Introduction: LCI is a sensitive assessment of ventilation inhomogeneity; a range of commercial devices exist to allow measurement. We examined the practicality and feasibility of one device measuring LCI via open circuit design (ndd EasyOne Pro LAB)

Method: 72 healthy children, aged 6-12 years, were recruited to perform LCI; all were naïve to lung function tests. Demographics, test time and success were recorded. Children received instruction and demonstration on the device

Results: 70.8% of children completed an LCI test, requiring 4-10 washouts to achieve an acceptable test (2 adequate washouts). 93% of children able to complete an adequate washout within the first 4 attempts went on to complete a successful test; only 37.9% of children unable to do this completed a successful test. 73.4% of washouts were rejected due to lack of tidal breathing (64.7%), leak (4.7%), subject withdrawal (1.9%) and excessive FRC variation (3.1%). There was a trend of increased tidal volume and reduced respiratory rate in children who were more successful. Success rate significantly increased over the study (1st vs. 2nd halves; 52.7% vs 88.8%, p=0.001), with no difference subject age, height, weight, nor number of washout attempts. Mean total test time was 29.1 (7.5 SD) min, mean length of time for a single washout was 102 (29 SD) seconds. Repeatability for LCI and FRC was good; 4.68 (coefficient of variation, CV%) and 3.21 CV% respectively

Conclusion: LCI is feasible using a commercial device (ndd EasyOne Pro LAB) in children. However considerable time, training and staff commitment is required in achieving these results