Evaluation of ventilation maldistribution as an early indicator of lung disease in children with cystic fibrosis

P.M. Gustafsson; P. Aurora; A. Lindblad

doi:10.1183/09031936.03.00049502

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Fig. 1.—
a) Forced expiratory volume in one second (FEV₁) % predicted versus age in 43 patients with cystic fibrosis (CF) (•) and 28 healthy controls (○). b) Maximum expiratory flow at 25% of forced vital capacity (MEF₂₅) % pred versus age in 34 patients with CF (•) and 26 healthy controls (○). c) Mixing ratio from multiple-breath washout (MBW) versus age in 43 patients with CF (•) and 28 healthy controls (○). d) Lung clearance index (LCI) from MBW versus age in 43 patients with CF (•) and 28 healthy controls (○). The dashed horizontal lines in figures c and d denote the upper limits of normality for mixing ratio (1.35) and LCI (7,17), respectively.
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Fig. 2.—
a) Mixing ratio (MR) versus forced expiratory volume in one second (FEV₁) % predicted in 43 patients with cystic fibrosis (CF) (•) and 28 healthy controls (○). The dashed horizontal line denotes the upper normal limit for MR (1.35). b) MR versus maximum expiratory flow at 25% of forced vital capacity (MEF₂₅) % pred in 34 patients with CF (•) and 26 healthy controls (○) aged ≥7 yrs. The dashed horizontal line denotes the upper normal limit for MR (1.35).

Tables

Figures

Table 1

Clinical data of the 43 cystic fibrosis (CF) patients and the 28 healthy controls

	CF patients	Controls
Patients	43	28
Males/females	23/20	14/14
Age yrs	11.5 (3.0–18.2)	11.4 (4.5–18.7)
Weight kg	35.5 (16.5–92.0)	38.3 (20.5–85.5)
Height cm	146 (101–181)	150 (113–189)
Genotype
ΔF508/ΔF508	24
ΔF508/other	17
Other/other	3
Pancreatic function
PI	36
PS	7
Chronically colonised
P. aeruginosa	10
S. maltophilia	2
B. cepacia	2

Data are presented as n or median (range)
PI: pancreatic insufficiency
PS: pancreatic sufficiency
P. aeruginosa: Pseudomonas aeruginosa
S.maltophilia: Stenotrophomonas maltophilia
B. cepacia: Burkholderia cepacia

Table 2

Comparison of lung function tests results from children with cystic fibrosis (CF) and the healthy controls

	CF	Controls	CF‐controls
Patients n	43	28
FEV₁ % pred	89.1 (19.8)	96.9 (10.3)	−15.9–0.3^#
MEF₅₀ % pred^¶	92.3 (41.2)	107.0 (30.2)	−33.9–4.6
MEF₂₅ % pred^¶	64.5 (33.5)	86.5 (28.2)	−38.3–−5.7**
RV/TLC⁺	26.5 (10.6)	22.8 (4.3)	−0.7–8.1
MR	1.61 (0.49)	1.19 (0.08)	0.23–0.61***
LCI	8.33 (2.48)	6.33 (0.43)	1.06–2.95***

Data are presented as mean (SD) and 95% confidence interval for the difference between the groups unless otherwise stated
FEV₁: forced expiratory volume in one second
% pred: % predicted
MEF₅₀: maximum expiratory flow at 50% of forced vital capacity
MEF₂₅: maximum expiratory flow at 25% of forced vital capacity
RV: residual volume
TLC: total lung capacity
MR: mixing ratio
LCI: lung clearance index
^#: p=0.06
^¶: MEF₅₀ and MEF₂₅ results were available for analyses in 34 CF patients and 26 controls
⁺: RV/TLC results were available for analyses in 35 CF patients and 27 controls
**: p<0.01
***: p<0.001

Table 3

Comparison of age and lung function tests results in the cystic fibrosis (CF) patients with or without chronic bacterial colonisation

	Colonised		Yes-no
	Yes	No	Yes-no
Patients n	14	29
Age yrs	13.7 (2.8)	9.3 (3.9)	2.0–6.7***
FEV₁ % pred	74.7 (22.8)	96.1 (13.9)	−32.3–−10.1***
MEF₅₀ % pred^#	67.1 (36.0)	110.0 (36.0)	−68.3–−17.6**
MEF₂₅ % pred^#	43.7 (30.9)	79.1 (27.5)	−55.9–−14.9**
RV/TLC %^¶	33.0 (14.4)	22.7 (5.4)	3.4–17.1**
MR	1.91 (0.69)	1.47 (0.28)	0.14–0.74**
LCI	9.85 (3.49)	7.60 (1.37)	0.76–3.74**

Data are presented as mean (sd) and 95% confidence interval for thedifference between the groups unless otherwise stated
FEV₁: forced expiratory volume in one second
% pred: % predicted
MEF₅₀: maximum expiratory flow at 50% of forced vital capacity
MEF₂₅: maximum expiratory flow at 25% of forced vital capacity
RV: residual volume
TLC: total lung capacity
MR: mixing ratio
LCI: lung clearance index
^#: MEF₅₀ and MEF₂₅ results were available for analyses in 20 noncolonised patients
^¶: RV/TLC results were available for analyses in 22 noncolonised patients and 13 colonised
**: p<0.01
***: p<0.001

Table 4

Comparison of age and lung function in the children with cystic fibrosis (CF) who did not show chronic colonisation and the healthy control children

	CF (noncolonised)	Controls	CF‐controls
Patients n	29	28
Age yrs	9.3 (3.9)	11.5 (3.2)	−4.0–−0.2*
FEV₁ % pred	96.1 (13.9)	96.9 (10.3)	−7.3–5.7
MEF₅₀ % pred^#	110.0 (36.0)	107.0 (30.2)	16.5–22.6
MEF₂₅ % pred^#	79.1 (27.5)	86.5 (28.2)	−24.1–9.3
RV/TLC^¶	22.7 (5.4)	22.8 (4.3)	−2.9–2.7
MR	1.47 (0.28)	1.19 (0.08)	0.17–0.39***
LCI	7.6 (1.37)	6.33 (0.43)	0.73–1.81***

Data are presented as mean (sd) and 95% confidence interval for the difference between the groups unless otherwise stated
FEV₁: forced expiratory volume in one second
% pred: % predicted
MEF₅₀: maximum expiratory flow at 50% of forced vital capacity
MEF₂₅: maximum expiratory flow at 25% of forced vital capacity
RV: residual volume
TLC: total lung capacity
MR: mixing ratio
LCI: lung clearance index
^#: MEF₅₀ and MEF₂₅ results were available for analyses in 20 CF patients and 26 control subjects
^¶: RV/TLC results were available for analyses in 22 CF patients and 27 control subjects
*: p<0.05
***: p<0.001

Table 5

Number of subjects with abnormal (+) or normal (−) mixing ratios (MR) and lung clearance index (LCI) findings in relation to spirometry and plethysmography results

	CF				Controls
	MR		LCI		MR		LCI
	+	−	+	−	+	−	+	−
FEV₁
+	9	1	9	1	0	0	0	0
−	22	11	18	15	0	28	0	28
MEF₅₀
+	10	1	10	1	0	2	0	2
−	12	11	9	14	0	24	0	24
MEF₂₅
+	12	2	12	2	0	4	0	4
−	10	10	7	13	0	22	0	22
RV/TLC
+	11	0	11	0	0	3	0	3
−	12	12	9	15	0	24	0	24
LCI
+	27	0			0	0
−	4	12			0	28

FEV₁: forced expiratory volume in one second
MEF₅₀: maximum expiratory flow at 50% of forced vital capacity
MEF₂₅: maximum expiratory flow at 25% of forced vital capacity
RV: residual volume
TLC: total lung capacity