iVAPS vs. S/T Modes as Non-invasive Weaning Strategy in COPD Patients

Invasive mechanical ventilation (IMV) is associated with numerous complications. Hence, patients should be weaned from the ventilator as early as possible. A number of randomized controlled trials have addressed whether noninvasive ventilation (NIV) can facilitate weaning in patients failing spontaneous breathing trials (SBT)s. Compared to invasive weaning, NIV weaning strategy showed reduced mortality, greater weaning success, less ventilator-associated pneumonia, shorter length of ICU and hospital stay and less re-intubation rate.

Most of the previous studies used pressure support ventilation with fixed pressure support, but no studies published on hybrid NIV modes.

Intelligent Volume Assured Pressure Support (iVAPS) is a recent NIV mode, which achieves a target alveolar ventilation by adjusting pressure support and respiratory rate automatically. In iVAPS, the target is alveolar ventilation not the tidal volume, taking into account a predicted dead space . This new mode has been investigated in stable chronic obstructive pulmonary disease (COPD) patients with domiciliary NIV and it was comparable to pressure support ventilation (PSV) regarding improvement in oxygenation, carbon dioxide (CO2) wash and therapy compliance.

Yet, less numerous studies have been performed on this mode when used for acute respiratory failure. These studies found that i-VAPS was comparable to PSV as regards PaCO2 and pH improvements, minute volume, pressure support and respiratory rate. No published data so far about the role of i-VAPS as a weaning mode in mechanically ventilated patients. So, this study aims to investigate this new mode in comparison to the standard S/T mode in weaning COPD patients using NIV.

Invasive mechanical ventilation (IMV) is associated with numerous complications. Hence, patients should be weaned from the ventilator as early as possible . Approximately 25% and (14-22) % of mechanically ventilated patients experience difficult and prolonged weaning respectively. A number of randomized controlled trials have addressed whether NIV can facilitate weaning in patients failing SBTs. The most recent systemic review included 16 trials -mainly COPD patients- found that patients weaned with NIV had reduced mortality, greater weaning success, less ventilator-associated pneumonia, shorter length of ICU and hospital stay and less reintubation rate.

Most of the previous studies used pressure support ventilation with fixed pressure support, but no studies published on hybrid NIV modes. Intelligent Volume Assured Pressure Support (iVAPS) is a recent NIV mode, which achieves a target alveolar volume by adjusting pressure and respiratory rate automatically. In iVAPS, the target is alveolar ventilation not the tidal volume. taking into account a predicted dead space. This new mode has been investigated in stable COPD patients with domiciliary NIV and it was comparable to pressure support ventilation (PSV) regarding improvement in oxygenation, CO2 wash and therapy compliance. Other studies focused on sleep quality and found that iVAPS was comparable to PSV regarding sleep quality, arousal, O2 de-saturation index, increase in therapy adherence and decrease in median PS needed with iVAPS.

Yet, less numerous studies have been performed on this mode when used for acute respiratory failure. These studies investigated the outcomes in acute hypercapnic respiratory failure and found that iVAPS was comparable to PSV as regards PaCO2 and logarithm of hydrogen ion concentration (pH) improvements, minute volume, pressure support and respiratory rate. No published data about the role of iVAPS as a weaning mode in mechanically ventilated patients.

Eligibility Criteria:
Inclusion Criteria:

All patients in acute exacerbation of COPD who are mechanically ventilated will be included in this study.

Exclusion Criteria:

* Age \< 18 years or \>75 years.
* Other chest diseases (pneumonia, bronchiectasis, pulmonary embolism, pulmonary fibrosis...).
* Tracheostomized patients.