SepAl: Sepsis Alerts on Low-Power Wearables With Digital Biomarkers and On-Device Tiny Machine Learning

Sepsis is a lethal syndrome of organ dysfunction that is triggered by an infection and claims 11 million lives per year globally. Prognostic algorithms based on deep learning have shown promise in detecting the onset of sepsis hours before the actual event but use a large number of biomarkers, including vital signs and laboratory tests. The latter makes the deployment of such systems outside hospitals or in resource-limited environments extremely challenging. This article introduces SepAl, an energy-efficient and lightweight neural network, using only data from low-power wearable sensors, such as photoplethysmography (PPG), inertial measurement units (IMUs), and body temperature sensors, designed to deliver alerts in real time. SepAl leverages only six digitally acquirable vital signs and tiny machine learning (TinyML) algorithms, enabling on-device real-time sepsis prediction. SepAl uses a lightweight temporal convolution neural network capable of providing sepsis alerts with a median predicted time to sepsis of 9.8 h. The model has been fully quantized, being able to be deployed on any low-power processors and evaluated on an ARM Cortex-M33 core. Experimental evaluations show an inference efficiency of 0.11 MAC/Cycle and a latency of 143 ms, with an energy per inference of 2.68 mJ. This work aims at paving the way toward accurate disease prediction, deployable in a long-lasting multivital sign wearable device, suitable for providing sepsis onset alerts at the point of care. The code used in this work has been open-sourced and is available at https://github.com/mgiordy/sepsis-prediction.