A new fibre optic intravascular oxygen sensor for measuring fast and dynamic arterial blood oxygen tension changes online

We have demonstrated, in the diseased lung, using a prototype intravascular electrochemical oxygen sensor, that lung alveolar units begin to collapse in expiration and re-open in inspiration, and that process ( known as cyclical atelactasis) causes the oxygen partial pressure in the arterial blood (PaO2) to oscillate widely on a breath-by-breath basis. These results have been confirmed independently by international investigators. However, the prototype oxygen sensors used by ourselves and others were unable to measure rapid PaO2 oscillations in flowing blood accurately, especially when the oxyhaemoglobin (the red pigmant in blood) saturation was changing. We now need to adapt and further develop a brand new intravascular sensor, using new technology, to measure these fast blood oxygen oscillations independent of oxyhaemoglobin saturation.It is also well established that the application of mechanical ventilation to hospital patients in Intensive Care Units exacerbates this repetitive atelactasis process and can cause further mechanical lung damage, known as Ventilator Induced Lung Injury (VILI). There is an international quest to understand the mechanisms underlying VILI and to reduce its incidence, and to reduce the deleterious effects of atelactasis on the lung.We believe, along with other workers, that the presence of PaO2 oscillations in arterial blood can be used (a) to detect the onset of cyclical atelactasis in the lung; and (b) also to direct the clinician to adjust the ventilator settings to reduce the amplitude of the oscillations / and thus reduce or else eliminate the atelactasis process itself.A clinical need therefore exists for a rapid-response intravascular oxygen sensor to measure these intrabreath PaO2 oscillations on-line and in real time. Currently available clinical intravascular oxygen sensors are, far too slow (60-90 sec time response) to be used for this breath-by-breath clinical measurement. Therefore a new fast response oxygen sensor must be developed, and that is the reason for this biomedical engineering grant application. The work will concentrate on developing this new sensor and testing it in the laboratory, before it is ultimately tested in physiological conditions (in vivo). The new sensor, based on a fibre optic technique, will enable measurements to be made in critically-ill patients in the Intensive Care Unit, in order to moderate the incidence and severity of VILI.