LCI:
Lessons learnt in
the lung function
lab
Dr Patrick Stafler
Pulmonary Institute
Schneider Children’s
Medical Center of Israel
ChIPaP February 2015
Today
 Physiology


Recap
Lung Clearance Index
Slope III Analysis
 Key
Publications in 2014
 Lessons learnt
 Conclusions and Future Prospects
Physiology
Recap
Lung Clearance Index



Number of volume turnovers required to
“washout” tracer to 1/40th of initial concentration
Peripheral airway function (generation 8+)
Ventilation homogeneity/ in-homogeneity
• Functional Residual Capacity
FRC =
Vol tracer
C init – C end
• Lung Clearance Index
LCI =
CEV
FRC
Slope III Analysis
Diffusion- Convection Front
Convection
Diffusion
Alveolar
Bronchial
Deadspace
Rise of SnIII over time (CF)
Tidal N2 multiple breath washout (MBW) from a 15-year girl
with cystic fibrosis (CF).
Volym (L)
1.000
0.500
0.000
N2 %
80
N2 %
70
#1
60
# 23
50
N2 (%)
Vol
40
Vol
30
20
10
0
0
30
60
90
120
Tid (s)
150
180
210
Verbank 1997
Convection dependent inhomogeneity
Diffusion-convection interaction dependent inhomogeneity
SF6 = MM 146
He= MM 4
N2= MM 28
Key
Publications
2014
Lung Clearance Index 2014
n=45
Asthma




Aim:
 Compare LCI in asthma and controls
 Assess effect of salbutamol in children with asthma on LCI
Methods:
 Outpatients with asthma compared to healthy controls
 MBW using SF6
Results:
 32 asthma (4.7-17.4 years) and 42 controls (5.3-20.8)
 LCI differed: mean LCI 6.48 (0.48) vs 6.21 (0.38) (P = 0.008)
 Salbutamol had no significant effect on LCI for asthmatics
(SF6!)
Conclusion:
 Asthmatics have LCI in the normal range
 LCI in asthma is significantly higher
Esophageal
Atresia

Purpose:


Methods:


28 patients operated for EA: Questionnaire, spiro & MBW
Results:




Investigate peripheral AW dysfunction vs spirometry
22/28 (79%) patients respiratory symptoms
17 (61%) abnormal peripheral AW function
6 (21%) central obstruction
Conclusion:


Peripheral airway disease is common in EA
Long-term follow-up of (peripheral) AW warranted
CF



Aim: Compare repeatability, sensitivity and test duration
of LCI 1/30, 1/20 and 1/10 to standard 1/40
Methods: 30 clinically stable CF vs 30 healthy controls
Results:





CF: Repeatibility (CV%) in all concentrations not significantly
different to controls
Sensitivity of LCI 1/40, LCI1/30 and LCI1/20 to presence of CF
equal (67%)
Sensitivity of LCI 1/ 10 and FEV1% pred. lower (53% and 47%)
Test duration of LCI 1/30, 1/20 and 1/10 significantly shorter
than 1/40
Conclusions: LCI1/20 shorter, repeatable and sensitive
measure with equal diagnostic performance to LCI1/40
Lessons learnt
So far...
Number of MBW tests (n=34)
1
ILD
Post BMT
4
Asthma
4
7
PCD
18
CF
0
2
4
6
8
10
12
14
16
18
... but the quality?
Good
14
Acceptable
6
Unacceptabl
e14
Get the basics right



Sit upright
Use silicon mouth piece
Breath on "true" FRC- find it during pre-phase



No swallow in first 5 breaths
Remain air tight



Switch off auto-start
Check entire circuit
No coughing
Inspiratory peak flow must not exceed bias
flow
Get the basics right
 Check

for re-equalibration
Between trials check O2 and N2 levels
 Despite
"locked system" for 1.5 times washout
 Intake
form- fill in during test for QC
 CetN2 falsely low with small breaths/
falsely high with deep breaths

Check the tidal volumes of the 3 breaths
below target to ensure endpoint accurate
N2 leak

Patient side

Sample line
Maintain breathing pattern
Changes in TV unacceptable
Hyperventilation- change in
Cet CO2
Shifting EEL- 23 yo PCD; FEV1 80%
Reset target alveolar
concentration
WO time 5.51 mins
LCI 12.4
More physiological
Shortens washout
Shifting EEL- 23 yo PCD; FEV1 80%
Check BTPS
WO time 5,51 mins
LCI 12.4
Direct effect on CO2
WO time 4,31
mins
LCI 10.1
7 yo
Post BMT
Good
short test
in young
child
17 yo Asthma
 FVC
113%  112%
 FEV1 76%  91% (19%)
 MEF 49%  71% (44%)
 FeNO
38.6 (<20)
12 yo CF ABPA; Pre- Ivacaftor
 FEV
76%  97%
 LCI 14.9 
Conclusions
and
Future
Prospects
Preliminary conclusions
 It‘s
not all about the number
 Don‘t start research studies without
experience
 Tests takes a long time

Chose patients carefully
The future
 Longitudinal
measurements
 Evaluate multitude of disease processes
 Shorter tests (single breath, LCI 5)
 Insights about location of various disease
processes
 Different techiniques

E.g. SBW from FRC more sensitive than RV?
 Assessment

of trapped gas
VC maneuvres at end of wash out