F Fo or rc ce ed d o os sc ci il ll la at ti io on n t te ec ch hn ni iq qu ue e ( (F FO OT T) ):: a a n ne ew w t to oo ol l f fo or r e ep pi id de em mi io ol lo og gy y o of f o oc cc cu up pa at ti io on na al l l lu un ng g d di is se ea as se es s? ? The first control group, was made up of face-workers having normal chest radiographs, whilst the second comprised underground non-face-workers with normal chest radiographs. Spirometric, plethysmographic and transfer factor of the lungs for carbon monoxide single-breath (TL,CO,sb) indices revealed no significant differences between the three groups. As regards the forced oscillation technique, a higher value of resistance/frequency slope (Pa·L -1 ·s 2 ) was found in the G group compared with the control groups; 2.11 vs 1.06 in the face-workers, and 1.58 in the underground workers. In all three groups, the forced oscillation technique indices (mean resistance (R), resistance at zero frequency (R0), resistance/frequency slope (S), and resonant frequency (f0)) were found to be higher in subjects having a decreased forced expiratory volume in one second (FEV1) (≤90% predicted) or a mildly obstructive pattern of ventilatory function, even though this did not reach statistical significance in each of the groups.These findings together with the feasibility and acceptability of the forced oscillation technique would suggest that it may be a suitable tool for epidemiological studies of occupational respiratory diseases. Eur Respir J., 1995Respir J., , 8, 1307Respir J., -1313 Lung function tests provide objective evidence of respiratory disability, particularly that due to occupational exposure. Spirometry is the most frequently used technique but requires a high degree of collaboration on the part of the subject. Furthermore, forced inspiratory and expiratory manoeuvres may change bronchial tone and modify airway patency. Currently, body plethysmography is used less often in respiratory epidemiology. It measures intrathoracic gas volume and airway resistance. Again these measurements require a high degree of understanding and co-operation on the part of the subject.As a result of on-line digital processing [1-5], respiratory impedance measurements by the forced oscillation technique (FOT), have been used increasingly in recent years [6][7][8][9][10]. This technique was first proposed by DUBOIS et al. [11] in 1956, and is based on the relationship between the sinusoidal pressure variations applied to the respiratory system via the mouth [7], by means of an external generator, and the induced flow oscillations. It assesses resistive, elastic and inertial properties of the respiratory system. Data collection takes place over a few respiratory cycles of quiet breathing, enabling serial measurements to be carried out, and requiring minimum co-operation on the part of the subject. Furthermore, the simplicity of the apparatus makes the FOT a potentially useful technique for epidemiological studies.This study compares FOT and conventional lung function tests (spirometry, p...

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...

Comparative manual and computer measurements of the alveolar N2 slope and closing volumes have indicated systematic differences. When a computerized system is used in field surveys, predicted values are to be obtained under the same conditions. Therefore, we measured the alveolar nitrogen slope (phase III, HID, closing volume (CV), and closing capacity (CC) from single-breath N 2 washout maneuvers in 158 healthy subjects (68 females), ages 21 to 64 years, from a rural community living in a nonpolluted area of northeast France. PIII, the CV to vital capacity ratio (CV:VC, %), and the CC to the total lung capacity ratio (CC:TLC, %) were regressed against age, height, weight, and the body mass index (BMI, kg/m 2) and prediction equations with 95% confidence intervals were computed. PIII increased with age in both sexes and tended to decrease with height in males (r = -0.19, p = .08). The CV:VC and CC:TLC ratios depended on age and, in males, increased with the BMI. Despite accepting a 15% difference between the test VC and the spirometric VC, only 46.3% of asymptomatic nonsmokers produced a valid single-breath nitrogen washout (SBN2) test. This high failure rate limits the usefulness of the test for epidemiologic purposes when older populations "naive" to pulmonary function testing are studied under field-survey conditions.

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