1.1 General information
Thirty four premature infants with NRDS admitted to the NICU ward of Fujian Children 's Hospital from April 2023 to January 2024 were selected and divided into groups according to treatment methods. Seventeen premature infants who only received high-frequency ventilation therapy served as the control group, including 9 males and 4 females; 7 to 15 hours after birth, with an average of gestational age(30.62 ± 2.31); an average of birth weight (1521.12 ± 462.02) g. 17 children were treated with high-frequency ventilation + closed-loop automatic oxygen control as a research group, including 10 males and 7 females; 7 to 16 hours after birth, with an average of gestational age(30.51 ± 2.37); an average of birth weight (1498.24 ± 325.93) g.
Inclusion criteria: ① Meet the clinical diagnostic criteria for moderate to severe RDS in "Practical Neonatology", and combined with clinical symptoms and arterial blood gas analysis results, it is clear that the child has respiratory failure, and the effect is not satisfactory after treatment with bronchodilators and other drugs; ② Gestational age 28 ~ 36 weeks of premature infants; ③ General oxygen therapy is ineffective and requires assisted ventilation; ④ Respiratory distress symptoms show progressive worsening; ⑤ Diagnosis and treatment data are kept intact; ⑥ Family members voluntarily agree to the child's participation in the study and sign an informed consent form. Exclusion criteria: ① The presence of congenital malformations and respiratory failure caused by pneumothorax; ② The presence of bleeding tendencies or bleeding diseases, complex congenital heart disease, severe circulatory failure, anemia, etc.; ③ The presence of contraindications to HFOV treatment. Comparing the general information of the two groups, the difference was not statistically significant (P > 0.05) and was comparable.
1.2 Method
Premature infants in both groups were given maintenance of water, electrolyte and acid-base balance, nutritional support, vasoactive drugs, infection prevention, and organ function protection .
1.2.1 HFOV treatment
HFOV treatment : The child uses a STEPHAN ventilator and a Mindray monitor, which emits an alarm sound. The medical staff promptly checks and evaluates the child's condition, and appropriately adjusts FiO2 to return SpO2 to the target range. Ventilator parameters: The initial value of MAP is set to 11 ~ 25 cmH2O. Based on the patient's condition and blood gas analysis results, adjust up or down by 1 ~ 2 cmH2O/time. Increase MAP cautiously to prevent pulmonary hyperventilation in children. Lower the MAP value immediately after the condition stabilizes. The initial value of the oscillation pressure amplitude is set to 26 ~ 65 cmH2O, and the upper and lower adjustment amplitude is 3 ~ 5 cmH2O/time. The initial value of oscillation frequency is set to 10 ~ 15 Hz/min. The initial value of the inspiration-to-exhalation ratio is set to 50%. The initial value of FiO2 is set to 85% (53% ~ 100%), and SaO2 needs to be maintained at ≥ 90% during adjustment. Reasonable increases or decreases will be made based on the blood gas analysis results of the child. Blood gas indicators must be maintained within an appropriate range. X-ray chest X-ray examination shows that the diaphragm surface is located between the 8th and 9th posterior ribs. MAP < 12 cmH2O, FiO2 < 0.4; arterial blood carbon dioxide partial pressure (PaCO2) is 35–50 mmHg, pH is 7.25–7.45, PaO2 is 50–80 mmHg; the child's SaO2 does not change significantly after the sputum suction operation, so it can be determined Treatment for HFOV was successful.
1.2.2 HFOV + Closed-loop oxygen treatment
The HFOV treatment plan, parameter settings, and treatment effectiveness evaluation criteria remain unchanged, and closed-loop automatic oxygen control is added, which is provided by the integrated OxyGenie software (SLE, Croydon, UK). The software uses proportional, integral, and differential algorithms to calculate and appropriately Adjust FiO2 to react to changes in SpO2. OxyGenie uses a proportional-integral-derivative algorithm. In this system, the error is defined as the distance from the midpoint of the target range, and the change in FiO2 is proportional to the error, integral, and derivative. Data is downloaded directly from the ventilator and includes second-by-second recording of ventilator settings, including paired FiO2 and SpO2 results. Data collected were the number and duration of severe desaturation episodes, with severe desaturation below 85%, whether > 30 seconds or > 60 seconds. Data were analyzed to determine time spent within, above, and below the patient's target SpO2 range. Record the time the child became hyperoxic (above their target SpO2 range) or hypoxemic (below their target SpO2 range), the number of manual adjustments, and the number of automatic adjustments made by OxyGenie. The SpO2 control range is between 90% and 94%. The monitor probe that comes with the ventilator is tied to the instep of the child's lower limb. When the FiO2 control has been adjusted to the maximum value of the FiO2 setting range, if the child's SpO2 Still at a low level ( < = SpO2 lower limit - the smaller of 5% and 85%), for the safety of the child, the FiO2 control value will exceed the set FiO2 range maximum value, but the maximum will not exceed the FiO2 set range maximum value + The lesser of 20% and 60% .
1.3 Observation indicators
1.3.1 Efficacy evaluationThe child's cyanosis, irritability and other symptoms disappeared, his body temperature returned to normal, his breathing returned to steady, his reaction was good, his complexion was rosy, and his lung function index levels returned to normal. PaCO2 was 35–45 mmHg, PaO2 was 70–90 mmHg, and SpO2 was 90%. ~95%, it is judged that the treatment is effective ; the patient's clinical symptoms and various physical indicators have returned to normal, shortness of breath and pauses occasionally occur, the reaction is average, the complexion is rosy, and the level of lung function indicators has improved significantly, it is judged that the patient has improved; the clinical symptoms of the child If the symptoms, signs and blood gas analysis indicators are not significantly improved compared with before treatment, or are further aggravated, it is judged as no improvement. At the same time, ventilator treatment and hospitalization time of children were observed.
1.3.2 Assessment of blood gas status and oxygenation function
The blood gas status of the children was dynamically observed during treatment, and blood gas analysis and detection were performed before treatment and different time point after treatment. The indicators included blood pH, PaCO2, SaO2, and PaO2, and the PaO2/FiO2 and alveolar-arterial blood oxygen fraction were calculated. Pressure difference and oxygenation index (OI) evaluate the patient's oxygenation function.
1.3.3 Security Assessment
The children were observed for complications such as pulmonary air leakage, patent ductus arteriosus (PDA), persistent pulmonary hypertension of the newborn (PPHN), intraventricular hemorrhage, chronic lung disease, and pulmonary hemorrhage.
1.4 Statistical methods
Statistical methods
SPSS 26.0 statistical software was used for data collection and analysis. If the measurement data conforms to the normal distribution, ‾it is expressed as x ± s, and the two independent samples t test is used between groups. Count data were expressed as frequencies (percentages), and chi-square tests were used for comparisons between groups. P < 0.05 indicates that the difference is statistically significant.