In adult patients place the esophageal balloon 35-40 cm from the lips or nose. During an expiratory hold, gently push on the chest to increase the pressure in the chest. Freeze the waveforms of the esophageal and ventilator graphics. Measure the change in pressure during the push. Good positioning results in a ratio of 0.80 - 1.20
Perform an expiratory hold on the ventilator for no more than 3 seconds, followed by an inspiratory hold for no more than 3 seconds. Freeze the waveforms of the esophageal and ventilator graphics. Measurements are taken at the onset of zero flow.
The Ventilatory Ratio (VR) is a simple bedside index of impaired efficiency of ventilation and correlates well with physiological dead space fraction (dead space to tidal volume ratio, VD/VT) in patients with ARDS. (Reference)
The value is the ratio between the compliance of the recruited lung to that of the respiratory
Values >= 0.5 suggest more potential for lung recruitment with respect to lung inflation. (Reference)
Maximal thickening fraction is measured during maximal (volitional) inspiratory effort by patient. Assessing the maximum thickening fraction is particularly helpful when the thickening fraction is lower than 15% during assisted ventilation.
This calculator is ideal for education and simulation purposes. It DOES NOT replace clinical or professional judgement. Use at your own discretion.
Calculator by Thomas Piraino RRT in collaboaration with Lu Chen MD, Michele Bertoni MD and Ewan Goligher MD PhD