Exercise-Induced Airway Characteristics of Young Asthmatics Measured by Impulse Oscillometry.

Abstract

Background: Impulse oscillometry (IOS); one of the forced oscillation techniques that is a good method for measuring airway resistance without any special breathing skill. This method might reflect different aspects of airway obstruction compared to conventional spirometry. Object: To evaluate airway characteristics of young asthmatics after exercise bronchial provocation test (EBT) using IOS technique Methods: 47 young adults who were recruited to the Korean military service were enrolled. All of them underwent methacholine bronchial provocation test (MBPT) and EBT (10 minutes of treadmill exercise) for their asthma status evaluation. The IOS and spirometry parameters were collected at baseline, immediate-post EBT, 5 min, 10 min, 20 min and 30 min after EBT. Subjects were divided into two groups according to MBPT results (PC20 > 25.0 mg/mL for airway hyperresponsiveness (AHR) absent group (n=12) and PC20 < 12.0 mg/mL for AHR present group (n=35)). Results: There were differences of FEV1 percent falls between two groups at 5 min (+0.12% vs-9.96%, p<0.001), 10 min (+1.28% vs-7.45%, p=0.002) and 20 min (+1.01% vs-3.41%, p=0.011) after exercise. Resistance at 5 Hz (R5); one of the IOS parameter, was higher in the AHR present group than AHR negative group at 5 min (0.018 kPa/L/sec vs 0.071 kPa/L/sec, p=0.027) and 10 min (-0.007 kPa/L/sec vs 0.055 kPa/L/sec, p=0.001) after exercise. Airway reactance (AX); integration of reactance (X) from 5 Hz to resonance frequency was also increased in AHR present group at 5 min (0.091 kPa/L vs 0.431 kPa/L, p=0.010) and 10 min (0.007 kPa/L vs 0.298 kPa/L, p=0.032) after exercise. Frequency dependency of airway resistance (R5-R20) and Resistance at 10 Hz (R10) values were increased too. Low-frequency reactance at 5 Hz (X5) was more decreased in AHR present group than absent The FEV1 percent fall was well-correlated with the changes of R5 at 5 min (r=-0.314, p=0.032), R5 at 10 min (r=-0.367, p=0.011), AX at 5 min (r=-0.545, p<0.001) and AX at 10 min (r=-0.441, p=0.002) after exercise. Conclusions: These results suggested that IOS parameters especially R5 and AX can be useful for understanding of exercise induced airway characteristics of young asthmatics.

Small-airways dysfunction associates with respiratory symptoms and clinical features of asthma: A systematic review

“…This systematic review demonstrates that small-airways dysfunction is associated with clinical features of asthma: worse control of asthma, 15,16,20,21 higher numbers of exacerbations, 21,27,33 nocturnal asthma, 40,41,44 more severe BHR, 55,56,59,60 exercise-induced asthma, 61,64,[67][68][69][70][71] and the late-phase allergic response (Table II). * It is important to mention that the data for this review are limited because most of the studies are small and not primarily designed to answer our research question.…”

“…Interestingly, a few studies have shown that small-airways dysfunction is not only a feature of severe asthma but can also be present in patients with mild asthma who have a low level of symptoms and FEV 1 values in the normal range. 15,47,55,61,68 This indicates that the possibility of small-airways dysfunction should be considered in the complete spectrum of asthma severity. The latter might be of clinical importance because a better small-airways response to treatment with extrafine-particle ICSs or montelukast is accompanied by better asthma control.…”

“…In line with this, Lee et al 68 observed that more severe exercise-induced bronchoconstriction is associated with a higher increase in peripheral airways resistance (R5-R20) but not with an increase in large-airways resistance (R20, Fig 5). 68 Two studies investigated the phase III slope of the single-breath helium and sulfur hexafluoride washout test before and after a cold, dry air hyperventilation test. 69,70 Both studies demonstrated that an increase in the helium and sulfur hexafluoride phase III slopes were associated with the decrease in FEV 1 .…”

“…Immediately after allergen challenge, FEF 50% increased, suggesting involvement of R5-R20, reflecting resistance of the small airways, is correlated with FEV 1 (r 5 20.375, P 5 .009), whereas R20, reflecting resistance of the large airways, did not correlate with FEV 1 (r 5 20.104, P 5 .487). Adapted with permission from Lee et al 68 mainly the large airways. Of interest, FEF 50% gradually decreased 6 and 24 hours after the allergen challenge, suggesting that the small airways contribute importantly to the late-phase asthmatic response.…”

Advances in the diagnosis of exercise-induced bronchoconstriction

“…elderly or paediatric populations). Therefore, IOS is advantageous in that results cannot be manipulated by the patient [86], nor does it induce respiratory fatigue [87]. In addition, IOS has previously been identified to correlate with both FEV1 [88,89] and airway resistance [90,91] as determined by spirometry and body plethysmography respectively.…”