-IBIS-1.5.0-
tx
respiratory system
pneumonia
diagnoses

definition and etiology

definition:
An acute infection of the parenchyma (alveolar spaces and/or interstitial tissue) of one or both lungs.

etiology:
Pneumonia is classified by the extent of lung involvement:
• Lobar: One entire lobe is involved
• Segmental or lobular: Parts of one lobe are involved.
• Bronchopneumonia: When it affects the alveoli next to the bronchi.

Pneumonia is also classified by the associated microorganism involved in creating the infection: under the main listings of bacterial or nonbacterial:

• Bacterial: Pneumococcal pneumonia (the most common), Strep pneumoniae, Staph aureus, Group A hemolytic strep, Klebsiella pneumoniae, Hemophilus influenzae, Francisella tularensis

• Non-bacterial: Viruses, fungi, rickettsias.

Risk factors for developing pneumonia include URI; malnutrition; hospitalization; debility or immobilization; alcoholism; exposure; coma; hypostasis; foreign object aspiration into the lungs; decreased cough reflex (e.g. from smoking); COPD; major bony abnormality or deformity (e.g. severe kyphoscoliosis); bronchial tumor; and treatment with immunosuppressive drugs.

signs and symptoms

signs and symptoms:
Often, pneumonia is preceded by a URI.
The onset is typically sudden. The following are typical for pneumonia (viral pneumonia may not be as severe).
• Shaking chills.
• Cough with sputum (mucoid, bloody or purulent) production.
• Fever.
• Chest pain.
• Dyspnea with tachypnea.
• Headache.
• Decreased respiratory excursion on affected side.
• Dullness on percussion.
• Auscultation uncovers high or low-pitched crackles.
• (+) bronchial breath sounds with (+) egophony and bronchophony.
• (+) x-ray.
• Patient flexed over to affected side, and the shoulder of affected side may droop. There may be recurrent flushing of one or both cheeks.

lab findings:
• (+) sputum analysis for bacteria.
• Increased WBCs with left shift; in non-bacterial pneumonia, the WBC count may be normal or even low.
• (+) x-ray.

course and prognosis

In pneumococcal pneumonia patients, 90-95% of patients aged 2-50 years old recover uneventfully after treatment. Factors that decrease the chance of survival include: patient <1 or > 60 year old; (+) blood culture; involvement of >2 lobes; WBC count of <5000; BUN >70 mg/100 ml; underlying systemic disease; or development of meningitis, endocarditis or other extrapulmonary illness. Early treatment leads to the best prognosis. Viral and Mycoplasma pneumonia are much more benign, often self-limiting and rarely need treatment other than rest and support (although pneumonia from Influenza A can be severe and fatal; and in either case, the illness may last for weeks).

differential diagnosis

• pleurisy
• bronchitis
• pulmonary embolism
• bronchiectasis
• pulmonary edema


footnotes