2. DEFINATION
Pneumonia is an infection of the pulmonary
parenchyma .
bronchopneumonia
refers to more patchy alveolar consolidation
associated with bronchial and bronchiolar
inflammation, often affecting both lower lobes.
3. CLASSIFICATION
Pneumonia has usually been classified as
community-acquired (CAP)
hospital-acquired (HAP), or ventilator-associated
(VAP)
4. EPIDEMEOLOGY
In UK, an estimated 5–11/1000 adults suffer from
community-acquired pneumonia (CAP) each year
This accounts for around 5–12% of all lower respiratory tract
infections.
CAP may affect all age groups but is particularly common at
the extremes of age; for example, worldwide, CAP continues
to kill more children than any other illness and the propensity
to ease the passing of the debilitated and the elderly led to
designation of pneumonia as the ‘old man’s friend’
5. pathophysiology
Mechanical defenses of the airway
hairs and turbinates of the nares
branching tracheobronchial tree
mucociliary clearance
gag and cough reflexes
all play a role in host defense but are insufficient to
effectively block bacterial access to the lower airways.
6. Cont..
In the absence of a sufficient barrier,
microorganisms may reach the lower respiratory
tract by a variety of pathways, including
inhalation
microaspiration
direct mucosal dispersion
7. Cont..
Lung microbiota is determined by three
factors:
Microbial entry into the lungs
Microbial elimination
regional growth conditions for bacteria, such as pH,
oxygen tension, and temperature
8. Cont.
An inflammatory event resulting in epithelial and or
endothelial injury results in the release of cytokines,
chemokines, and catecholamines, some of which may
selectively promote the growth of certain bacteria, such as
Streptococcus pneumoniae and P. aeruginosa
This cycle of inflammation, enhanced nutrient availability,
and release of potential bacterial growth factors may result in
a positive feedback loop that further accelerates
inflammation and the growth of particular bacteria, which
may then become dominant.
9. Cont..
In cases of CAP and HAP, the trigger may be a
viral infection compounded by microaspiration
of oropharyngeal organisms
In cases of true aspiration pneumonia, the trigger
may simply be the macroaspiration event itself
10.
11.
12. Clinical features
CAP
usually presents as an acute
illness. Systemic features
include
fever,
rigors,
shivering
malaise
Delirium may be present.
The appetite is invariably
lost
headache frequently
reported
13. Pulmonary symptoms include
cough, which at first is characteristically short, painful and dry,
Later is accompanied by the expectoration of mucopurulent
sputum.
Rust-colored sputum may be produced by patients with Strep.
Pneumonia infection and the occasional patient may report
haemoptysis
Pleuritic chest pain may be a presenting feature and on
occasion may be referred to the shoulder or anterior abdominal
wall.
Upper abdominal tenderness is sometimes apparent in patients
with lower lobe pneumonia or those with associated hepatitis.
15. Hospital acquired pneumonia
Hospital-acquired pneumonia (HAP) or nosocomial
pneumonia refers to a new episode of pneumonia
occurring at least 2 days after admission to hospital.
It is the second most common hospital-acquired
infection (HAI) and the leading cause of HAI
associated death
The elderly are particularly at risk, as are patients in
intensive care units, especially when mechanically
ventilated
16. Cont..
Health-care-associated pneumonia (HCAP) refers
to the development of pneumonia in a person who has
spent at least 2 days in hospital within the last 90 days
or has attended a haemodialysis unit
or received intravenous antibiotics,
or been resident in a nursing home or other long-
term care facility
17. Clinical features and investigation
The diagnosis should be considered in any hospitalised or
ventilated patient who
develops purulent sputum (or endotracheal secretions)
new radiological infiltrates
an otherwise unexplained increase in oxygen
requirement
A core temperature >38.3°C, and a leucocytosis or
leucopenia.
18. DDX OF HAP
The clinical features and radiographic signs are variable
and non-specific, however, raising a broad differential
diagnosis that includes
pulmonary embolism,
ARDS,
pulmonary oedema,
pulmonary hemorrhage
drug toxicity.
19. Therefore, in contrast to CAP, microbiological confirmation
should be sought whenever possible.
Adequate sputum samples may be difficult to obtain in the
frail elderly person
Physiotherapy should be considered to aid expectoration.
In patients who are mechanically ventilated, bronchoscopy-
directed protected brush specimens, Broncho alveolar
lavage (BAL)
Endotracheal aspirates may be obtained
20. Investigations
Full blood count
Very high (>20×109/L) or low (<4×109/L) white cell countt: marker
of severity
Neutrophil leucocytosis >15×109/L: suggests bacterial aetiology
Haemolytic anaemia: occasional complication of Mycoplasma
Urea and electrolytes
Urea >7 mmol/L (~20 mg/dL): marker of severity
Hyponatraemia: marker of severity
21. Cont..
Liver function tests
Abnormal if basal pneumonia inflames liver
Hypoalbuminaemia: marker of severity
Erythrocyte sedimentation rate/C-reactive protein
Non-specifically elevated
Blood culture
Bacteraemia: marker of severity
22. Cont..
Cold agglutinins
Positive in 50% of patients with Mycoplasma
Arterial blood gases
Measure when SaO2 <93% or when clinical features are
severe, to
assess ventilatory failure or acidosis
Sputum samples
Gram stain , culture and antimicrobial sensitivity
testing
23. Cont..
Polymerase chain reaction for Mycoplasma pneumoniae and other
atypical pathogens
Pneumococcal and/or Legionella antigen test
Air bronchogram (air-filled bronchi appear lucent against
consolidated lung tissue) may be present
Bronchopneumonia
Typically patchy and segmental shadowing
Complications
• Para-pneumonic effusion, intrapulmonary abscess or empyema
Staphylococcus aureus
24. Cont..
Suggested by multilobar shadowing, cavitation,
pneumatoceles and
abscesses
Laboratory samples used
Sputum
Oropharynx swab
Pleural fluid
25. X-RAY
Pneumonia of the right
middle lobe.
Posteroanterior view:
consolidation in the right
middle lobe with characteristic
opacification beneath the
horizontal fissure and loss of
normal contrast between the
right heart border and lung
28. Cont..
Endotracheal intubation/tracheostomy
Infected ventilators/nebulisers/bronchoscopes
Dental or sinus infection
Abdominal sepsis
Intravenous cannula infection
Infected emboli
Reduced host defenses against bacteria
Aspiration of nasopharyngeal or gastric secretions
Bacteria introduced into lower respiratory tract
Bacteremia.
29. Pneumonia in immunocompromised
Patients immunocompromised by drugs or disease
particularly human immunodeficiency virus (HIV)
infection; are at increased risk of pulmonary
infection and pneumonia is the most common cause
of death in this group
majority of infections are caused by the same
pathogens that cause pneumonia in
immunocompetent individuals
30. Cont..
They are susceptible to opportunistic’ pathogens
like
Gram-negative bacteria, especially P. aeruginosa,
viruses,
Fungi
mycobacteria,
less common organisms such as Nocardia spp.
Infection is often due to more than one organism
31. Clinical features
These typically include fever, cough and breathlessness
but are influenced by the degree of immunosuppression,
and the presentation may be less specific in the more
profoundly immunosuppressed.
The onset of symptoms tends to be swift in those with a
bacterial infection but more gradual in patients with
opportunistic organisms such as Pneumocystis jirovecii
and mycobacterial infections
32. Cont..
In P. jirovecii pneumonia, symptoms of cough
and breathlessness can be present several
days or weeks before the onset of
systemic symptoms or the appearance of
radiographic abnormality
33. investigations
HRCT can be helpful:
• focal unilateral airspace opacification favours
bacterial infection, mycobacteria or Nocardia
• bilateral opacification favours P. jirovecii
pneumonia, fungi, viruses and unusual bacteria,
e.g. Nocardia
• cavitation may be seen with N. asteroides,
mycobacteria and fungi
34. Cont..
the presence of a ‘halo sign’ (a zone of
intermediate attenuation between the nodule and
the lung parenchyma) may suggest aspergillosis
pleural effusions suggest pyogenic bacterial
infections and are uncommon in P. jirovecii
pneumonia
37. Management
The most important aspects of management include
oxygenation
fluid balance
and antibiotic therapy.
In severe or prolonged illness, nutritional support
may be required
38. Oxygen
Oxygen should be administered to all patients with
tachypnoea, hypoxaemia, hypotension or acidosis
with the aim of maintaining the PaO2 ≥8 kPa (60
mmHg) or SaO2 ≥92%
39. Fluid balance
Intravenous fluids should be considered in those with
severe
illness, in older patients and those with vomiting.
It may be appropriate to discontinue hypertensive
agents temporarily
Otherwise, an adequate oral intake of fluid should be
encouraged
Inotropic support may be required in patients with shock
40. Treatment of pleural pain
It is important to relieve pleural pain in order to
allow the patient to breathe normally and cough
efficiently.
For the majority, simple analgesia with
paracetamol, co-codamol or NSAIDs is sufficient
In some patients, opiates may be required but must
be used with extreme caution in individuals with
poor respiratory function
44. prognosis
Most patients respond promptly to antibiotic therapy.
Fever may persist for several days, however, and
the chest X-ray often takes several weeks or even
months to resolve, especially in old age.
Delayed recovery suggests either that a
complication has occurred or that the diagnosis is
incorrect
45. references
Davidson's principles and practice of medicine. 24st ed. E.L.B.S. and Churchill
Livingstone, London.
Harrison's principles of internal medicine. 21st ed. New York :McGraw-Hill, Health
Professions Division
46. Sir Robert Hutchison’s prayer.
From the inability to let well alone;
From too much zeal for the new and contempt for what is
old;
From putting knowledge before wisdom, science before art,
and cleverness before common sense;
From treating patients as cases;
And from making the cure of disease more grievous than the
endurance of the same;
Good Lord, deliver us.”
