Comparative Impulse Oscillometry Parameters Among Childhood Asthma, Obesity With and Without Asthma

Thitaya Sangsawang M.D., Tassalapa Daengsuwan M.D.

Division of Allergy and Immunology, Department of Pediatrics, Queen Sirikit National Institute of Child Health, Bangkok, Thailand

NO. 376

Deterioration of lung function is recognized in both asthma and obesity

and required monitoring. Impulse oscillometry (IOS), a non-invasive

measurement of lung function, is increasing popularity to measure both

small and large airway resistance in children. The aim of this study is to

compare the IOS parameters among Thai childhood asthma and obese

children with and without asthma.

A cross-sectional study was conducted in 120 participants, aged 4-15 years

old. Forty children were in each group (asthma, obesity and obesity with

asthma). All participants were consented to measure airway resistance by

IOS technique (Jaeger, Germany).

BACKGROUND

METHODS

RESULTS

Asthma (N=40)

Obesity (N=40)

Asthma + Obesity(N=40)

p-valueANOVA

Age (year) 9.01 ± 2.59 9.03 ± 2.5 8.48 ± 2.78 0.566

Sex: male (n) 24 (60%) 34 (85%) 30 (75%) 0.039*

BW (kg) 28.91 ± 9.2 62.67 ± 21.13 48.35 ± 18.17 <0.001*

Height (cm) 133.82 ± 14.6 141.36 ± 15.69 136.78 ± 16.58 0.099

BMI (kg/m2) 15.79 ± 2.14 29.89 ± 5.9 24.68 ± 3.37 <0.001*

%W/H 98.69 ± 10.9 183.01 ± 29.34 154.55 ± 14.79 <0.001*

Duration of ICS (mo) 14 (0, 36) N/A 18 (3, 42.5) 0.426

Duration of

asthma control (mo)0 (0, 2) N/A 2 (0, 4.5) 0.006*

Asthma severity 3.25 ± 0.63 N/A 2.98 ± 0.8 0.092

Table 1 Clinical characteristics of participants

Asthma ObesityAsthma + Obesity

Asthma VS ObesityAsthma VS

Asthma + ObesityObesity VS

Asthma + Obesity

Mean

difference

(95%CI)

p-value

Mean

difference

(95%CI)

p-value

Mean

difference

(95%CI)

p-value

R5 0.81 ± 0.24 0.93 ± 0.32 0.92 ± 0.24-0.12

(-0.27, 0.02)0.137

-0.11

(-0.25, 0.04)0.214

0.01

(-0.13, 0.16)1

X5 -0.23 ± 0.09 -0.13 ± 0.08 -0.19 ± 0.11-0.11

(-0.16, -0.06)<0.001*

-0.05

(-0.1, 0)0.083

0.06

(0.01, 0.11)0.013*

Fres 23.06 ± 4.62 23.86 ± 6.38 23.58 ± 4.2-0.81

(-3.61, 1.99)1

-0.52

(-3.32, 2.28)1

0.28

(-2.52, 3.08)1

AX 2.66 ± 1.74 2.76 ± 1.99 2.99 ± 1.42-0.1

(-1.04, 0.84)1

-0.33

(-1.27, 0.61)1

-0.23

(-1.17, 0.71)1

Z5 0.85 ± 0.24 0.95 ± 0.32 0.95 ± 0.24-0.1

(-0.24, 0.05)0.323

-0.1

(-0.24, 0.05)0.337

0

(-0.14, 0.15)1

R20 0.5 ± 0.13 0.58 ± 0.16 0.53 ± 0.14-0.08

(-0.16, 0)0.058

-0.03

(-0.11, 0.05)1

0.05

(-0.03, 0.13)0.372

X20 -0.05 ± 0.08 -0.04 ± 0.14 -0.06 ± 0.06-0.01

(-0.06, 0.05)1

0.01

(-0.05, 0.06)1

0.02

(-0.04, 0.07)1

R5-R20 0.31 ± 0.17 0.35 ± 0.2 0.39 ± 0.17-0.04

(-0.14, 0.06)0.895

-0.08

(-0.18, 0.02)0.146

-0.04

(-0.14, 0.06)1

X5 are potentially useful to

differentiate small airway

dysfunction in asthma from

obesity.

The percentage changes in

resonant frequency, area of

reactance, R5-R20 post

bronchodilator found significant

higher in asthma than obese with

asthma.

Table 2 Baseline IOS parameters of 3 group participants (kPa/L/s)

Bronchodilatorresponse

Asthma Asthma + Obesity

Mean difference

(95%CI)p-value

Adjusted mean difference (95%CI)

p-value

% Change R5 -22.1 ± 10.27 -17.9 ± 10.11 -4.2 (-8.74, 0.34) 0.069 -3.38 (-8.06, 1.3) 0.155

% Change X5 -34.75 ± 28 -22.15 ± 84.42 -12.6 (-40.6, 15.4) 0.373 -7.03 (-35.85, 21.8) 0.629

% Change Fres -24.57 ± 15.82 -13.77 ± 16.42 -10.8 (-17.98, -3.62) 0.004* -9.32 (-16.71, -1.94) 0.014*

% Change AX -58.28 ± 13.37 -43.35 ± 21.4 -14.93 (-22.87, -6.98) <0.001* -11.39 (-19.11, -3.68) 0.004*

% Change R5-R20 -51.32 ± 20.13 -34.72 ± 18.21 -16.6 (-25.15, -8.06) <0.001* -13.64 (-22.18, -5.09) 0.002*

Table 3 Bronchodilator response of IOS parameters in asthma and asthma with obesity

CONCLUSIONS

The cut-off value of X5 for

predicting asthma in obese

patients was -0.16 kPa/L/s which

demonstrated the best 70%

sensitivity and 70% specificity

with 70% accuracy (AUC 0.69).