The Usefulness of Pulmonary Function Test as Successful Weaning Index in Very Low Birth Weight Infants with Chronic Lung Disease

ABSTRACT

PURPOSE: To evaluate the usefulness of pulmonary function test for the prediction of successful weaning and extubation from the ventilator in very low birth weight(VLBW) infants with chronic lung disease. METHODS: This study included 15 VLBW infants(<1,500 g) with chronic lung disease who were admitted to Neonatal Intensive Care Unit of Samsung Medical Center from July, 1995 to June, 1996. They had extubation failure more than one time. This study was performed by reviewing of patients records retrospectively. The extubation criteria were based on clinical status, ABGA profiles and ventilatory parameters. At the time of last extubation failure and final success, we analyzed the distribution of age and weight of infants, ventilator profiles, ABGA profiles, dynamic and static pulmonary function test profiles measured by Bicore CP-100R from the infant with ventilator assistance daily in line monitoring. The paired T-test and linear logistic regression analysis were used to compare the variables between the evets of extubation failure and success. RESULTS: At the time of successful extubation, expiratory airway resistance was significantly lower and minute volume was significantly higher in dynamic pulmonary function test and respiratory system resistance was significantly lower in static pulmonary function test(P<0.05). In ventilator parameter, Fi02 and respiratory rate were lower at successful extubation(P<0.05). No statistically significant differences in ABGA profiles were seen between unsuccessful and successful extubation. CONCLUSION: The pulmonary function test is a useful predictor for successful weaning and extubation in VLBW infants with chronic lung disease. Among various parameters of pulmonary function test, expiratory airway resistance, minute ventilation and respiratory system resistance are suggested as successful weaning parameters.