Mechanical ventilation has been known to produce changes in the flow of blood through the major blood vessels in the body. These changes may go undetected, but with continuous arterial blood pressure measurements, changes in the arterial waveform can be visualized. Although we know that these arterial pressure variations occur during mechanical ventilation, little is known about the effects of various modes of mechanical ventilation on these changes. The most common modes of ventilation used in ICU are Volume control, Pressure control and Airway pressure release ventilation.

Objective We have designed a prospective randomized pilot study to determine the effects of the commonly used ventilator modes on the arterial pressure.

Inclusion Criteria:

Patients 18 yrs of age and older, Patients on mechanical ventilation, Patients deeply sedated in the ICU with RASS scores of atleast -3, Patients having an A-line for blood pressure monitoring, Patients with stable hemodynamics.

Exclusion Criteria:

Patients with moderate-severe ARDS, Patients requiring high inspiratory oxygen requirements, High peak inspiratory pressures requirement for ventilation, Presence of arrhythmia, Patients with spontaneous breathing activity, Patients on weaning mode, Patients having CHF or Cor pulmonale.