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Biomedical subjects

L J Toop

Publications and source records attributed to L J Toop.

8 recordsLinked to original sources
PubMed1992

Towards a quantitative description of asthmatic cough sounds.

This study describes a method of quantitatively characterizing cough sounds using digital signal processing techniques. Differences between asthmatic and non-asthmatic cough sounds are presented. Coughs from 12 asthmatic and 5 non-asthmatic subjects were analysed. Cough sounds and flows were digitized, at a sampling rate of 5 kHz, before and after a free-running exercise test. Individual coughs were divided into two or three phases, corresponding to the initial glottal opening burst, the quieter middle phase, and (sometimes) the final closing burst. Standard signal processing techniques were then invoked to characterize the spectral and temporal shapes of the first two phases. Factor analysis indicated that the spectral shapes of the two phases are independent, with each being largely described by the degree of "peakedness" in the spectrum, and by the balance of energy between low and high frequencies. Both the duration of the initial burst and zero-crossing rates of the cough waveform (which indicates the "spectral balance") during each of the first two phases were smaller for asthmatic than for non-asthmatic coughs. Fewer asthmatic coughs contained a final burst. Discriminant analysis between the two groups gave classification error rates of 20-30%. The peak flow recorded during the cough was significantly smaller for asthmatics, and correlated very well with the peak flow recorded during forced expiration. Thus, significant differences exist between asthmatic and non-asthmatic cough sounds. An effective representation of the temporal structure of the cough sound is required to successfully characterize the cough.

Asthma, Exercise-Induced↗
PubMed1991

A microcomputer-based interactive cough sound analysis system.

The occurrence and nature of cough sounds, especially those occurring in asthma in young children, is of considerable interest to workers in paediatrics and general practice. To facilitate our research into the characteristics of such sounds, we have developed a microcomputer-based analysis system, which we call COFF. In this paper we discuss the design and implementation of the system, emphasising its user-friendly, interactive features, and the manner in which it efficiently manages the large amounts of data that research into sounds incurs. We illustrate the operation of the system with examples of spectrograms computed from cough sounds recorded simultaneously at the mouth and through the chest wall.

Asthma↗
PubMed1990

A portable system for the spectral analysis of cough sounds in asthma.

A practical and portable method is described to analyze the sound spectra of coughs. The system is based upon a personal computer and simultaneously collects the sounds of cough heard both at the mouth and through the chest wall together with the airflow at the mouth produced during the cough. Subsequent analysis produce spectrographs of the cough sound linked to the corresponding airflow. The system will be used initially to examine the effects of exercise on the sound of cough in asthma. Further study of cough spectra in this way may be useful in the management of asthma either diagnostically or in the assessment of therapeutic interventions.

Asthma↗
PubMed1989

Cough sound analysis: a new tool for the diagnosis of asthma?

A method of computerized cough sound analysis is described. The sounds of nocturnal and post-exercise coughs from a child with asthma were compared with those from a child without asthma. The spectrographic patterns of voluntary cough at rest from the two children were similar. The pattern seen after exercise from the asthmatic child was different from the resting cough but similar to that seen during recorded nocturnal cough. In contrast the post-exercise cough from the non-asthmatic child was similar to the cough seen at rest. Refinement of this method of cough sound analysis may be useful in the diagnosis of asthma in young children.

Asthma↗
PubMed1987

General practitioner fees: the effect of an additional 10% goods and services tax.

The effects of an increase in general practitioner fees on the timing of decisions to seek certain consultations were studied at the time of the introduction of a 10% goods and services tax (GST) on 1 October 1986. Fifty-six general practitioners collected information on 4113 consecutive paediatric consultations over a four week study period. The price rise itself appeared to have little or no effect either on numbers attending, pattern of illness or on the timing of consultations. However, private medical insurance may have influenced decisions on when to seek medical attention.

Child↗
PubMed1986

Night cough and general practice research.

Thirty-four children, aged between three and nine years, presenting with nocturnal cough, were studied on successive nights using an automatic voice activated tape recorder system. Children with a family history of atopy coughed significantly more than children without such a family history. A wide variation in cough frequency was found both between and within subjects. No effects of treatment on cough frequency were demonstrated. Some of the physiological and pathological mechanisms underlying night cough are discussed.

Albuterol↗
PubMed1985

Active approach to recognising asthma in general practice.

The general practice medical records of 214 children born in 1977 were scrutinised for a diagnosis of asthma. In 18 (8%) of these a diagnosis of asthma had been entered. Using a scoring system based on the medical record a further group of children who were thought likely to have undiagnosed asthma was exercise tested. Twelve children (6%) had demonstrable exercise induced asthma. In addition, seven children (3%) had both frequent respiratory symptoms and borderline exercise test results, indicating that they too had clinically important airways obstruction. As expected, histories of atopic eczema, nocturnal cough, persistent cough (more than one week), and wheezing appeared often in the medical records of the children with asthma. In combinations these diagnostic clues were more than 50% predictive of asthma. A more active approach in general practice to the diagnosis of asthma in children is both necessary and possible.

Asthma↗