Positive Pressure and Gravity Affect Volumetric Capnography

The Effect of Positive Pressure and Body Position on Volumetric Capnography Assessed by Electrical Impedance Tomography

Volumetric capnography is an interesting and non-invasive tool for monitoring ventilation in mechanically ventilated patients. The aim of this study was to test the effect of positive pressure ventilation and different body positions on volumetric capnograms.

In this interventional study awake and healthy volunteers will be submitted to spontaneous, pressure support and control pressure ventilation using a tight nasal mask. Volumetric capnography and electrical impedance tomography (EIT) will be continuously recorded during the protocol. Different body positions were randomly tested. Analysis of global and regional distribution of ventilation using EIT will be matched with changes observed in volumetric capnography-derived parameters.

Inclusion Criteria:

• American Society Anesthesia physical status I.
• Age between 25-39 years old,
• Body mass index between 23-28 kg/m2,
• Non-smokers.

Exclusion Criteria:

• Presence of pulmonary or cardiac diseases.
• Abnormal spirometry.