A successful procedure for preterm infants suffering from respiratory distress syndrome (RDS) is Intubation-Surfactant-Extubation (INSURE). This is carried out as soon as possible once RDS is diagnosed, when the infant is just a few hours old, to reduce the need for mechanical ventilation and the risk of bronchopulmonary dysplasia. To allow the intubation to be done safely and comfortably, the infant must be sedated, most often with propofol. A sedative dose must be chosen to sedate the infant sufficiently so that the INSURE procedure may be carried out, but not over-sedate. It is widely agreed that dose should be quantified by amount per kilogram of the infant's body weight, but very little is known about what an optimal sedative dose may be. GSS is a composite event defined in terms of several established ordinal sedation assessment variables scored within five minutes of the first sedative administration.