Randomized placebo-controlled study on the characteristics and duration of action of surfactant treatment in premature lambs.
In a placebo-controlled study, the characteristics and duration of action of a commercially available bovine lung surfactant factor (LSF; 50 mg/kg body weight) were investigated in premature lambs at 124-127 days gestational age. Exact mating of ewes was controlled by progesterone hormone analysis. To minimize unwanted effects of narcotics through transplacental transfer to the fetus, spinal anaesthesia of the ewes was performed. The physiological status 'in utero' was demonstrated by arterial blood gas analysis (partial arterial oxygen pressure (PaO2), partial arterial carbon dioxide pressure (PaCO2) and arterial blood pH) of the fetus before umbilical cord ligature. The values for blood gases, blood pressure and lung mechanics measured after onset of ventilation and before LSF treatment were indicative of fetal maturity. Immediately after LSF treatment, PaO2 increased significantly, then decreased for about 2 h and finally stabilized on a plateau until the end of the experiment. In contrast, arterial blood pH and PaCO2 values normalized more slowly and remained normal for a longer period in the LSF group, whereas both parameters did not normalize in the placebo group. Total dynamic lung compliance also showed a slow improvement and remained on a higher level for a longer period than PaO2. Using a low respiratory rate it was possible to ventilate at lower peak inspiratory pressures and this resulted in higher compliance values. In conclusion, the presented data suggest that artificial ventilation greatly influences lung mechanics. Due to a relatively short substance effect concerning PaO2 we assume that higher or repeated doses of LSF may be necessary to produce sustained improvements in clinical trials.
Häfner
D
D
Bky Gulden Lomberg Chemische Fabrik GmbH, Department of Respiratory Pharmacology, Konstanz, Germany.
Hanauer
G
G
Kilian
U
U
Beume
R
R
Dillmann
G
G
D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005260:Female; D005312:Fetal Blood / Q000187:drug effects / Q000502:physiology; D008055:Lipids / Q000627:therapeutic use*; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D010743:Phospholipids; D010919:Placebos; D011247:Pregnancy; D011663:Pulmonary Surfactants / Q000627:therapeutic use*; D011897:Random Allocation; D012120:Respiration Disorders / Q000188:drug therapy*; D012756:Sheep; D013997:Time Factors
D008055:Lipids; D010743:Phospholipids; D010919:Placebos; D011663:Pulmonary Surfactants; C078272:SF-RI 1, bovine surfactant preparation; D002245:Carbon Dioxide; D010100:Oxygen