or a small space. Breathing in the same air as with someone who has tuberculosis can put you at risk of having the disease.

Airborne precautions are mandatory for nurses who are caring for tuberculosis clients. Instead of the usual surgical mask, healthcare providers in charge of clients with tuberculosis wear N95 masks. N95 masks help in preventing inhalation of outside air.


As the bacteria goes inside the lungs, it spreads through the lymphatic system and into the bloodstream. Once the body’s immune system is alerted, the B cells will create antibodies against the infection and the T cells, which are the natural born killers, will attack the tuberculosis bacteria. The macrophages will then make a perimeter to quarantine the bacteria and cease reproduction and growth inside the lungs.

Unfortunately, the T cells cannot kill the bacteria; the best thing that they can do is to isolate the bacteria so it cannot spread out. It’s like putting the bacteria inside the prison. Captive bacteria are now called granulomas.

Assessing Tuberculosis

When a client comes into the ER, they usually are not aware that they have TB. Therefore, there are a couple of ways to assess if this client has tuberculosis.

  1. A blood-tinged cough

A blood-tinged cough related to tuberculosis usually comes out in NCLEX® . Hemoptysis is the medical term given to coughing up of blood.

  1. Difficulty of breathing

Along with bloody sputum, there would also be the difficulty of breathing or dyspnea and pallor due to the infection and lack of oxygen exchange inside the lungs.

  1. Crackles (rales)

Crackles are sounds that are distinguishingly heard clients are auscultated that are mainly caused by fluid accumulation inside the small airways of the lungs or the alveoli. Crackles can either be coarse or fine. Aside from tuberculosis, crackles can also be heard from clients with CHF, bronchitis, and pneumonia.

Other Lung Sounds

  • Ronchi is snore-like sounds caused by airway secretions and are usually cleared by coughing.
  • Wheezing is like a whistle, mostly manifested by clients with bronchitis, emphysema, and asthma.

These lung issues are usually resolved by bronchodilators and anti-inflammatories.

  1. Anorexia

Loss of appetite can lead to anorexia or weight loss. When a person is sick and is experiencing lack of oxygen, the craving to eat becomes absent. Furthermore, the client gets easily tired or fatigued.

  1. Night Sweats

Night sweats get worse in time, and it’s because of the infection brewing inside the body.

Laboratory Tests

There are a couple of ways to confirm a diagnosis of tuberculosis.

  1. X-ray

Granulomas that show on the x-ray result as small ducts or bumps indicate positive tuberculosis reading from radiology.

  1. Sputum

The sputum test is done first thing in the morning so that the bacteria can brew overnight. This is done for three consecutive days, always upon waking up in the morning.

  1. Skin test

A skin test, also known as a positive protein derivative (PPD) test that shows a raised lump within 48 hours indicates that there is a positive reaction. This means that the T cells and macrophages have effectively surrounded and caused inflammation to the protein injected in the arm.

  1. Increased WBCs

If the tuberculosis infection has spread to other parts of the body, white blood cells will increase more than 10,000.

  1. ESR

Erythrocyte segment rate (ESR), on the other hand, is more specific because this indicates the presence of inflammation, assisting with the diagnosis of tuberculosis.

A negative tuberculosis screening, also known as latent phase, does not necessarily mean that there is absolutely no sign of the bacteria inside the body. To achieve a negative result in a latent stage, the client should have the following outcomes:

  • A negative chest x-ray
  • Negative sputum cultures (done three times)
  • Positive PPD test

A positive, active result will yield the following:

  • Positive chest x-ray
  • Positive sputum test

For our next video, we’ll be discussing the nursing intervention of tuberculosis clients. For other respiratory lectures and nursing-related topics, you can visit our SimpleNursing website and YouTube channel.

Peripheral Catheters: Pulmonary Caths explained (SWANS) Pt 5

In this lecture we are going to talk about the following:

  1. Hemodynamics
  2. SWANS catheter
  3. Cardiac output
  4. Pulmonary artery wedge pressure
  5. Atrium pressure (central venous pressure)


The main reason for to run a hemodynamics test is to measure four different things:

  1. Vascular capacity – how much pressure is going into the heart
  2. Blood volume – how much volume of blood the heart should push
  3. Pump effectiveness – deals with cardiac output, stroke volume, preload, afterload
  4. Tissue perfusion – concerned with the oxygen that the body consumes

SWANS Catheter

SWANS catheter (pulmonary artery catheter), on the other hand, measures three things, namely:

  1. Pressure
  2. Cardiac output – how much blood the heart pushes in one minute
  3. Oxygen – how much oxygen is going out of the heart

To measure pressure, the doctor inserts the catheter into the right atrium (adjacent to the SA node) and inflates the balloon. Through natural force, the air follows the pressure of the fluid inside the heart and will rest at the pulmonary arteries. Take note that the right side of the heart is responsible for pumping blood directly into the lungs; therefore, the inserted catheter will measure the pressure from the body, into the lungs.

Now, remember, right-sided heart failure is equivalent to body failure. This means that the body does not have sufficient amount of pressure to pump blood into the lungs, causing blood to be forced back into the body, which then leads to edema.

Whereas, if there is a backflow of blood into the left ventricle and goes back into the lungs, there will be the presence of crackles, which is one of the symptoms of left-sided heart failure. Remember that left-sided heart failure can also be considered as a lung-heart failure because the fluid from the heart is being sent back into the lungs.

There are three specific ways to measure the pressure inside the heart.

  1. Right atrial pressure (central venous pressure) – this should be between 1 – 8 mmHg.
  2. PAP (pulmonary artery pressure) – always deflated; resulting in systolic pressure of 15-26 mmHg and a diastolic of 5 – 15 mmHg.
  • Systolic pressure is the squeeze, the force that the heart exerts during contraction (depolarization) and into the lungs and the left ventricle.
  • Diastolic pressure is the decompression or relaxation
  1. PAWP (pulmonary artery wedge pressure) – catheter inflation in the pulmonary artery down to the lungs. Inflation lasts for three to five seconds, cutting off circulation for a quick moment. This will provide a direct measurement of the pressure being back-flowed from the lungs to the prongs. The pressure should be between 4 – 12 mmHg. Furthermore, this measures left ventricular pressure and the diastolic pressure; these are just fancy words for left ventricle “filling time.”

Trivia: in a laboratory setting, this phenomenon is determined by brain natriuretic peptides (BNP). BNP inside the left ventricle helps in the stretching of this specific chamber.

If in case the PAWP is less than 4 mmHg, the client will experience hypovolemia or decreased pressure being pushed into the left ventricle. Hypervolemia, on the other hand, happens if PAWP is more than 12 mmHg; which is also indicative of left ventricular failure.

Example, if your client has 18 mmHg, there will be increased pressure on the left ventricle due to the pooling of blood inside the chamber which causes it to stretch further. The backflow will extend into the right ventricle.

Cardiac Output

Cardiac output (CO) measures the blood flowing into the heart. SWANS measures cardiac output through the thermodilution method which you can remember as the cold choo-choo train.

Take note that normal cardiac output is 4 – 8 L/min. In the thermodilution method, how is that measured with the catheter?

The doctor will pump 5 to 10 ml of cold, normal saline into the catheter, which goes through the heart. The measurement will depend on how fast or how long it took for normal saline to travel into the heart; thus, the cold choo-choo train.


This measurement basically focuses on how much oxygen is present in the heart and how much oxygen is going back into the lungs. Here, the SVO2 caliber in the catheter is used. Normal SVO2 is between 60% to 80% hemoglobin going back into the lungs. A fiber optic light is used in this type of measurement.

As a recap, a SWANS catheter measures a client’s:

  • Pressure
  • Cardiac Output
  • Oxygenation
  • Heart and blood volume

When is a SWANS catheter (pulmonary artery catheter) used?

SWANS catheter is inserted in clients who underwent cardiac surgery, usually post-CABG. Here, we wanted to observe how the heart is coping with the procedure. Aside from that, SWANS is also inserted in cases of heart failure wherein the doctor has already exhausted all pharmacologic measures like taking volume-depleting drugs which includes ACE inhibitors, Lasix (furosemide), beta-blockers, and calcium-channel blockers.

How is the SWANS catheter inserted?

The client is put on a supine or Trendelenburg position. The doctor will insert the catheter into the jugular vein of the neck or the subclavian vein right under the clavicle or collarbone. From there, the catheter will then be inserted in the right atrium of the heart.