Abstract
The key to managing a process or system is accurate measurement. From an engineering viewpoint, accurate measurement and acquisition of system observers is a fundamental necessity in order to model, understand and ultimately control a system. From a clinical viewpoint, the basis of a diagnosis is derived from observations and measurements. In this special issue of Physiological Measurement we compile a broad spectrum of papers with an emphasis on measurement.
The papers have been selected from the 2100 papers presented at the World Congress (WC2003) on Medical Physics and Biomedical Engineering. This Congress was held in Sydney, Australia, on 24-29 August 2003 and was the culmination of over six years of planning. WC2003 was the triennial Congress of the International Union for Physical and Engineering Sciences in Medicine (IUPESM) as the umbrella to the International Federation for Medical and Biological Engineering (IFMBE) and the International Organization for Medical Physics (IOMP). WC2003 also incorporated the local meeting of the Australasian College of Physical Sciences and Engineers in Medicine and the Biomedical Engineering College of Engineers Australia.
While, to many, the acronyms and the number of sponsoring and affiliated societies may have been confusing, one thing that was not in the least confusing or in question was the breadth and quality of the scientific programme. The Congress covered biomedical engineering and medical physics in the broadest sense with 21 tracks and over 260 topics within these tracks. Papers were drawn from 74 different countries.
The Congress fulfilled the principal objectives of the IUPESM, namely to contribute to the advancement of physical and engineering science in medicine for the benefit and well-being of humanity; and to organize international cooperation and promote communication among those engaged in health care science and technology.
This special issue serves as another example of these objectives by promoting the communication of high quality research in one particular aspect of physical sciences and biomedical engineering, namely that of physiological measurement.
Of the 2100 papers presented, 23 have been selected for publication in expanded form in this special issue. Those papers were chosen by taking into account both the scope and the interdisciplinary nature of the journal. Emphasis was therefore placed on selecting high-quality papers that addressed the quantitative assessment and visualization of physiological function in clinical research and practice. Selected authors were invited to submit an extended mansucript which then went through the normal refereeing process of Physiological Measurement. The result of this process has been a diverse mix of papers both in topic and geographical location of authors.
The first two papers are based around measurement techniques in electrical impedance tomography. Armstrong and Jennings describe a design for current injecting electronics to be used in electrical impedance tomography. Serrano et al assess unilateral pulmonary function by electrical impedance tomography incorporating a reduced electrode set.
Optical imaging and specifically near-infrared spectroscopy are featured. Coyle et al report on the suitability of near-infrared functional brain imaging for next-generation brain--computer interfaces. Szufladowicz et al use near-infrared spectroscopy in the evaluation of cerebral oxygenation during vasovagal syncope, and Suter et al use the complimentary information from computed tomography and optical imaging to examine the human airway.
The close relationship between measurements and models is highlighted in several papers, spanning various organ systems. Buist et al describe an anatomical model of the gastric system based on biophysical data. Smith reports on an anatomically based computational model of coronary blood flow that is coupled to cardiac mechanics and is used to investigate the mechanisms by which myocardial contraction inhibits coronary blood flow. Camacho et al estimate the pressure pulse amplification using stepwise linear regression models. Geven et al develop a lumped parameter mathematical model of the coronary circulation. Hovorka et al present a nonlinear model predictive controller to maintain normoglycemia in subjects with type 1 diabetes.
Similarly the important role of biosignal processing in physiological measurement is clear. Sleigh et al examine the correlation between depth of anaesthesia and a measure of spectral entropy of the cortex. Hassanpour et al use a time--frequency technique incorporating both low and high frequency features to detect EEG seizures in neonates. Bruce assesses contrast-enhancing frequency shaping and multiband compression in hearing aid devices. Rahman et al introduce a high-frequency electrocardiogram technique for non-invasive detection of coronary artery disease. de Chazal et al report on an automated algorithm for the detection of obstructive sleep apnoea using the ECG. Castiglioni and Di Rienzo propose a procedure to automatically check steady-state conditions from cardiovascular time series.
Other papers focus on the cardiovascular system, including cardiac electrical activity and autonomic control. Olbrich and Murray report on a technique for determining the mechanical properties (compliance) of coronary arteries using mock arteries. Jordan and Christini define a new protocol that allows the researcher to investigate the effects of memory and action potential duration alternans on cardiac restitution. Penzel et al examine sleep apnoea and arousal through autonomic nervous function measures derived from peripheral arterial tonometry. Chase et al quantify agitation in sedated intensive care patients using heart rate and blood pressure variability measures.
Finally, there are those interesting papers that do not fit into a particular category but which highlight the diversity of the field. Hallberg et al describe an applanation resonance tonometry method for measuring intraocular pressure in humans. Brown et al compare two methods (nitrogen washout and forced oscillation) for measuring airway distensibility in asthmatic and normal patients. Beebe et al describe how nanosecond pulsed electric fields modulate cell function through intracellular signal transduction mechanisms.
Collectively, the papers in this special issue illustrate the central role that physiological measurement plays in biomedical research.