Pneumonia

Introduction

Pneumonia is an infection of the lung tissue. The alveoli become filled with micro-organisms, fluid and inflammatory cells causing impaired gaseous exchange and consolidation on Chest X-ray.

Pneumonia has many potential causes. Both viral and bacterial. Below are the most common causes.

  • Strep pneumoniae (commonest), H. influenza (more common in older, COPD, Chronic lung conditions), Staph aureus (post influenza, IVDU)

  • Atypical Bacteria – Mycoplasma pneumoniae (younger), C. pneumoniae, Legionella spp (commoner in smokers, outbreaks due to contaminated water)

  • Viruses – COVID 19, Influenza, RSV,

  •  Hospital Acquired – E.coli, Klebsiella pneumoniae, Enterobacter spp, Pseudomonas, S. aureus, MRSA

  • Aspiration Pneumonia – Usual bacteria & Gut flora (anaerobes, enteric gram -ves)

Treatment for pneumonia varies and depends on

  • Community Acquired versus Hospital Acquired (in patient > 48 hrs/recently discharged) versus Aspiration

  • How unwell the patient is. (CURB 65)

  • Risk Factors e.g. immunosuppression, Asthma/COPD, Alcoholism, Chronic conditions, risk of aspiration

Clinical Features

 

Symptoms

Systemic

  • Chills, fevers, rigors, anorexia, lethargy

Chest

  • Cough, change in colour or sputum if chronic cough, dyspnoea, pleuritic chest pain

Signs

 Signs of sepsis

  • fever, tachycardia, hypotension, hypoxia, tachypnoea

Chest Signs

  • Focal Decreased air entry, crackles, bronchial breath sounds, dullness to percussion, increased focal resonance

Complications

Respiratory Complications

  • Pleural effusion, empyema, Cavitation, Abscess Formation

Systemic Complications

  • Bacteraemia, Septic Shock + Multiorgan Failure, Respiratory Failure

 

Differential Diagnosis

 

Respiratory

  • LRTI - bacterial or viral

  • Bronchiectasis

  • Bronchitis

  • Asthma/COPD exacerbation

  • PE

  • TB

  • Malignancy

  • ARDS

Cardiac

  • CCF

  • Angina

  • ACS

  • Pericarditis

  • Myocarditis

  • Infective Endocarditis

Biliary Pathology

  • Cholecystitis

  • Choledocholithiasis

 

Clinical Investigation

 
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Bedside

Arterial Blood Gas (if Hypoxic)

  • Low pH = acidosis (resp or metabolic i.e. sepsis)

  • PaO2 < 8kPA = Respiratory Failure.

    • with normal or low PaCO2 = Type 1 resp failure

    • with high PaCO2 (>6.7kPa) = Type 2 resp failure

  • High PaCO2 = Resp Acidosis. Low PaCO2 = Resp Alkalosis (Tachypnoea)

  • Electrolytes, Hb, Lactate, BM

ECG

  • ? Cardiac cause for symptoms

POCUS

  • Lung US more sensitive and specific for consolidation than CXR

  • Bedside Echo - ? CCF, ? pericardial effusion

 
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Laboratory

  • Bloods Tests

    • Inflammatory markers - High neutrophils, Low lymphocytes (viral), High CRP

    • U&E – AKI, Low Na often associated with chest sepsis

    • LFT – often abnormal, especially with Mycoplasma

    • Mycoplasma serology

    • Blood cultures if ? sepsis

  • Sputum for Culture

  • Urine for Culture and Legionella/Pneumococcal Antigen

  • Nasal/Throat Swab for Viral PCR

Lobar pneumonia.jpg

Radiology

CXR

  • Consolidation, air bronchograms, parapneumonic effusion, Cavitation

  • Normal CXR doesn’t out rule pneumonia as CXR changes can lag behind clinical findings

CT Chest

  • Diagnosis may be made when looking for other pathology e.g. PE on CTPA. May have role in atypical pneumonia e.g. COVID 19

CURB65 Score

CURB 65 grades severity of pneumonia and likely mortality rates

  •  5 criteria. 1 point each. Score 0-5

  • 1 = 1% Mortality (mild pneumonia) 2 = 8%, 3 =20%, 4 = 40%, 5 = 60%

    • C Confusion

    • U Urea > 7

    • R RR > 30

    • B BP. Systolic <90mmHg or Diastolic < 60mmHg

    • 65 Age > 65 years

Management and Disposition

 

Initial Resuscitation

  • ***PPE and appropriate isolation if ? COVID

  • Resuscitation as required. ABC approach

  • Oxygen as required to keep sats > 94%, or > 88% in COPD

  • Assess for volume depletion and IV fluids as required.

  • May require vasopressors if septic and non responsive to fluid challenge

 
 
 

Symptomatic Treatment

  • Analgesia as required

  • Encourage rest, fluids and not to smoke

  • Nebulised bronchodilators e.g. salbutamol, if associated bronchospasm

Specific Treatment

  • Antibiotics as per local guidelines. Below is an example of SJH guidelines

    • Mild CAP

      • Amoxicillin 500mg TDS PO x 5/7

    • Mod/Severe CAP (includes atypical cover)

      • Co-Amoxyclav 1.2 g TDS IV + Clarithromycin 500mg BD PO/IV

    • Hospital Acquired Pneumonia (HAP)

      • Piperacillin-Tazobactam 4.5g QDS IV +/- IV Amikacin +/- IV Vancomycin (if hx of MRSA)

 

Disposition

  • Mild Cases (Curb 0 -1) can be managed in the community with PO antibiotics

  • Moderate (Curb 2) and Severe (Curb 3-5) need to be managed in the hospital setting with IV antibiotics and supportive care +/- ventilatory and organ support in the ICU setting if appropriate

References

1.    NICE Guidance. Pneumonia in adults. Quality Standard [QS110] Jan 2016

2.    File TM et al. Epidemiology, pathogenesis and microbiology of community-acquired pneumonia in adults. Uptodate.com

3.    Putland M, Cameron P et al. Chapter 6.3 Community Acquired Pneumonia. The Textbook of Adult Emergency Medicine 4th Edition

4.    British Thoracic Society community acquired pneumonia guideline. Oct 2009

5.    SJH Prescriber Capsule. Empiric Antimicrobial Guidelines.

This blog was written by Dr Deirdre Glynn and was last updated in October 2020

 

Before you go have another look at the clinical case and see have your answers to any of the questions changed and if so how?