<unk> is used as a medication to treat and prevent respiratory distress syndrome in newborn babies. Prevention is generally done in babies born at a gestational age of less than 32 weeks. It is given by the endotracheal tube. Onset of effects is rapid. A number of doses may be needed. Side effects may include slow heart rate and low oxygen levels. Its use is also linked with intracranial bleeding.<unk> may be isolated from the lungs of cows or pigs or made artificially.<unk> was discovered in the 1950s and a manufactured version was approved for medical use in the United States in 1990. It is on the World Health Organization's List of Essential Medicines.
Pulmonary surfactant 
Hyalobarrier
Bruch's membrane
Fluid compartments
Reticular membrane
Schneiderian membrane
Neurotrophic factors
Endobronchial valve