PNEUMONIA

Pneumonia is defined as an acute inflammation of lower respiratory tract (lung parenchyma) associated with recently developed radiological pulmonary shadowing.

Classification:

1.      Community Acquired Pneumonia: Bacterial (Strep. Pneumoniae, H. influenzae, Staph. Aureus, Kl. Pneumoniae), Viral (RSV seen mainly in infancy, influenza virus, para influenza virus, measles virus and varicella virus), Chlamydia, Mycoplasma pneumoniae, Rickettsiae can also give rise to primary pneumonia.

2.      Hospital-acquired pneumonia (pneumonia occurring atlas 2 days after admission to hospital) Common organism are E. coli, Pseudomonas, Klebsiella, Staph. Aureus and anaerobic organism.

3.      Pneumonia in immunocompromised pt. e.g – Pneumocystis carinii, Aspergillus fumigatus, CMV, Herpes virus, M. tuberculosis.

4.      Pneumonia in damaged lung (including supportive and aspiration pneumonia) e.g. – Staph aureus, Klebsiella and anaerobic bacteria.

Some definition in Pneumonia: 

Bronchopneumonia – It is primary a spreading inflammation of the terminal bronchioles and their related alveoli.

Lobar pneumonia – It is a pathological state of the lung, where the alveolar air has been replaced by cellular exudate and transudate.

Pneumonitis – It is localized inflammation of the lung parenchyma due to non-infectious causes.

Post-measles bronchopneumonia – It is a mixed pneumonia involving the alveoli, supporting tissue and bronchioles, usually manifest with or after the onset of measles. Radiographically it is seen as peribronchial

Thickening, usually bilateral and often offensive.

Interstitial Pneumonia – It is characterized pathologically by massive proliferation and desquamation of alveolar cells and thickening of alveolar cells.

Persistent pneumonia – It is defined as persistence of symptoms and roentgenographic abnormalities for more than one month.

Recurrent pneumonia – It is defined as 2 episodes of pneumonia in one year or>3 episodes at any time with radiographic clearance between 2 episodes of illness.

A guide to radiological diagnosis of pneumonia:

1. Acute lobar pneumonia – Consider pneumococcal pneumonia

2. Right upper lobe pneumonia – suspect aspiration, especially in neonates and  infants.

3. Upper lobe pneumonia with cavitation – TB

4. Recurrent right middle lobe pneumonitis – Consider partial bronchial obstruction due to glands.

5. Lower lobe pneumonia – Chemical pneumonitis

6. Multiple small abscess – Staphylococcal/ Klebsiella pneumonia.

7. Severe bilateral interstitial pneumonia – viral

8. Bilateral interstitial pneumonia with malignancy – pneumocystic carinii.

D/D –

1.      Bronchiolitis

2.      CCF

3.      Asthma

4.      Aspiration of FB

5.      TB

6.      Pulmonary abscess

Symptoms –

1.      Cough or difficult breathing –

         Respiratory rate – distinguish b/w child who had pneumonia and 

         who had not. Cut-off rates are -

                       2mo-12 mo: 50 breaths/min or more

                       12mo-5 yrs : 40 breaths/min or more.

  Chest indrawing – which indicates severe pneumonia.

          Defines a the inward movement of the lower chest wall with 

          inspiration, is a useful indicator of severe pneumonia.

          Stridor – This indicates upper airway obstruction. Is a harsh sound 

          heard during inspiration due to obstruction of upper airway. Stridor in a 

          calm child is an acute emergency and should be referred.

Viral Pneumonia

In general, LRT viral infection are much more common during winter months.

C/F – Rhinitis, cough low grade fever, Cyanosis, Respiratory distress, Tachypnea accompanied by chest indrawing, nasal flaring and use of accessory muscle is common. Hyper- resonant chest, wide spread crackles and wheezing may be present.

Dx – Increased TWBC, N/I ESR/CRP, CXR – diffuse infiltrates.

Rx – 1. Specific measure: Antiviral agents like aerosolized ribavirin (for RSV), 

             Oral amantidine or Rimantadine (Influenza virus)

1.      Supportive measure: as mentioned earlier.

Pneumococcal Pneumonia

S. pneumoniae is still the most cause of bacterial infection of the lungs. The classical four stages of congestion, red hepatization, grey hepatization and resolution.

C/F - The onset is sudden with high fever, cough, pain in the chest on the affected site, tachypnea, circumoral pallor, inspiratory dilatation of the alae nasi.

Dx – TWBC increased, Hypoxemia with hypercapnia, CXR – consolidation, Pleural effusion, isolation of bacteria in blood.

Rx – Crystalline penicillin G (100,000units/kg/24hrs).

         Cefotaxime, 150 mg/kg/24hr or Ceftriaxone 75mg/kg when resistant to 

          Penicillin.

          Vancomycin should be used when resistant to Cephalosporin and 

          Penicillin.

Staphylococcal pneumonia

Pneumonia caused by S. aureus is a serious and rapidly progressive infection. It is less common.

C/F – The illness usually follow URTI, Pyoderma or other associated purulent disease. The infant becomes acute ill with high fevr, cough, respiratory distress, tachypnea, grunting respirations, chest indrawing, nasal flaring, cyanosis, dullness on percussion, diminished breath sounds.

Dx –

1. CXR reveals bronchopneumonia early in the illness. The infiltrate soon becomes patchy or may be dense and homogenous and involve an entire lobe or hemithorax. A pleural effusions or empyema may be found and pyopneumothorax in 25% of pts.

Rapid progression from bronchopneumonia to effusion or pyopneumothorax with or without pneumatoceles is highly suggestive of staphylococcal pneumonia.

2. TWBC – Increase PMN with Leucocytosis.

3. Gram stain of aspirated material.

4. Blood culture.

5. Pleural fluid examination – PMN increase, protein>2.5gm/dl. And a low glucose concentration.

Rx –

1. Specific – Cloxacillin/Flucloxacillin (50-100mg/kg/day) and Ampicillin (50-100mg/kg/day) in 4 DD. Alternative Cefuroxime or Nafcillin.

Empyema should be drain by chest tube.

2. Supportive – As above.

H. Influenzae Pneumonia

This type is an important cause of serious bacterial infection in infants and children who have not received H. influenzae type b vaccine.

C/F – The onset of the illness is gradual with nasopharyngeal infection. The child has moderate fever, cough, dyspnea, grunting respiration, and chest indrawing.

Dx – The Dx is established by isolating the organism from the blood, pleural fluid or lung aspirate. Moderate leukocytosis is usually found.

Rx –

1. Specific – Ceftriaxone (75mg/kg/24hr) or Cefotaxime (150mg/kg/24hr) included in the initial antibiotic therapy. Chloramphenicol 50-100 mg/kg/dai in 4 DD may also be given. Ampicillin if sensitive. Pleural effusion may require drainage.
2. Supportive – As treatment plan.

Hospital- Acquired Pneumonia

HAP refers to a new episode of pneumonia occurring at least 2 days after admission to hospital.

Etiology – The majority of infections are caused by Gram negative bacteria. These include Escherichia, Pseudomonas, Klebsiella, Staph. Aureus (MRSA) and anaerobic organism.

C/F – Cough, fever, rigors, vomiting or febrile convulsions, loss of appetite, tachycardia, tachypnea, breathlessness, cerebral cyanosis.

Dx – CBC shows neutrophilic leucocytosis. CXR shows mottled opacities in both lung fields, chiefly in lower zones.

Rx –

1. Specific – 3^rd gen Cephalosporin and Aminoglycoside or Imipenem.
2. Aspiration pneumonia can be treated with co-amoxiclav plus metronidazole.
3. Supportive – As treatment plan.

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