Positive end-expiratory pressure modifies response to recombinant and natural exogenous surfactant in ventilated immature newborn rabbits.
OBJECTIVE
Different types of surfactant preparations were shown not to exert uniform response in preterm infants suffering from respiratory distress syndrome (RDS). Therefore, the effects of a recombinant surfactant protein C (rSP-C) based preparation and a natural surfactant were compared applying different levels of positive end-expiratory pressure (PEEP) in experimental RDS.


METHODS
Preterm rabbits (n = 7-14 per group; 27 days gestation; term 30 days) were randomized for receiving either 100 mg/kg rSP-C or natural bovine surfactant and were compared with saline treated controls. Animals were ventilated for 30 min with either 0.3 or 0 kPa PEEP at standardized tidal volumes and lung mechanics were measured as well as lung histology and mRNA expression of surfactant associated proteins B and C by real-time PCR.


RESULTS
The PEEP level applied (0.3 vs. 0 kPa) largely influenced dynamic compliance after administration of rSP-C surfactant (4.45 vs. 2.58 ml/kg), whereas natural surfactant improved compliance regardless of the PEEP applied (4.86 vs. 4.24 ml/kg) compared to controls (2.41 vs. 1.55 ml/kg). Accordingly, administration of PEEP significantly increased alveolar count in all groups as well as SP-C mRNA expression, whereas SP-B expression and protein content both remained unchanged.


CONCLUSIONS
Response to rSP-C surfactant depends on the PEEP level applied in our model of neonatal RDS. These findings should be considered for the conception of clinical trials regarding treatment strategies in neonatal RDS.
Hilgendorff
Anne
A
Department of Pediatrics and Neonatology, Justus-Liebig-University Giessen, Giessen, Germany. anne.hilgendorff@paediat.med.uni-giessen.de
Reiss
Irwin
I
Ruppert
Clemens
C
Hanfstingl
Thilo
T
Seliger
Ann Sophie
AS
Gunther
Andreas
A
Ebsen
Michael
M
Gortner
Ludwig
L
D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D015870:Gene Expression; D005865:Gestational Age; D008168:Lung / Q000737:chemistry; D011175:Positive-Pressure Respiration; D011650:Pulmonary Alveoli / Q000033:anatomy & histology; D037701:Pulmonary Surfactant-Associated Protein B / Q000235:genetics; D037721:Pulmonary Surfactant-Associated Protein C / Q000008:administration & dosage / Q000235:genetics; D011663:Pulmonary Surfactants / Q000008:administration & dosage*; D012333:RNA, Messenger / Q000032:analysis; D011817:Rabbits; D011994:Recombinant Proteins / Q000008:administration & dosage; D013990:Tidal Volume
D037701:Pulmonary Surfactant-Associated Protein B; D037721:Pulmonary Surfactant-Associated Protein C; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D011994:Recombinant Proteins