SURFACTANT ABNORMALITIES IN ALTE AND SIDS

Abnormalities in the relative concentrations of the components of surf actant have been implicated in prolonged expiratory apnoea (PEA) and s udden infant death syndrome (SIDS). Controversy has, however, surround ed these findings, as they may be secondary to terminal Life events. I n this study the physical properties of surfactant were measured in ch ildren with recurrent apparent life threatening events (ALTEs), PEA, a nd SIDS. Bronchial lavage samples were obtained from 21 children with recurrent ALTEs, two SIDS victims, and 26 control patients. Lipid comp onents were immediately elutriated from these samples with liquid chlo roform. The physical properties of the extracted surfactant were studi ed on a Langmuir trough in which the area (A) of the monolayer was cyc led continuously as the surface tension (gamma) was measured by the Wi lhelmy method using a platinum 'flag'. The investigators performing th ese tests were unaware of the clinical diagnosis. Twenty one of 23 pat ients displayed abnormal physical properties while seven of 26 control s displayed similar abnormalities. These abnormalities were partially inverted hysteresis (figure of eight) loops and inverted (anticlockwis e) loops that also generally exhibited less hysteresis. Of the 26 cont rols 20 exhibited a wide hysteresis pattern that cycled in a normal (c lockwise) direction. These differences were significantly different. I t is concluded that children with recurrent ALTEs have definable abnor malities in the physical properties of surfactant and that these findi ngs may provide a sensitive means of identifying those at risk of recu rrent ALTEs and SIDS.