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Eleven preterm infants with gestational age (GA) ranging from 24 to 34 weeks were observed during the neonatal period to determine state, posture, quantity and quality of motor activity, and any effect of ventilatory assistance (VA) upon these functions for the 7 VA infants in the group. Infants were observed for a 10 minute period at a specific time daily during the first week, then weekly throughout the nursery course. State was determined using Brazelton grading. Posture was recorded at the beginning of the observation. All movements of head, eyes, body and limbs were recorded according to defined categories. The predominant behavioral states observed were light sleep and dozing. No specific preference for body and/or limb posture was observed. All infants had frequent twitches and movements predominantly of the limbs which produced posture changes. Quantity of movements did not follow any particular patterns. However, a marked change in quantity of movements was usually associated with sedation and/or illness. Clonus and tremors were almost always seen in the ventilatory assisted infant, and rarely the non-respirator infants. Posture as well as quantity and quality of movements was not related to GA or conceptual age (CA). In conclusion, the serial and systematic observation of motor activity in the preterm infant confirms the time honored clinical observation that changes in motor activity may herald significant illness. In spite of previous work by others, in this group of preterm infants posture preference did not relate to GA or CA.

We assessed oxygen and carbon dioxide tension during sleep in 7 healthy preterm infants between 36 and 52 wks. conceptual age in 4 wks. intervals and related the mean values, obtained separately during both regular (without apnoea) and periodic breathing in quiet sleep to the entire profile of apnoea at each age studied. During regular breathing the mean oxygen tension gradually increased from 71 mmHg at 40 wks. to 80 mmHg at 52 wks. and the mean carbon dioxide tension decreased over the same period of time from 57 to 51 mmHg, while the total amount of apnoea showed a sharp decline from 13% at 40 wks. to 1.7% at 52 wks. Thus, there was an inverse relation between the mean oxygen tension during regular breathing (without apnoea) and the total amount of apnoea beyond 40 wks. conceptual age. During periodic breathing the mean oxygen tension also steadily increased from 63 to 73 mmHg between 40 and 52 wks. but remained always well below ( 7-10 mmHg ) the corresponding values of regular breathing. Whereas in general recurrant hypoxemia is supposed to be due to single apneic events, our data clearly show that also oxygen tension during regular breathing is related or even determined by the apnoea profile.

The mortality of premature infants has decreased over the last two decades with significantly more high risk infants surviving. Different results exist concerning the neurological outcome of these infants. Most follow-up studies were performed only with patients of single neonatal care units. In 1983 a prospective multicenter follow-up study of VLBW-infants (< 1500 g) was initiated for the whole region of Hamburg, West Germany. In the first year 125 of the surviving 147 VLBW-infants could be followed up to at least 18 months of age. In 94 % of these cases a cerebral ultrasound was performed at 64 weeks conceptual age. Major changes from periventricular leucomalacia were seen in 18 %. At 18 months of age 14 cases (11.2 %) had cerebral palsy. 9 % had signs of minimal brain dysfunction, 17 % were developmentally retarded without any neurological signs. Compared with AGA more SGA-infants were retarded at follow-up, but only one had cerebral palsy. Major changes at ultrasound examination coincided with neurological abnormalities in 90 %, 52 % had cerebral palsy. Compared with previous studies from single neonatal centers, our results are less favourable probably because of our multi-center approach covering the entire region. Permanent major periventricular changes visualized by ultrasound are of important prognostic value.

Forty low risk newborn infants were studied with conceptual ages between 28 and 42 weeks. They were distinguished from high risk infants on the basis of neonatal medical complications. Brainstem auditory evoked potentials (BAEP) were recorded from vertex-ipsilateral and contralateral ear reference sites. Monaural 70 dBHL rarefaction clicks were presented at a repetition rate of 11 per second. Both ears were tested. The peak and interpeak latencies of waves I, III and V were measured in term and preterm infants. These intervals were analyzed in relationship to conceptual age in order to assess the relative contributions of the peripheral and central portions of the auditory system to the process of infant development. Since it is expected that BAEPs will have increasing diagnostic and prognostic significance for the neurologic and otologic outcome of newborns, a short term study of these responses in relationship to risk factors is underway in our laboratory. This data forms, in part, a basis for comparison of auditory brainstem function in low and high risk infants. (Supported by USPHS Grant NS15254).