Postnatal pulmonary distension for the treatment of pulmonary hypoplasia: pilot study in the neonatal piglet model

Abstract

Background Accelerated lung growth has previously been demonstrated after fetal tracheal occlusion. The purpose of this study was to determine if short-term perfluorocarbon (PFC) distension could increase lung growth postnatally in neonatal piglets. Methods Eleven piglets aged 5 to 8 days were divided into 3 groups: ( a) controls (n = 4), ( b) PFC × 6 hours (n = 3), and ( c) PFC × 12 hours (n = 4). A right posterolateral thoracotomy was performed and a pressure-monitoring catheter was placed in the posterior segment of the right upper lobe. Perfluorocarbon was infused and a mean intrabronchial pressure of 12 mm Hg (range, 5-21 mm Hg) was maintained. The control piglets also had a thoracotomy with right upper lobe bronchus dissection without ligation or PFC distension. All piglets were injected with [ 3H]-thymidine 3 hours before killing. Both right and left posterior segments of each upper lobe were analyzed for their respective amount of total DNA by fluorometry. Rates of DNA synthesis for each segment were determined by precipitating incorporated [ 3H]-thymidine with 5% trichloroacetic acid and reporting this value by the total amount of DNA. The differential lung DNA synthesis rate was calculated as (right posterior segment/left posterior segment) × 100. Statistical analysis consisted of 1-way analysis of variance and Student's t tests with significance at P ≤ .05. Results Heart rate, mean arterial pressure, temperature, oxygen saturation, pH, P co 2, and P o 2 were similar in all 3 groups. Lung DNA synthesis was nearly doubled in the PFC × 6 hours group compared with controls (302% vs 165%, P = .05). Animals in the PFC × 12 hours group experienced a 261% increase ( P = NS). Conclusion Short-term PFC distension in neonatal piglets resulted in increased DNA synthesis within 6 hours presumably because of stretch-induced mechanisms.