What is Acute Interstitial Pneumonia (Pneumonia)?
Acute interstitial pneumonia, also known as AIP or Hamman-Rich syndrome, is a severe lung disease that can rapidly worsen and often results in extreme respiratory failure and acute respiratory distress syndrome (ARDS). This disease stands out from other forms of interstitial pneumonia because it causes rapid respiratory failure in someone who doesn’t have a previous lung condition.
The disease was first identified by Louis Hamman and Arnold Rich in 1935. They described it as a rapidly advancing lung disorder involving inflammation and scarring of lung tissue. Later, in 1986, Katzenstein used the term AIP to differentiate it from long-term interstitial pneumonia conditions.
The American Thoracic Society (ATS) and the European Respiratory Society (ERS) both categorize AIP as a major type of idiopathic interstitial pneumonia, compared with other rare or less well-defined types of the same disease.
What Causes Acute Interstitial Pneumonia (Pneumonia)?
Acute interstitial pneumonia (AIP) is a condition whose cause is not currently known.
Risk Factors and Frequency for Acute Interstitial Pneumonia (Pneumonia)
The average age of people with AIP (Autoimmune Pancreatitis) is about 55 years old. Both males and females have an equal chance of developing the condition.
Signs and Symptoms of Acute Interstitial Pneumonia (Pneumonia)
People with acute Diffuse Alveolar Damage (DAD) typically begin by experiencing symptoms similar to those of a viral infection. This is usually followed by difficulty breathing, cough, and fever. These symptoms rapidly worsen, leading to severe trouble with breathing. Physical symptoms of acute DAD are often vague and can include low levels of oxygen in the blood, rapid breathing, and a crackling sound in both lungs. Most patients with acute DAD have very low levels of oxygen in their blood and need help breathing from a machine.
A detailed medical history and thorough physical check-up are incredibly important in investigating other potential causes of acute DAD.
Testing for Acute Interstitial Pneumonia (Pneumonia)
Patients suffering from Acute Interstitial Pneumonia, a lung condition, can experience a quick worsening of their breathing ability. Hence, it’s important to frequently monitor essential body functions such as pulse, temperature, breathing, and blood pressure. Conducting arterial blood gas tests helps in understanding the extent of low oxygen levels in the blood and whether a ventilation system might be needed to help with breathing.
Doctors generally conduct a chest X-ray to examine the lungs. The x-ray generally shows signs similar to ARDS – a severe lung condition that causes insufficient oxygen in the blood due to fluid build-up in the air sacs, with symptoms noticeable across both lungs. Hence, it becomes crucial to rule out heart-related causes of fluid build-up in the lungs. An echo test (echocardiography) helps rule out any underlying heart diseases or abnormalities with the heart valves that could cause such a condition.
Within the first 12 hours of the onset, High-Resolution Computed Tomography (HRCT), a special type of x-ray that gives detailed images of the lungs, is generally conducted. The scan shows unique opacity signs that may appear scattered or diffused. Moreover, these scan findings can also point to signs of the bronchial tubes’ abnormal widening, indicating progression of the condition.
Blood tests are usually done to check for any autoimmune diseases or diseases related to connective tissues that might potentially cause lung diseases. These can range from rheumatoid arthritis and systemic lupus erythematosus to skin conditions and dry mouth/eyes syndrome.
Further, doctors also need to rule out any infections in the lungs. For this purpose, blood and mucus tests as well as influenza screening are conducted. They also test for Legionella, a bacteria causing a form of pneumonia that can be detected via urine tests.
Bronchoscopy, a procedure to look directly at the airways in the lungs through a thin viewing instrument called a bronchoscope, is conducted. This also helps in obtaining samples from the respiratory system for culture in cases where there is no mucus production. These samples are sent for various tests and checks.
In some cases, if these tests don’t help in making a diagnosis, a lung biopsy might be required. This can help reveal causes like tuberculosis, sarcoidosis, vasculitis, abscesses, or viral infection.
Acute interstitial pneumonia is a disease of unknown origin. After ruling out other causes, a pathological confirmation is needed to establish the diagnosis.
Treatment Options for Acute Interstitial Pneumonia (Pneumonia)
There’s no established treatment for Acute Interstitial Pneumonia (AIP). The primary focus of management is generally supportive care. Acute Interstitial Pneumonia often leads to difficulty in breathing, which can’t typically be managed without the aid of a machine called a mechanical ventilator, used to support or replace the function of the lungs.
The severity of this respiratory issue is usually determined by analyzing arterial blood gases based on the Berlin Criteria. The ventilator management primarily involves a ventilation technique that involves small breaths to reduce injury to the lungs, along with other advanced ventilation strategies used in Acute Respiratory Distress Syndrome (ARDS).
Broad-spectrum antibiotics, which work against a wide range of bacteria, are initially recommended until it can be proven that the condition is not caused by an infection.
Although steroids are often given as a treatment, their effectiveness in treating Acute Interstitial Pneumonia is not proven. For example, in a study of 29 patients with this condition, 12 patients survived. The survival rate was slightly higher in patients who received steroids compared to those who didn’t. However, in a different study involving 9 patients who all received a specific type of steroid, the mortality rate was 100%.
In extreme cases, where conventional treatment strategies have not been effective, both Extra-Corporeal Membrane Oxygenation (ECMO, a machine which takes over the function of the heart and lungs) and lung transplantation should be considered for suitable candidates.
What else can Acute Interstitial Pneumonia (Pneumonia) be?
When doctors are trying to determine if someone has acute interstitial pneumonia, there are several other conditions they need to consider before making a diagnosis. These include:
- Other types of pneumonia that affect the spaces between lung tissue, such as cryptogenic organizing pneumonia, acute eosinophilic pneumonia, and hypersensitivity pneumonitis
- A sudden worsening of a previously diagnosed lung disease, or a lung-related issue brought on by a disease affecting the connective tissues of the body
- Acute heart failure
- Infections
- Diffuse alveolar hemorrhage, a condition where tiny blood vessels in your lungs start to leak
- Lung injuries caused by medicine
- Lung damage caused by radiation therapy
From this list, they can then conduct the appropriate tests to confirm the correct diagnosis.
What to expect with Acute Interstitial Pneumonia (Pneumonia)
The death rate is over 50%, either when first diagnosed or within six months of the disease starting. Additionally, in those who survive, there are reports of the disease reoccurring and of chronic lung disease developing.
Preventing Acute Interstitial Pneumonia (Pneumonia)
Acute interstitial pneumonia is a condition that appears suddenly and its exact causes are unknown, making it difficult to prevent or foresee. The early symptoms are not unique to this condition and can resemble any other lung disease. Because of this, it’s important for individuals to seek medical attention quickly if they experience any respiratory issues.
Diagnosing this kind of pneumonia isn’t straightforward, as there’s no specific test for it. A lung biopsy, which involves taking a small sample of lung tissue, is the only way to definitely confirm its presence. Unfortunately, there isn’t a specific medication for treating acute interstitial pneumonia. Instead, the approach usually involves providing supportive care to manage symptoms and improve quality of life.
