Surfactant proteins and stable microbubbles in tracheal aspirates of infants with respiratory distress syndrome: relation to the degree of respiratory failure and response to exogenous surfactant.
Surfactant proteins (SP-A and SP-BC), albumin (ALB), and stable microbubble (SM) count were measured in tracheal aspirates from infants with respiratory distress syndrome (RDS) receiving single-dose Surfactant-TA (surfactant group, n = 32) or no surfactant (control group, n = 12), and those without RDS (non-RDS group, n = 8) to determine biochemical and biophysical status of surfactant in the course of RDS after surfactant replacement. Surfactant therapy resulted in immediate and sustained elevations of SP-BC/ALB and SM count with a rapid fall in ventilatory index to levels measured in the non-RDS group, whereas these indices improved slowly in the control group. The SP-A/ ALB was initially low in both RDS groups and increased to levels measured in the non-RDS group by age 48 h. Multiple regression analysis showed that SP-BC/ALB, postnatal age, SM count, SM count/SP-A plus SP-BC, and surfactant therapy were independently associated with the severity of RDS as assessed by ventilatory index (r = 0.75, P < 0.0001; number of samples = 256). Infants with a relapse response to surfactant (n = 9) had levels of SP-A/ALB and SP-BC/ALB similar to those measured in the sustained group (n = 23), but had significantly lower SM count and SM count/SP-A plus SP-BC between 24 and 96 h of age.


CONCLUSIONS
Surfactant therapy normalizes the surfactant and respiratory status of infants with RDS. Surfactant dysfunction rather than depletion may explain the relapse response seen in some surfactant recipients.
Chida
S
S
Department of Paediatrics, Iwate Medical University School of Medicine, Morioka, Japan.
Fujiwara
T
T
Konishi
M
M
Shimada
S
S
Takahashi
A
A
D000418:Albumins / Q000032:analysis; D001688:Biological Products; D015415:Biomarkers / Q000032:analysis; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011663:Pulmonary Surfactants / Q000032:analysis* / Q000627:therapeutic use*; D012044:Regression Analysis; D012127:Respiratory Distress Syndrome, Newborn / Q000188:drug therapy* / Q000503:physiopathology*; D012720:Severity of Illness Index; D013396:Suction; D014132:Trachea
D000418:Albumins; D001688:Biological Products; D015415:Biomarkers; D011663:Pulmonary Surfactants; C072197:beractant