RESUMO
OBJECTIVE: Because meconium directly inhibits surfactant function, we sought to determine the effect of meconium on endogenous surfactant synthesis and clearance. STUDY DESIGN: We studied surfactant phosphatidylcholine kinetics with the use of stable isotopes in 11 newborn infants with meconium aspiration syndrome (MAS) who required extracorporeal membrane oxygenation (ECMO). For comparison we studied 6 neonates with persistent pulmonary hypertension (PPHN) on ECMO and 10 term neonates ventilated for non-pulmonary indications and not on ECMO. All patients received a 24-hour [U- 13C]glucose infusion as precursor for the palmitic acid in surfactant phosphatidylcholine. RESULTS: In the meconium group, the maximal 13C-incorporation in phosphatidylcholine (PC) was half of that in controls (0.09 +/- 0.01 vs 0.18 +/- 0.03 atom percent excess [APE], P = .027). There was a trend toward lower surfactant synthesis in the MAS group (3.3 +/- 0.7%/day) and PPHN group (2.6 +/- 0.3%/day) compared with controls 8.0 +/- 2.4%/day, P = .058). Significantly lower PC concentrations in tracheal aspirates were found in the MAS group (4.4 +/- 2.6 mg/mL) and PPHN group (3.6 +/- 2.0 mg/mL) compared with controls (12.8 +/- 2.6 mg/mL, P = .01). Endogenously synthesized surfactant had a similar half-life in all groups, ranging from 63 to 98 hours. CONCLUSION: We conclude that surfactant synthesis is disturbed and that surfactant PC concentrations are low in infants with MAS on ECMO.
Assuntos
Oxigenação por Membrana Extracorpórea , Síndrome de Aspiração de Mecônio/metabolismo , Fosfatidilcolinas/metabolismo , Fosfatidilcolinas/uso terapêutico , Surfactantes Pulmonares/metabolismo , Surfactantes Pulmonares/uso terapêutico , Análise de Variância , Estudos de Casos e Controles , Terapia Combinada , Feminino , Glucose/administração & dosagem , Glucose/análogos & derivados , Meia-Vida , Humanos , Recém-Nascido , Infusões Intravenosas , Masculino , Síndrome de Aspiração de Mecônio/fisiopatologia , Síndrome de Aspiração de Mecônio/terapia , Ácidos Palmíticos/metabolismo , Síndrome da Persistência do Padrão de Circulação Fetal/metabolismo , Respiração Artificial , Fatores de Tempo , Traqueia/metabolismo , Resultado do Tratamento , Ureia/administração & dosagem , Ureia/análogos & derivados , Ureia/sangueRESUMO
OBJECTIVE: We measured surfactant phosphatidylcholine (PC) pool size and half-life in human congenital diaphragmatic hernia (CDH) patients who required extracorporeal membrane oxygenation (ECMO). Study design Surfactant PC pool size and half-life were measured by endotracheal administration of deuterium-labeled dipalmitoylphosphatidylcholine in 8 neonates with CDH on ECMO (CDH-ECMO), in 7 neonates with meconium aspiration syndrome on ECMO (MAS-ECMO), and in 6 ventilated infants (NON-ECMO). RESULTS: Lung PC pool size in the CDH-ECMO group was 73 +/- 17 mg/kg (mean +/- SEM), which was not significantly different from the MAS-ECMO (50 +/- 18 mg/kg) and the NON-ECMO group (69 +/- 38 mg/kg). Surfactant PC concentration in tracheal aspirates was not different between groups (~6 mg/mL). However, the percentage of palmitic acid in surfactant PC was significantly lower in the MAS-ECMO (56.3%) and the NON-ECMO (55.8%) group compared with the CDH-ECMO (67.6%) group. Surfactant PC half-life (~24 hours) was not different between the groups. A correlation was found between the surfactant PC half-life and the duration of ECMO. CONCLUSIONS: These data show no decreased surfactant PC pool size in high risk CDH patients who require ECMO. A shorter half-life of surfactant PC, indicating a faster turnover, may result in a faster improvement of the pulmonary condition during ECMO.
Assuntos
1,2-Dipalmitoilfosfatidilcolina , Oxigenação por Membrana Extracorpórea , Hérnia Diafragmática/metabolismo , Hérnias Diafragmáticas Congênitas , Fosfatidilcolinas/análise , Deutério , Feminino , Meia-Vida , Hérnia Diafragmática/complicações , Humanos , Recém-Nascido , Marcação por Isótopo , Masculino , Síndrome de Aspiração de Mecônio/metabolismo , Síndrome de Aspiração de Mecônio/terapia , Surfactantes Pulmonares/química , Respiração Artificial , Insuficiência Respiratória/etiologia , Insuficiência Respiratória/terapiaRESUMO
OBJECTIVE: To determine if high frequency oscillatory ventilation (HFOV) decreases surfactant production in premature infants with respiratory distress syndrome (RDS). STUDY DESIGN: We randomized 19 infants <28 weeks of gestation to either HFOV (n = 8) or conventional ventilation (CV, n = 11) at 24 hours of life. After a 24-hour continuous infusion of uniformly labeled carbon 13 glucose (U-(13)C(6)) glucose, we measured (13)C enrichment in surfactant phosphatidylcholine (PC) in tracheal aspirate samples using gas chromatography/mass spectrometry. We calculated the fractional synthetic rate (FSR) of surfactant PC from labeled glucose and its half-life of clearance (T(1/2)). RESULTS: FSR did not differ between groups (4.7% +/- 2.7%/day CV vs 4.2% +/- 3.1%/day HFOV, P =.7). T(1/2) was 79 +/- 18 hours in the CV group and 76 +/- 23 hours in the HFOV group (P =.7). Neither degree of ventilatory support nor supplemental oxygen exposure correlated with surfactant metabolic indices. Three of 4 infants who died from RDS within the first month of life had a shorter T(1/2) than 14 of 15 infants who survived. CONCLUSION: Surfactant metabolism is similar in preterm infants ventilated with HFOV and CV. Shortened surfactant half-life may characterize a subset of preterm infants with lethal RDS.