Extracorporeal Carbon Dioxide Removal for Acute Respiratory Distress Syndrome
Condition: Acute Respiratory Distress Syndrome; Lung Diseases
MeSH terms: Lung Diseases; Respiratory Distress Syndrome; Respiratory Distress Syndrome, Newborn; Acute Lung Injury; Syndrome
Study type: Interventional
Phase: Phase 3

Summary: 
      To compare conventional therapy using low frequency positive pressure ventilation with
      extracorporeal CO2 removal for the treatment of adult respiratory distress syndrome (ARDS).
    

Detailed description: 
      BACKGROUND:

      It is estimated that at least 150,000 individuals die each year of adult respiratory distress
      syndrome. Treatment remains largely supportive. The National Heart, Lung, and Blood Institute
      (NHLBI) conducted the Extracorporeal Support for Respiratory Insufficiency (ECMO,
      Extracorporeal Membrane Oxygenation) trial from June 1974 through 1978. In ECMO, 90 patients
      were randomized to either extracorporeal membrane oxygenation plus conventional therapy or to
      conventional therapy. Survival rates were less than ten percent in both groups. The failure
      of the trial to demonstrate the superiority of ECMO over conventional ventilatory support
      resulted in the virtual elimination of the use of ECMO in clinical medicine.

      In the earlier NHLBI trial, ECMO was implemented with a veno-arterial shunt which
      approximated 90 percent of the baseline cardiac output. Ventilation of the lungs was
      continued with reduced function of inspiration oxygen. Thus, the lungs were deprived of the
      principle source of blood supply while continuously exposed to potentially injurious
      ventilatory pressures and gas composition. The present patient trial used a new form of
      therapy developed by Dr. Gattinoni and co-workers in Milan, Italy with the collaboration of
      Dr. Kolobow at the National Institutes of Health in Bethesda. The authors reported a 77
      percent survival rate for the new therapy. In Step 1 of the new therapy, the patient was
      initially ventilated with pressure-controlled, inverted ratio ventilation. If the patient did
      not improve, Step 2 using extracorporeal perfusion was performed with a veno-venous shunt in
      contrast to a veno-arterial shunt. The veno-venous shunt preserved pulmonary blood flow
      whereas the veno-arterial shunt diminished it. Step 3 was reserved for those patients who did
      not meet the therapeutic criteria of Step 2. They underwent low frequency positive-pressure
      ventilation and extracorporeal CO2 removal involving veno-venous bypass via the internal
      jugular and femoral or bilateral saphenous veins.

      DESIGN NARRATIVE:

      Randomized, fixed sample. Patients were stratified by age (under and over 40 years) and by
      the presence or absence of trauma. Patients were assigned to conventional positive pressure
      ventilation therapy or to a three-step therapeutic program employing
      pressure-controlled-inverted-ratio-ventilation, continuous positive airway pressure, and
      low-frequency positive pressure ventilation-extracorporeal CO2 removal. The main outcome
      measure was survival at 30 days after randomization. Secondary outcome measures included
      hospital costs, physiologic data, length of hospital stay, and blood product consumption.
      Follow-up took place during the year after hospital discharge.
    

Intervention name(s): positive-pressure ventilation; extracorporeal membrane oxygenation (CO2 removal)
Intervention type(s): Procedure; Procedure
Intervention description(s): Detailed computer protocol controlled positive pressure ventilation; Detailed computer protocol controlled Extracorporeal CO2 Removal with reduced positive pressure ventilation
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment