Makindo Medical Notes

Related Subjects:Pneumonia |Pontiac fever (Legionella Pneumophila) |Legionella Pneumophila pneumonia |Asthma |Acute Severe Asthma |Exacerbation of COPD |Pulmonary Embolism |Cardiogenic Pulmonary Oedema |Pneumothorax |Tension Pneumothorax |Respiratory (Chest) infections Pneumonia |Fat embolism |Hyperventilation Syndrome |ARDS |Respiratory Failure |Diabetic Ketoacidosis |Breathlessness

You must know about CURB65 scoring for Community-acquired pneumonia. Atypical pneumonias have unusual presentations e.g. with headache and a viral meningitis picture, diarrhoea, vomiting, abdominal pain, myalgia and the chest symptoms may take time to appear both clinically and radiologically

About

• Infection of the air spaces and substance of the lung which are normally sterile
• Lobar - restricted to the whole of one lobe ? is there a bronchostenotic lesion
• Bronchopneumonia - affecting lobules and bronchi

Aetiology

• Classification depends on location as different organisms
• Community acquired - symptoms + signs of consolidation
• Hospital acquired - onset > 48 hours after admission.

Organisms numbers vary by study, age group, other pathologies

Types

• Community acquired Pneumonia - at-risk groups : Aspiration (Stroke, MND), Alcohol, Diabetes, Steroids/Immunosuppression, Smokers, COPD, Nursing home residents
• Hospital acquired - same as CAP. Elderly, immunosuppressed, respiratory disease, post-operative, ITU. Usually Gram-negative enterobacteria - pseudomonas, klebsiella and Anaerobes

Risk Groups

• Cigarette smoking and underlying lung disease.
• Stroke or other neuromuscular disorder (aspiration pneumonia often by anaerobes).
• Immunosuppression and AIDS in particular P. jirovecii.
• Intravenous drug abusers, Alcoholics and vagrants.
• Hospital patients (more often Gram-negative organisms).

Pathology stages

• 1. Congestion and vascular engorgement and alveolar bacteria
• 2. Red hepatization - alveolar spaces full of polymorphous and fibrin and red cells
• 3. Grey hepatization - RBC breakdown, fibrin and suppurative inflammation
• 4. Resolution - exudate removed by macrophages

Clinical

• Fever, sweats, rigors, Dry cough initially, malaise
• Confusion, Delirium (elderly and Legionella)
• Breathlessness, Cyanosis
• Tachycardia, Hypotension
• Pleuritic type chest pain
• Cough, Rusty sputum (Pneumococcus) yellow/green sputum
• Haemoptysis
• Flare up of herpes simplex (Pneumococcus)
• Atypical - diarrhoea, myalgia, headache
• Reduced air entry and expansions and dullness to percussion
• Increased vocal resonance
• Stony dull if effusion/empyema

Complications

• Abscess formation, Pleural effusion
• Parapneumonic effusion and Empyema
• Bacteraemia, Sepsis
• Cerebral abscess, Meningitis
• ARDS, Respiratory Failure, Cardiac Failure, Death

Investigations

• Sputum - gram stain and culture and sensitivity is not recommended for patients in the community. Is useful for those who do not respond to empirical therapy. In hospital, sputum should be sent. The sample should be obtained from a deep cough and should be grossly purulent The sample should be transported promptly to the laboratory for processing. A purulent portion of the sputum should be selected for Gram stain and culture Cytological screening should be done as a contingency for culture The sample should be cultured using standard techniques Interpretation should be based on the correlation of Gram stain, semi-quantitative culture results and clinical picture
• FBC - elevated WCC. Low WCC with legionella.
• Pulse oximetry: An oxygen saturation (SaO₂) of <92% defines hypoxaemia (grade A-), and patients with SaO₂ <92% should have an arterial blood gas measurement
• Blood film - red cell agglutination suggests cold agglutinins and Mycoplasma
• ESR and CRP elevated
• U&E - raised urea, low Na with legionella
• LFT'S - abnormal with legionella
• Blood cultures and sensitivities
• CXR - patchy consolidation with bronchopneumonia. More defined consolidation with lobar pneumonia. Cavitation may be seen, parapneumonic effusion. Changes often lag behind clinical changes. Not recommended in those managed in the community (BTS). Watch out that CXR may be normal in the first 24 hours in cases of severe neutropenia (no inflammatory response) and in Pneumocystis pneumonia
• Arterial blood gas - hypoxia and possibly hypercarbia with V/Q mismatch
• Serology - Mycoplasma, Chlamydia, Coxiella, Influenza, Adenoviral, RSV
• Legionella: Urine test for legionella antigens in any high-severity CAP
• Pneumococcus: Urinary testing for Pneumococcus in those with moderate or high-severity CAP
• Bronchoscopy in some cases to look for any broncho stenotic lesions or remove foreign bodies or mucus plugging
• CT chest - to look for other related pathology

Differentials

• Pulmonary embolism: breathlessness (about 75% of cases) , pleuritic pain (about 66% of cases) and cough (about 33% of cases
• Spontaneous pneumothorax typically presents with pleuritic chest pain and breathlessness
• Pulmonary oedema
• ARDS, Pulmonary haemorrhage
• Cryptogenic organising pneumonia
• Lung cancer
• Acute extrinsic allergic alveolitis

CURB Scoring

Additional evidence of severity

• Hypoxaemia < 8Kpa
• WCC > 20 or < 4
• CXR - multi lobe involvement on CXR
• Albumin < 35 g/L
• Microbiology - positive blood culture
• Others - stroke, COPD, cardiac disease, diabetes

Management

• Start with 28% in COPD use 35-40% if no COPD and repeat ABG. Oxygen - aim for PO₂ > 8 Kpa
• IV fluids - hydration important but avoid overload in elderly or with CCF
• May need CPAP, BIPAP, or ITU if worsening respiratory failure
• Aspirate pleural effusions and If the fluid looks turbid, a chest tube should be inserted promptly for empyema

All patients need follow up CXR or CT follow up radiology at 6 weeks to ensure complete resolution and no underlying pathology

Antibiotic management

Offer an antibiotic(s) within 4 hours of establishing a diagnosis. When microbiological results available: review the choice of antibiotic(s), and change the antibiotic(s) according to results, using a narrower spectrum antibiotic, if appropriate. If fails to improve Seek specialist advice from a microbiologist

• First-choice oral antibiotic if low severity (based on clinical judgement and guided by CRB65 score 0, or CURB65 score 0 or 1
  • Amoxicillin 500 mg 3 times a day (higher doses can be used see BNF) for 5 days
  • Consider adding a macrolide to Amoxicillin if atypical pathogens are suspected.
• Alternative oral antibiotics if low severity, for penicillin allergy or if Amoxicillin unsuitable (for example, atypical pathogens suspected)
  • Doxycycline 200 mg on first day, then 100 mg once a day for 4 days (5-day course) then review
  • Clarithromycin 500 mg twice a day for 5 days
  • Erythromycin (in pregnancy) 500 mg 4 times a day for 5 days
• First-choice oral antibiotics if moderate severity (based on clinical judgement and guided by CRB65 score 1 or 2, or CURB65 score 2); guided by microbiological results when available
  • Amoxicillin with (if atypical pathogens suspected): 500 mg 3 times a day (higher doses can be used see BNF) for 5 days
  • Clarithromycin 500 mg twice a day for 5 days OR
  • Erythromycin (in pregnancy) 500 mg 4 times a day for 5 days
• Alternative oral antibiotics if moderate severity, for penicillin allergy; guided by microbiological results when available
  • Doxycycline 200 mg on first day, then 100 mg once a day for 4 days (5-day course in total)
  • Clarithromycin 500 mg twice a day for 5 days
• First-choice antibiotics if high severity (based on clinical judgement and guided by CRB65 score 3 or 4, or CURB65 score 3 to 5); guided by microbiological results when available
  • Co-Amoxiclav 500/125 mg 3 times a day orally or 1.2 g 3 times a day IV for 5 days WITH
  • Clarithromycin 500 mg twice a day orally or IV for 5 days OR
  • Erythromycin (in pregnancy) 500 mg 4 times a day orally for 5 days
• Alternative antibiotic if high severity, for penicillin allergy; guided by microbiological results when available
  • Levofloxacin (consider safety issues) 500 mg twice a day orally or IV for 5 days
  • Consult local microbiologist if fluoroquinolone not appropriate.

References

• Pneumonia (community-acquired): antimicrobial prescribing