Pneumonia.pdf

Pneumonia is a lower respiratory tract infection caused by a variety of pathogens and may present with cough, sputum, dyspnoea, pleuritic chest pain, fever or extra-pulmonary and constitutional symptoms. It is characterised by inflammation of the lung parenchyma, along with consolidation or intersti...

Pneumonia is a lower respiratory tract infection caused by a variety of pathogens and may present with cough, sputum, dyspnoea, pleuritic chest pain, fever or extra-pulmonary and constitutional symptoms. It is characterised by inflammation of the lung parenchyma, along with consolidation or interstitial lung infiltrates. There are several subtypes of pneumonia based on the location of acquirement and immune status of the patient.  Aetiology and Pathogenesis Alveolar and lung parenchyma inflammation, causing damage to General Principles: tissues Pathogenesis: Production of intra-alveolar exudate 1. Presence of pathogens in the environment Ventilation/Perfusion (V/Q) mismatch, patient exists in or as part of oropharyngeal resulting in impaired alveolar ventilation flora. (not enough oxygen reaching 2. Pathogen spread via micro-aspiration (droplet capillaries) formation) of environmental source or Development of hypoxia oropharyngeal secretions - Transmission and Shedding Special Considerations: 3. Failure of pulmonary protective mechanisms Community Acquired Pneumonia: and pathogen infiltrates lung parenchyma Lobar Pneumonia: Invasion 1. Consolidation Protective mechanisms that have failed ○ Day 1: serous exudate in blood rich lungs include: due to initiation of the inflammatory process ○ Cough reflex heavy, boggy and red in appearance ○ Mucociliary clearance due to vascular engorgement ○ Macrophage clearance ○ numerous bacteria Pathogen factors contributing to 2. Red Hepatisation infiltration: ○ Day 2-3: exudate rich in RBCs, fibrin and ○ High virulence inflammatory cells ○ Increased adherence of pathogen red in appearance to respiratory epithelium liver-like texture ○ Large inoculum size loses spongy quality 4. Development of lower respiratory tract infection ○ Heavy bacterial load in the alveolar spaces that results in: 3. Grey Hepatisation  ○ Day 4-7: red blood cells degraded but fibrin ○ Diabetes Mellitus and inflammatory cells persist ○ Haematological Malignancies grey in appearance ○ Chronic Alcoholism firm texture ○ Immunosuppressive agents 4. Resolution Steroids ○ Day 8 - Week 4: fibrinolysis by enzymatic Methotrexate processes and removal of purulent exudate Chemotherapy agent (pus-like, due to the presence of inflammatory cells) Epidemiology productive cough ingestion by macrophages Pneumonia, in combination with influenza, was organisation of fibrin network to the 9th leading cause of death in Australia in pulmonary adhesions 2017 Mortality rate increases with age Bronchopulmonary Pneumonia: 1. Inflammation of bronchioles Mortality rate for Hospital Acquired Pneumonia 2. Consolidation is most significant at >20% a. Multilobar in nature b. Typically lower lobes due to gravity Community Acquired Pneumonia: Most common cause of typical pneumonia is Immunocompromised Patients: Streptococcus pneumoniae Pneumocystis jirovecii Pneumonia (PJP): Most common cause of atypical pneumonia is 1. Development of lower respiratory tract infection Mycoplasma pneumoniae that leads to the formation of pneumatoceles Atypical pathogens cause ~22% of cases of (cysts/blebs/cavities) and pneumothoraces due to Community Acquired Pneumonia erosion of the lung parenchyma Hospital Acquired Pneumonia: Most common nosocomial infection due to Risk Factors improvements in prevention of Urinary Tract Infections Older age, typically >65 years Most common cause is ​Streptococcus Chronic disease pneumoniae ○ COPD ○ Asthma Immunocompromised Patients: ○ Bronchiectasis Pneumocystis jirovecii​ pneumonia remains the ○ Cystic Fibrosis most common HIV/AIDs related cause of ○ Heart Failure mortality in hospitalised patients Smoking Antiretroviral therapy used in conjunction with ○ Damage to respiratory tract cilia PJP prophylaxis is reducing this mortality Environmental exposures Pneumocystis jiroveci Pneumonia prevalence ○ E.g. water cooling towers, soil and is low in other populations and almost agriculture Hospitalisation exclusively occurs in immunocompromised ○ Poor infection control patients ○ Prolonged rest ○ Low inspiratory volumes due to pain Immunosuppression ○ Congenital immunodeficiency disorders ○ Human Immunodeficiency Virus (HIV)  Typical pneumonia Atypical pneumonia Presentation Sudden onset of Slow onset with Symptoms: symptoms caused by extrapulmonary Typical: lobar infiltration symptoms Fever, cough, dyspnoea and chest pain Severe malaise Low-grade fever High fever and chills Non-productive, dry Atypical/Non-Specific: Productive cough cough Tachypnoea Tachypnoea, dyspnoea Dyspnoea Lethargy Dullness on percussion Unremarkable Alterations in sleep-wake cycles Enhanced bronchophony, auscultation Loss of appetite egophony, tactile fremitus Common Functional decline Crackles, bronchial and extrapulmonary features Incontinence (new onset) decreased breath sounds include: on auscultation ○ Fatigue Increased confusion or agitation Pleuritic chest pain, often ○ Headaches with pleural effusion ○ Sore throat Typical symptoms are often absent in the Pain radiating to the ○ Myalgia elderly abdomen/ epigastric ○ Malaise region (particularly in General inspection: children) Looking unwell Diaphoresis Chills/rigors Diagnosis Cough ± Sputum production Bedside Tests: Respiratory distress Urinary Streptococcus Dyspnoeic/Breathless at rest Pneumoniae/Legionella/Chlamydia antigens Vital Signs:​ febrile, tachycardic, ± tachypnoeic Laboratory Tests: Respiratory Examination: FBE: Elevated WBC count is suggestive Tactile fremitus of infection Dullness to percussion CRP Crackles, rales or bronchial breathing UEC/LFT Vocal fremitus Serum Glucose Serum LDH Arterial blood gases Induced sputum ± Blood cultures: If temperature above 38° or concerned for Sepsis Imaging: Chest X-Ray: Opacification of lung parenchyma Air bronchogram (air containing bronchioles passing through consolidated lung)  Silhouette Sign: Treatment Due to loss of sharp borders of lung parenchyma Loss of left heart border = left lingula lobe Main Aim: ​Determine the severity of the pneumonia pneumonia and treat appropriately Loss of right heart border = right middle lobe pneumonia 1. Is it ‘severe’ community-acquired pneumonia? Consider lung ultrasound: Looking for Presence of 2+ CORB/CURB criteria (see consolidation additional resources) indicates presumptive See additional resources for image severe pneumonia so that broad-spectrum empiric antibiotics are required from the start. Special Tests: Bronchoalveolar lavage (BAL): A The patient should be assessed by the ICU threshold of 10^4 colony forming units team (CFU)/mL in BAL samples indicated 2. Inpatient or outpatient? Patients with chronic infection. cardiac, respiratory or neurological problems or Protected specimen brushing (PSB): who are immunosuppressed should be threshold of 10^3 CFU/mL to distinguish considered for admission. All colonisation from infection immunocompromised patients with CAP should be discussed with a consultant upon admission Differential Diagnosis and before discharge 3. Diagnosis investigation: Targeting the Acute Bronchitis​: No signs of causative pathogen infiltrate/consolidation on chest x-ray Duration of therapy Pulmonary Embolism​: Chest x-ray may appear normal, no elevated CRP and 3 day short course therapy: Can be considered minimal sputum production. Presence of if there was rapid response to initial antibiotic risk factors therapy/an alternative diagnosis for Pulmonary Oedema​: Extrapulmonary consolidation has been documented signs of fluid overload such as ankle 5-7 days: For non-ICU or high dependency swelling, jugular venous distension patients Empyema:​ Signs of pleural effusion on 7-14 days: Intensive care cases, up to 14 days chest x-ray, may have family history of therapy required for proven pseudomonal a1-antitrypsin deficiency or risk factors infection Malignancies​ (lung cancer, Typical Pneumonia mesothelioma): Other features such as hemoptysis, chest x-ray/CT showing Low Severity:​ ​Oral Amoxycillin or Doxycycline round primary centres or cannonball sign Moderate Severity:​ ​Intravenous Benzylpenicillin AND for metastasis Doxycycline Aspiration pneumonia​: Possible signs of pleural effusion, interstitial infiltrates, Severe Severity:​ ​Intravenous Ceftriaxone AND cavitations on chest x-ray. May affect Azithromycin upper lobes  Atypical Pneumonia:​ Doxycycline or Macrolide X-ray Images (oral Clarithromycin or intravenous Azithromycin) If hypersensitive to penicillin: Azithromycin instead of oral amoxycillin Vancomycin IV instead of benzylpenicillin or cefotaxime/ceftriaxone Clinical and microbiology status should be reviewed at 48 hours: Cease therapy if alternate diagnosis is made Narrow the spectrum of antibiotics to target identified pathogens Switch to oral therapy once there is clinical improvement Immunocompromised Patients: Consultation with an infectious diseases specialist and broad-spectrum antimicrobial therapy is indicated Antibiotic depends on the immune system defect and the risk factors for specific pathogens If patients with conditions other than HIV infection do not improve with 5 days of antibiotic therapy, antifungal therapy is Lung Foundation Australia Pneumonia Patient frequently added empirically. Information Sheets Therapies to enhance immune system function are an important adjunct Criteria to determine inpatient vs outpatient treatment CORB Complications CURB-65 Sepsis CORB Criteria Respiratory Failure Advantage: Less investigations needed Pleural Effusion C​onfusion (acute) Cavitations on chest x-ray O​xygen saturation 90% or less May affect upper lobes R​espiratory rate > 30 breaths per minute Abscess B​lood pressure Cardiac failure CURB-65 1 point for each of the following criteria Additional Resources Risk of death increases as score increases C​onfusion of new onset  U​rea > 7 mmol/L 8. Morris A, Nolley E. ​Pneumocystis jirovecii R​espiratory rate >30/min or greater pneumonia. (​2018). Retrieved from: B​lood pressure https://bestpractice.bmj.com/topics/en-us/19 Age >​65​ years 9. Husain A N. (2015). Chapter 15: The Lung. In: Disposition recommendations based on score: Kumar V, Abbas and A K, Aster J (Ed), ​Robbins 0-1: Treat as an outpatient and Cotran Pathological Basis of Disease​ (9th 2-3: Consider a short stay in hospital or watch Ed). (p 670-724) Canada: Elviser. very closely as an outpatient 4-5: Requires hospitalisation, consider ICU 10. Australian Bureau of Statistics. ​Causes of admission Death, Australia, 2017​. (2018). Retrieved from: https://www.abs.gov.au/ausstats/[email protected]/L ookup/by%20Subject/3303.0~2017~Main%20 References Features~Australia's%20leading%20causes%2 0of%20death,%202017~2 1. AMBOSS. ​Pneumonia​. (2019) Retrieved from: https://www.amboss.com/us/knowledge/Pn 11. Australian and New Zealand Society for eumonia Geriatric Medicine. Position Statement – Immunisation of older people. Australas J 2. BMJ Publishing Group. ​Overview of Ageing 2016: 35(1); 67-73 pneumonia​.(2019). Retrieved from: https://bestpractice.bmj.com/topics/en-us/1 113 3. Salati U, Smyth A D and Wall C A. (2010). Lifting the veil: a case of lobar atelectasis. BMJ case reports, 2010​. 4. Therapeutic Guidelines. (2019). C ​ ommunity Acquired Pneumonia in Adults​. Available from: https://tgldcdp-tg-org-au/viewTopic?topicfile =community-acquired-pneumonia-adults​. 5. Cilloniz C, Torres, A. ​Community acquired pneumonia​. (2019) Retrieved from: https://bestpractice.bmj.com/topics/en-us/1 7 6. Arnold F.. ​Hospital acquired pneumonia​. (2018) Retrieved from: https://bestpractice.bmj.com/topics/en-gb/72 0 7. Nir-Paz R. (2018). A ​ typical pneumonia​. (2018) Retrieved from: https://bestpractice.bmj.com/topics/en-us/18