A medical information system for monitoring respiratory function and related nonlinear dynamics

In this paper the nonlinear effects in the respiratory systems at low frequencies are measured and evaluated in healthy children and healthy adults. To this aim forced oscillations technique (FOT) has been used to non-invasively measure the lung tissue mechanics. FOT does not require any special effort from the patient in contrast with standardized tests where maneuvers are necessary. Hence, FOT is an ideal lung function test for extreme ages, more specifically children and elderly, given the simpleness of measurement technique. Hitherto, measurements at low frequencies (i.e. close to the breathing frequency similar to 0.3 Hz) have been invasively performed in sacrificed animals and on anesthetized humans. Here we measure in the frequency interval 0.1-2 Hz a total number of 94 volunteers (37 adults with ages between 25-35 years and 57 children with ages between 8-11 years). To evaluate the nonlinear contributions of the respiratory tissue, a novel T-index has been introduced. We have tested the hypothesis whether the nonlinear distortions are changing with growth/development of the respiratory tree and aim to quantify its dependence to biometric values. The results obtained indicate that the proposed index can differentiate between the two analyzed groups and that there is a dependence to age, height and weight. A medical information system may use this information to update predictions of respiratory function and provide aid in decision-making process of drug therapy

Influence of the Ageing Process on the Resistive and Reactive Properties of the Respiratory System

INTRODUCTION: In an increasingly old society, the study of the respiratory system changes and new techniques dedicated to older patients are of interest in physiologic studies as well as in the diagnosis of respiratory diseases. OBJECTIVES: (1) To investigate the impact of ageing on the resistive and reactive properties of the respiratory system, and (2) to compare the easiness of accomplishment of spirometry and forced oscillation for assessing lung function. METHODS: We conducted a cross-sectional study in which forced oscillation was used to investigate respiratory system resistive and reactive properties, while spirometry was used as a reference test to evaluate 80 normal subjects aged between 20 and 86 years. A questionnaire was used to evaluate the easiness of accomplishment of spirometry and forced oscillation. RESULTS: There was a significant increase in the respiratory system resonance frequency (p<0.003) and a reduction in the mean reactance (p<0.004) with increasing age. Respiratory system resistance and dynamic compliance were not related to the ageing process. The easiness of accomplishment of forced oscillation measurements was greater than that of spirometry. This result was particularly relevant in subjects over 70 years old (p<0.05). CONCLUSIONS: Respiratory system resistance and dynamic compliance are not modified with ageing. On the other hand, respiratory system homogeneity decreases during the ageing process. Forced oscillation is easy to perform and provides information complementary to spirometry. This technique may be a promising alternative and/or complement to other conventional exams used to evaluate older people who are unable to adequately perform spirometric tests

Contrasting diagnosis performance of forced oscillation and spirometry in patients with rheumatoid arthritis and respiratory symptoms

OBJECTIVES: Pulmonary involvement in rheumatoid arthritis is directly responsible for 10% to 20% of all mortality. The best way to improve the prognosis is early detection and treatment. The forced oscillation technique is easy to perform and offers a detailed exam, which may be helpful in the early detection of respiratory changes. This study was undertaken to (1) evaluate the clinical potential of the forced oscillation technique in the detection of early respiratory alterations in rheumatoid arthritis patients with respiratory complaints and (2) to compare the sensitivity of forced oscillation technique and spirometric parameters. METHODS: A total of 40 individuals were analyzed: 20 healthy and 20 with rheumatoid arthritis (90% with respiratory complaints). The clinical usefulness of the parameters was evaluated by investigating the sensibility, the specificity and the area under the receiver operating characteristic curve. ClinicalTrials.gov: NCT01641705. RESULTS: The early adverse respiratory effects of rheumatoid arthritis were adequately detected by the forced oscillation technique parameters, and a high accuracy for clinical use was obtained (AUC.0.9, Se = 80%, Sp = 95%). The use of spirometric parameters did not obtain an appropriate accuracy for clinical use. The diagnostic performance of the forced oscillation technique parameters was significantly higher than that of spirometry. CONCLUSIONS: The results of the present study provide substantial evidence that the forced oscillation technique can contribute to the easy identification of initial respiratory abnormalities in rheumatoid arthritis patients that are not detectable by spirometric exams. Therefore, we believe that the forced oscillation technique can be used as a complementary exam that may help to improve the treatment of breathing disorders in rheumatoid arthritis patients

Mathematical Modeling and Analysis of Asthma Stability and Severity

Asthma is one of the most common chronic conditions in the United States. Asthma affects about one in fifteen people. It affects children more than adults and blacks more than whites. People with asthma experience attacks of wheezing, breathlessness, chest tightness, and coughing. Asthma can be fatal and the costs for the disease (direct and indirect) are approximated to be tens of billions of dollars each year. There is no cure for asthma. However; for most people if asthma is controlled well they can lead normal, active lives. Therefore asthma controllability is a main factor in clinical practice. In order to control asthma, the disease has to be completely understood. Asthma is very heterogeneous and this makes the exact diagnosis and control procedures difficult. To better evaluate and study asthma, mathematical tools can be very beneficial. In this study we first develop a complete system for lung impedance analysis of laboratory models of asthma. Our designed system is capable of precisely diagnosing the diseased models and predicting the severity of their condition. We also evaluate the treatment progress in mouse models of asthma. We then study an asthma database of humans including measurements of four related laboratory parameters and cluster patients based on inherent properties of the study variables. This mathematical approach clustered patients with specific characteristics and segregated the unstable asthmatic patients in a single group. Our method is very promising in predicting the instability of asthma, which is highly correlated with frequent asthma attacks and increased utilization of care

Aerospace medicine and biology: A continuing bibliography with indexes, supplement 128, May 1974

This special bibliography lists 282 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1974

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 401)

This bibliography lists 140 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during May 1995. Subject coverage includes: aerospace medicine, behavioral sciences, man/system technology and life support, and space biology

Simpler methods of assessing respiratory function and their application in infancy

The need to develop and evaluate simple non-invasive tests to measure respiratory function in wheezy infants, in order to investigate the physiological basis of lung disease and move towards a more rational basis for the treatment of airway disease in infancy was well recognised at the inception of this work. The main aims of this thesis were: to evaluate simpler methods of assessment of lung function such as the tidal breathing parameter tPTEF:tE, passive respiratory mechanics using the Single Breath technique and the rapid thoraco-abdominal compression technique (RTC) by comparison with established "gold standard" techniques, and: to address applications of such assessments, when comparing respiratory function in survivors of each limb of the Collaborative ECMO trial. tPTEF:tE and specific airway conductance were measured in healthy infants and those with recurrent wheezing and it was found that both parameters were significantly lower in the wheezy compared to the healthy group. There was a significant although weak association between these variables in infants, irrespective of prior wheezing status, which was also confirmed in the ECMO Respiratory Follow-up population. Although a variable relationship between respiratory and airway resistance was found, both were significantly higher in infants with prior wheeze. Measurements obtained using the Single Breath technique had a relatively high failure rate. Inter observer variability was compared within and between two specialised infant lung function testing centres and a strategy developed for performing and analysing infant respiratory function tests to facilitate future similar trials. A collaborative approach to trials with infant respiratory function as an outcome measure appears feasible, providing close attention is paid to study design. Airway function was compared in survivors of the Collaborative ECMO trial. Respiratory function outcomes in those managed conventionally suggested that the larger proportion of these infants receiving respiratory medication and reporting respiratory symptoms may be attributed to subtle impairment of small airway function, relative to those assigned to ECMO. These findings probably reflected differences in neonatal management, since initial disease severity and background characteristics were similar in both groups

Design, development, and characterization of breathforce : a respiratory training system for patients with spinal cord injuries.

Pulmonary and cardiovascular dysfunction are consistently reported as the leading causes of morbidity and mortality among the 1,275,000 people who are living with chronic spinal cord injury (SCI) in the United States. Respiratory-cardiovascular complications from neurological disorders (primarily COPD and sleep apnea) are currently the number one cause of death and disability in the US. The main goal of this project is to develop an inspiratory-expiratory training device for use in the rehabilitation of patients with respiratory motor and cardiovascular deficits that incorporates existing technologies and promotes successful training methodologies performed at the clinic and at home. An embedded microprocessor was to convert pressure from a physiological range pressure sensor into appropriate units and guide the user through a therapy session, while saving the data for later use by the clinician. Rechargeable batteries were used to allow for portability. A bi-directional breathing apparatus to accompany the microprocessor was developed using FDA approved, off-the-shelf parts. Two therapy modes were programmed into the microprocessor to 1) find max expiratory pressure (MEP) and max inspiratory pressure (MIP) of the user and 2) function as a spirometer to track and display user data during respiratory muscle training (RMT). A transducer tester was used to apply a calibrated pressure to the device to validate the measurement accuracy. Measured values differed from the tester by 1.91%-3.78%. No drift was noticed in the device when left running for an extended period of time and humidity, moisture, and temperature effects did not affect the accuracy of the sensor measurement. A SCI test subject showed an average pressure deviation from target values (10-18.51%) that were less than that of a healthy subject (~40%). The prototype device that was given the name BreathForce. Validation studies are underway for accuracy and effectiveness

The determination of respiratory impedance by the oscillatory airflow technique

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Biomedical Engineering

Biomedical engineering is currently relatively wide scientific area which has been constantly bringing innovations with an objective to support and improve all areas of medicine such as therapy, diagnostics and rehabilitation. It holds a strong position also in natural and biological sciences. In the terms of application, biomedical engineering is present at almost all technical universities where some of them are targeted for the research and development in this area. The presented book brings chosen outputs and results of research and development tasks, often supported by important world or European framework programs or grant agencies. The knowledge and findings from the area of biomaterials, bioelectronics, bioinformatics, biomedical devices and tools or computer support in the processes of diagnostics and therapy are defined in a way that they bring both basic information to a reader and also specific outputs with a possible further use in research and development