Atelectasis is a common pulmonary complication in acute trauma patients maintained on ventilator support who would benefit from VHI but even though recent studies indicate that VHI technique is an improvement on the MHI technique there are relatively few study of the hemodynamic responses to VHI. There is controversy in hemodynamic responses to VHI, Ventilator hyperinflation technique (VHI) is especially valuable in treating patients in the ICU because other techniques such as percussion and postural drainage may not be possible because of wounds, broken bones or surgical drains. However, the technique is very rarely used by physical therapists in the ICU, possibly because they are concerned that increasing in the intra-thoracic pressure by uses VHI to inflate lung will result in dangerous changes in heart rate and blood pressure; that any such changes may persist after the treatment leading to complications such as pulmonary edema and, lastly, the positive pressure to the patient may precipitate episodes of cardiac arrhythmia.