Dr Justin Paul Phillips
Google Visiting Faculty
Research Centre for Biomedical Engineering, City, University of London
Tel: +44 (0)207 040 8920
Figure 1 (a) Me, (b) ‘my’ book.
I am a Senior Lecturer (=Associate Professor) in Biomedical Engineering at City, University London and am privileged to work at the interface of three fascinating disciplines: physics, engineering and medicine. Last academic year I was awarded a Senior Research Fellowship awarded jointly from the Royal Academy of Engineering and the Leverhulme Trust, which enabled me to concentrate on research, specifically to solve the problem of measuring intracranial pressure, an important vital sign for head injured patients, using completely non-invasive methods. I am also the Course Director for the MEng/BEng in Biomedical Engineering degree programmes at City. During 2017 I am working as a Visiting Research Scientist at Google in London.
I graduated in Physics from Durham University and started my career at Ciba Corning Diagnostics in the UK where I worked for two years on the design and evaluation of prototype biomedical instrumentation. I then worked at the Royal Brompton Hospital and later St Bartholomew's Hospital where I was involved in research in anaesthesia and physiological measurement. I completed my PhD from Queen Mary, University of London for work developing new methods of monitoring cerebral oxygen saturation in head injury patients using fibreoptic sensors. I am a member of the Institute of Physics (IoP), Institute of Physics and Engineering in Medicine (IPEM) and the Institute of Electronic and Electrical Engineers (IEEE). I am also a co-author of Physics in Anaesthesia, a key textbook for medical students and postgraduate trainees studying for their FRCA (Fellow of the Royal College of Anaesthesia) examinations, and rated as 4.6/5 in 19 Amazon reviews.
My research is focused on developing new devices and algorithms for non-invasive health monitoring for all levels of healthcare; from wearable cardiovascular monitors to critical care and anaesthetic monitoring applications. This work also extends to the development of new technologies for screening patients for cardiovascular disease as well as developing solutions for monitoring patients in their homes.
Main Research Areas
Photoplethysmography and Wearable Sensors
Much of my research focuses on photoplethysmography, acquisition and analysis of optical pulse signals collected from tissue, usually the skin. This signal, the photoplethysmogram (or PPG), arises from the small arteries as they fill and empty over the cardiac cycle and therefore contains information about the function of the cardiovascular system. Simple analysis of the PPG waveform reveals the pulse rate, from the interval between PPG pulses, while more sophisticated examination of the signal may produce new clinical diagnostic tools. The factors affecting the exact shape and characteristics of the PPG signal, which vary according to the sensor and patient, are poorly understood, however there has been recent renewed interest in the potential of PPG due to the explosion in wearable health monitoring technology.
Figure 2 (a) Red and infrared PPG signals (orange/blue traces) collected from the finger of a volunteer breathing periodically,
together with airway pressure (green trace). (b) Spectral plot of red and infrared PPG signals showing cardiac and respiratory signal components.
At City, we have worked for several years developing sensors to collect PPG signals of optimum quality from internal end external monitoring sites. An essential (and growing) area of our PPG research is development of new algorithms and methods of extracting clinical data from PPG signals, including artificial neural networks and other machine learning approaches. This work is uncovering an abundance of clinically relevant data from this enigmatic signal, including heart rate variability data, measurement of respiratory volume, oxygen consumption, body hydration levels, blood pressure, arterial stiffness etc. etc.
Vascular Biomechanical Modelling
Understanding the physics and physiology of the vascular system is key to developing new tools for diagnosing cardiovascular disease, the largest cause of death in the developed world. In our labs at City we study use physical models of the heart and vascular system to study the effects of changes in cardiac function on the behaviour of the large and small arteries over the cardiac cycle. The models, which comprise artificial blood, programmable pumps, synthetic and real blood vessels and ‘phantoms’ of specific organs (such as the cerebro-cranial tissue) enable us to control many of the variables that influence the signals (such as heart rate, stroke volume, extravascular pressure, vascular resistance) and better understand measurable variables such as pulse wave velocity. This will enables better interpretation of ‘real’ signals from the body and allow us to develop sensors and software for analysing them to provide useful clinical data. An example application is analysing PPG data (see above) from a wearable heart rate monitor so the wearer can be alerted to an underlying heart condition.
Figure 3 In vitro cardiovascular model in the RBCE laboratory.
Current Funded Projects
The ‘Sensing Endotracheal Tube’
2014-16 – Funder: Barts Charity (PI: JP Phillips; Co-Is: J May, PA Kyriacou, S Snidvongs)
This project is based on development of a ‘Sensing ET Tube’, an optoelectronic sensor that may be attached to a standard endotracheal (ET) tube. It will be used in anaesthesia and in ventilated intensive care patients and provide key vital signs monitoring. Continuous monitoring of patients’ arterial oxygen saturation is essential during surgery, however pulse oximeters often misread or fail altogether as a result of peripheral vasoconstriction, hypotension or loss of blood. The Sensing ET Tube will allow continuous measurement of oxygen saturation and other parameters, such as pulse rate, from a single internal site, and will reduce the number of surface sensors placed on the skin and the number of electrical connections to the patient. A pilot clinical evaluation of the device will be completed in anaesthetised patients undergoing surgery. The project will lead to further development of a multi-sensor tracheal platform for comprehensive anaesthesia and intensive care monitoring.
Figure 4 Endotracheal tube sensor for recording heart rate, oxygen saturation and respiratory rate from the trachea
Non-invasive intracranial pressure (nICP)
2015-16 – Funder: RAEng/Leverhulme Trust Senior Research Fellowship (PI: JP Phillips)
Intracranial pressure (ICP) is routinely monitored in patients suffering from traumatic brain injury (TBI). Raised ICP is a life-threatening condition that can result in compression of brain tissue and a reduction in the flow of oxygenated blood to the brain. In fact, increased ICP is the most common cause of death in patients with severe TBI. The standard ICP monitoring method requires drilling a hole in the skull and inserting a pressure-sensing catheter into a cranial bolt screwed into the hole. This invasive technique is associated with certain risks including infection as well as delay in establishing monitoring in emergency situations. The project aims to develop a completely non-invasive probe placed on the forehead, for continuous external monitoring of the ICP. The ICP reading will provide warning of the need for rapid intervention and guide long-term treatment. Ultimately this could lead to significant improvements in mortality, length of hospital stays and reduced post-trauma disability.
Figure 4 (a) Conceptual image of nICP monitor, (b) schematic showing approximate mean optical paths through tissue.
Early Warning of the Multiple Organ Failure
2014-17 – Funder: NIHR (PI: PA Kyriacou; Co-Is: JP Phillips, JJ Davenport, M Hickey, S Snidvongs, T Fitchat)
Patients in the intensive care unit (ICU) are extremely vulnerable to complications related to sepsis, which can develop into more serious conditions such as septic shock and multiple organ dysfunction syndrome (MODS), both of which are associated with very high mortality rates. Monitoring the blood supply to the lower oesophagus (gullet), stomach or small intestine can give an early warning of the onset of sepsis, allowing rapid treatment to prevent septic shock and MODS. This project is to develop a disposable optics-based probe to continuously monitor the oxygen and carbon dioxide levels in the wall of the lower gullet. This will provide valuable information regarding the adequacy of the blood supply to the gut and vital organs. The sensor will be evaluated in Intensive Care Unit (ICU) patients, following informed, written consent. The sensor will not interfere with normal patient care and will be designed not to cause discomfort to the patient. The ultimate aim is to develop a new type of sensor to reduce death from sepsis and MODS, leading to significant reductions in mortality and shorter stays in intensive care.
For more information about my research, including opportunities for PhD research at City University London, please contact me: Justin.Phillips.firstname.lastname@example.org.