Although these parameters will provide a measure of ventilation, other ventilatory parameters, which can provide mechanistic insight or identify site of action, should also be considered.
Although these parameters will provide a measure of ventilation, other ventilatory parameters, which can provide mechanistic insight, should also be considered.
The area under the compensated CV density curve (AUC), for CV values greater than a threshold value CVT, AUC CV > CVT), was used as the measure of ventilation heterogeneity.
It was also found that in some circumstances the ventilation rate determined from the flow rate through the building openings may not accurately represent the actual ventilation rate of a building, and measurements/simulations of contaminant decay may form a more accurate measure of ventilation rate.
The proposed method generates as a global measure of ventilation inhomogeneities, an AUC CVTT) value that can differentiate with statistical significance between the activity distributions corresponding to varying severity of COPD changes and the healthy normal activity distribution in a breathing lung phantom.
The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq 99mTc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm−1.
A two-dimensional map was produced from these values, and standard deviation was calculated as an aggregate measure of ventilation homogeneity.
This hypothesis is suggested by the results of a recent study by Amin and colleagues [ 18], who used lung clearance index (LCI), a measure of ventilation non-homogeneity.
A second pressure sensitive catheter was then inserted subcutaneously through a small opening made on the right lateral thoracic wall to record changes in intrathoracic pressure, a measure of ventilation (VENT).
The review included only studies comparing two ventilation modes in a randomized controlled study and reporting one of the following outcome measures: length of ventilation (LOV), oxygenation, mortality, chronic lung disease and weaning.
