Early human development
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Early human development · Jul 1987
Failure of observation and impedance respirography to detect active expiration in ventilated preterm infants.
Twenty preterm infants ventilated for the respiratory distress syndrome were studied on 44 occasions to identify the pattern of interaction between their spontaneous respiratory efforts and the ventilator, using three techniques: (1) an oesophageal balloon and pneumotachograph, (2) impedance respirography and (3) clinical scoring. The information was in agreement on 23 of the occasions. ⋯ This study shows that only a system incorporating an accurate assessment of the baby's own respiratory pattern is able to detect different patterns of interaction. Impedance respirography and clinical observation appear to be unsatisfactory in this context.
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Early human development · May 1985
Comparative StudyGrowth velocity and plasma alkaline phosphatase activity in the preterm infant.
The relationship between growth and plasma alkaline phosphatase activity differs in the preterm infant when compared with older children and adolescents. 18 preterm infants were studied over the first 12 postnatal weeks; growth velocity and plasma alkaline phosphatase activity were measured serially. Plasma calcium, inorganic phosphate, the vitamin D metabolites and parathyroid hormone were assayed at a median age of 3 and 6 weeks. ⋯ There was no difference in caloric intake between the groups. In the preterm infant biochemical rickets is common and unlike older children and adolescents an increase in plasma alkaline phosphatase activity correlates with decreased rather than increased growth.
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The stimulating and moderating factors of augmented inspirations provoked by artificial ventilation have been studied in 40 preterm babies on 182 different occasions. Provoked augmented inspirations were demonstrated by recording spontaneous respiratory activity during artificial ventilation by means of an oesophageal balloon and a pneumotachograph. Augmented inspirations were only seen during 18% of the study occasions. ⋯ Augmented inspirations were always provoked during the rapid rise in ventilator pressure at the onset of each inflation. Neonates who were recovering from paralysis by pancuronium and others being treated with theophylline both showed an increased frequency of augmented inspirations. It is possible that theophylline could be used to harness this advantageous reflex for the benefit of the ventilated preterm neonate.
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The respiratory response to therapeutic lung inflation by artificial ventilation in premature babies has been studied. Both the Hering-Breuer and an augmented inspiratory reflex could be provoked by ventilator inflation in neonates as premature as 25 weeks gestational age. ⋯ The frequency of elicitation of augmented inspirations was shown to be inversely related to the dynamic compliance. The relative stimulation of these two respiratory reflexes may explain why some infants are easy to ventilate and others difficult.