Influence of age on postischaemic reactive hyperaemia.

This work was carried out to evaluate the response of skin microcirculation to ischaemia in younger and older subjects, to determine if there were functional changes in microcirculation in the older skin. Skin perfusion during reactive hyperaemia was measured at volar sites on the forearms in five younger (mean age: 25.2 years) and five older normal subjects (mean age: 64.6 years). Ischaemia was produced by the application of loads of 22.3 N (24.5 kPa) and 44.5 N (49.0 kPa) applied to the skin surface for 3 min by means of a hollow cylindrical indentor. The skin perfusion within the area indented was continuously monitored by a laser Doppler flowmeter before, during and after loading. In the pre-loaded condition, there was no difference in skin perfusion between the younger and the older groups. Following loading with 22.3 N a significantly lower value of the peak perfusion relative to the pre-loaded value was observed in the older group (P less than 0.05). The perfusion in the older group following loading with 44.5 N was significantly reduced compared to the younger group (P less than 0.05). It is concluded that postischaemic reactive hyperaemia in the older skin was reduced compared with the younger skin.

Biomechanical highlights--the personal miscellany of a decade.

Developments of the past decade, primarily in biomechanics, are characterized through personal recollections. Topics covered include pressure treatment of hypertrophic scars, laser eradication of tattoos, amputation stump and artificial limb interactions, elbow arthoplasty, disability rehabilitation and training for sports performance, functional electrical stimulation and joint goniometry. The review is prefaced by comments on the present day context and resource environment of bioengineering research and ends by discussing the anticipated advent of health maintenance oriented community care as the activity of first priority for the future.

The importance of certification/registration in expanding engineering career opportunities.

The difficulties of the engineering profession in exploiting to the full the opportunities available to it are not due to the oft-repeated and reputed lack of academic/industrial orientation and liaison. I am convinced that the reasons are due to present-day attempts to guide the profession in a characteristically multiprofessional world by inapplicable, restrictive and inhibitive uni-professional concepts and principles. The Engineering Council in particular should evolve active, rather than passively reactive means of recognizing and encouraging multi-professional team efforts on a much wider spectrum of activities than at present. This spectrum should, in particular, recognize the Health Service as the industry pertinent to biomedical engineering. The way forward lies in pre-experience registration of the newly qualified, followed by training 'on-the-job' accredited by the professional Institutions, culminating in 'certified' specialties. The process of accreditation/certification should be flexibly designed so as to permit changes of specialty orientation and even that of total career content.

Thrombus formation and microaggregate removal during extracorporeal membrane oxygenation.

Contemporary microporous membrane oxygenators have adequate gas transfer capacity and even prolonged oxygenation is relatively atraumatic to the blood elements. However, even with adequate heparinization, thrombus formation still takes place, albeit to a lesser degree than in direct blood-gas contact devices. In this work, scanning electron microscopy of the dissected devices in the extracorporeal circuit was performed on devices used during four aorto-coronary bypasses and two cardiac valve replacements. Membrane surfaces remained free of major deposits although thrombotic material could still be observed in parts of the oxygenators and the filters. Blood filtration from the cardiotomy reservoir may be more critical as it removes surgical debris and cells injured by suction which appear to enhance thrombus formation within the oxygenator. The return line arterial filter appears more useful as a bubble remover; its value appears much diminished as microemboli do not leave the device in large quantities.

A kneeless leg prothesis for the elderly amputee, advanced version.

The work described in this paper is part of a development and evaluation program, the aim of which was to bring a telescopic kneeless leg prosthesis to a reliable, commercially viable, and easily manufacturable stage. It is considered that these aims have been almost achieved, as the prosthesis appears to improve the gait characteristics significantly, compared with its first prototypes and compared with the conventional National Health Service (N.H.S.) above-knee prostheses. The clinical evaluation was carried out with three patients and its results were found satisfactory. The specific advantages of this prosthesis compared with the conventional prostheses are: improved proprioception and stability, and improvements of certain kinematic characteristics. The paper describes briefly the modified version of the prosthesis an the investigations undertaken, and also discusses the results obtained.