ARDS is mostly prevalent in critically ill hospitalized patients. The initial presentation of ARDS includes acute onset of dyspnea, tachypnea, hyperventilation, low oxygen saturation, cyanosis, and anxiety. A cough with frothy sputum may also be seen. The underlying cause will most likely exhibit signs and symptoms as well such as in the cases with pneumonia. Ominous signs are hypotension, tachycardia, confusion, and fatigue which are indicative of inadequate oxygen perfusion of organs. 

Hospitalized patients with ARDS are susceptible to other medical conditions such as pneumonia. Ventilation is also a risk factor for pneumonia. In addition to infection, there are other complications. One of them is pneumothorax, in which ventilated air pressure enters the space around the lungs causing subsequent collapse in one or both. In addition, lung scarring inhibits its ability to expand. Another major and potentially fatal complication is clot formation. Thromboembolism can occur due to prolonged immobility and other pathological mechanisms.

• Hypoxemia

  By expert consensus, ARDS is defined by three categories based on the degrees of hypoxemia ( Table 322-2 ). [accessmedicine.mhmedical.com]

  A subset of patients with ARDS has mixed hypercapnia and hypoxemia despite high-level ventilator support. [ncbi.nlm.nih.gov]

• Fever

  The diseases generally present as undifferentiated fever, but thrombocytopenia, leucopenia, and transaminitis are important laboratory features. [ncbi.nlm.nih.gov]

  Call your doctor or 911 if you experience severe shortness of breath, or if you have a new cough or fever. [lung.org]

  Inside the Lungs and Airways With pneumonia: You usually cough up mucus You have chest pain, chills, fever, or trouble breathing Your symptoms can be very mild (sometimes called "walking pneumonia") or very serious Symptoms are often worse in young children [msdmanuals.com]

• Fatigue

  Twenty four hours later she had worsening dyspnoea, fatigue, and hypotension, and was transferred to the intensive care unit for vasopressor infusion and invasive ventilation. The ventilation was weaned at 3 weeks, but rehabilitation was slow. [bmj.com]

  As lung becomes edematous and consolidated, tachypnea and hypoxemia are caused by progressive restrictive lung dz and muscle fatigue. CXR w/ diffuse opacities +/- small effusion. [uichildrens.org]

  Extreme fatigue and confusion. Low blood pressure. How is acute respiratory distress syndrome diagnosed? You may need any of the following tests: Blood tests may show if you have an infection. They may also show how your body is working. [northmemorial.com]

  For example, a patient with severe pneumonia, in general, initially presents hypoxemic ARF that may progress to respiratory muscle fatigue and secondary failure of the ventilatory “pump” and hypercapnia. [xlung.net]

• Hypothermia

  Early evidence suggests that therapeutic hypothermia (TH) could be a viable treatment for acute respiratory failure. [ncbi.nlm.nih.gov]

  Coma Scale score Aspiration History of drug abuse, especially inhalational Drug toxicity Facial burns, singed eyebrows, carbonaceous sputum, history of working near organic solvents or toxic chemicals Inhalation injury History of needing water rescue, hypothermia [aafp.org]

  Management of Pediatric Hypothermia and Peripheral Cold Injuries in the Emergency Department - $49.00 Appropriate management of cold injuries depends on their severity. [ebmedicine.net]

  Using a radiant warmer or incubator to keep newborns warm and reduce the risk of hypothermia. Living With - Respiratory Distress Syndrome After your baby leaves the hospital, he or she will likely need follow-up care. [nhlbi.nih.gov]

• Multiple Organ Dysfunction Syndrome

  All patients had influenza A (H1N1) viral pneumonia (confirmed with RT-PCR) complicated by ARDS and septic shock with multiple organ dysfunction syndrome. None of the patients received seasonal influenza vaccines. [ncbi.nlm.nih.gov]

  organ dysfunction syndrome (MODS) DAD is the most common morphological pattern of ARDS; however the clinical syndrome of ARDS is not synonymous with the pathologic diagnosis of DAD DAD pattern is often characterized by hyaline membranes in acute phase [pathologyoutlines.com]

  View Article PubMed Google Scholar Vincent JL, Zambon M: Why do patients who have acute lung injury/acute respiratory distress syndrome die from multiple organ dysfunction syndrome? Implications for management. [doi.org]

• Respiratory Distress

  The acute respiratory distress syndrome. N Engl J Med. 2000; 342(18):1334-49. Ashbaugh DG, Bigelow DB, Petty TL, Levine BE. Acute respiratory distress in adults. Lancet. 1967; 2(7511):319-23. Murray JF, Matthay MA, Luce JM, Flick MR. [aacc.tums.ac.ir]

  Synonyms of Acute Respiratory Distress Syndrome acute lung injury adult respiratory distress syndrome ARDS noncardiogenic pulmonary edema increased-permeability pulmonary edema General Discussion Acute respiratory distress syndrome (ARDS) is a type of [rarediseases.org]

  What is Acute Respiratory Distress Syndrome (ARDS, Acute Alveolar Injury, Traumatic Wet Lungs) Statistics on Acute Respiratory Distress Syndrome (ARDS, Acute Alveolar Injury, Traumatic Wet Lungs) Risk Factors for Acute Respiratory Distress Syndrome (ARDS [myvmc.com]

  PATIENTS: Mechanically ventilated children with acute respiratory distress syndrome. INTERVENTIONS: Blood collection within 24 hours of acute respiratory distress syndrome onset and biomarker measurements. [ncbi.nlm.nih.gov]

• Dyspnea

  The symptoms include dyspnea, hypotension and multovisceral failure. The disease is characterized by bilateral pulmonary infiltrates and severe hypoxemia due to increased alveolar-capillary permeability. [orpha.net]

  A 43-year-old man was transferred to the emergency department because of accidental chlorine inhalation and rapidly progressive dyspnea. The patient was diagnosed with acute respiratory distress syndrome due to chlorine gas exposure. [ncbi.nlm.nih.gov]

  Acute respiratory distress syndrome (ARDS) is a clinical syndrome of severe dyspnea of rapid onset, hypoxemia, and diffuse pulmonary infiltrates leading to respiratory failure. [accessmedicine.mhmedical.com]

  Shortness of breath Other names Dyspnea, dyspnoea, breathlessness, difficulty of breathing, respiratory distress Pronunciation Dyspnea: /dɪspˈniːə/ Specialty Pulmonology Shortness of breath (SOB), also known as dyspnea, is the feeling that one cannot [en.wikipedia.org]

• Cough

  Call your doctor or 911 if you experience severe shortness of breath, or if you have a new cough or fever. [lung.org]

  We present a Case Report of a previously healthy 18-year-old woman who presented with dyspnea, cough, and pleuritic chest pain after e-cigarette use. [ncbi.nlm.nih.gov]

  Inside the Lungs and Airways With pneumonia: You usually cough up mucus You have chest pain, chills, fever, or trouble breathing Your symptoms can be very mild (sometimes called "walking pneumonia") or very serious Symptoms are often worse in young children [msdmanuals.com]

• Tachypnea

  Tachypnea Other names Tachypnoea Pronunciation Specialty Respirology Tachypnea is abnormally rapid breathing. [en.wikipedia.org]

  As lung becomes edematous and consolidated, tachypnea and hypoxemia are caused by progressive restrictive lung dz and muscle fatigue. CXR w/ diffuse opacities +/- small effusion. [uichildrens.org]

  The symptoms usually appear shortly after birth and may include tachypnea, tachycardia, chest wall retractions (recession), expiratory grunting, nasal flaring and cyanosis during breathing efforts. [orpha.net]

  Tachypnea, hypoxia, and respiratory alkalosis are typical early clinical manifestations, and they are usually followed by the appearance of diffuse pulmonary infiltrates and respiratory failure within 48 hours. [ncbi.nlm.nih.gov]

• Pleural Effusion

  Real-time polymerase chain reaction tests of sputum and pleural effusion samples confirmed adenovirus serotype 7. Chest x-rays showed progressively increasing infiltrations and pleural effusions in both lung fields within 11 days. [ncbi.nlm.nih.gov]

  There are diffuse, bilateral airspace disease without pleural effusions or cardiomegaly. The person was involved in a near-drowning. [learningradiology.com]

  Chest tubes were placed to drain worsening pleural effusions. Computed tomography of the chest revealed dependent opacities in both lung bases, superimposed smooth interlobular septal thickening, and pleural effusions. [pediatrics.aappublications.org]

  Gorg C, Restrepo I, Schwerk WB (1997) Sonography of malignant pleural effusion. Eur Radiol 7:1195–1198 PubMed CrossRef Google Scholar 74. Qureshi NR, Rahman NM, Gleeson FV (2009) Thoracic ultrasound in the diagnosis of malignant pleural effusion. [doi.org]

• Cyanosis

  The symptoms usually appear shortly after birth and may include tachypnea, tachycardia, chest wall retractions (recession), expiratory grunting, nasal flaring and cyanosis during breathing efforts. [orpha.net]

  The person has shortness of breath, usually with rapid, shallow breathing, the skin may become mottled or blue (cyanosis), and other organs such as the heart and brain may malfunction. [merckmanuals.com]

  Patients initially present with acute onset cyanosis, dyspnea, and tachypnea. [amboss.com]

• Hypotension

  The symptoms include dyspnea, hypotension and multovisceral failure. The disease is characterized by bilateral pulmonary infiltrates and severe hypoxemia due to increased alveolar-capillary permeability. [orpha.net]

  It is feasible that severe acidosis, hypotension, azotemia, hypoalbuminemia and the superimposed aggressive intravenous fluid administration were important risk factors for the development of cerebral edema and ARDS in the index patient. [ncbi.nlm.nih.gov]

  Twenty four hours later she had worsening dyspnoea, fatigue, and hypotension, and was transferred to the intensive care unit for vasopressor infusion and invasive ventilation. The ventilation was weaned at 3 weeks, but rehabilitation was slow. [bmj.com]

  Per EMS, the patient was hypotensive on their arrival, with initial blood pressure of 80/40 mm Hg, but it rapidly improved with 2 L of crystalloid given in the field. A second large-bore IV is placed and labs are drawn. [web.archive.org]

• Tachycardia

  The symptoms usually appear shortly after birth and may include tachypnea, tachycardia, chest wall retractions (recession), expiratory grunting, nasal flaring and cyanosis during breathing efforts. [orpha.net]

  On arrival to the emergency department (ED) the patient was noted to be febrile with tachycardia, tachypnea, and hypoxia and was intubated for respiratory failure. [ncbi.nlm.nih.gov]

  Proliferative, Fibrotic Phases) Signs and Symptoms of ARDS (acute respiratory distress syndrome): Tachypnea, refractory hypoxemia (hallmark sign and symptoms), cyanosis, mental status changes, abnormal lungs sounds like crackles in the late stages, tachycardia [youtube.com]

  Signs: cyanosis (reflecting hypoxia refractory to oxygen therapy), tachypnoea, tachycardia, peripheral vasodilatation, bilateral fine inspiratory crackles. Investigations FBC, U&E, LFTs, amylase, clotting, CRP, blood cultures, ABG. [patient.info]

• Confusion

  There may also be signs, such as confusion or low blood pressure, that the vital organs aren't getting enough oxygen. [columbiasurgery.org]

  You can go into shock from losing too much blood, not having enough fluids in your body, or having heart problems, severe infections, or allergic reactions Shock makes you feel weak, dizzy, and confused, and you may pass out Doctors treat the cause of [msdmanuals.com]

  Symptoms include: Shortness of breath Low blood pressure Unusually fast breathing Fast heartbeat Cough Fever Chest pain, especially when breathing deeply Confusion and exhaustion Blue-tinted lips or nails from lack of oxygen in your blood Dizziness ARDS [webmd.com]

  It can lead to infections and pneumonia, a collapsed lung, kidney failure, muscle weakness, and confusion. Studies show that ARDS is less common in children, and less likely to be fatal. [medicalnewstoday.com]

  The main common signs and symptoms are shortness of breath, difficulty breathing, fast and shallow breathing, blue colored skin, and other signs showing brain (confusion, lethargy) and heart dysfunction. [symptoma.com]

• Cognitive Impairment

  ARDS is associated with a long initial ICU stay and hospitalization leading to muscle wasting and cognitive impairment. [faron.com]

  ARDS survivors often have long-lasting impairments such as cognitive dysfunction, mental health issues and physical impairments, all of which may affect employment. [hopkinsmedicine.org]

  […] function returns to normal at 6-12 months in survivors occasionally patient have severe restrictive lung disease although this is the case, many patient have a severe reduction and pulmonary QOL -> depression, anxiety and PTSD are common patient often have cognitive [lifeinthefastlane.com]

• Agitation

  […] unit Recovery – Characterized by restoration of the alveolar epithelial barrier, gradual improvement in pulm compliance, resolution of arterial hypoxemia, and eventual return of pulm function Clinical presentation First signs are tachypnea, dyspnea, agitation [uichildrens.org]

  The person with ARDS may initially appear agitated as a result of breathing difficulty (rapid breathing or shortness of breath), but later may become lethargic and or even comatose. [rarediseases.org]

  This is characterized by the combination of one or more findings: altered state of consciousness (from agitation to lethargy), increased work of breathing [nasal flaring, use of accessory muscles, intercostal retraction, Hoover sign, suprasternal and [xlung.net]

  This often leads to restlessness and patient agitation, which can lead to high pressures in the lung or even cause oxygen levels to drop even further. [foundation.chestnet.org]

  […] trial Able to meet oxygen requirement with noninvasive methods Hemodynamically stable Minute ventilation ≤ 15 L Positive end-expiratory pressure ≤ 5 cm H 2 O Parameters for weaning off of ventilator* Airway can be protected Hemodynamically stable No agitation [aafp.org]

• Altered Mental Status

  Systemic signs (depending on the severity of illness) eg central or peripheral cyanosis as a result of hypoxemia, tachycardia, and altered mental status. Despite 100% oxygen, patients have low oxygen saturation. [physio-pedia.com]

  mental status; white blood cell count > 12,000 per mm 3 (12 × 10 9 per L), < 4,000 mm 3 (4 × 10 9 per L), or > 10 percent immature forms; elevated C-reactive protein level; arterial hypotension; acute oliguria; hyperlactatemia Sepsis Less common History [aafp.org]

  mental status, unstable dysrhythmia, stridor, intercostal indrawing, cyanosis, tripod positioning, pronounced use of accessory muscles (sternocleidomastoid, scalenes) and absent breath sounds.[11] A number of scales may be used to quantify the degree [en.wikipedia.org]

• Difficulty Concentrating

  Common problems in people recovering from ARDS include: memory problems, such as difficulty recalling certain words or remembering people's names difficulty concentrating low attention span problems doing complex mental tasks, such as mental arithmetic [hse.ie]

The diagnosis of ARDS is clinical and should be considered in ill patients presenting with acute respiratory failure. The Berlin definition guides the clinician in terms of timing of the onset, chest X-ray findings (opacities not consistent with effusion, atelectasis, or nodules) and oxygenation criteria per the Berlin definition [2].

In addition to the above, a full history and physical is key. The clinician should investigate and ascertain any underlying conditions. One should be highly suspicious for sepsis, which is associated with the highest rate of mortality. Examination of patient involves lung exam and determination of basilar or diffuse rales [11]. Also another critical finding is the requirement of high oxygenation and/or PEEP to maintain saturation greater than 90%. Workup is comprised of the following tests:

1. Arterial blood gas analysis provides values to calculate the PaO2/FIO2 ratio per the Berlin definition.
2. Chest X-ray will show any opacities indicative of pulmonary edema.
3. Brain natriuretic protein (BNP) can determine the etiology of pulmonary edema. BNP<100 picograms/mL suggest non cardiac causes while BNP> 500 picograms/mL are suggestive of cardiac etiology.
4. Echocardiogram is performed to assess cardiac function if BNP and other findings are inconclusive.
5. Pulmonary artery catheterization measures estimation of left ventricular end diastolic pressure. This is used to differentiate cardiogenic versus noncardiogenic etiology of pulmonary edema if BNP levels, echocardiogram and findings from history and physical are inconclusive. This is not a routine procedure. 
6. Other significant laboratory tests include cultures of blood, urine, and sputum to assess for infection. Lipase and liver functions tests are helpful to detect pancreatitis. 
7. Bronchoalveolar lavage (BAL) or endotracheal aspiration provides samples for culture and Gram stain are done to confirm suspected pneumonia [12]. There is a high mortality risk associated with these procedures. Therefore, the risks and benefits have to be weighed.
8. CT of chest is more sensitive than a chest X-ray and is useful in diagnosing pneumonia and underlying lung processes [13].

• Atelectasis

  However, the predicted body weight approach is imperfect in patients with ARDS because the amount of aerated lung varies considerably due to differences in inflammation, consolidation, flooding, and atelectasis. [ncbi.nlm.nih.gov]

  Alveolar protective ventilation utilizing appropriate positive-end expiratory pressure (PEEP) minimizes atelectasis and shearing injury. [hamilton-medical.com]

  CT w/ dense regions in dependent areas reflecting collapse of edematous lung/ w secondary atelectasis. Aerated regions prevail in non-dependent areas. PFTs show decreased FRC. Total lung compliance is ↓’d but some regions may be normal. [uichildrens.org]

  The Berlin definition guides the clinician in terms of timing of the onset, chest X-ray findings (opacities not consistent with effusion, atelectasis, or nodules) and oxygenation criteria per the Berlin definition. [symptoma.com]

  […] alveolar spaces bronchial dilatation within areas of ground-glass opacification some publications also report pulmonary cysts in the early phase 11 Postulated reason for inhomogeneity of appearances: increased weight of overlying lung causing compressive atelectasis [radiopaedia.org]

• Pulmonary Infiltrate

  It is characterized by the acute onset of diffuse, bilateral pulmonary infiltrates secondary to noncardiogenic pulmonary edema, refractory hypoxia, and decreased lung compliance. [ncbi.nlm.nih.gov]

  Abstract The acute respiratory distress syndrome (ARDS) is a heterogeneous group of illnesses affecting the pulmonary parenchyma with acute onset bilateral inflammatory pulmonary infiltrates with associated hypoxemia. [vumc.org]

  The disease is characterized by bilateral pulmonary infiltrates and severe hypoxemia due to increased alveolar-capillary permeability. The severity depends on the degree of alveolar epithelial injury, with a mortality rate of 30-50%. [orpha.net]

  Acute respiratory distress syndrome (ARDS) is a clinical syndrome of severe dyspnea of rapid onset, hypoxemia, and diffuse pulmonary infiltrates leading to respiratory failure. [accessmedicine.mhmedical.com]

  English Serious and sometimes fatal reactions, including bronchospasm, hypoxia, syncope, pulmonary infiltrates, acute respiratory distress syndrome (ARDS), respiratory arrest, myocardial infarction, arrhythmias, acute cardiac insufficiency and cardiac [mymemory.translated.net]

• Pulmonary Infiltrates

  It is characterized by the acute onset of diffuse, bilateral pulmonary infiltrates secondary to noncardiogenic pulmonary edema, refractory hypoxia, and decreased lung compliance. [ncbi.nlm.nih.gov]

  Abstract The acute respiratory distress syndrome (ARDS) is a heterogeneous group of illnesses affecting the pulmonary parenchyma with acute onset bilateral inflammatory pulmonary infiltrates with associated hypoxemia. [vumc.org]

  The disease is characterized by bilateral pulmonary infiltrates and severe hypoxemia due to increased alveolar-capillary permeability. The severity depends on the degree of alveolar epithelial injury, with a mortality rate of 30-50%. [orpha.net]

  Acute respiratory distress syndrome (ARDS) is a clinical syndrome of severe dyspnea of rapid onset, hypoxemia, and diffuse pulmonary infiltrates leading to respiratory failure. [accessmedicine.mhmedical.com]

  English Serious and sometimes fatal reactions, including bronchospasm, hypoxia, syncope, pulmonary infiltrates, acute respiratory distress syndrome (ARDS), respiratory arrest, myocardial infarction, arrhythmias, acute cardiac insufficiency and cardiac [mymemory.translated.net]

• Bilateral Pulmonary Infiltrates

  The disease is characterized by bilateral pulmonary infiltrates and severe hypoxemia due to increased alveolar-capillary permeability. The severity depends on the degree of alveolar epithelial injury, with a mortality rate of 30-50%. [orpha.net]

  It is characterized by the acute onset of diffuse, bilateral pulmonary infiltrates secondary to noncardiogenic pulmonary edema, refractory hypoxia, and decreased lung compliance. [ncbi.nlm.nih.gov]

  […] edema (air space disease) diffuse bilateral pulmonary infiltrates normal sized heart makes CHF less likely Respiratory compliance ( Positive end-expiratory pressure (>10cm H20) Corrected expired volume per minute (>10L/min) Differential Cardiogenic pulmonary [orthobullets.com]

  Radiography ARDS is defined by the presence of bilateral pulmonary infiltrates. [emedicine.medscape.com]

• Air Bronchogram

  bronchograms 20% 20% 70% Adult Respiratory Distress Syndrome. [learningradiology.com]

  CT Scan shows widespread patchiness and air bronchogram. Criteria for diagnosis of acute respiratory distress syndrome (ARDS) include symptoms within 1 week of inciting event, x-ray and CT opacities and rule out cardiogenic pulmonary edema. [youtube.com]

  CXR shows bilateral alveolar shadowing, often with air bronchograms. Other investigations as deemed by the clinical scenario - eg, echocardiography. [patient.info]

  Imaging : chest x-ray Diffuse bilateral infiltrates (perihilar bat wing or butterfly distribution of infiltrates) Air bronchogram Atelectasis Pleural effusions ARDS is a likely diagnosis in the presence of both typical causes and therapy-resistant hypoxemia [amboss.com]

• Hypercapnia

  A subset of patients with ARDS has mixed hypercapnia and hypoxemia despite high-level ventilator support. [ncbi.nlm.nih.gov]

  V/Q dysfunction mechanisms in the pulmonary parenchyma may cause hypoxemia and/or hypercapnia. [xlung.net]

• Neutropenia

  […] study [ 4 ] were continuous infusion of a neuromuscular blocking agent at enrollment, actual body weight exceeding 1 kg per centimeter of height, severe chronic liver disease (Child–Pugh class C), bone marrow transplantation or chemotherapy-induced neutropenia [ncbi.nlm.nih.gov]

  Oncologic Complications in the Emergency Department (Pharmacology CME) - $49.00 This issue reviews 3 of the more common presentations of oncology patients to the emergency department: metastatic spinal cord compression, tumor lysis syndrome, and febrile neutropenia [ebmedicine.net]

  Ognibene FP, Martin SE, Parker MM, Schlesinger T, Roach P, Burch C, et al: Adult respiratory distress syndrome in patients with severe neutropenia. N Engl J Med 1986;315:547-551. [karger.com]

• Hyponatremia

  VQ Mismatch and Hyponatremia lectures have been popular among medical students and physicians. [youtube.com]

  Conivaptan is the first medication approved by US Food and Drug Administration for the treatment of euvolemic hyponatremia in those with heart failure.[40] In rare cases hypertonic 3% saline together with diuretics may be used to correct hyponatremia. [en.wikipedia.org]

• Decreased Lung Compliance

  Hallmarks of ARDS include hypoxemia and decreased lung compliance, increased work of breathing, and impaired gas exchange. Mortality is often accompanied by multiple organ failure. [ncbi.nlm.nih.gov]

  [with] hypoxemia and bilateral radiographic opacities, associated with increased venous admixture, increased physiological dead space, and decreased lung compliance." [pulmccm.org]

  Also decrease lung compliance is another feature of ARDS due to decrease area of aeration and fibrosis. [youtube.com]

  […] plasma proteins invading the alveolar spaces; thus creating an environment that can lead to surfactant inhibition and decreased lung compliance. [hamilton-medical.com]

• Pleural Effusion

  Real-time polymerase chain reaction tests of sputum and pleural effusion samples confirmed adenovirus serotype 7. Chest x-rays showed progressively increasing infiltrations and pleural effusions in both lung fields within 11 days. [ncbi.nlm.nih.gov]

  There are diffuse, bilateral airspace disease without pleural effusions or cardiomegaly. The person was involved in a near-drowning. [learningradiology.com]

  Chest tubes were placed to drain worsening pleural effusions. Computed tomography of the chest revealed dependent opacities in both lung bases, superimposed smooth interlobular septal thickening, and pleural effusions. [pediatrics.aappublications.org]

  Gorg C, Restrepo I, Schwerk WB (1997) Sonography of malignant pleural effusion. Eur Radiol 7:1195–1198 PubMed CrossRef Google Scholar 74. Qureshi NR, Rahman NM, Gleeson FV (2009) Thoracic ultrasound in the diagnosis of malignant pleural effusion. [doi.org]

These patients are admitted to ICU. Treatment is divided into 3 categories: Respiratory support, cardiovascular resuscitation, and other therapies.

Respiratory support: Most patients require ventilation when: PaO2 <8.3kPa (60mm HG) despite using FIO2 60% and PaCO2 >6kPa (45mm HG). Clinicians should be aware that increased tidal volumes coupled with poor lung compliance can further increase lung damage. Lower tidal volumes have been shown to improve survival [10].

Cardiovascular support: Clinicians should remain vigilant while monitoring the cardiovascular status in these ill patients. It is critical to maintain cardiac output and oxygenation. In many cases, drugs such as dobutamine and other vasodilators are beneficial. Fluid resuscitation is carefully monitored as well. Blood transfusions may be warranted. Clinician may consider Swan-Ganz catheter placement for invasive monitoring of cardiac output and pulmonary capillary wedge pressure.

Further therapy depends on underlying diseases. It is critical to treat sepsis and the source if the organism(s) is/are known. In certain cases where organisms are not found on culture, broad spectrum renal safe antibiotics are used.  

Other supportive therapies include prophylactic drugs such as low molecular weight heparin for venous thromboembolism prophylaxis and antacids for gastric ulcer prophylactics. Also nutrition has to be maintained. 

While steroids were commonly used in ARDS patients, their use is no longer recommended. Steroids have been linked to many cases of septicemia and hyperglycemia. Results from the Late Steroid Rescue Study report the increase in the mortality rate with methylprednisolone therapy.

The mortality rate in patients with ARDS is 30 to 50% and increases with severity [2]. Fatality is usually secondary to multiorgan failure [5]. Furthermore, younger age is associated with better prognosis [6]. Residual lung damage may be seen in survivors [7] [8]. Post ARDS residual effects can include neuropathies, joint disorders, chronic pain, and muscle weakness [9].

Mechanical ventilation can cause lung damage and increased mortality. Furthermore, the 2000 ARDS Network Trial shows that lower tidal volumes decrease mortality from 40 to 31% [2]. This research study further demonstrates that tidal volumes at 4-6 mL/kg are protective [10].

The etiology of ARDS is extensive. Underlying diseases serve as risk factors. Sepsis is the most common cause and can be attributed to pulmonary and nonpulmonary etiologies [4]. Direct pulmonary insults such as pneumonia, aspiration of gastric contents, inhalation injury, pulmonary contusion, transfusion-related lung injury, and cardiopulmonary bypass are risk factors for ARDS. Nondirect pulmonary insults such as acute pancreatitis, fat embolism, noncardiogenic shock, disseminated intravascular coagulation, drug overdose, and trauma also place patients at risk for this debilitating pulmonary failure [1]. Other risk factors may include previous lung disease, smoking, obesity, and alcohol abuse.

Due to the usage of varied definitions of ARDS in older research studies, there is an inaccurate estimate regarding the actual incidence of ARDS. However, research emerging from the United States and international regions provide some insight on the incidence.

About 4 decades ago, the National Institute of Health (NIH) estimated that the incidence is 75 cases per 100,000 population. However, the ARDS Study Network suggests that the incidence is actually greater than that. The 2005 study in King County, Washington, using the outdated definition from the 1994 AECC, reports the incidence of ALI as 86.2 per 100,000 population [4]. A further statistical analysis of the data yields an estimate of 190,600 annual cases in the United States of which 74,500 result in death. Furthermore it is estimated that ALI is associated with an annual 3.5 million hospital days [4].

The same study also shows that age is directly proportional to the incidence of ALI. In the 15-19 year old range, the incidence was 16 per 100,000 while it was 306 in the age range of 75 to 84 [4]. As for gender, the incidences are similar with the exception of trauma patients in which females have a higher incidence of ARDS.

The complex pathophysiology of ARDS is not completely clear. The early stages consist of diffuse alveolar damage and increased permeability across the alveolar capillary membrane. Capillary endothelial cells and alveolar pneumocytes (Type I and Type II) undergo necrosis and apoptosis marking an exudative inflammatory process. This involves flooding of alveolar air spaces with edema, neutrophils and activated alveolar macrophages, in addition to mediators such as cytokines and oxidants [1]. The acute onset of alveolar flooding may result in recovery due to active clearance of pulmonary edema or may progress to disease [1].

Type II cell injury and exudative flooding contribute to surfactant dysfunction. This consequently increases alveolar-arterial oxygen gradient and leads to acute hypoxemic respiratory failure. The main features of this phase include respiratory failure, high minute ventilation and low compliant lungs [1].

Severe epithelial injury can cause progression of the inflammatory phase to a fibroproliferative phase. Necrotic type I cells denude the basement membrane thereby allowing fibrin deposition. Histologically, hyaline membranes are observed. This irreversible devastating phase consists of extensive formation or fibrous and collagen deposition [1] [4].

ARDS cannot necessarily be prevented but cessation of smoking and alcohol may help. It is also important for all individuals, especially those as risk, to comply with appropriate immunization recommendations such as flu (annual) and pneumococcal (per guidelines) vaccines. 

Acute respiratory distress syndrome (ARDS) is characterized by rapidly progressive respiratory failure. Individuals with ARDS can develop multiorgan damage and are usually at high risk for mortality [1].

The European Society of Intensive Care Medicine, the American Thoracic Society and the Society of Critical Care Medicine formulated the new criteria for ARDS in 2011. The new updated guidelines, referred to as the Berlin definition, are as follows: [2]

Timing of ARDS: Occurs within one week of clinical risk factor/insult or within one week of new or worsening respiratory condition.
Chest imaging: Bilateral opacities that are not explained by effusions, atelectasis, or nodules.
Etiology of edema: Respiratory failure not due to cardiac etiology or fluid overload.
Oxygenation: Degree of oxygenation determines the severity. 

• Mild: PaO2/FIO2 ≤300 mmHg and >200 mmHg  with PEEP or CPAP ≥5 cmH2O
• Moderate: PaO2/FIO2 ≤200 mmHg and >100mm Hg with PEEP ≥5 cmH2O
• Severe: PaO2/FIO2 ≤100 mmHg with PEEP ≥5 cmH2O

The Berlin definition replaces the previous American -European Consensus Committee (AECC) definition which differentiated ARDS from other varied or lesser forms such as acute lung injury (ALI), noncardiac pulmonary edema, and increased permeability pulmonary edema [2] [3]. This AECC definition presented diagnostic limitations and therefore was updated for accuracy.

Acute respiratory distress Syndrome (ARDS) is a condition in which respiratory failure occurs. The most common cause is sepsis, which is an overwhelming response of the body to an infection. Other causes are acute pancreatitis, fat embolism, aspiration, inhalation injury, acute pancreatitis, disseminated intravascular coagulation, drug overdose, and trauma.

In ARDS, fluid accumulates in the lungs and makes it very difficult to expand and facilitate oxygen exchange. Therefore, there are low oxygen blood levels in the body which can lead to damage of organs. The main common signs and symptoms are shortness of breath, difficulty breathing, fast and shallow breathing, blue colored skin, and other signs showing brain (confusion, lethargy) and heart dysfunction.

In patients with suspected ARDS, a chest X-ray is done to evaluate for any fluid in the lungs. Also, a blood test is done to determine the levels of oxygen. Other laboratory tests may be important to determine the exact cause. Also an ultrasound of the heart may be done to look for any cardiac problems. Individuals with ARDS are likely very ill from other diseases as well. Patients with ARDS are admitted to the intensive care unit for special care. Since the lungs are not working properly and oxygen is low in the body, most patients require mechanical ventilation to help deliver oxygen to the organs. These patients are monitored closely to make sure their heart, lungs, kidneys, and other organs are receiving adequate oxygen. Other treatments are for prevention of blood clots, stomach ulcers and nutritional care.

1. Ware LB, Matthay MA. The acute respiratory distress syndrome. New England Journal of Medicine. 2000;342(18):1334-1349.
2. Ranieri VM, Rubenfeld GD, Thompson BT, et al. Acute respiratory distress syndrome: the Berlin Definition. Journal of American Medical Association. 2012;307(23):2526-2533. doi:10.1001/jama.2012.5669.
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