A miniaturised laser isotope ratiometer for early diagnosis of sepsis by exhaled breath analysis

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This project aims to develop a prototype medical instrument for the rapid and accurate diagnosis of sepsis. Sepsis is a serious complication of infections, and without timely treatment can lead to multiple organ failure and death. In the UK 44,000 deaths per annum are attributed to sepsis, and 14,000 of those are thought to be preventable with improved diagnosis and reduced delays in beginning treatment. Delays in treatment of just a few hours can have a significant impact on the outcome for the patient. Current tests for sepsis require samples of blood or other fluid from the patient to be taken to a laboratory for analysis. There are two drawbacks associated with current testing: Firstly, the process of sending samples for analysis introduces delay, which in turn reduces the chances of successful treatment; secondly, patients cannot be monitored continuously and so the onset of the condition may be missed.Researchers at the Rutherford Appleton Laboratory (RAL) have developed an instrument called a laser isotope ratiometer (LIR) that should be able to identify the very early stages of sepsis by analysing the composition of exhaled breath from the patient. Changes in the ratio of naturally occurring forms carbon dioxide exhaled by patients can indicate the presence of sepsis. The LIR will be capable detecting these changes in real time by analysing subtle changes in the infrared light absorbed by the exhaled breath. Crucially the results of this analysis will be interpreted by the instrument and presented to medical staff as a simple "yes" or "no" indication of whether the patient has sepsis or not. The method is non-invasive and, for the sickest patients that are not able to breathe for themselves, the LIR could be attached to ventilators to provide continuous monitoring.During the project the instrument scientists at RAL will work with clinicians at King's College London (KCL) to determine whether the LIR can provide a reliable way of identifying patients with sepsis. This will be done through clinical trials where KCL will provide anonymised sample bags containing exhaled breath from patients with and without sepsis for blind testing by the LIR at RAL.The LIR has been successfully demonstrated in other application areas, and is being exploited commercially for the oil and gas industry. During this project the work at RAL will include preparation of an existing miniaturised version of the LIR for breath analysis, characterization of its performance, and development of the test protocol to ensure accuracy and reliability. If initial tests using sample bags are successful there will be an opportunity for the LIR to be deployed in a clinical environment at King's College Hospital for further testing. This will enable a better idea of the effectiveness of the approach, including potential cost savings.