Comparison Study of High Frequency Percussive Ventilation With Conventional Ventilation

Specific Aim 1: This prospective randomized trial will enroll 180 patients with ALI/ARDS over a forty-eight month period. One cohort will receive conventional mechanical ventilation adhering to our well defined protocol of protective lung strategies. A second cohort will have these same strategies applied utilizing the VDR/HFPV. Out come measures will include; ICU/Hospital length of stay, pulmonary infectious complications, airway pressure related complications, PaO2/PaCO2 levels, hemodynamic profiles, and ventilators days. We hypothesize that patients with Acute Lung Injury (ALI )and/or Acute Respiratory Distress Syndrome (ARDS) managed primarily with HFPV will have fewer ventilators days, fewer infectious complications, and shorter ICU/hospital lengths of stay than patients managed with conventional mechanical ventilation techniques, while maintaining similar oxygenation (PaO2), ventilation (PaCO2), metabolic (pH), and hemodynamic (cardiac output) parameters. ARDS and ALI have been shown to cause elevations in circulating inflammatory mediators as well as local (alveolar) mediators. The presence of increased amounts of both circulating and alveolar cytokines (inflammatory mediators) has been associated with increased mortality in patients with ARDS/ALI. The pulmonary capillary bed is a rich source of these inflammatory cytokines and the effects of ventilator strategies on circulating and compartmentalized (alveolar) cytokine levels may affect outcome. Specific Aim 2: Circulating and alveolar inflammatory mediators (IL-6, IL-1-beta, IL-10, and TNF-alpha) will be measured, and activation of other markers of increased synthesis of inflammatory mediators (NF-kappa B and p38 map kinase) will be determined in isolated peripheral blood and alveolar leukocytes. We hypothesize that patients with ALI/ARDS managed with HFPV will have lower levels of circulating and alveolar pro-inflammatory cytokines (IL-6, IL-1-beta and TNF-alpha) as well as less activation of NF-kappa B and p38 MAP kinase from peripheral blood and alveolar leukocytes.