Ammann, R.A.

Baldwin, D.N.

Frey, U.

Gallafi, S.

Kraemer, R.

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213 Progression of pulmonary hyperinflation and trapped gas associated with genetic factors in children with cystic fibrosis (CF) 

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I~  Progression of pulmonary hyperinflation and trapped 
gas associated with genetic factors in children with 
cystic fibrosis (CF) 
R. Kraemer 1'3, D.N. Baldwin 1, R.A. Ammann 2'3, S. Gallati 2'3, U. Frey 1'3. 
1Division of Paediatric Respiratory Medicine, 2Division of Human Genetics, 
3Department of Paediatrics, University of Berne CH-3010 Berne, Switzerland 
Functional deterioration i CF is best reflected by increased egree of ventilation 
inhomogeneities (Am J Respir Crit Care Med 2005; 171:371 8). A clinically 
similarly important mechanism is gas trapping, known to impair gas exchange 
dramatically. We aimed to determine which lung physiological factors (airway 
resistance, ventilation inhomogeneities, pulmonary hyperinflation) orgenetic factors 
dominantly influence these mechanisms in CE Serial annual ung function tests, 
performed in 164 CF-children (81 males; 83 females; age: 6 18 y), provided ata 
pertaining to functional residual capacity (FRCpleth, FRCMBNW), lung clearance 
index (LCI), volume of trapped gas (VTG), effective specific airway resistance 
(sRefl), and forced expiratory indices (FEV1, FEF50). Pulmonary hyperinflation 
(FRCpleth >2SDS) was already present in 43% of patients at age 6 8 yrs, increas- 
ing to 84% at age 20 yrs. The proportion of patients with VTG increased from 41% 
to 83%. All lung function parameters showed age-related progression. Children with 
severe pulmonary hyperinflation and gas trapping at the age 6 8 yrs have the worst 
progression of their disease over time. Gas trapping was more associated with airway 
obstruction than with ventilation inhomogeneities and significantly associated with 
the CFTR genotype. Similar to the tracking of lung function in asthma, tracking 
in CF starts very early whereby genetic factors play an important role. Thus, early 
assessment of pulmonary hyperinflation, ventilation inhomogeneities and trapped 
gas in conjunction with CFTR genotypes will help to monitor functional disease 
progression i CE 
5. Immunology pulmonology 
1~ Baseline pulmonary function as a predictor of blood oxygenation 
while breathing a normobaric, hypoxic gas mixture in adults with 
Cystic Fibrosis 
A. de Keiser, G.WM. van der Meijden, A.C. Roldaan, H.G.M. Heijerman. 
Department of Pulmonology, Haga Teaching Hospital, The Hague, The Netherlands' 
Study objective: To develop a Pre-Flight assessment for adults with cystic fibrosis 
to predict he need for in-flight oxygen supplementation. 
Subjects: Sixty ambulatory and clinically stable adults with cystic fibrosis with a 
mean FEV1 of 52.6% (range 22 112%) predicted. 
Methods: The study contained two parts. Part one was the routinely pulmonary 
function test in our lungfunction laboratory. Part two was the inhalation of a 
normobaric, hypoxic gasmixture (15% 02 in 85% N2) with finger-probe pulse- 
oximetry and on-line breath-by-breath registration for the simulation of air travel 
or the remaining at an altitude of 2,438 m (n-HAST). 
Results: None of the subjects had a baseline oxygen saturation lower than 90%. In 
all subjects there is a significant lower O2-sat (%) during n-HAST whereas heart 
rate and minute ventilation are significant higher. 
Baseline O2-sat correlated best with O2-sat during n-HASZ None of the subjects 
who were not at risk (FEV1)50% predicted) had clinically significant desatura- 
tions, O2-sat <85%, during n-HAS% In the at risk group, subjects with an FEV1 
<50% predicted, six subjects had dangerous desaturations. In three of them n-HAST 
was ended prematurely when their O2-sat reached a value of <80%. 
Conclusions: We conclude that all patients with an FEV1 < 30% predicted and 
baseline O2-sat ~<95% require in-flight oxygen. Patients with an FEV1 <30% 
predicted and baseline O2-sat > 95% and patients with an FEV1 30 50% predicted 
and baseline O2-sat ~<95% are at risk when exposed to a hypoxic challenge such 
as an altitude simulation test or air travel. In these patients further assessment in 
order to predict necessity of in-flight oxygen is highly recommended. 
[ •  Airway reactivity in Cystic Fibrosis 
C. Ciofu, I. Cernatescu, E.R Ciofu. Institute for Mother and ChiM Care, 
"A. Rusescu", Bucharest, Romania 
Variability in responsiveness to bronchodilator d ugs is one of the features of inflam- 
mation in cystic fibrosis (CF). A subpopulation of CF patients (pts) demonstrates 
airway reactivity. Bronchial reactivity may be considered one of the markers of 
poor prognosis. 
Aim of the study was to asses the reversibility of FEV1 after bronchodilator 
(Salbutamol) and the bronchial hyperreactivity after histamine aerosols in our CF pts 
followed in one CF Center from Bucharest. 
Methods and Results: 27 CF pts, age range 5 20 years (mean age 10.6 years), 
18/27 chronically infected with Pseudomonas aeruginosa or Staphylococcus' aureus 
were enrolled in the study. Baseline FEV1 values was used to define three groups 
of pts. First group (12 pts) demonstrate normal FEV1 (mean value 103.48% of 
predicted). The second group (9 pts) had moderate decrease of FEV1 (mean 
value 64.9% of predicted) and a third group (6 pts) had a severe decrease of 
FEV1 (mean value 45.5% of predicted). All the children were tested for response 
to bronchodilator aerosols and positive response was defined as )12% change 
in FEV1 from baseline value.13/27 (48.7%) had a positive response represented 
by an increase in FEV1 (11.5% to 17.5%). The bronchodilator response was 
negative in all the pts from the third group (mean increase FEV1 of 0.4% of 
predicted). The bronchial reactivity was assessed in 7 pts with FEV1 )80% of 
predicted. The percentage of fall FEV1 and FEF50 from baseline was determined. 
Decrease of FEVl~<12% and of FEF50 ~<15% was considered significant. The 
hyperresponsiveness wa  found in 6/7 cases. 
Conclusions: Our results confirm the data from previous studies regarding vari- 
ability of airway reactivity in CF pts due to the chronic bronchial inflammation. 
The follow-up prospective study of our cases may demonstrate correlation between 
bronchial reactivity and deterioration of respiratory function. 
Abreviations: FEV1 forced expiratory volume in one second. FEF 50 forced 
expiratory flow at 50% of vital capacity. 
1• Compact and portable gas mixing measurements using a 
photoacoustic analyzer 
A.R. Horsley 1, A. McCullagh 2, A.R Greening 1 , J.A. Innes 1 , RM. Gustafsson 3. 
1 Western General Hospital, Edinburgh; 2Royal Brompton Hospital, London, UK; 
3Queen Silvia Childrens' Hospital Goteborg, Sweden 
Background: Evidence is increasing that a simple index of ventilation inhomogene- 
ity (lung clearance index; LCI) derived from a multiple-breath inert gas washout is a 
more sensitive measure of airway dysfunction i  children with CF than spirometry. 
To date, this has required a mass spectrometer (MS), which is both expensive and 
complex to maintain. Innocor is a photoacoustic gas analyzer that has been designed 
to measure cardiac output by inert gas rebreathing. Its capacity to measure sulfur 
hexafluoride (SF6) means that it can be adapted to measure LCI. 
Aims; To compare the performance of Innocor to a MS, the current gold standard 
for measuring LCI. 
Methods; Using a specially constructed syringe, instantaneous step changes in flow 
and gas concentration were generated. Speed of response is given as the 10 90% 
rise and fall time. We also compared the signal:noise ratio of the two devices during 
LCI measurements. Signals from both machines were sampled at 100Hz. 
Results; Innocor can measure SF6 concentrations a low as 0.005% with minimal 
noise compared to a MS. Both MS and Innocor track changing SF6 concentrations 
similarly, but the Innocor signal is slower (rise time 150 msecs compared to MS rise 
time of 80 msecs). During LCI measurement, this leads to a small but acceptable 
difference of 4% in the calculated total expired volume of SF6. 
Conclusions: The modified Innocor device provides a promising alternative to the 
MS in assessing ventilation inhomogeneity. The device is both much smaller and 
less expensive, and has excellent signal resolution down to below 0.005% SF6. The 
signal rise time is slower, but this is unlikely to cause major error in the calculation 
of lung volumes or LCI during normal breathing. 


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213 Progression of pulmonary hyperinflation and trapped gas associated with genetic factors in children with cystic fibrosis (CF)

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