ARDS

Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome

Introduction

Ashbaugh and colleagues (1967) first coined the term adult respiratory distress syndrome (ARDS; more recently called acute respiratory distress syndrome) to describe a clinical syndrome in a cohort of 12 critically ill patients with acute respiratory failure, cyanosis refractory to oxygen therapy, decreased lung compliance, and diffuse infiltrates evident on the chest radiograph. Since that time, this syndrome has become a leading cause of prolonged intensive care unit (ICU) stays and late deaths.

Mortality from acute respiratory distress syndrome (ARDS) ranges from 40% to 50%. Multiple strategies have been used to improve outcomes in this patient population. Low tidal volume strategy, using 6 ml per kilogram of ideal body weight for tidal volumes, has been universally adopted for ventilator management of patients with ARDS. Despite advances in intensive care unit (ICU) management of critically ill patients; the mortality from ARDS is still high. Signs and symptoms of the condition are subtle, and diagnosis usually comes after irreversible necrosis is present. Therefore, it is recommended to withhold or decrease the rate of tube feeds for patients with circulatory shock or increasing vasopressor requirements.

Patients with ARDS develop atelectasis in the dependent portions of the lungs. Due to maintenance of perfusion to these atelectatic areas, intrapulmonary shunting occurs, resulting in hypoxemia. Multiple studies have demonstrated the positive impact of prone position on gas exchange. Despite improvement in oxygenation, none of the studies to date have shown improvement in survival. There are complications associated with prone positioning such as conjunctival edema, accidental dislodgement of equipment, and facial skin necrosis.

Discussion and Analysis

Different techniques of prone positioning have been used. Some of these used thoracopelvic support to keep the anterior wall of the thorax and abdomen above the plane of bed while others did not. The technique requires at least 4 staff members to help place the patient in the prone position and again to turn patient back to the supine position. Automated prone positioning and axial rotation using kinetic therapy beds recently have been introduced. Stiletto et al presented the results of computer supported continuous axial rotation therapy in prone position for complex poly trauma patients with ARDS, in an abstract at ACCP chest meeting in 2001. They showed that the bed has the advantages of requiring minimal staff, minimizing the risk of dislodgement of the endo-tracheal tubes and other intravascular devices commonly used in the ICU. To date, ...