Mechanisms for isolated volume response to a bronchodilator in patients with COPD

We hypothesized that an altered effect of lung inflation on airway caliber may in part explain the isolated volume response to bronchodilators, i.e., an increase of forced vital capacity (FVC) without change in 1-s forced expiratory volume (FEV1). Small-airway caliber was measured by high-resolution computed tomography at functional residual capacity and total lung capacity in five chronic obstructive pulmonary disease patients with an isolated increase of FVC (FVC responders) and five with an increase of both FVC and FEV1 (FVC-FEV1 responders) after inhalation of salbutamol. In FVC-FEV1 responders, the airway diameter increased with the cube root of increase in lung volume but was unchanged or even decreased in four of five FVC responders. FVC responders had more severe emphysema, as inferred from lung function and imaging studies, than FVC-FEV1 responders. We speculate that longitudinal traction or space competition (Verbeken EK, Cauberghs M, and Van de Woestijne KP, J Appl Physiol 81: 2468–2480, 1996) are possible underlying mechanisms. We conclude that the isolated volume response to bronchodilators is associated with severe emphysema and likely results from an altered effect of lung inflation on airway caliber

Acquiring symptoms in response to odors: a learning perspective on multiple chemical sensitivity

In this chapter, a learning account is discussed as a potential explanation for the symptoms in multiple chemical sensitivity. Clinical evidence is scarce and anecdotal. A laboratory model provides more convincing results. After a few breathing trials containing CO2-enriched air as an unconditioned stimulus in a compound with harmless odor substances as conditioned stimuli, subjective symptoms are elicited and respiratory behavior is altered by the odors only. Also, mental images can become conditioned stimuli to trigger subjective symptoms. The learning effects cannot be explained by a response bias or by conditioned arousal, and they appear to involve basic associative processes that do not overlap with aware cognition of the relationship between the odors and the CO2 inhalation. Learned symptoms generalize to new odors and they can be eliminated in a Pavlovian extinction procedure. In accordance with clinical findings, neurotic subjects and psychiatric cases are more vulnerable to learning subjective symptoms in response to odors. Consistent with a learning account, cognitive-behavioral treatment techniques appear to produce beneficial results in clinical cases. Several criticisms and unresolved questions regarding the potential role of learning mechanisms are discussed.status: publishe

Guidelines for mechanical lung function measurements in psychophysiology

Studies in psychophysiology and behavioral medicine have uncovered associations among psychological processes, behavior, and lung function. However, methodological issues specific to the measurement of mechanical lung function have rarely been discussed. This report presents an overview of the physiology, techniques, and experimental methods of mechanical lung function measurements relevant to this research context. Techniques to measure lung volumes, airflow, airway resistance, respiratory resistance, and airflow perception are introduced and discussed. Confounding factors such as ventilation, medication, environmental factors, physical activity, and instructional and experimenter effects are outlined, and issues specific to children and clinical groups are discussed. Recommendations are presented to increase the degree of standardization in the research application and publication of mechanical lung function measurements in psychophysiology

The rate of respiratory symptoms among primary school children in two Dutch regions

A cross-sectional study was conducted to evaluate possible interregional differences in respiratory health in primary school children living in two different towns of the Netherlands, Melick/Herkenbosch Asenray (MHA) (n = 511) and Leek (LK) (n = 612). The prevalence of respiratory symptoms was determined by means of a questionnaire and respiratory impedance was measures using the forced oscillation technique (FOT). Respiratory symptoms were reported consistently more often in MHA than in LK; chronic cough (17% MHA vs 5% LK), shortness of breath (15% vs 8%), wheeze (16% vs 13%) and attacks of shortness of breath with wheeze (10% vs 7%). However, doctor-diagnosed asthma was reported as 7% in MHA and 6% in LK. The prevalence rates expressed as odds ratios of MHA versus LK were all > 1 even when adjusted for known indoor environmental factors. Living in MHA appeared to be a statistically significant determinant of the reported symptom prevalence. Furthermore, the child's age, maternal smoking (> 10 cigarettes/day), and having had domestic animals were positively associated with one or more respiratory symptoms. Calculating adjusted differences in respiratory impedance between the regions resulted in a small but statistically significant difference in resonant frequency, LK being slightly at a disadvantage. Measured outdoor air pollution levels of SO2, NO2, O3 and PM10 were in general higher in MHA. In both regions however, the average levels remained below the present WHO guidelines, except for NO2 in MHA where the guideline was slightly exceeded. CONCLUSION: In this study prevalence rates of key symptoms of asthma were found to be significantly higher in children living in one region of the Netherlands (MHA) compared to another (LK). Known (indoor) risk factors for respiratory disease could not explain the observed differences in symptom prevalence between the regions. However, statistically but not clinically significant interregional differences in respiratory impedance values were found between children living in MHA and children living in LK. Further research will have to incorporate techniques to evaluate the potential influence of information bias