History

Fact Explanation
Sepsis Sepsis is the commonest risk factor for the development of acute lung injury. [1]
Symptoms of respiratory tract infection Fever, chest pain and productive cough are the usual complains. [5]
Chronic lung disease Patients with chronic lung disease are at risk of developing acute respiratory failure. [1]
Aspiration Patients with chronic alcohol abuse or near drowning are at risk due to aspiration. [1]
Burns [4] Patients with facial burns are especially at risk. Acute respiratory failure occurs due to the inhalational injury. [5]
History of inhalational drug abuse People who are inhaling illicit drugs are at risk of acute respiratory failure. [5]
History of blood transfusion Transfusion associated respiratory distress syndrome occurs within 6 hours of transfusion. [3,5]
Shortness of breath [5] This is seen in almost every patient.
References
  1. HUDSON LD, MILBERG JA, ANARDI D, MAUNDER RJ. Clinical risks for development of the acute respiratory distress syndrome. Am J Respir Crit Care Med [online] 1995 Feb, 151(2 Pt 1):293-301 [viewed 03 June 2014] Available from: doi:10.1164/ajrccm.151.2.7842182
  2. MOSS M, BUCHER B, MOORE FA, MOORE EE, PARSONS PE. The role of chronic alcohol abuse in the development of acute respiratory distress syndrome in adults. JAMA [online] 1996 Jan 3, 275(1):50-4 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/8531287
  3. FRUTOS-VIVAR F, NIN N, ESTEBAN A. Epidemiology of acute lung injury and acute respiratory distress syndrome. Curr Opin Crit Care [online] 2004 Feb, 10(1):1-6 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/15166842
  4. ZIMMERMAN JJ, AKHTAR SR, CALDWELL E, RUBENFELD GD. Incidence and outcomes of pediatric acute lung injury. Pediatrics [online] 2009 Jul, 124(1):87-95 [viewed 03 June 2014] Available from: doi:10.1542/peds.2007-2462
  5. SAGUIL A, FARGO M. Acute respiratory distress syndrome: diagnosis and management. Am Fam Physician [online] 2012 Feb 15, 85(4):352-8 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22335314

Examination

Fact Explanation
Fever Patients with sepsis and pneumonia are febrile. [2]
Tachypnea Tachypnea is a common examination finding. [2]
Cyanosis Bluish discoloration of the skin and mucus membranes occur when the deoxygenated hemoglobin in the capillaries or tissues is equal or more than 5 g/dL. [4]
Asterixis Asterixis can occur with carbon dioxide retention. [3]
Signs of right ventricular failure Some patients develop right ventricular failure secondary to pulmonary hypertension. [1]
References
  1. WARE LB, MATTHAY MA. The acute respiratory failure. N Engl J Med [online] 2000 May 4, 342(18):1334-49 [viewed 03 June 2014] Available from: doi:10.1056/NEJM200005043421806
  2. SAGUIL A, FARGO M. Acute respiratory distress syndrome: diagnosis and management. Am Fam Physician [online] 2012 Feb 15, 85(4):352-8 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22335314
  3. ALLAN H GOROLL, ALBERT G MULLEY. Primary Care Medicine: Office Evaluation and Management of The Adult Patient. 6th ed. Lippincott Williams & Wilkins, Jan 1, 2011.
  4. LUNDSGAARD C. STUDIES ON CYANOSIS : I. PRIMARY CAUSES OF CYANOSIS. J Exp Med [online] 1919 Sep 1, 30(3):259-269 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2126682

Differential Diagnoses

Fact Explanation
Cardiogenic pulmonary edema Acute left heart failure can cause pulmonary edema, these two conditions cannot be separated from the chest X-ray features. Distended jugular veins, peripheral edema, and third heart sound are examination findings. [1]
Asthma History of bronchial asthma, cough, wheeze, presence of identifiable precipitating factor and response to bronchodilator are all suggestive of acute exacerbation of bronchial asthama. [1,2]
Chronic obstructive pulmonary disease Commonly seen in chronic smokers. Patients characteristically have increased antero-posterior diameter of the chest, wheezing, increased sputum production dyspnea and prolonged expiratory phase. [1,3]
Pneumonia Patients can have productive cough, fever, pleuritic chest pain and dyspnea. [1]
Acute eosinophilic pneumonia This is relatively less common. Patients present with fever and cough. Diffuse chest infiltrates are seen in imaging. Bronchoalveolar lavage will show increased eosinophils. [1,4]
Hypersensitivity pneumonitis This is an acute respiratory distress secondary to an exposure to an antigen. Patients complain of sudden onset dyspnea and cough. [1,5]
Pneumothorax [1] An acute and life threatening condition. Present with sudden onset dyspnea, and pleuritic chest pain. Spontaneous pneumothorax can occur in tall and thin people or in patients diagnosed with chronic lung disease. [6]
Salicylate toxicity [1] Patients present with nausea, vomiting, abdominal pain, dizziness, hyperventilation, tachycardia, seizure and coma. [7]
Sepsis Fever or hypothermia, tachypnea, tachycardia or bradycardia are common findings. [1]
References
  1. SAGUIL A, FARGO M. Acute respiratory distress syndrome: diagnosis and management. Am Fam Physician [online] 2012 Feb 15, 85(4):352-8 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22335314
  2. ROWE AH, ROWE A JR. BRONCHIAL ASTHMA IN ADULTS--Causes and Treatment Calif Med [online] 1950 Apr, 72(4):228-233 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1520541
  3. STEPHENS MB, YEW KS. Diagnosis of chronic obstructive pulmonary disease. Am Fam Physician [online] 2008 Jul 1, 78(1):87-92 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/18649615
  4. JANZ DR, O'NEAL HR JR, ELY EW. Acute eosinophilic pneumonia: A case report and review of the literature. Crit Care Med [online] 2009 Apr, 37(4):1470-4 [viewed 03 June 2014] Available from: doi:10.1097/CCM.0b013e31819cc502
  5. LACASSE Y, CORMIER Y. Hypersensitivity pneumonitis Orphanet J Rare Dis [online] :25 [viewed 03 June 2014] Available from: doi:10.1186/1750-1172-1-25
  6. BAUMANN MH, NOPPEN M. Pneumothorax. Respirology [online] 2004 Jun, 9(2):157-64 [viewed 03 June 2014] Available from: doi:10.1111/j.1440-1843.2004.00577.x
  7. REINGARDIENE D, LAZAUSKAS R. [Acute salicylate poisoning]. Medicina (Kaunas) [online] 2006, 42(1):79-83 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/16467617

Investigations - for Diagnosis

Fact Explanation
Pulse oxymetry Arterial hypoxemia is characteristically refractory to oxygen treatment. [1]
Lung function test If lung function does not improve with the treatment within the 1st week, it indicates poor prognosis. [5]
Chest X-ray Pulmonary edema and pleural effusions are present. Coexisting pneumothorax is also evident in chest X-ray. [1,2,4,6]
CT scan of the chest Chest CT will demonstrate, fluid filled alveoli, consolidation, and atelectasis predominantly in the dependent parts of the lungs. [1,3]
Bronchoalveolar-lavage [1] Lavage has high counts of neutrophils, macrophages, red blood cells and protein-rich edema fluid.
Arterial blood gas analysis Hypoxemia and respiratory acidosis are common. [6]
Full blood count Aids in diagnosing sepsis. White blood cell count of more than 12,000 per mm3 or less than 4,000 mm3 or immature white cell count of more than 10% are supportive of sepsis. [6]
C- reactive protein Elevated in sepsis. [6]
References
  1. WARE LB, MATTHAY MA. The acute respiratory distress syndrome. N Engl J Med [online] 2000 May 4, 342(18):1334-49 [viewed 03 June 2014] Available from: doi:10.1056/NEJM200005043421806
  2. WIENER-KRONISH JP, MATTHAY MA. Pleural effusions associated with hydrostatic and increased permeability pulmonary edema. Chest [online] 1988 Apr, 93(4):852-8 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/3349844
  3. GATTINONI L, BOMBINO M, PELOSI P, LISSONI A, PESENTI A, FUMAGALLI R, TAGLIABUE M. Lung structure and function in different stages of severe adult respiratory distress syndrome. JAMA [online] 1994 Jun 8, 271(22):1772-9 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/8196122
  4. SCHNAPP LYNN M., CHIN DANIEL P., SZAFLARSKI NANCY, MATTHAY MICHAEL A.. Frequency and importance of barotrauma in 100 patients with acute lung injury. Critical Care Medicine [online] 1995 February, 23(2):272-278 [viewed 03 June 2014] Available from: doi:10.1097/00003246-199502000-00012
  5. HEFFNER JE, BROWN LK, BARBIERI CA, HARPEL KS, DELEO J. Prospective validation of an acute respiratory distress syndrome predictive score. Am J Respir Crit Care Med [online] 1995 Nov, 152(5 Pt 1):1518-26 [viewed 03 June 2014] Available from: doi:10.1164/ajrccm.152.5.7582287
  6. SAGUIL A, FARGO M. Acute respiratory distress syndrome: diagnosis and management. Am Fam Physician [online] 2012 Feb 15, 85(4):352-8 [viewed 03 June 2014] Available from: http://www.ncbi.nlm.nih.gov/pubmed/22335314

Investigations - Followup

Fact Explanation
Lung function tests Most patients recover completely with normal lung capacities. [1]
Serum electrolytes Renal function should be monitored as a guide to fluid administration. Fluid administration should be sufficient enough to maintain adequate renal perfusion. [1]
Serum creatitine Serum creatinine will reflect the adequacy of fluid replacement. [1]
Arterial blood gas analysis [1] Progression of the disease and the success of treatment is monitored with arterial blood gas analysis.
Chest X-ray Although some patients recover completely from the acute attack, some develop pulmonary hypertension, right heart failure and fibrosing alveolitis. Once the patient develop fibrosing alveolitis chest Xray will show linear opacities. [1]
CT scan of the chest Diffuse interstitial opacities and bullae are seen in fibrosing alveolitis. [2]
References
  1. WARE LB, MATTHAY MA. The acute respiratory distress syndrome. N Engl J Med [online] 2000 May 4, 342(18):1334-49 [viewed 03 June 2014] Available from: doi:10.1056/NEJM200005043421806
  2. GATTINONI L.. Lung structure and function in different stages of severe adult respiratory distress syndrome. [online] 1994 June, 271(22):1772-1779 [viewed 03 June 2014] Available from: doi:10.1001/jama.271.22.1772

Management - General Measures

Fact Explanation
Treat coexisting infection [1] Pneumonia and sepsis are commonly seen and proper antibiotic treatment should be prescribed.
Nutrition Enteral feeding is considered a better approach when compared to parenteral feeding. A nasogastric tube can be used in patients with significant risk of aspiration. [1]
Adherence to standards of patient care Patients should be handled according to the standard practices to minimize the risk of nosocomial infections. [1]
Fluid management Fluid should be administered in order to maintain sufficient systemic circulation, renal perfusion, metabolic homeostasis and to avoid worsening of pulmonary edema. If the volume resuscitation is not enough to maintain tissue perfusion avoiding the risk of volume overload, vasopressors can be administered. [1]
References
  1. WARE LB, MATTHAY MA. The acute respiratory distress syndrome. N Engl J Med [online] 2000 May 4, 342(18):1334-49 [viewed 03 June 2014] Available from: doi:10.1056/NEJM200005043421806

Management - Specific Treatments

Fact Explanation
Mechanical ventilation Mechanical ventilation is necessary in maintaining tissue oxygenation till the lungs recover from the acute distress. [1]
Surfactant-replacement therapy This is beneficial in infants with respiratory distress syndrome. Adults with acute lung injury may also benefit from surfactant therapy. [1]
Nitric oxide This is a potent vasodilator. When administered by inhalation localized vasodilatation in the pulmonary circulation can be achieved. But this is not very effective mode of treatment and used only if hypoxia is refractory to other treatment modalities. [2]
Glucocorticoids Glucocorticoids has an anti-inflammatory action, which can be used to treat severe and refractory disease. [3]
References
  1. WARE LB, MATTHAY MA. The acute respiratory distress syndrome. N Engl J Med [online] 2000 May 4, 342(18):1334-49 [viewed 03 June 2014] Available from: doi:10.1056/NEJM200005043421806
  2. ROSSAINT ROLF, FALKE KONRAD J., LOPEZ FRANK, SLAMA KLAUS, PISON ULRICH, ZAPOL WARREN M.. Inhaled Nitric Oxide for the Adult Respiratory Distress Syndrome. N Engl J Med [online] 1993 February, 328(6):399-405 [viewed 03 June 2014] Available from: doi:10.1056/NEJM199302113280605
  3. MEDURI G U. Corticosteroid rescue treatment of progressive fibroproliferation in late ARDS. Patterns of response and predictors of outcome.. Chest [online] 1994 May [viewed 03 June 2014] Available from: doi:10.1378/chest.105.5.1516