Title: Development of a novel rapid intravascular PO2 sensor
Funder: Department of Health (England)

Abstract: Background Mechanical ventilation of patients with acute lung injury can cause further lung damage known as Ventilator Induced Lung Injury. Alveoli may collapse in expiration and re-open in inspiration, a process known as cyclical atelactasis (CA).There is an international quest to reduce the deleterious effects this has on the lung. CA causes the arterial oxygen partial pressure (PaO2) to oscillate breath-by-breath and we believe that detection of PaO2 oscillations can be used to detect the onset of CA and to direct the clinician to better manage the condition. There is a clinical need to measure these oscillations on-line and in real time. No currently available intravascular oxygen sensor is sufficiently rapid or stable to do this. Our project aim is develop and translate such a device. Aims We therefore aim to develop a new fast response oxygen sensor. We will build upon a feasibility study which we have recently conducted to develop a rapid response intravascular optical sensor. We now need to adapt and further develop this novel optical sensor, using new technology, to measure high frequency blood PaO2 oscillations independently of oxyhaemoglobin saturation, and in real time. The aim is for this sensor to be stable in use, to span the entire range of values observed clinically and to have a response time of 200 msec, so that it is appropriate for measuring such a dynamic PaO2 signal. We aim to optimise the fibre type and waveguide, optimise the nanostructure of the fluorophore and to test the device in flowing blood in a bench test rig. Plan of Investigation 1. To redesign our prototype sensor, redeveloping the fluorophore to widen the dynamic range to span 0 to 100kPa and to incorporate a flexible polymer body. 2. To develop a thin optically efficient coating with high diffusivity and minimal scattering (with nanoparticles of fluorophore) which will afford a response time of at 200 msec or better, and to incorporate a new enhancement algorithm to speed-up the time response yet further. 3. To render the sensor tip resistant to protein fouling by substrate selection, irrigation, and bonded anticoagulant/fibrinolytics. 4. To bench test this sensor in-vitro, using oxygenated flowing saline and oxygenated flowing stored blood, in a new flowing blood test rig, in order to examine and maximise the sensor performance. Potential Impact Potential beneficiaries will be: Intensive Care Unit (ICU) patients and clinicians. When developed for clinical use, the sensor could monitor the atelectatic state of the lung in patients with Acute Respiratory Distress Syndrome in the ICU, to inform therapeutic decision making and to direct ventilator settings on an individual patient with the aim of reducing the danger of Ventilator Induced Lung Injury (VILI). This will be a world wide impact. Premature babies. This similarly applies to the Neonatal ICU. The Critical Care research community, since this sensor will allow new studies to investigate cyclical atelactasis and VILI. It is likely that a new area of clinical research interest in dynamic oxygen signalling and sensing will be spawned.


Research activity codes: 4.1 DISCOVERY AND PRECLINICAL TESTING OF MARKERS AND TECHNOLOGIES
Health categories: RESPIRATORY