The changes of oxygen concentration in nasal cavities of neonates when supplied with different oxygen concentration and flow rates via different sizes of oxygen hood

Objective To study the relationships between supplied oxygen concentration (FsO_ 2 ), flow rate (flow) and inhaled oxygen concentration (FiO_ 2 ) in neonates when oxygen is given via oxygen hood; and to study what are the most effective ways of supplying oxygen in neonates. Methods Oxygen concentrations were measured in nasal cavities of neonates when different FsO_ 2 and Flow were given. FsO_ 2 and Flow were adjusted and measured by Air-oxygen blender and Pigeon I analyzer. Results When FsO_ 2 was 100% and Flow was greater than 3 L/min, the oxygen concentration measured in nasal cavities of neonate was greater than 40% in all groups with different sizes of oxygen hood; when Flow was increased to or greater than 7L/min, the oxygen concentrations in nasal cavities of neonate were close to 60% for groups with medium and big oxygen hood and greater than 60% for groups with small oxygen hood. Among the groups with same size oxygen hood, the difference of oxygen concentration in nasal cavities showed statistical significance (P0.01) when FsO_ 2 was equal to or greater than 21%. The oxygen concentrations in nasal cavities and the changes of FsO_ 2 and Flow showed linear relationships (P=0.000) in all studied groups with three different sizes of oxygen hood. Conclusions When oxygen is given via oxygen hood, FiO_ 2 changes in a wide range with the changes of FsO_ 2 and Flow; when 100 % oxygen is given, low flow is required to keep FiO_2 in a satisfied range. Therefore, for the safety of oxygen supply, it is important to use air-oxygen blender to choose the right FsO_2 and flow when oxygen is given via oxygen hood.