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Pulmonary clearance of 99mTc-DTPA in infants who subsequently develop bronchopulmonary dysplasia
1Department of Paediatrics, University of Toronto, Hospital for Sick Children, Ontario, Canada.
Insights
Rapid lung clearance of 99mTc-DTPA in premature infants with hyaline membrane disease (HMD) may normalize before 28 days, even in those later diagnosed with bronchopulmonary dysplasia (BPD). This finding impacts monitoring strategies for HMD infants.
Area of Science:
- Neonatal Medicine
- Pulmonary Medicine
- Nuclear Medicine
Background:
- Premature infants with acute hyaline membrane disease (HMD) exhibit biphasic lung clearance of 99mTc-DTPA, with rapid initial clearance.
- A return to slower, monophasic clearance occurs before extubation in recovering infants.
- Persistently rapid clearance might predict non-recovery and subsequent bronchopulmonary dysplasia (BPD) diagnosis.
Purpose of the Study:
- To investigate if persistently rapid lung clearance of 99mTc-DTPA in premature infants with HMD can predict the later development of BPD.
- To analyze the lung clearance patterns in ventilator-dependent premature infants who subsequently developed BPD.
Main Methods:
- Retrospective review of 8 intubated, ventilator-dependent premature infants.
- Inhalation of 99mTc-DTPA aerosol on 14 occasions during weeks 2-4 of life.
- Analysis of biphasic and monophasic lung clearance rates (T1/2).
Main Results:
- Biphasic clearance with very rapid initial lung clearance (T1/2 < 2 min) occurred in 4 infants during weeks 2-3.
- Other infants showed much slower monophasic clearance (T1/2 = 52 ± 26 min).
- All infants diagnosed with BPD were ventilator- and/or oxygen-dependent at Day 28.
Conclusions:
- Lung clearance of 99mTc-DTPA is rapid during acute HMD.
- Rapid clearance can normalize before 28 days of life in infants who are subsequently diagnosed with BPD.
- This suggests that a persistently fast clearance rate may not reliably predict BPD in all cases.
Abstract:
The lung clearance of inhaled and deposited 99mTc-DTPA is biphasic, with a very rapid initial clearance in premature infants with acute hyaline membrane disease (HMD). Infants who rapidly recover from HMD revert to a monophasic slower clearance rate prior to successful extubation. This raises the possibility that a persistently fast clearance might identify infants who will not recover and in whom bronchopulmonary dysplasia (BPD) will subsequently be diagnosed. To examine this possibility, we reviewed our experience using this technique and identified infants who had subsequently developed BPD. These 8 intubated, ventilator-dependent, premature infants inhaled a submicronic aerosol containing 99mTc-DTPA on 14 occasions during the second, third, and fourth weeks of life. Clearance was biphasic, with very rapid initial lung clearance (T1/2 less than 2 min) on 5 occasions in 4 infants during their second or third week of life. The other infants had monophasic clearances that were much slower (T1/2 = 52 +/- 26 SD min). At Day 28 of life, all infants with BPD were ventilator-and/or oxygen-dependent. We conclude that lung clearance of 99Tc-DTPA is very rapid during acute HMD, but that it can normalize before 28 days of life in infants in whom BPD is subsequently diagnosed.