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·
What’s the next step? Get a chest X-ray (CXR)!
Although this is easily possible in a UH setting, it’s
not always feasible as in a clinic where
Community Acquired Pneumonia
diagnosis may be simply based on the H& P.
o
The
CXR of this patient showed loss of diaphragm on left
side, consolidation, fluid near the apex of the lung,
and opacity in right mid-lung suggestive of infiltrate.
o
The
CXR confirms the presence of infiltrates and
opacities which indicate the filling of alveoli with
inflammatory cells. It also shows how much of the lung
is actually involved in the disease. It’s a method of
risk assessment (severity and likely outcome of disease)
and provides a baseline to assess improvement or
deterioration.
o
It
also reveals co-existing problems such as pleural
effusion (suggestive on the CXR above), bronchiectasis,
CHF (seen as a cardiac silhouette), obstructing tumor
(seen as volume loss of part of the lung), etc.
§
Pleural effusion – fluid in the pleural space usually
due to inflammation that can result in permanent
fibrotic thickening. The fluid gravitates to the bottom
of the pleural space so you will hear patients with
crackles caused by pulmonary fibrosis near the base of
the lungs.
§
Bronchiectasis – chronic dilation of bronchi or
bronchioles as a sequel of inflammatory disease or
obstruction.
§
Congestive heart failure (CHF) - A chronic, progressive
disease in which the myocardium weakens and can not pump
blood efficiently. Fluid accumulates in the lungs,
hands, ankles, or other parts of the body resulting in
congestion and edema.
§
Obstructive tumor
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Additional diagnostics
that should be considered:
o
Risk
assessment – ABG (arterial blood gas) to see how
much O2 is exchanged for CO2 within the lungs, WBC
to measure the strength of the inflammatory
response, Na+ to detect dehydration, BUN
also to detect dehydration and renal function, and
glucose to detect diabetes.
o
Do a
gram stain sputum and make sure that you have a sample
representative of the lower lung, not the saliva. A
deep sputum specimen should normally have 10-15 PMNs/hpf
(high power field), and <5 squamous epithelial cells/hpf.
The utility of this technique is controversial.
o
Culturing the sputum is also controversial, but
if it’s done, it should be prior to antibiotics.
o
Most
physicians do a blood culture.
o
Other tests can be administered depending on associated
clinical conditions present.
·
Diagnostic evaluation:
o
ABG
on RA: pH 7.31, pO2 78, pCO2 34 (all are decreased)
o
WBC:
18,500 (elevated > 10,000 so an inflammatory response is
detected here)
o
Na+:
137 (within normal limits, WNL)
o
BUN:
32 (increased, confirming dehydration and dry mucous
membranes)
o
Glucose: 122 (WNL)
·
Risk
assessment – ATS (American Thoracic Society) guidelines
(these require conditions require attention when the
patient presents with pneumonia because of posed risk of
developing serious complications, so consider
hospitalization; bolded conditions mandate
hospitalization and central monitoring; * conditions
were risk factors in the presented patient):
o
Age
> 60
o
Comorbidity: COPD (chronic obstructive pulmonary
disease), diabetes, CRF (chronic renal failure), CHF,
liver disease
o
Aspiration pneumonia
o
Altered mental status
(lethargic, comatose patients)
o
Post-splenectomy (these patients can’t handle
encapsulated organisms well)
o
*Alcohol abuse
o
*RR
> 30
o
DBP
< 60, SBP < 90
(hypotension)
o
WBC
<4,000 or > 30,000
o
*BUN
> 20 (dehydration)
o
pO2
< 60 or pCO2 > 50 on RA, room air
(widened alveolar oxygen difference)
o
*Multi-lobar involvement
o
Malnutrition
·
Treatment
(antibiotics based on most likely pathogen and
severity of pneumonia):
o
Causative agents include S. pneumoniae (leading
cause), M. pneumoniae, H. influenzae, S. aureus, C.
pneumoniae, Legionella, M. tuberculosis, respiratory
viruses, aerobic gm- bacilli. The likelihood of the
organism’s involvement varies with the demographics of
the population.
o
Recognize the pneumonia quickly and start treatment ASAP
because the outcome is influenced by how fast the
medication is started. Obtain blood cultures prior to
starting the antibiotics and then start antibiotics 4
hours after arriving at the ER. With the treatment,
go on your best guess, so S. pneumoniae has to be
accounted for. If the cultures come back different,
then change the treatment accordingly.
o
Follow-up with CXR to assess the efficacy of the
treatment seen by clearing of infiltrates. If the
pneumonia is caused by a tumor obstructing an airway, it
may persist and clue you in that you’re dealing with a
post-obstructive pneumonia instead.
·
Summary:
o
Pneumonia is important due to its high prevalence and
societal burden.
o
Key
diagnostic features: acute, fever, cough, sputum,
dyspnea, pleuritic chest pain.
o
Evaluate with physical exam, CXR, labs (ABG, CBC, Na+,
BUN, glucose, cultures), and risk assessment (to
determine whether you will treat as inpatient or
outpatient)
o
Treatment consists of empirical antibiotic therapy.
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