The purpose of this prospective randomized clinical trial is to evaluate three different types of hyperinflation respiratory therapies, Intermittent Positive Pressure Breathing (IPPB), Intermittent positive end expiratory pressure (EzPAP), Metaneb. Investigators will examine which hyperinflation therapy provides better lung expansion and may improve lung recovery after surgery.

Postoperative pain due to surgical incision may limit lung expansion. After cardiac surgery, all patients receive respiratory therapies, because it is critical to expand lung after surgery to prevent respiratory complications such as lung collapse (atelectasis) due to shallow breathing or accumulation of airway secretions.

Although incentive spirometer is the most common method used for lung recovery after cardiac surgery, some studies were not able to find any benefits from the use of incentive spirometer. Inspiratory positive-pressure breathing (IPPB), Intermittent positive end expiratory pressure (EzPAP), and chest airway clearance (Metaneb) are hyperinflation therapies used after surgery. The purpose of this research study is to determine which hyperinflation respiratory therapy provide better lung recovery after cardiac surgery.

Hyperinflation Respiratory Therapies:Participants will be randomly assigned one of the hyperinflation respiratory therapy, intermittent positive pressure breathing (IPPB) and the EzPAP or the Metaneb.

1. Intermittent positive pressure breathing (IPPB) is a respiratory therapy technique which will support your breathing by providing pressure support. This respiratory method will increase air volume breathing in.
2. The EzPAP is another respiratory treatment and participants will breath against to resistance in order to prolong the time the lung remain open.
3. The Metaneb will provide resistance when patients breathing in order to prolong the lung opening.

Hyperinflation therapy will be performed every 4 hours in the intensive care unit (ICU). Each respiratory therapy session will take about 15 minutes. Participants' pulmonary function will be evaluated daily to monitor the lung recovery with microspirometer which will take place approximately 5 minutes. Total study duration is about 96 hours after surgery or until discharge from the Intensive Care Unit.

Risk for Lung over expansion (hyperinflation) therapy:

Hyperinflation respiratory treatments target to expand your lung to prevent complication such as collapse of small airway after surgery. This over expansion of your lung may increase work of breathing. All expected complications are typical in the post-operative cardiac patients and not unique to hyperinflation therapy.

The possible complications listed below:

1. Over distention of air sucks (alveoli). Sometimes pressure trauma in your lung may cause pneumothorax.
2. Infection
3. Bloody sputum (hemoptysis)
4. Blood gas changes such as decrease carbon dioxide or increase oxygen in your blood.
5. Sometimes stomach may distend
6. Impaction of airway secretions if gas mixture not humidified enough.
7. Your blood return to the heart maybe decreased which may affect your blood pressure.
8. Exacerbation of low blood oxygen level (hypoxemia),
9. Decreased or increased respiration
10. Air trapping in your airway
11. You may psychologically dependence to device

Inclusion Criteria:

1. Age 18 years and older
2. Admitted to Cardiovascular ICU (CVICU) after coronary artery bypass grafting (CABG), isolated valve repair/replacement, or CABG + valve repair/replacement
3. Cardiac surgery performed via median sternotomy

Exclusion Criteria:

1. BMI>40
2. Refusal to be consented
3. Prior or current lung transplant patients

Assessment respiratory therapist will be blinded to respiratory therapy modalities.