Weaning induced cardiac dysfunction is a common cause of weaning failure in critically ill patients. plethysmography variability index (PVI) is a non-invasive, real-time, and automated parameter for evalu¬ating fluid responsiveness.

By proving the validity of (PVI) in predicting successful spontaneous breathing trial Massimo can be used an easy noninvasive method that help in deciding the right time for weaning.

Inclusion Criteria:

1. Intubation and mechanical ventilation
2. Fulfilling criteria for extubation
3. Fraction inspired oxygen less than 50%

Exclusion Criteria:

• a. Hemodynamic instability b. b. tracheostomy

intubated mechanically ventilated patients candidate for extubation