We develop optimal respiratory airflow patterns using a nonlinear multicompartment model for a lung mechanics system. Specifically, we use classical calculus of variations minimization techniques to derive an optimal airflow pattern for inspiratory and expiratory breathing cycles. The physiological interpretation of the optimality criteria used involves the minimization of work of breathing and...

OBJECTIVES To assess the Pre-bronchodilator criteria and the Post-bronchodilator criteria of FEV1/FVC ratio in diagnosing Airflow obstruction. METHODS An observational study was conducted from 1988 to 2006 at the Aga Khan University Hospital Patients referred to the pulmonary function test laboratory for spirometry with bronchodilator reversibility at the hospital during the above said period...

This paper considers factors that play a significant role in determining inspiratory pressure and energy losses in the human trachea. Previous characterisations of pathological geometry changes have focussed on relating airway constriction and subsequent pressure loss, however many pathologies that affect the trachea cause deviation, increased curvature, constriction or a combination of these. ...

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed p...

Asthma is a chronic respiratory disease characterised by fluctuating respiratory symptoms and reversible airflow obstruction.1,2 Confirmation of the diagnosis hinges on demonstrating airflow obstruction varying over time. Patients with undiagnosed asthma who consult repeatedly with symptoms ranging in severity3 may demonstrate perfectly normal spirometry. As there is no single ‘gold standard’ t...

A uniform pollutant concentration in indoor environments can be an inappropriate representation of breathing concentration. This is especially true when local airflow in the vicinity of an occupant is dominant in transporting pollutants. The present study investigates the airflow in the vicinity of a human body, effects of respiration on breathing concentration of particulate and gaseous pollut...

Airflow-induced bronchoconstriction (AIB) in mammals can be broadly categorized as either vagal-dependent or vagal-independent. Among mammals, rabbits and cats belong to the former and guinea-pigs belong to the latter categories. Although insufficient data are available to classify monkeys, dogs and man appear to occupy the middle ground in which a small but significant parasympathetic componen...

The potential that forced-air warming systems may increase the risk of surgical site infections (SSIs) by acting as a vector or causing unwanted airflow disturbances is a concern to health care providers. To investigate this potential, we examined the literature to determine whether forced-air warming devices increase the risk of SSIs in patients undergoing general, vascular, or orthopedic surg...

BACKGROUND Previous research suggests that obesity is an important risk factor for asthma. However, since obesity can cause dyspnea through mechanisms other than airflow obstruction, diagnostic misclassification of asthma could partially account for this association. OBJECTIVE To determine whether there is a relationship between obesity and airflow obstruction. METHODS A total of 16 171 par...

BACKGROUND Early detection of airflow obstruction is particularly important among young adults because they are more likely to benefit from intervention. Using the forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) (FEV(1)/FVC) <70% fixed ratio, airflow obstruction may be underdiagnosed. The lower limit of normal (LLN), which is statistically defined by the lower fifth perc...