Objective: To verify the accuracy of oxygen concentration (FiO2) of modified oxygen treatment with Venturi and humidity system.
Methods: Patients just after ventilator weaning and before the removal of tracheal intubation/tracheotomy tube, who admitted to the intensive care unit (ICU) of Henan Provincial People's Hospital from May 1st to December 15th in 2017, were enrolled. All patients were given a modified oxygen treatment with Venturi and humidity system, and the oxygen flow rate (Flow) of the Venturi device and the oretical value of FiO2 were adjusted according to the patient's condition. Patients were divided into five groups based on doctor's orders: Flow 3 L/min FiO2 0.24, Flow 3 L/min FiO2 0.26, Flow 6 L/min FiO2 0.28, Flow 6 L/min FiO2 0.30, Flow 9 L/min FiO2 0.35. The value of FiO2 at the inhalation end of patients of each group was measured by TSI airflow analyzer, and the consistency between the measured value of FiO2 at the inhalation end and the FiO2 marked value of Venturi was compared and analyzed.
Results: When the FiO2 theoretical value of Venturi were adjusted to 0.24, 0.26, 0.28, 0.30, and 0.35, the measured values of FiO2 at the inhalation end of patients were 0.38±0.05, 0.38±0.05, 0.40±0.04, 0.41±0.04, and 0.77±0.11, respectively, which were all significantly higher than the theoretical value of FiO2 (all P < 0.01). The difference between the measured value of FiO2 at the inhalation side and the FiO2 value of the Venturi annotated and the difference rate were both "V"-shaped, both of which decreased with the increase in theoretical value of FiO2 to a Flow of 9 L/min and a theoretical value of FiO2 0.35, the accuracy was the worst, with the FiO2 difference of 0.42±0.11, and the FiO2 difference rate of (121.6±36.5)%.
Conclusions: There is a difference between the measured value and the theoretical value of FiO2 at the inhalation end of the modified Venturi oxygen therapy humidification system, which needs to be paid attention to during clinical oxygen therapy.