Objective To verify if “physiologic definition” of BPD is more useful than classic definition.
Methods Neonates with BW 500–1250 g were prospectively studied to evaluate incidence of BPD. Respiratory outcome at 28 days and/or 36 wks PMA was defined in 2 ways: a clinic one based on O2 administration and a physiologic one based on O2 administration and saturations. Neonates who received FiO2 ⩽0.30 with or without CPAP were eligible. The test was divided into 3 parts, baseline, challenge and post-test: every minute we recordered ptcO2, ptcCO2, HR, RR, SpO2. Presence of apnoea (breathing cessation >20 sec) and bradycardia (HR<80 bpm<10 sec) was noted. Failure was defined as SpO2 80–90% for 5 minutes with ptcO2 <50 mmHg, or SpO2 <80% for 1 minute, or occurrence of an adverse event during the test or a FiO25% increasing one hour after reduction.
Results 21 neonates were tested, 2 were examined at 28 days and 36 wks PMA.
At 28° day BPD incidence passed from 50.8% (clinical definition) to 44.2% (physiological definition), because 4/15 (27%) passed the test.
At 36 wks PMA BPD incidence passed from 21.3% to 15%, because 4/8 (50%) passed the test.
The mean ptcCO2 was significantly higher in neonates that failed the test (p<0.05) in respect to those who overcame it both at 28 days and 36 wks PMA, while the mean SpO2 was always lower but significant only at 28 days (p<0.05).
Conclusions In our study the test was used as a clinical guide and performed not only at 36 wks PMA as reported in the literature but also at 28 days and in neonates with CPAP. The ptcCO2 and SpO2 resulted in being good criteria for predicting test’s failures.