Original Article Low- versus high-flow oxygen delivery systems in children with lower respiratory infection Pinar Uygur, Sedat Oktem, Perran Boran, Engin Tutar and Gulnur Tokuc Second Clinic of Pediatrics, Dr Lutfi Kırdar Kartal Research and Training Hospital, Istanbul, Turkey Abstract Background: Delivery of supplemental oxygen is the initial vital management of hypoxemic acute lower respiratory infection (HALRI). Oxygen delivery systems include low-flow and high-flow devices. In high-flow devices such as the Venturi mask, a constant mixture of oxygen is delivered. As a result, increased rate of breathing does not affect the concen- tration of oxygen delivered. In this study, we compared the efficacy of oxygen masks and Venturi masks in the management of hypoxemia in pediatric patients. Methods: A total of 65 children, aged 3–36 months, diagnosed with HALRI, were enrolled. Patients were allocated into groups, via simple alternate randomization, to receive oxygen through an oxygen mask or through a Venturi mask. Respi- ratory rate, heart rate, retraction, blood gas parameters, oxygen saturation, length of hospitalization, and oxygenation were recorded before and after oxygen treatment. Results: After 24h of treatment, respiratory rate was significantly lower among patients in the Venturi mask group compared with the oxygen mask group. Duration of supplemental oxygen and length of hospitalization were significantly lower in the Venturi mask group compared with the oxygen mask group. Conclusion: In both groups, there was marked improvement in all measured parameters following introduction of supple- mental oxygen. Oxygen was delivered more efficiently, however, by high-flow systems. The Venturi mask may decrease the total duration of oxygen usage time as well as the length of hospitalization among young children with HALRI through rapid symptom resolution. Key words acute, child, hypoxemia, oxygen inhalation therapy, respiratory infection. Acute infections of the lower respiratory tract are a major cause of preventable death among children, causing approximately one- third of all childhood deaths. 1 Hypoxemia is the most serious man- ifestation of severe acute lower respiratory infection in children. The case fatality rate of acute lower respiratory infection is in- versely related to the arterial hemoglobin oxygen saturation (SaO 2 ). 2,3 The delivery of supplemental oxygen is the initial vital management of acute lower respiratory tract infections. 4–8 There are two basic types of oxygen delivery systems: low-flow or vari- able performance devices (e.g. oxygen masks, nasal cannulae, na- sopharyngeal catheters etc.) and high-flow or fixed-performance devices (e.g. Venturi masks). 9,10 A plastic mask connected to an oxygen source, fitted over the patient’s nose and mouth with side-to-side perforations, allows room air entrance when placed over the child’s face. High-flow rates are usually needed to avoid risk of carbon dioxide accumula- tion. With this method, oxygen concentration delivery varies depending on the child’s respiratory flow rate and oxygen flow into the system. 11 High-flow systems deliver approximately 40 L/min of gas through the mask, which is usually sufficient to meet total respiratory demand. This ensures that changes in breathing do not affect the oxygen concentration delivered. 12–15 Venturi masks contain valves, which have the effect of increasing gas flow using the Bernoulli effect. 9 Oxygen is delivered at a high velocity that draws in a con- stant proportion of room air through a small orifice. Air entrainment depends on the size of the orifice and gas flow rate. Because a constant mixture of oxygen and air is delivered at a rate above that of maximum inspiratory flow, tachypnea does not affect the concen- tration of oxygen delivered. 12–15 Venturi masks can be accurately controlled to deliver an oxygen concentration of 24–60%. In children with hypoxemic acute lower respiratory tract infec- tion (HALRI), the respiratory rate increases while inspiratory flow rate and volume decrease. 10,16,17 When total ventilation exceeds capacity of the reservoir, room air is entrained, and oxygen mask performance loss occurs. 18–23 When oxygen flow is administered at a rate of 4–5 L/min, depending on patient respiratory flow rate, fraction of inspired oxygen (FiO 2 ) varies between 28% and 60%. 15 If the holes of the mask are plugged, performance will change. 18–23 High-flow systems provide constant FiO 2 , however, by delivering the gas at a flow rate that exceeds the patient’s peak inspiratory flow rate, thus overcoming these problems. 12–15 In the present study, we compared the efficacy of oxygen mask with that of Venturi mask in children with HALRI. Correspondence: Sedat Oktem, MD, 2nd Clinic of Pediatrics, Dr Lutfi Kırdar Kartal Research and Training Hospital, Feneryolu Mah. Yildiray Sok, Altun Apt. No. 13/28, Kadiköy, Istanbul 34570, Turkey. Email: sedatoktem@hotmail.com Received 13 May 2012; revision 21 June 2013; accepted 15 June 2015. © 2015 Japan Pediatric Society Pediatrics International (2016) 58, 49–52 doi: 10.1111/ped.12750