Roger Baldwin

A randomized, placebo-controlled trial of effects of dexamethasone on hypothalamic-pituitary-adrenal axis in preterm infants

As part of a blinded, randomized, placebo-controlled study of dexamethasone therapy in 27 preterm infants with bronchopulmonary dysplasia, we investigated the effect of 7 days of high-dose glucocorticoid therapy on the hypothalamic-pituitary-adrenal axis. Before therapy the median basal cortisol concentration in all infants was 8.2 micrograms/dl (226 nmol/L). After stimulation with 1-24 ACTH, the serum cortisol concentration rose in all infants to a median concentration of 23.5 micrograms/dl (649 nmol/L), resulting in a median rise of 13.4 micrograms/dl (37 nmol/L). Immediately after 7 days of glucocorticoid therapy basal and peak cortisol concentrations were significantly decreased in the dexamethasone group. The rise in serum cortisol following 1-24 ACTH, however, remained equivalent in both groups. Ten days after the end of therapy basal and peak cortisol concentrations in the dexamethasone group had returned to levels equivalent to those seen in the placebo group. Weight gain was markedly diminished while the infants were receiving dexamethasone. Weight gains were, however, equivalent 10 days after the end of treatment. These data indicate that 7 days of dexamethasone therapy has significant but short-term effects on cortisol secretion and possibly on weight gain.

Circadian and Sleep Development in Preterm Infants Occurs Independently From the Influences of Environmental Lighting

This study investigated the effect of intermediate nursery illumination on circadian rhythm and sleep development of preterm infants. Preterm infants were randomly assigned to one of two intermediate nursery rooms: a dimly lighted room, the dim (control) group, or a day-night lighted room, the cycled (intervention) group. Continuous rectal temperature and sleep were recorded at 36 wk postconceptional age (before discharge) and at 1 and 3 mo corrected age at home. Forty infants, 21 in the dim group and 19 in the cycled group, were recorded. The clinical demographic data and neonatal scores were similar between groups before the intervention. Circadian rhythms and sleep showed significant development with age, but there was no environmental lighting effect. Circadian and sleep organization seems to develop endogenously in preterm infants.

Periodic breathing cycle duration in preterm infants.

ABSTRACT: Periodic breathing cycle duration (PCD), the time interval from the beginning of one respiratory pause to the beginning of the next pause within an episode of periodic breathing (PB), was measured by examination of 24-h impedance pneumograms in 51 preterm infants. Calculations of the SD of PCD within a given PB episode (~3 s) and comparison of PCD values between two PB episodes in each infant (r=0.68) revealed considerable variability in PCD. This variability was not related to the number of cycles in the PB episode or to the amount of PB in the recording. Contrary to the decrease in PCD from 15.0 s at 1 wk to 12.4 s at 12 wk in term infants reported previously, PCD did not vary as a function of postconceptional, gestational, or postnatal age in our preterm population. PCD has limited value as an indicator of chemoreceptor maturation in the preterm infant, and most likely reflects transient adjustments in respiratory system control.

TIME-LAPSE VIDEO SLEEP STATE DETERMINATION COMPARED WITH POLYSOMNOGRAPHY: RECORDING SLEEP IN PRETERM/TERM INFANTS † 973

TIME-LAPSE VIDEO SLEEP STATE DETERMINATION COMPARED WITH POLYSOMNOGRAPHY: RECORDING SLEEP IN PRETERM/TERM INFANTS † 973

Effects of Prone and Supine Position on Sleep in Preterm Infants at One Month Corrected Age

Effects of Prone and Supine Position on Sleep in Preterm Infants at One Month Corrected Age

INDIVIDUALIZED DEVELOPMENTAL CARE FOR VERY LOW BIRTH WEIGHT (VLBW) PREMATURE INFANTS: IMPROVED |[ldquo]|STATE SYSTEM CONTROL|[rdquo]| WITHOUT ADVANCED DEVELOPMENT IN SLEEP MEASURES USING THE MOTILITY MONITORING SYSTEM (MMS).

Objective: We hypothesized that individualized developmental care for the VLBW Neonatal Intensive Care Unit (NICU) infant would result in advanced sleep development (measured by the MMS). Population: We conducted sleep studies using the MMS on 28 preterm infants who were part of a larger group enrolled in the Neonatal Individualized Developmental Care and Assessment Program (NIDCAP) at Stanford. Enrollment criteria for this program included birth wt. ≤1250g and mechanical ventilation for more than 24h during the first 48h of life. Infants were randomly assigned to Intervention(INT, n=14) or Control (C, n=14) groups. Groups were similar for severity of illness. Researchers recording and scoring the sleep data were blinded. Care plans were devised and implemented for the INT infants, as described (Als et al. JAMA. 1994). C infants received routine NICU nursing care. Both INT and C infants were evaluated at 42 weeks post-conceptional age (PCA) by a blinded examiner using the Assessment of Premature Infant Behavior (APIB) tool. The APIB assesses an infants behavior in five areas or systems including“state system control” (evaluation of sleep and wake states for maturity). Methods: MMS technique used a pressure sensitive pad, amplifier, and recorder. Studies were conducted for 48 continuous hours at 36 wks PCA and at 3 mos corrected age (CA). Data were scored for states, state transitions, and out of crib time. Results: INT infants showed better sleep and wake “state system control” than C infants as measured by the APIB (p=.03). However, there was no significant difference between the two groups at either age on any MMS sleep measure. There were significant maturation effects in both groups between 36 wks PCA and 3 mos CA(% Quiet Sleep/Total Sleep Time increase: INT=11, C=6 and% Active Sleep/Total Sleep Time decrease: INT=11, C=6 all ps <0.006). Conclusion: Improved medical outcome measured by shorter time on mechanical ventilation, fewer days to full enteral feeds and decrease in length of hospitalization reported in infants who have had developmental care implemented does not appear to be associated with improvement in sleep development or in the amount of sleep. Improvement in “state system control” occurs without neurodevelopmental maturation in sleep as measured by the MMS.

A COMPARISON OF POLYSOMNOGRAPHIC (PSG) VS MOTILITY MONITORING SYSTEM (MMS) SLEEP STATE DETERMINATION DURING NAPS IN INFANTS. † 1139

A COMPARISON OF POLYSOMNOGRAPHIC (PSG) VS MOTILITY MONITORING SYSTEM (MMS) SLEEP STATE DETERMINATION DURING NAPS IN INFANTS. † 1139

1538 GROWTH FAILURE DURING DEXAMETHASONE THERAPY IN PRETERM NEONATES

Recent reports suggest that steroid treatment may improve lung function in infants with chronic lung failure. Glucocorticoid therapy has many potential toxicities, including growth failure. Growth retarding effects have been reported with 200 mg/kg of cortisol. Suggested mechanisms include inhibition of cell mitosis, loss of thymic growth factor, and increased consumption of amino acids by liver. We have noted that growth cruves of ventilator dependent infants were flat during dexamethasone (D) therapy; we retrospectively evaluated 13 such infants 27±2 wks GA, 1057±251 gms b.wt. with chronic lung failure. Parenteral D was started at mean age of 6±2 wks at a dose of 1 mg/kg/day for 4 days and 0.5 mg/kg/day for 6 days. The mean weight of the infants the week prior to treatment was 1346 gms ± 474 and 1420 gm ± 464 at the time D was started. The median daily weight change (gms) prior to and during D therapy are plotted below.This pattern was not related to differences in mean fluid intake or output for the 2 periods. These preliminary data suggest that growth during D may be impaired. Further research is needed to determine if this is a transient or long term effect.

1624 5 YEAR EXPERIENCE WITH INFANTS REFERRED FOR APNEA/ CYANOSIS

The recognition that apnea may be a possible mechanism for sudden infant death syndrome (SIDS) has led to increasing concern regarding the evaluation and management of infants who present with a history of “apnea.” Apnea has recently been defined as a respiratory pause lasting for 20 sec or longer or a shorter episode leading to cyanosis and bradycardia. The presenting event is most often witnessed by only the parents. Over the past 5 years, we have had 308 infants referred for respiratory related problems during the 1st year of life. The most frequent referral diagnosis was unexplained apnea and/or cyanosis. After extensive medical evaluation there was no diagnosis to explain the event and 173 infants (25% preterms and 75% terms) were considered “near miss for SIDS.” In 10% of these infants, a potential cause was found to explain the presenting event. In 67% of the patients there was a second event within 8 wks of the presenting episode. Thirty-one percent of patients had a documented recurrence of apnea in the hospital. In 142 patients (83%) a home apnea/cardiac monitor was recommended. The duration of home monitoring was from 1-18 mos. with a mean of 5 mos. The most common criterium for discontinuing monitoring was an apnea-free period of 1-2 mos. as reported by the parents. In the past 5 years, we have had 1 mortality and this infant was never managed on a monitor. Infants who present for evaluation of apnea are a heterogeneous group and home apnea/cardiac monitoring is helpful in the management of these patients.

1623 EVALUATION OF GASTROESOPHAGEAL REFLUX AND APNEA IN NEAR MISS FOR SIDS INFANTS

Continuous endoesophageal pH monitoring is an accepted technique to evaluate gastroesophageal reflux (GER). Although several studies have reported GER in infants who have apnea, few studies have recorded endoesophageal pH and respiration simultaneously to examine for a chronological relationship between these 2 events. We have examined 43 full-term near miss for SIDS infants (1-34 wk old; mean 10 wk) who were referred after medical evaluation, where a parent witnessed the infant to be pale or cyanotic, flaccid or stiff and vigorous stimulation or mouth-to-mouth resuscitation was needed. Endoesophageal pH, respiration (using an abdominal strain gauge) and electrocardiogram were recorded. A flexible glass pH electrode (Microelectrodes, Inc.) 1.2 mm in diameter was passed nasally into the stomach to confirm a pH < 4 then the tip was positioned with fluoroscopy at the mid-left atrial position. The pH probe was calibrated before insertion with standard buffer solutions of pH 7.0 < 4.0. Infants were monitored for a period of 18-20 hrs; they were fed and handled in the usual manner. There was a mean of 8 events (range 0-29) of pH < 4.0 of which 53% were < 1 min and 47% > 1 min. No events were longer than 30 min. 85% of recorded reflux events occurred with body movement. The majority (71%) of the GER reflux occurred when the infant was very active or awake. Apnea was not seen concurrent with a fall in pH <4.0. In this study we were unable to document an association between GER reflux and apnea.