Respiratory Diseases and the Fire Service

Limitations
• The material obtained from a needle biopsy may not be sufficient to
make a diagnosis.
• Needle may not be in an active site of lesion and thereby give a false
negative result (false reassurance). This possibility must be carefully
considered when the diagnosis appears to be non-cancerous.
• Small nodules less than one centimeter are difficult to diagnose on
needle biopsy.
• Certain diseases like cystic lungs, emphysema, severe heart failure,
bleeding disorders and patients with poor oxygenation may be
contraindications for this procedure.
IMAGING OF PULMONARY ARTERIES AND VEINS
The pulmonary arteries carry de-oxygenated blood from the right ventricle of
the heart to the lungs for oxygenation. The oxygenated blood is then returned
by the pulmonary veins into the left atrium of the heart. The main pulmonary
artery starts as a trunk approximately two inches long and slightly over one
inch wide that arises from the right ventricle outflow tract. It then branches
into right and left pulmonary arteries, which further divide to supply the
corresponding lung.
The pulmonary arteries are involved in several disease processes. A pulmonary
embolism (PE) is a sudden blockage of one or more pulmonary arteries, caused
by a blood clot, which forms, usually in the leg or pelvic veins.
In fire fighters, probably the most common cause for a blood clot is leg
trauma with subsequent prolonged inactivity (casting and or bed rest). See
the separate chapter on pulmonary embolism for further details. Once the
blood clot goes to the lung, the patient experiences sudden shortness of breath,
chest pain and depending on the relative size of the clot, sudden death, if
not promptly treated. Another vascular disease is pulmonary hypertension
which is a more insidious disease of the pulmonary arteries, which occurs as
a consequence of several chronic lung conditions including interstitial lung
diseases and severe emphysema. It can also be caused by severe sleep apnea
and certain cardiac conditions. It results in poor exercise tolerance and may
lead to a progressive, fatal course.
Pulmonary Angiography
The classic test for imaging pulmonary arteries is pulmonary angiography. It
involves injection of iodinated dye into the circulation with subsequent direct
x-ray visualization (fluoroscopy) of the lungs. The test can be done in either
invasively or in a non-invasive manner using CT scanning.
Conventional (Catheter) Pulmonary Angiography
Conventional pulmonary angiography is invasive because a catheter is
introduced into the right heart through one of the thigh veins. Contrast or
dye is then injected through this catheter into the pulmonary artery. Catheter
pulmonary angiography is now infrequently performed as a CT pulmonary
angiography, a non-invasive test has gained wide acceptance.
Chapter 4-2 • Imaging Modalities in Respiratory Diseases 309