Development of a Robust and Reliable Pulse Oximeter for Children With Pneumonia in Low-income Countries

Inclusion Criteria: Patient participants: * Inpatients (or child awaiting surgery on pre-operative ward) in Great Ormond Street Hospital, or government facilities in Malawi and Bangladesh * Aged 0 - 59 months * Clinically stable (as judged by the ward sister and medical team) * Parent (or adult with parental responsibility) present * Informed consent from the parent (or adult with parental responsibility) Healthcare worker participants: * Nursing staff employed at Great Ormond Street Hospital who are trained in the use of pulse oximetry or government healthcare providers working in Malawi and Bangladesh * Written informed consent from the healthcare worker Exclusion Criteria: Patient participants: * Unstable or critically unwell patients (as judged by their medical team) * Parents (or adult with parental responsibility) who are not able or willing to give informed consent * Parents (or adult with parental responsibility) unable to speak English well enough to understand study methods or consent form (UK only) * For part of the study assessing usability of the probe by healthcare workers, patients with oxygen saturation 95% or below will be excluded Healthcare worker participants: * Healthcare providers who are not trained to use a pulse oximeter * Healthcare providers who have not given written informed consent