PROJECT SUMMARY: This is a submission for a National Institutes of Health R21/R33 award aiming to develop and validate a context-appropriate, inexpensive mobile phone-based pediatric reflectance pulse oximeter compatible with an interoperable hypoxemia surveillance system (R21 period), and then to evaluate the field implementation of a mobile phone reflectance pulse oximeter and hypoxemia eHealth system using a cluster, randomized controlled trial (R33 period). Lower respiratory infections (LRIs) are the leading infectious cause of death globally among children below five years of age in low-income and middle-income countries (LMICs). Hypoxemia, a low oxyhemoglobin saturation, is a key indicator of elevated LRI mortality risk. Pulse oximeters are devices that non-invasively measure the peripheral oxyhemoglobin saturation (SpO2) to identify hypoxemia, but are not widely available in LMICs for children, especially at primary healthcare clinics where children first access care. Although oxygen is potentially a life-saving treatment for hypoxemic LRIs, health systems in LMICs do not have well established oxygen systems to appropriately match supply with demand to optimally benefit children. We aim to develop, validate, and rigorously evaluate the implementation of an innovative, inexpensive mobile phone-based reflectance pulse oximeter, embedded within an electronic health DHIS2 platform for real- time hypoxemia diagnosis and surveillance of children in LMICs. We hypothesize that the pulse oximeter's performance will be valid and that its implementation within a DHIS2 electronic health platform will address key implementation endpoints in a conceptual framework and theory of change construct for improving pediatric LRI mortality in LMICs. To accomplish our overall project goal we will build upon our prior successful pediatric pulse oximeter development work in sub-Saharan Africa and South Asia using an innovative, multidisciplinary product development process called human centered design. During the two-year R21 period we will apply the human centered design approach to develop a mobile phone-based reflectance pulse oximeter and eHealth system (Aim 1). The device will be validated in a breath-down laboratory and field tested in various clinical settings with a range of practitioners in Cape Town, South Africa. We will then implement the pulse oximeter and DHIS2 system within a large township in Cape Town, South Africa and conduct a cluster, randomized controlled trial to evaluate implementation fidelity as the primary outcome (Aim 2), as well as secondary outcomes of implementation acceptability and feasibility. Successful completion of the research described in this application could lead to broader scale-up of an affordable, sustainable interoperable hypoxemia eHealth system with advanced but accessible mobile phone technology contextually appropriate for LMICs, where most pediatric deaths from hypoxemic LRIs occur.