Clinical features of pneumonia in children include fever, respiratory distress, and hypoxemia. Respiratory distress is a useful clinical summary description with good inter-observer consistency among experienced medical practitioners. The following clinical signs may indicate increased work of breathing: sustained nasal flaring; indrawing (recession) of the bony structures of the chest wall (subcostal, intercostal, supraclavicular) on inspiration; tracheal tug; and deep breathing (acidotic or Kussmaul breathing). Respiratory distress is a sign that one or more serious pathological processes are at play: metabolic acidosis, fluid overload, acute lung injury, and/or co-morbid pneumonitis. Respiratory distress, together with alteration of consciousness, is a strong predictor of mortality in children with severe febrile illness in sub-Saharan Africa. The grim prognostic significance of respiratory distress applies to several disease states, irrespective of microbial etiology, including malaria as well as non-malaria febrile illness.

Arterial hypoxemia in pneumonia results from several mechanisms: pulmonary arterial blood flow to consolidated lung resulting in an intrapulmonary shunt, intrapulmonary oxygen consumption, and ventilation-perfusion mismatch. Hypoxemia is a risk factor for mortality in pediatric pneumonia, and was associated with a 5-fold increased risk of death in studies from Kenya and Gambia. In one report from Nepal, the prevalence of hypoxemia (SpO2 \< 90%) in 150 children with pneumonia was 39% overall, with increasing rates of hypoxemia across strata of pneumonia severity (100% of very severe, 80% of severe and 17% of pneumonia patients). General features of respiratory distress were associated with hypoxemia in this study, including chest indrawing, lethargy, grunting, nasal flaring, cyanosis, inability to breastfeed or drink.

Oxygen is a lifesaving therapy for children with pneumonia and hypoxemia; however, challenges remain in oxygen delivery globally. Two main systems of oxygen delivery have been implemented and evaluated in resource-constrained settings, oxygen cylinders and oxygen concentrators. Oxygen cylinders are ready to use, simple to operate and do not require any electricity. However, cylinders are very costly and distribution and use is challenging. Oxygen concentrators have proven to be an effective means of delivering oxygen and are significantly less expensive that cylinders. However, oxygen concentrators require continuous and reliable electricity to operate which is not readily available in many regions, particularly in resource-limited settings where the majority of pneumonia deaths occur. In order to meet the demand for oxygen therapy in resource-limited settings, the investigators developed a novel strategy for oxygen delivery: solar-powered oxygen (SPO2). This system uses free inputs (sun and air) and could be implemented in remote locations with minimal access to an electrical power supply. Our group is the first to conduct rigorous scientific trials of SPO2.

To date, the investigators have accumulated substantial clinical experience with SPO2, having treated \>150 hypoxemic children, over several years, at two Ugandan hospitals. Compared to other oxygen delivery methods, SPO2 is superior. SPO2 is more reliable than oxygen concentrators connected to grid electricity, because it is not affected by frequent power outages. SPO2 utilizes a renewable, sustainable and freely available source of energy. SPO2 is more reliable than compressed oxygen cylinders, which are frequently out of stock in the public hospital system. SPO2 is more user-friendly and safer for nurses than cylinders, which require physical strength to change regulators on high-pressure cylinders. SPO2 is less wasteful than cylinders, which tend to leak through ill-fitting regulators under real-world conditions.

The study is a multi-centre prospective evaluation of SPO2. The investigators will use a stepped-wedge cluster-randomized design to allow for robust scientific conclusions about the efficacy of SPO2. Importantly, demonstration of a mortality benefit of SPO2 will provide strong supportive evidence and could catalyse the widespread implementation of SPO2 in resource-limited settings across Africa and Asia.