Impulse oscillometry in patients with pulmonary arterial hypertension: an exploratory study

Bôas, Helena Jannuzzi Villas; Paschoal, Ilma Aparecida; Pereira, Mônica Corso

doi:10.1016/j.clinsp.2023.100313

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Sumário

Original articles • Clinics 79 • 2024 • https://doi.org/10.1016/j.clinsp.2023.100313 copy

Impulse oscillometry in patients with pulmonary arterial hypertension: an exploratory study

Authorship SCIMAGO INSTITUTIONS RANKINGS

Highlights

Impulse Oscillometry (IOS) can be used to analyze lung resistance and reactance in patients with PAH.

Patients with PAH show increased resistance and pulmonary reactance compared to healthy individuals.

The IOS findings showed a good correlation with the spirometric variables.

Abstract

Introduction

Studies suggest peripheral airway abnormalities in Pulmonary Arterial Hypertension (PAH). Impulse Oscillometry (IOS) is a noninvasive and sensitive technique for assessing the small airways. It evaluates the impedance of the respiratory system ‒ Resistance (R) and reactance (X) ‒ to a pulse of sound waves sent to the lungs, in a range of frequencies (5‒20 Hz).

Method

Resistance variables: R5, R20, R5-R20 and reactance variables: AX (reactance area) and Fres (resonance frequency). The aim is to evaluate R and X in patients with idiopathic PAH (IPAH) and to investigate whether there is a correlation between IOS and spirometry.

Results

Thirteen IPAH patients and 11 healthy subjects matched for sex and age underwent IOS and spirometry. IPAH patients had lower FVC and FEV₁ values (p < 0.001), VEF₁/CVF (p = 0.049) and FEF 25-75 (p = 0.006) than healthy patients. At IOS, IPAH patients showed lower tidal volumes and higher AX (p < 0.05) compared to healthy individuals, and 53.8 of patients had R5-R20 values ≥ 0.07 kPa/L/s. Correlation analysis: X5, AX, R5-R20 and Fres showed moderate correlation with FVC (p = 0.036 r = 0.585, p = 0.001 r = -0.687, p = 0.005 r = -0.726 and p = 0.027 r = -0.610); Fres (p = 0.012 r = -0.669) and AX (p = 0.006 r = -0.711) correlated with FEV₁; [R5 and R20, (R5-R20)] also correlated with FEV₁ (p < 0.001 r = -0.573, p = 0.020 r = -0.634 and p = 0.010 r = -0.683, respectively) in the IPAH group. There were also moderate correlations of FEF 25-75 % with Z5 (p = 0.041), R5 (p = 0.018), Fres (p = 0.043) and AX (p = 0.023).

Discussion

Patients showed changes suggestive of increased resistance and reactance in the IOS compared to healthy individuals, and the IOS findings showed a good correlation with spirometry variables.

Keywords
Pulmonary arterial hypertension; Pulmonary hypertension; Impulse oscillometry; Spirometry; Lung function

	IPAHG (n = 13)	CG (n = 11)	p-value
Female sex	12 (92.3)	9 (81.8)	0.576^c
Age years	44.85 ± 12.82	37.91 ± 14.18	0.223^a
Body mass index, kg/m²	25.11 ± 5.59	23.38 ± 3.23	0.602^a
Functional class (I/II/III)	I - 3 (23.1)
	II - 7 (53.8)	‒	‒
	III - 3 (23.1)
Systemic arterial hypertension	1 (7.6)	1 (9)	‒
Sedentary lifestyle	6 (46.2)	6 (54.5)	0.682^b
Vital signs
Systolic blood pressure	102.31 ± 12.35	108.18 ± 11.68	0.151^a
Diastolic blood pressure	66.92 ± 7.51	71.82 ± 13.28	0.439^a
Heart rate	74.46 ± 14.09	67.09 ± 10.67	0.385^a
Respiratory frequency	18.62 ± 3.80	16.18 ± 2.99	0.064^a
Peripheral oxygen saturation	95.31 ± 2.21	96.91 ± 1.14	0.060^a

		IPAHG (n = 13)	CG (n = 11)	p-value
IOS	TV (L)	0.61 ± 0.27	1.07 ± 0.38	0.002
	Z5 [kPa/(L/s)]	0.43 ± 0.14	0.38 ± 0.09	0.417
	R5 [kPa/(L/s)]	0.40 ± 0.12	0.36 ± 0.09	0.542
	R20 [kPa/(L/s)]	0.32 ± 0.08	0.33 ± 0.08	0.816
	R5-R20[kPa/(L/s)]	0.08 ± 0.08	0.03 ± 0.02	0.063
	R5-R20 ≥0.07 kPa/(L/s)	7 (53.84)	0 (0)	‒
	X5 [kPa/(L/s)]	-0.16 ± 0.09	-0.12 ± 0.04	0.123
	Fres (L/s)	16.50 ± 7.14	11.67 ± 2.25	0.093
SPIROMETRY	AX (kPa/L)	0.97 ± 1.11	0.33 ± 0.16	0.034
	FVC (L)	3.01 ± 0.66	4.11 ± 0.69	0.001
	FVC%	86.65 ± 13.60	106.80 ± 8.12	0.001
	FEV₁ (L)	2.28 ± 0.61	3.35 ± 0.79	0.001
	FEV₁%	79.48 ± 15.06	104.55 ± 11.62	0
	FEF 25-75 %	61.69 ± 25.25	97.81 ± 27,20	0.006

Variables		IPAHG					CG
		FVC (L)	FVC (%)	FEV₁ (L)	FEV₁ (%)	FEF 25-75 (%)	FVC (L)	FVC (%)	FEV₁ (L)	FEV₁ (%)	FEF 25-75 (%)
TV (L)	ρ correlation	-0.080	-0.325	-0.419	-0.330	-0.515	0.232	-0.378	0.150	-0.173	0.027
TV (L)	p-value	0.796	0.279	0.154	0.271	0.072	0.492	0.252	0.659	0.611	0.936
Z5 (kPa/(L/s)	ρ correlation	-0.421	-0.534	-0.526	-0.752	-0.572	-0.400	-0.445	-0.382	-0.418	-0.273
Z5 (kPa/(L/s)	p-value	0.151	0.060	0.065	0.003	0.041	0.223	0.170	0.247	0.201	0.417
R5 (kPa/(L/s)	ρ correlation	-0.448	-0.558	-0.573	-0.818	-0.642	-0.402	-0.429	-0.384	-0.420	-0.296
R5 (kPa/(L/s)	p-value	0.125	0.048	0.041	0.001	0.018	0.221	0.188	0.244	0.198	0.375
R20 (kPa/(L/s)	ρ correlation	-0.110	-0.199	-0.241	-0.634	-0.438	-0.202	-0.312	-0.202	-0.257	-0.174
R20 (kPa/(L/s)	p-value	0.720	0.515	0.428	0.020	0.135	0.552	0.350	0.552	0.446	0.608
R5- R20 (kPa/(L/s)	ρ correlation	-0.726	-0.679	-0.683	-0.510	-0.517	-0.684	-0.244	-0.553	-0.384	-0.323
R5- R20 (kPa/(L/s)	p-value	0.005	0.011	0.010	0.075	0.071	0.020	0.470	0.078	0.243	0.332
X5 (kPa/(L/s)	ρ correlation	0.585	0.330	0.405	0.313	0.304	0.511	0.507	0.466	0.479	0.247
X5 (kPa/(L/s)	p-value	0.036	0.271	0.170	0.297	0.312	0.108	0.112	0.149	0.136	0.465
Fres (l/s)	ρ correlation	-0.610	-0.560	-0.669	-0.610	-0.567	-0.533	-0.178	-0.601	-0.569	-0.752
Fres (l/s)	p-value	0.027	0.046	0.012	0.027	0.043	0.091	0.601	0.050	0.067	0.008
AX (kPa/L)	ρ correlation	-0.687	-0.516	-0.711	-0.593	-0.622	-0.542	-0.351	-0.524	-0.547	-0.374
AX (kPa/L)	p-value	0.010	0.071	0.007	0.033	0.023	0.085	0.290	0.098	0.082	0.258

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[1] *Corresponding author. E-mail address:moncorso@unicamp.br (M.C. Pereira)