Pneumonitis

Pneumonitis is an of the lung that is different from pneumonia, but also leads to breathing problems. As the causes of this disease entity can be quite varied (see below), the clinical presentation can differ from case to case. A common cause of pneumonitis is a chemical internal burn when gastric acid secretions are aspirated into the lungs, a condition called "Mendelson's syndrome"(note that the left side is the patient's right).This leads to an acute inflammatory reaction of the alveolar lining of the affected lungs.

Other causes of pneumonitis are occupational exposure to grain dust, dust from the Western Red Cedar, molds etc. This leads to a hypersensitivity pneumonitis such as grain dust elevator workers get or farmers exposed to moldy hay get Farmer's lung. Histologically there is interstitial granulation tissue in the lung, which makes oxygen transport more difficult and eventually leads to lung fibrosis.

Yet another cause of pneumonitis can be "lymphocytic interstitial pneumonitis" (LIP). This is rare in adults, but more common in children and infants, particularly as up to 50% of infants presenting with LIP have AIDS. Symptoms of this form of pneumonitis is a chronic cough and difficulties to breathe (dyspnea), which may go on for months or years. These children do not thrive and eventually are referred to a pediatrician. A work-up shows that on chest X-rays there are streaky infiltrates on the lungs. Details of a "honey comb lung" can be seen on high resolution CT scan.

Symptoms:

The patient presents with an acute shortness of breath, fast heart beat (tachycardia) and fast, shallow breath movements (tachypnea). There also is a fever, cyanosis (bluish discoloration of the skin) due to a lack of oxygen being transported through the lungs. Often there is production of a pinkish, bubbly sputum. Oxymetry and blood gas analysis confirms a lack of oxygen in the blood. X-rays done when the patient is more stable confirms streaky infiltrates in the lower lung segments.

Treatment:

The most important thing to do for the patient is to provide respiratory support in terms of intubation and what is called "positive pressure ventilation" with help of a respirator. These patients are very sick and often need several days, if not weeks in an Intensive Care Unit setting of a hospital. A respirologist and infection specialist are often needed for their care.

Corticosteroid therapy often improves children with lymphocytic interstitial pneumonitis. If AIDS is also present, this must be treated with antiviral therapy (cocktail mix).

Infections overview

Respiratory Infection

Disclaimer:

This outline is only a teaching aid to patients and should stimulate you to ask the right questions when seeing your doctor. However, the responsibility of treatment stays in the hands of your doctor and you.

References:

1. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 161.

2. TC Dixon et al. N Engl J Med 1999 Sep 9;341(11):815-826.

3. F Charatan BMJ 2000 Oct 21;321(7267):980.

4. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 43.

5. JR Zunt and CM Marra Neurol Clinics Vol.17, No.4,1999: 675-689.

6. The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 162.

7. LE Chapman : Antivir Ther 1999; 4(4): 211-19.

8. HW Cho: Vaccine 1999 Jun 4; 17(20-21): 2569-2575.

9. DO Freedman et al. Med Clinics N. Amer. Vol.83, No 4 (July 1999): 865-883.

10. SP Fisher-Hoch et al. J Virol 2000 Aug; 74(15): 6777-6783.

13. PE Sax: Infect DisClinics of N America Vol.15, No 2 (June 2001): 433-455.

14. David Heymann, MD, Editor: Control of Communicable Diseases Manual, 18th Edition, 2004, American Public Health Association.

Last Modified: Jan. 19, 2008