ABSTRACT
Most patients requiring invasive mechanical ventilation for acute respiratory
failure are rapidly liberated from the ventilator after improvement or resolution
of the acute precipitating illness. Nevertheless, approximately 5% to 20% of
patients prove more difficult to liberate taking many weeks to be successfully
weaned or, in a smaller number of cases, proving impossible to remove from mech-
anical ventilation. The definition of prolonged mechanical ventilation varies
whether one refers to those given by regulatory agencies or by investigators pub-
lishing in this field. In earlier reports, patients with underlying obstructive lung
disease, severe chest wall deformities, or neuromuscular disease comprised the
majority of patients undergoing prolonged mechanical ventilation. More recently,
the demographics have changed, with patients suffering from acute lung injury,
prolonged acute hospitalization for multi-organ system failure, or post-operative
complications making up the majority requiring prolonged ventilation (1).
