Acute severe community-acquired pneumonia: pulmonary complications and ARDS

^{[2] [3] [4] [5]}

Severe community-acquired pneumonia (CAP) is the single commonest cause of ARDS worldwide. The same pneumonia that fills alveoli with inflammatory exudate can, in a subset of patients, trigger the runaway diffuse alveolar damage (DAD) cascade that defines ARDS. Beyond the lung, bacteraemic CAP seeds the pleura (effusion, empyema), destroys parenchyma (abscess), disseminates (endocarditis, meningitis, septic arthritis), and drives systemic organ failure (AKI, DIC). This topic follows that chain: how severe pneumonia becomes ARDS, how to ventilate it, and how to recognise and manage the complications that determine who survives. ^[1][25]

Meet the patient

It is the small hours in the ICU. A middle-aged man with a five-day history of productive cough, fever, and rigors is intubated for type 1 respiratory failure. The CXR shows bilateral opacities with dense right-sided consolidation and a moderate left pleural effusion. On high PEEP and high FiO2 his saturation barely holds despite maximal support. Plateau pressure is above the lung-protective ceiling, driving pressure high. He is hypotensive on noradrenaline, lactate raised, platelets low with a prolonged INR and low fibrinogen, creatinine tripled from baseline. Urine pneumococcal antigen positive. The trainee asks: is this ARDS, and how do we ventilate it; what about the effusion, the DIC, the kidneys? Three questions wearing one disease. ^[1][2]

You answer in three moves. First, confirm ARDS by Berlin criteria and start lung-protective ventilation immediately. Second, look for the complications — pleural, parenchymal, systemic — because each one lifts the mortality curve. Third, treat the pneumonia, not just the syndrome. ^[1][3]

References27ShowHide

1. [1]Niederman MS, Torres A Severe community-acquired pneumonia Eur Respir Rev, 2022.PMID 36517046
2. [2]Ranieri VM, Rubenfeld GD, Thompson BT, et al. Acute respiratory distress syndrome: the Berlin Definition JAMA, 2012.PMID 22797452
3. [3]Brower RG, Matthay MA, Morris A, et al. Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome N Engl J Med, 2000.PMID 10793162
4. [4]Guérin C, Reignier J, Richard JC, et al. Prone positioning in severe acute respiratory distress syndrome N Engl J Med, 2013.PMID 23688302
5. [5]Amato MBP, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome N Engl J Med, 2015.PMID 25693014
6. [6]Combes A, Hajage D, Capellier G, et al. Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome N Engl J Med, 2018.PMID 29791822
7. [7]Peek GJ, Mugford M, Tiruvoipati R, et al. Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial Lancet, 2009.PMID 19762075
8. [8]Papazian L, Forel JM, Gacouin A, et al. Neuromuscular blockers in early acute respiratory distress syndrome N Engl J Med, 2010.PMID 20843245
9. [9]Moss M, Huang DT, Brower RG, et al. Early Neuromuscular Blockade in the Acute Respiratory Distress Syndrome N Engl J Med, 2019.PMID 31112383
10. [10]Rahman NM, Maskell NA, West A, et al. Intrapleural use of tissue plasminogen activator and DNase in pleural infection N Engl J Med, 2011.PMID 21830966
11. [11]Bellani G, Laffey JG, Pham T, et al. Epidemiology, Patterns of Care, and Mortality for Patients With Acute Respiratory Distress Syndrome in Intensive Care Units in 50 Countries JAMA, 2016.PMID 26903337
12. [12]Wiedemann HP, Wheeler AP, Bernard GR, et al. Comparison of two fluid-management strategies in acute lung injury N Engl J Med, 2006.PMID 16714767
13. [13]Cavalcanti AB, Suzumura ÉA, Laranjeira LN, et al. Effect of Lung Recruitment and Titrated Positive End-Expiratory Pressure (PEEP) vs Low PEEP on Mortality in Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial JAMA, 2017.PMID 28973363
14. [14]Dequin PF, Meziani F, Quenot JP, et al. Hydrocortisone in Severe Community-Acquired Pneumonia N Engl J Med, 2023.PMID 36942789
15. [15]Briel M, Meade M, Mercat A, et al. Higher vs lower positive end-expiratory pressure in patients with acute lung injury and acute respiratory distress syndrome: systematic review and meta-analysis JAMA, 2010.PMID 20197533
16. [16]Gorman EA, O'Kane CM, McAuley DF Acute respiratory distress syndrome in adults: diagnosis, outcomes, long-term sequelae, and management Lancet, 2022.PMID 36070788
17. [17]Fan E, Brodie D, Slutsky AS Acute Respiratory Distress Syndrome: Advances in Diagnosis and Treatment JAMA, 2018.PMID 29466596
18. [18]Metlay JP, Waterer GW, Long AC, et al. Diagnosis and Treatment of Adults with Community-acquired Pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America Am J Respir Crit Care Med, 2019.PMID 31573350
19. [19]Porcel JM Distinguishing complicated from uncomplicated parapneumonic effusions Curr Opin Pulm Med, 2015.PMID 26016577
20. [20]Kellum JA, Lameire N; KDIGO AKI Guideline Working Group Diagnosis, evaluation, and management of acute kidney injury: a KDIGO summary (Part 1) Crit Care, 2013.PMID 23394211
21. [21]Lameire N, Kellum JA; KDIGO AKI Guideline Working Group Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2) Crit Care, 2013.PMID 23394215
22. [22]Levi M, Toh CH, Thachil J, et al. Guidelines for the diagnosis and management of disseminated intravascular coagulation. British Committee for Standards in Haematology Br J Haematol, 2009.PMID 19222477
23. [23]Goligher EC, Tomlinson G, Hajage D, et al. Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome and Posterior Probability of Mortality Benefit in a Post Hoc Bayesian Analysis of a Randomized Clinical Trial JAMA, 2018.PMID 30347031
24. [24]Hammond NE, Semler MW, et al. Balanced Crystalloids versus Saline in Critically Ill Adults - A Systematic Review with Meta-Analysis NEJM Evid, 2022.PMID 38319180
25. [25]Tong SYC, Davis JS, Eichenberger E, et al. Staphylococcus aureus infections: epidemiology, pathophysiology, clinical manifestations, and management Clin Microbiol Rev, 2015.PMID 26016486
26. [26]Colice GL, Curtis A, Deslauriers J, et al. Medical and surgical treatment of parapneumonic effusions: an evidence-based guideline Chest, 2000.PMID 11035692
27. [27]Palraj BR, Baddour LM Predicting Risk of Endocarditis Using a Clinical Tool (PREDICT): Scoring System to Guide Use of Echocardiography in the Management of Staphylococcus aureus Bacteremia Clin Infect Dis, 2015.PMID 25810284