Dose-response slope of forced oscillation and forced expiratory parameters in bronchial challenge testing

Abstract

In population studies, the provocative dose (PD) of bronchoconstrictor causing a significant decrement in lung function cannot be calculated for most subjects. Dose±response curves for carbachol were examined to determine whether this relationship can be summarized by means of a continuous index likely to be calculable for all subjects, namely the two-point dose response slope (DRS) of mean resistance (Rm) and resistance at 10 Hz (R10) measured by the forced oscillation technique (FOT).Five doses of carbachol (320 mg each) were inhaled by 71 patients referred for investigation of asthma (n=16), chronic cough (n=15), nasal polyposis (n=8), chronic rhinitis (n=8), dyspnoea (n=8), urticaria (n=5), post-anaphylactic shock (n=4) and miscellaneous conditions (n=7). FOT resistance and forced expiratory volume in one second (FEV1) were measured in close succession. The PD of carbachol leading to a fall in FEV1 $20% (PD20) or a rise in Rm or R10 $47% (PD47,Rm and PD47,R10) were calculated by interpolation. DRS for FEV1 (DRSFEV1), Rm (DRSRm) and R10 (DRSR10) were obtained as the percentage change at last dose divided by the total dose of carbachol. The sensitivity (Se) and specificity (Sp) of DRSRm, DRS10 D%Rm and D%R10 in detecting spirometric bronchial hyperresponsiveness (BHR, fall in FEV1 $20%) were assessed by receiver operating characteristic (ROC) curves.There were 23 (32%) "spirometric" reactors. PD20 correlated strongly with DRSFEV1 (r=-0.962; p=0.0001); PD47,Rm correlated significantly with DRSRm (r= -0.648; p=0.0001) and PD47,R10 with DRSR10 (r=-0.552; p=0.0001). DRSFEV1 correlated significantly with both DRSRm (r=0.700; p=0.0001) and DRSR10 (r=0.784; p=0.0001). The Se and Sp of the various FOT indices to correctly detect spirometric BHR were as follows: DRSRm: Se=91.3%, Sp=81.2%; DRSR10: Se=91.3%, Sp=95.8%; D%Rm: Se= 86.9%, Sp=52.1%; and D%R10: Se=91.3%, Sp=58.3%.Dose±response slopes of indices of forced oscillation technique resistance, especially the dose±response slope of resistance at 10Hz are proposed as simple quantitative indices of bronchial responsiveness which can be calculated for all subjects and that may be useful in occupational epidemiology. Eur Respir J 1999; 13: 295±300. Bronchial challenge tests with nonspecific stimuli are extensively used to assess bronchial responsiveness in the chest clinic [1] as well as in population [2] and occupational samples [3]. Usually, changes in airway calibre are evaluated by means of a pulmonary function test, the most widely used of which is the forced expiratory volume in one second (FEV1). However, FEV1 has two disadvantages: firstly, it requires full subject co-operation and, secondly, the deep respiratory manoeuvres required can cause changes in airway smooth muscle tone likely to influence the result of the test [4]. Airway resistance (Raw) measured by body plethysmography is sensitive and does not require forced expiratory manoeuvres but the equipment is cumbersome, expensive, and relatively complex to operate. Finally, impedance of the respir...

The forced oscillation technique in clinical practice: methodology, recommendations and future developments

“…When a 65% increase in Rrs0 was used to classify the subjects according to the presence or absence of a 20% fall in FEV1, FOT reached a sensitivity of 75% and a specificity of 76%. Using a simplified FOT index, the two-point dose response slope of the change in Rrs10, BOHADANA et al [82] established a sensitivity of 91% and a specificity of 96% in the accurate detection of "spirometric" BHR in various patients referred for BHR testing. This suggests that this simple index can be used for BHR testing in occupational epidemiology.…”

“…For both agents, PC40Rrs8 was about three times lower than PC20FEV1. Using the same argument on the average within-subject CV, BOHADANA et al [82] compared PD47Rrs10 (and PD47Rrsmean) to PD20FEV1 in assessing BHR to carbachol challenge. However, by using this cut-off value, far more patients were classified as positive responders than based on FEV1 (for Rrsmean and Rrs10, 58 and 52 positive responders of the 71 tested patients, respectively, compared to the 23 positive responders for FEV1).…”

Normal values for respiratory resistance using forced oscillation in subjects >65 years old

“…FOT has been studied in infants, children, children with asthma or chronic nocturnal cough, intubated patients [28], patients with restrictive disorders or COPD [29] and in obstructive sleep apnoea patients [30]. Highly significant correlations between results of spirometry and FOT have been reported in previous studies [3,5,31].…”

Impulse Oscillometry for Leukotriene D4Inhalation Challenge in Asthma

“…Bohadana et al 16 reported a lower cumulative dose of carbachol and higher positive rate when using a 47% increase in mean resistance when the dose-response curve was employed. By using the average reaction in IOS parameters and linear regression model, Wang et al 25 reported that an 80% increase in resonance frequency, 50% increase in Z 5 or R 5 , or 100% increase in X 5 could be regarded as significant.…”

“…[6][7][8][9][10][11][12][13][14][15] Although spirometry has been the recommended method for assessing bronchial provocation, repetitive forced inhalation might result in bronchodilation, leading to false negative results. Impulse oscillometry (IOS), a novel lung function testing method characterized by shorter test duration, 16,17 minimal requirements to subjects, and low likelihood of bronchodilation, does not influence airway smooth muscle tone. Theoretically, IOS parameters correlate negatively with airway caliber, as evidenced by the fact that bronchospasm significantly increases airway impedance, resistance, and resonance frequency, and reduces airway capacitance, 18 which suggests that IOS may be a surrogate for spirometry.…”