Early human development
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Early human development · Jul 1991
Patterns of oxygenation during periodic breathing in preterm infants.
The characteristics of the arterial oxygen saturation (SaO2) signal during episodes of hypoxaemia (SaO2 less than or equal to 80% for greater than or equal to 4 s) associated with periodic and non-periodic apnoeic pauses were studied in 16 preterm infants with cyanotic episodes (patients). and 15 asymptomatic preterm infants (controls), matched on birthweight and gestational age. The patients showed a significantly higher percentage of apnoeic pauses followed by a hypoxaemic episode (25 vs. 6%, P less than 0.01), and a two-fold increase in the slope of the desaturation curve (8.4 vs. 4.3% per s, P less than 0.005) in periodic compared with non-periodic breathing. All other characteristic of oxygenation (baseline SaO2 before episodes of hypoxaemia, delay between onset of apnoeic pause and onset of desaturation, lowest SaO2 during episodes of hypoxaemia) were similar for periodic and non-periodic breathing patterns. ⋯ An analysis of episodes of bradycardia (less than or equal to 100 beats per minute (bpm] showed that out of 121 episodes in the patients 118 were accompanied by a fall in SaO2 to less than or equal to 80%, and in the remaining three SaO2 fell to 82%, 85% and 86%, respectively. Thus all episodes of bradycardia (less than or equal to 100 bpm) were associated with a fall in SaO2 detected by beat-to-beat pulse oximetry. Examination of hypoxaemic episodes and their relationship with bradycardia and with apnoeic pauses, periodic and non-periodic, may help the further understanding of the control of arterial oxygenation in preterm infants with cyanotic episodes.
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Early human development · May 1991
Spontaneous respiratory effort during mechanical ventilation in infants with and without acute respiratory distress.
Respiratory interactions of 27 ventilated preterm infants were recorded daily during the first 14 days of life to assess the effect on respiratory efforts of recovery from acute respiratory distress syndrome (RDS). Active expiration and persistent asynchrony only occurred during acute RDS (P less than 0.01). Throughout the 14-day period, in the majority of infants making respiratory efforts, a ventilator rate could be found from a standard sequence 30, 60, 90, 120 breaths/min which provoked a synchronous interaction, but with increasing postnatal age apnoea became more common (P less than 0.01). We conclude that the preterm infants' spontaneous respiratory efforts are a less important influence on the outcome of mechanical ventilation following recovery from acute RDS.
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The effects of ventilator rate and inspired humidity on the large airway epithelium of newborn lambs have been studied using scanning electron microscopy. Significant deciliation, denudation and necrosis occurred at both high and conventional rates if the inspired gas had low humidity. The damage observed was mild in the high humidity groups.
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Early human development · May 1988
The premature infant's respiratory response to mechanical ventilation.
Comparisons of the components of ventilator waveform were made in two groups of preterm infants ventilated for the respiratory distress syndrome. Infants actively expiring against positive pressure inflation were compared to infants not showing this interaction. ⋯ The two groups were well matched for gestational and postnatal age and there were no other significant differences in the components of ventilator waveform. Adoption of a ventilator waveform with a shorter positive pressure plateau and less steep rise in positive pressure might reduce the incidence of active expiration and hence pneumothoraces.
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Early human development · Sep 1987
Relationship of serum bilirubin levels and hearing impairment in newborn infants.
A comparison has been made between 39 infants with a birthweight of 1500 g or less and a bilirubinlevel of 240 mumol/l or above, born between January 1980 and December 1983 and 19 infants with the same criteria, born between January 1984 and December 1985. Eight of the 22 high risk and two of the 17 low risk infants were diagnosed to have sensorineural deafness (SND) during the first period and this was strongly associated with the duration of the hyperbilirubinaemia. During the second period, more active intervention for hyperbilirubinaemia led to an increased number of exchange transfusions and a marked drop in the mean duration of hyperbilirubinaemia (less than 240 mumol/l). ⋯ Impairment of the ABRs was found in four infants, with further deterioration with the persistence of high bilirubin levels in two. Although recovery of hearing thresholds was noted in all infants with impaired ABRs, an absence of wave I was noted in three infants at 6 months of age, which could indicate damage to the auditory nerve-cochlear complex. These findings suggest that hyperbilirubinaemia in itself can have an adverse effect on hearing and that careful management of hyperbilirubinaemia may reduce the incidence of sensorineural deafness.