Background: Early management of respiratory distress is critical to reducing mortality in infants and children in resource-limited settings. Bubble continuous positive airway pressure (bCPAP) can offer effective and affordable non-invasive respiratory support. Objective: To determine the best physical components of bubble CPAP circuits for respiratory support of children in low-resource settings. Methods: Using PubMed, CINAHL and LILACS, studies of any design in any language published before June 2017 which examined the physical components of bCPAP circuits were identified and reviewed. Results: After screening, the review included 45 articles: 17 clinical trials, 11 literature reviews, 10 technical assessments of bCPAP components, three reports of real-world implementation in low-resource settings, three cost analyses and one case report. There is no ideal bCPAP circuit for all settings and patients, but some choices are generally better than others in designing a circuit for low-resource settings. Oxygen concentrators are usually the best source of oxygen. As yet, there is no affordable and accurate oxygen blender. Nasal prongs are the simplest patient interface to use with the fewest complications but are not the cheapest option. Expiratory limbs should be at least 1 cm in diameter. Home-made pressure generators are effective, safe and affordable. Conclusion: This narrative review found many studies which evaluated the real clinical outcomes with bCPAP in the target population as well as technical comparison of bCPAP components. However, many studies were not blinded or randomised and there was significant heterogeneity in design and outcome measures. Abbreviations: bCPAP, bubble continuous positive airway pressure; CPAP, continuous positive airway pressure; FiO2, fractional oxygen concentration; HFNC, high-flow nasal cannula; HIC, high-income countries; LMIC, low- and middle-income countries; NP, nasopharyngeal; O2, oxygen; PEEP, positive end-expiratory pressure; PICO, Population, Intervention, Comparison and Outcome.