The objective of this study (Part II) will be to compare the performance of the Trilogy device and a conventional ventilator (participant's current device). Both devices will be set to the participants' current mode and prescription settings.

A. Primary Hypothesis and end-point In patients with respiratory insufficiency, when compared to conventional ventilators, the Trilogy device achieves comparable level of gas exchange (measured as partial pressure of CO2 in arterial or venous blood)and SpO2 levels during various modes of ventilation.

B. Secondary Hypothesis and end-points In patients with respiratory insufficiency, when compared to conventional ventilators, the Trilogy device achieves comparable breathing pattern (tidal volume, respiratory rate, minute ventilation), hemodynamics (heart rate), and subjective measures of breathing comfort (measured by modified Borg dyspnea scale).

Inclusion Criteria:

1. Age > 21 years of age; < 85 years of age
2. Able to follow instructions
3. Able to provide informed consent
4. Considered clinically stable, with low flow oxygen requirements less than 15 LPM (or FIO2 less than 60 %) and PEEP no greater than 10 cm H2O.
5. Requiring mechanical ventilation through nasal/facial mask,tracheostomy or endotracheal tube (ET Tube)

Exclusion Criteria:

1. Clinically unstable, i.e.,

   1. Acute Respiratory Failure
   2. Participants with refractory hypotension defined as systolic blood pressure less than 90 mm Hg despite inotropic agents),
   3. Uncontrolled cardiac ischemia or arrhythmias,
   4. or as otherwise determined inappropriate for the study as determined by the investigator.

2. Patients suffering from metastatic or terminal cancer and patients with do-not-resuscitate orders

3. Pregnancy