Airway Pressure Release Ventilation (APRV) Versus AC/VC Conventional Ventilation

This prospective un-blinded randomized trial will follow patients with respiratory failure
and ALI/ARDS who require invasive mechanical ventilation in select ICUs. Patients will be
allocated to respiratory support with either APRV mode or volume control (AC) mode of
mechanical ventilation. Qualifying patients will be randomized by permuted block
randomization within 24 hours of admission to the ICU. Identical ventilation and oxygenation
thresholds will be utilized to guide titration of each ventilator protocol. Patients will
remain on the assigned mode of ventilation until they are extubated and discharged from the
ICU.

Procedures for treatment evaluation include daily monitoring of the Ventilator protocol in
each arm. Clinical coordinator and study respiratory therapist will perform 2 daily checks
of the study patients to determine compliance with the protocol and if patient meets weaning
criteria. The previously published ARDS Network continuous positive airway pressure (CPAP)
weaning protocol will be used for all patients enrolled.

Inclusion Criteria:

- Hypoxemic respiratory failure requiring mechanical ventilation for >24 hours.

Exclusion Criteria:

- Age under 18

- Severe chronic obstructive lung disease

- Patients in whom the only indication for mechanical ventilation is airway protection
from poor neurological status.