No criteria, just description of the disease, course and outcome.
Physicians faced many problems in selecting cases and no definite research can be focused.
In 1988 Murray and colleagues proposed an expanded definition intended to describe the syndrome in three parts.
Definition Murray, J. F., M. A. Matthay, J. M. Luce, and M. R. Flick. 1988. An expanded definition of the adult respiratory distress syndrome. Am Rev Respir Dis 138(3):720-3. Acute or chronic depending on course. Severity of lung injury depending on LIS. Cause or associated risk factor. Part One. Part Two. Part Three. Three part expanded definition of ALI/ARDS proposed by Murray and colleagues
Definition Bernard, G. R., A. Artigas, K. L. Brigham, J. Carlet, K. Falke, L. Hudson, M. Lamy, J. R. Legall, A. Morris, and R. Spragg. 1994. The American-European Consensus Conference on ARDS. Definitions, mechanisms, relevant outcomes, and clinical trial coordination. Am J Respir Crit Care Med 149(3 Pt 1):818-24. Bilateral chest infiltrates consistent with pulmonary edema. Radiographic criteria. PAOP > 18 mm Hg, or clinical evidence of left atrial hypertension. Exclusion criteria. ALI. ARDS. PaO 2 /FIO 2 ≤ 300. PaO 2 /FIO 2 ≤ 200. Acute and persistent. Onset The 1994 AECC definition for ALI/ARDS
Definition Does not specify the cause. Radiographic data are not specific. Simple and easy to use. Recognizes clinical spectrum Acute onset. ALI or ARDS. Bilateral chest infiltrates. PAOP < 18 mm Hg. 1994 Bernard et al LIS not predictive of outcome. Does not include exclusion criteria Identify clinical spectrum. Identifies etiology. 3 part definition. LIS. 1988 Murray et al No specific criteria to identify patients. First description and describes Clinical manifestations well. No criteria 1971 Petty & Ashbaugh Disadvantages Advantages Criteria Year Reference comparison between various definitions of ARDS
Now it had been established that ALI/ARDS is divided into pulmonary and extrapulmonary ARDS according to the cause.
This classification had been made as Pathophysiology, course, treatment and outcome are not the same.
Thus risk factors are now classified as ARDSp or ARDSexp.
Pulmonary or extra-pulmonary Acute pancreatitis. Cardiopulmonary bypass. Drug overdose. DIC. Burns. Head injury. Inhalation injury. Pulmonary contusion. Fat embolism. Near drowning. Reperfusion injury. Less common Less common Sepsis. Severe trauma with prolonged hypotension Multiple fractures. Aspiration pneumonia. Pneumonia. Common Common Indirect (Extra Pulmonary) Direct (Pulmonary) Clinical disorders associated with the development of ALI/ARDS.
Lung injury is primarily initiated by a specific insult (sepsis, trauma, VILI); with the initiation of inflammation there is rapid and increased recruitment of leucocytes, together with inflammatory mediators to the site of injury, several mechanisms had been involved in the pathogenesis of ARDS.
In the past the disease was named as Adult respiratory distress syndrome, due to the resemblance between ARDS and respiratory distress syndrome in infants, which is mainly due to surfactant deficiency.
In order to hasten the development of effective therapy for ARDS, the National Heart, Lung, and Blood Institute, National Institutes of Health, initiated a clinical network to carry out multi center clinical trials of ARDS treatments.
A third trial examined lower tidal volume ventilation versus a traditionally recommended higher tidal volume approach in patients with acute lung injury.
This landmark randomized controlled trial, which enrolled 861 subjects, clearly demonstrated that lower tidal volumes result in improved survival.
The Acute Respiratory Distress Syndrome Network. 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; Vol 342: 1301-1308).
This study examined two different strategies for managing intravenous fluids and fluid balance in patients with acute lung injury.
A second goal of this trial was to determine if a Pulmonary Artery Catheter (PAC) was superior to a smaller, and less invasive central venous catheter in the management of patients with ARDS.
No benefit was seen with the PAC guided therapy.
restrictive or conservative fluid administration was superior to the traditional approach by shortening the duration of mechanical ventilation.
Wheeler AP, Bernard GR, Thompson BT, Schoenfeld D, Wiedemann HP, deBoisblanc B, Connors AF, Jr., Hite RD, Harabin AL: Pulmonary-artery versus central venous catheter to guide treatment of acute lung injury. N Engl J Med 2006; 354: 2213-24
A prospective, randomized trial of Aerosolized Albuterol vs. Placebo to test the safety and efficacy of aerosolized beta-2 adrenergic agonist therapy for improving clinical outcomes in patients with acute lung injury.
Most patients requiring mechanical ventilation for acute lung injury and the acute respiratory distress syndrome (ARDS) receive positive end-expiratory pressure (PEEP) of 5 to 12 cm of water. (!!!5-12)
Higher PEEP levels may improve oxygenation and reduce ventilator- induced lung injury but may also cause circulatory depression and lung injury from overdistention . (1ry outcome should be VILI or cardiac depression)
We conducted this trial to compare the effects of higher and lower PEEP levels on clinical outcomes in these patients.