Surfactant replacement therapy.
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Costs and Cost Analysis↗
Biomedical subjects
D J Henderson-Smart
Publications and source records attributed to D J Henderson-Smart.
A review of chest physiotherapy in neonatal intensive care units in Australia.
Clinical techniques and protocols for chest physiotherapy vary greatly from one Neonatal Intensive Care Unit to another. In 1988 a questionnaire designed to investigate differing techniques used was distributed to Neonatal Intensive Care Units (NICU) around Australia. Fourteen of the 15 questionnaires were completed and returned. The results revealed that the methods of chest treatment and the indicators for commencing chest treatment were similar throughout NICU. Both physiotherapists and nursing staff played a role in the performance of chest treatment in all but one unit where it was the responsibility of nursing staff. However, the area in which there was most variability between NICU was the individual treatment protocols employed pre- and postextubation of the neonate. A review of literature over the past 10 years also demonstrates variability in chest physiotherapy. It was concluded that further well-controlled studies with larger sample sizes are needed to validate the use of chest physiotherapy for the neonate, especially in relation to the techniques and specific protocols employed.
Australia↗
Possible causes linking asphyxia, thick meconium and respiratory distress.
The cause of fetal distress and neonatal respiratory distress (RD) in association with meconium-stained liquor is not always clear. To clarify this, a prospective study was undertaken in a tertiary referral maternity hospital for 1 year. In all infants born after meconium-stained liquor who developed RD, evidence was sought for 1) fetal distress (from the cardiotocograph (CTG), the cord blood pH, the Apgar score and the asphyxial complications in the neonate) 2) causes of fetal distress (including maternal risk factors, fetal infection and fetal malnutrition) 3) causes of respiratory distress (including meconium aspiration syndrome (MAS), persistent pulmonary hypertension of the newborn (PPHN) and infection). Of 4,026 livebirths, 717 (17.8%) had meconium-stained liquor and 44 term and 5 preterm infants developed RD. In the 44 term infants, there was frequent evidence of fetal distress possibly caused by previously unrecognized factors such as fetal malnutrition with reduced neonatal skinfold thickness in 35% triceps and 41% subscapular measurements, and histological chorioamnionitis (CA) in 74%. The cause for respiratory distress was identified in only 48% of infants, and included clinical evidence of PPHN (41%), MAS (16%) and infection (2%). However in preterm infants, 80% had definite or suspected infection. The findings indicate that fetal distress is common in infants who develop respiratory distress after meconium-stained liquor. A role for histological CA and reduced nutrition in the fetus, as factors contributing to the vulnerability of the term infant to intrapartum fetal distress, is suggested.
Apgar Score↗
Electronic fetal heart rate monitoring during labour: does it prevent perinatal asphyxia and cerebral palsy?
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Asphyxia Neonatorum↗
A longitudinal study of early leg postures of preterm infants.
The prone and supine resting postures of the pelvis and legs of 106 preterm infants (25 to 34 weeks gestation) were studied longitudinally between 30 and 38 weeks post-menstrual age. All the infants subsequently had normal motor development. Posture was graded in relation to three items: the angle of elevation of the pelvis and the weight-bearing surface of the knee in prone, and the angle of rotation of the leg in supine. Although no grade was found to be exclusive to a particular postmenstrual age, all three items showed a statistically significant progressive trend. Only less than 6 per cent of the infants regressed in grade during the study. Infants dependent on oxygen for more than 28 days had significantly lower grades for leg posture in both prone and supine. Posture was not significantly altered by time ex utero or by intra-uterine growth retardation. The results show that these observation items are suitable measures of the progressive development of antigravity postures of preterm infants.
Gestational Age↗
A modified rebreathing method to study the ventilatory response of the newborn to carbon dioxide.
Measurement of the ventilatory response of the newborn to carbon dioxide using the rebreathing method usually involves raising the concentration of oxygen in the inspired gas in order to prevent hypoxaemia developing during the test. Described here is a modified rebreathing method which avoids the need to use hyperoxic gas mixtures. Subjects rebreathed 5-7% carbon dioxide in air for 1.5-3 min; hypoxaemia was prevented by the addition of oxygen to the rebreathing circuit at the rate of approximately 7 ml/min per kg body weight. Arterial oxygen saturation (measured by a pulse oximeter) was maintained at approximately 95% throughout the tests. The technique was successfully used to study the ventilatory responses of eight full-term and 4 pre-term babies during behaviorally defined rapid-eye movement and quiet sleep. The reproducibility of the ventilatory response measured by this method was evaluated by repeated testing of each subject. This revealed considerable variability in the magnitude of the response from test to test. Some of the factors which might contribute to this variability are discussed.
Carbon Dioxide↗
Middle latency auditory evoked responses in normal term infants: a longitudinal study.
Middle latency auditory evoked responses (MLAERs) were measured in 21 normal term infants, three to five days after birth and then at 6 weeks, 7 months and 1 year of age. A polyphasic waveform was elicited during natural sleep in all infants at each recording session by monaural click stimulation at a rate of 9 per second. A 70 dBHL stimulus was found to be optimal as the MLAER became less well defined when the stimulus intensity approached the threshold hearing level. The first 60 to 70 msec of the waveform was found to be most stable, with decreasing detectability of peaks at longer latencies. There was no change in wave latency or reproducibility of MLAERs recorded during different sleep states. Waves Po and Na showed a significant decrease in latency with increasing stimulus intensity at term and/or 6 weeks of age. This was not evident for the remainder of the waveform. Waves Po, Na, Pa, Nb, Pb and Nc exhibited significant decreases in latency with age, attaining values indistinguishable from adults by 7 months of age.
Acoustic Stimulation↗
Fifth day fits in the newborn.
During the 1970s, there was an epidemic of neonatal convulsions occurring in apparently normal babies during the fourth and fifth days of life. This syndrome was noted in France as well as in Australia. A study was undertaken to review the King George V Hospital (KGV) experience with these 'fifth day fitters'. All cases of neonatal convulsions at KGV during the years 1972-85 were reviewed. A total of 94 cases of fifth day fits occurred during this period, accounting for 57% of all neonatal convulsions occurring during 1972-79. The fits occurred in healthy term infants after an uncomplicated pregnancy. They appeared on the fourth and fifth days of life. The seizures lasted an average of 24 h, were refractory to drug therapy and, despite extensive investigation, no cause was found. The infants were assessed as normal at the time of discharge from hospital. Follow-up of these infants was incomplete. However, from the data available, it cannot be assumed to be a benign entity. The 'fifth day fit' syndrome reached epidemic proportions at a number of maternity units during the 1970s. At KGV, no case has been observed since 1982.
Cross-Sectional Studies↗
Upper airway muscle activity during nasal occlusion in newborn babies.
Submental electromyorgams (SM EMG) were recorded from 20 preterm babies (gestational age 30 +/- 2 wk, postmenstrual age at study 35 +/- 2 wk) (mean +/- SD) and 3 full-term infants (7-14 days old). SM EMG was evaluated during eupnea and brief experimental airway occlusion. Phasic inspiratory SM EMG was rarely seen during eupnea. SM EMG tended to increase on the first occluded effort, although this increase was not statistically significant in most babies. All infants showed progressive breath-by-breath augmentation of phasic SM EMG during occlusions in rapid-eye-movement (REM) as well as quiet (QS) sleep; phasic increases in SM EMG were similar during REM and QS occlusions in the majority (16/22) of babies. Periods of airway closure were detected during 24 occlusions in 5 infants; phasic SM EMG was reduced on these occasions. The results are consistent with the idea that recruitment of upper airway muscles contributes to the stability of the airway of the preterm human.
Electromyography↗
Perinatal risk factors in preterm infants with moderate-to-profound hearing deficits.
The perinatal histories of 16 preterm infants with confirmed moderate-to-profound hearing loss were examined to determine the perinatal factors that might have been associated with their abnormal auditory development. Of the 11 factors that were examined, eight factors occurred significantly more frequently in hearing-impaired infants when they were compared with 226 preterm infants who were cared for in the same intensive care unit in 1984. However, when the histories of the 16 infants with hearing loss were compared with those of 16 infants with normal hearing, who were matched according to gestational age, birthweight percentile and sex, there were no differences. The prevalence of aminoglycoside therapy was high in both groups of infants, but the mean duration of therapy in the infants with a hearing deficit was significantly longer (15 days compared with eight days; P less than 0.025). These observations suggest that younger, smaller, preterm infants with a complicated perinatal course and prolonged aminoglycoside therapy are at higher risk of auditory handicap. We recommend that the early identification of preterm infants with a hearing deficit should be achieved by recording brainstem auditory-evoked responses just before discharge from the intensive care unit.
Aminoglycosides↗
Chemical control of breathing in early life.
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Acidosis, Respiratory↗
Perinatal factors and the development of chronic lung disease in preterm infants: a case control study.
A case control study of neonates was performed to determine those factors contributing to the development of chronic lung disease (CLD). During the 5 years 1981-84 there were 487 neonatal survivors at gestations of 25-32 weeks; 391 of these developed respiratory failure (oxygen therapy required for more than 6 h). Fifty-six of the latter developed CLD (oxygen therapy required for more than 28 days and a coarse reticular pattern on chest X-ray). These neonates were predominantly of the shortest gestational ages, regardless of the initial chest X-ray diagnosis. Forty-three of these infants with CLD were matched for gestation and initial chest X-ray appearance (respiratory distress syndrome, n = 20; normal, n = 15; non-specific, n = 8) with 42 control infants. The mean duration of oxygen therapy (P less than 0.001), maximum FiO2 (P less than 0.001), incidence (P less than 0.01) and duration of intermittent positive pressure respiration (IPPR; P less than 0.05) and peak IPPR (P less than 0.05) were significantly greater in the CLD group. Mean birthweight (P less than 0.001), arterial cord pH (P less than 0.05) and base excess (P less than 0.05) were significantly lower in the CLD group. Factors that were not statistically significant in the development of CLD included antenatal fetal heart rate abnormality, hypertensive disease of pregnancy, acute intrauterine infection (chorioamnionitis or umbilical vasculitis), administration of antenatal steroids, sex, patent ductus arteriosus and pneumothorax. The association between CLD and ventilator/oxygen therapy is confirmed. Contrary to other reports, male sex, clinical patent ductus arteriosus and pneumothorax were not associated with CLD.
Birth Weight↗
Screening for auditory dysfunction in high risk neonates.
Brainstem auditory evoked responses were recorded in 117 pre-term and 71 full-term infants from the general population of infants born at a referral obstetric unit. The threshold intensity required to evoke a reliable BAER was determined at different post-menstrual ages (PMAs) and in many cases at follow-up clinics. The BAER thresholds for 12 infants born and tested at less than 31 wk PMA were all greater than or equal to 50 dBHL. Sixty-two low-gestational-age infants who were tested between 31 and 36 wk PMA had BAER thresholds between less than or equal to 30 dBHL and greater than or equal to 80 dBHL. The majority of pre-term and term infants tested at term equivalent age had BAER thresholds less than or equal to 30 dBHL. Longitudinal studies also indicated that BAER thresholds can decline rapidly during the pre-term period. Follow-up studies showed that those pre-term and term infants with BAER thresholds less than or equal to 30 dBHL had normal auditory thresholds as determined using conventional behavioural testing at 4 or more months of age. Of those infants with BAER thresholds greater than or equal to 40 dBHL at the time of discharge or at term equivalent age, 67% (n = 16) were confirmed later as having a moderate to profound hearing deficit. The remaining 8 infants in this group had had BAER thresholds at term of 40 or 50 dBHL and had normal BAER and behavioural thresholds at follow-up. The cross-sectional and longitudinal data indicate that the majority of low-gestational-age infants who are at risk of hearing deficit achieve BAER thresholds less than or equal to 30 dBHL by term equivalent age. We recommend that auditory screening of infants in this group is best performed at the time of discharge from hospital or at term equivalent age, whichever is the later. Those infants with thresholds greater than or equal to 40 dBHL at that time should be encouraged to attend follow-up testing and, if high thresholds persist, they should then be referred on for behavioural testing and assessment for habilitative support.
Audiometry, Evoked Response↗
Incidence and mechanism of bradycardia during apnoea in preterm infants.
Bradycardia occurred during 363 of 1520 apnoeas of 10 seconds' duration recorded in 28 preterm infants. The incidence increased with increasing duration of apnoea (10% of 10-14 seconds, 34% of 15-20 seconds, and 75% of greater than 20 seconds, p less than 0.001). This was similar for each type of apnoea--central, mixed, and obstructive. During 133 apnoeas in five infants the time from the start of the apnoea to the onset in the fall in oxygen saturation (mean 6.9 seconds) was significantly related to the onset of the fall in heart rate (mean 9.3 seconds) (r = 0.67, p less than 0.001). Recovery in heart rate coincided with resumption of air flow rather than breathing efforts and preceded the recovery in oxygen saturation. These results suggest that bradycardia occurs during apnoea as a response to falling oxygen saturation, probably through a peripheral chemoreceptor reflex that is manifest when breathing efforts are absent or ineffective.
Bradycardia↗
Upper airway stability and apnea during nasal occlusion in newborn infants.
Brief end-expiratory airway occlusions were performed in 22 preterm babies, 17 with and 5 without clinical apnea, and 4 full-term babies, 1 with Pierre-Robin syndrome. Airway stability was evaluated by comparing pressures measured simultaneously in the chest and nasal passages during occluded inspiratory efforts. The airway remained patent throughout all 301 trials in 20 babies during rapid-eye-movement (REM) and quiet sleep. Airway closure occurred during 31/102 trials in 6 babies (5 preterm and 1 term with Pierre-Robin syndrome), more commonly in quiet than in REM sleep. Overall and within individuals, mean closing pressures were significantly lower than the mean maximum falls in airway pressure recorded during occlusions without closure. Mixed-obstructive and obstructive apnea was significantly more frequent in babies with airway closure than in those without (5.3 +/- 4.0 vs. 0.4 +/- 0.8 episodes/h). Pauses in breathing greater than or equal to 3 s occurred during 28% of occlusions in preterm infants and 2% of occlusions in full-term babies. There was no significant difference between the mean frequency of pauses during occlusion and during the preceding control period or in the incidence of pauses in occlusions with vs. those without closure. It is concluded that the airway of most preterm and full-term babies is remarkably stable under load. Intermittent closure occurs in certain infants and may be related to airway muscle dysfunction.
Airway Obstruction↗
Apnoea in the newborn infant.
Clinical apnoea in infants is defined as a pause in breathing of more than 20 s duration or a briefer pause associated with bradycardia. Such events are uncommon in term infants and usually are due to some precipitating factor. They occur more commonly in preterm infants and there is an exponential increase in incidence with decreasing gestational age at birth. Although insults such as infection or hypoxia can accentuate the problem, the major factor appears to be immaturity. Studies of brain-stem maturity using auditory evoked responses indicate that infants with immature responses have a higher incidence of apnoea. Brain-stem immaturity has also been implicated in histopathological studies of infants dying from Sudden Infant Death Syndrome (SIDS). In preterm infants, upper airway obstruction occurs commonly at the end of longer events and some infants have a predominantly obstructive pattern. These latter infants are often neurologically abnormal and have had prolonged endotracheal intubation. Both of there factors could be associated with disordered control of upper airway patency. This notion is supported by the finding of upper airway instability during nasal occlusion in these infants. A link with SIDS is uncertain, although preterm infants with chronic pulmonary insufficiency, usually following a prolonged intubation, are said to be at particularly high risk of dying suddenly and unexpectedly during infancy.
Apnea↗
The early development of head control in preterm infants.
This study documents the longitudinal development of head control in 104 infants born at 25-33 weeks gestation. Protective side turning of the head was found to have a developmental sequence of reducing spinal extension. In the 93 infants with normal motor outcome, individual differences in the rate of development correlated with caudo-cephalic muscle development (P less than 0.001, r = 0.5) but not with the length of extra-uterine experience. As a group, the 11 infants with later motor handicap showed a persistence of the early form of movement at 35-39 weeks post-menstrual age, without a significant correlation with the ratio of upper-lower limb muscle development. Head control, supine to sitting, in the infants with normal motor outcome showed variations in the rate of preterm development. The infants born at less than 31 weeks showed significantly higher scores at 33-35 weeks post-menstrual age than those born at 31-33 weeks (P less than 0.01). There was no difference at later ages. The spinal extension movement accompanying protective side turning of the head is age specific to the preterm infant. Individual rates of normal preterm development can be evaluated by longitudinal standardised examination. As a group, the infants with subsequent abnormal motor development showed delay at preterm age but this was not individually significant.
Cerebral Palsy↗
Peripheral nerve conduction velocity and brainstem auditory evoked responses in small for gestational age preterm infants.
Ulnar nerve conduction velocity (NCV) and brainstem auditory evoked responses (BAER) were measured in each of 11 preterm small for gestational age (SGA) infants born at less than 35 weeks gestation. The mean motor NCV in the SGA infants was similar to that reported for infants who were appropriately grown for their gestational age (AGA). However, the mean central conduction time of the BAER in SGA infants was significantly shorter than that of AGA infants of the same post-menstrual age. Thus, the precocious development of auditory brainstem neural function in preterm SGA infants is not accompanied by changes in functional maturation of the peripheral motor nerves.
Brain Stem↗