Developmental outcome in extremely premature infants. Impact of surfactant

Management decisions in extremely premature infants

Survival rates in excess of 25% at 23 weeks' gestation and in excess of 50% at 24 weeks' gestation have been reported among live births in the 1990s within tertiary perinatal care centres in the USA and Australia. Decisions about medical management at these gestational ages can no longer be based merely on whether survival is possible. Relevant moral considerations include the primacy of the newborn's best interests, parental autonomy, physicians' duties of beneficence and non-maleficence, and distributive justice. There is significant variability between developed nations in the survival of extremely premature infants among cohorts born within perinatal tertiary care centres. This is, at least to some degree, the result of differences in the aggressiveness of obstetrical and neonatal management at these gestational ages. There is also great variability in the prevalence of major neurodevelopmental disability among survivors. Moreover, the prevalence of major disabilities does not inform quality-of-life considerations adequately. Despite similar gestational age ranges over which the benefit:burden ratio of aggressive obstetric and neonatal care is questioned in developed countries, there is marked variation in the frequency with which it is provided within these ranges. This is understandable given the relevant moral values and the different ways in which competing values will be balanced by different individuals, cultures and societies; the increasing survival of extremely premature infants, but the persistence of high (but widely variable) prevalences of major disabilities reported among survivors and even higher prevalences of mild-to-moderate neurodevelopmental sequelae; our imperfect ability to estimate an individual extremely premature infant's prognosis; and the complexities of estimating the quality of life from the individual's own perspective.

Effect of postural supports on neuromotor function in very preterm infants to term equivalent age

OBJECTIVE

To determine the effect of a postural support nappy and/or a postural support roll on neuromotor function in very preterm infants when nursed prone to term equivalent age.

METHODS

A randomized observer blind controlled trial of 123 very preterm infants was conducted in the neonatal intensive care unit of the sole tertiary referral centre in Western Australia. Infants were stratified by gestational age (< 29 weeks or 29-30 weeks), then randomized into one of three intervention groups: postural support nappy, postural support nappy and postural support roll, or disposable nappy and postural support roll. Interventions started when infants were stable and ceased when routine side-lying commenced. Measurements of shoulder and hip posture were performed pre-intervention, 5 weeks post-intervention and term postmenstrual age.

RESULTS

Infants nursed with a postural support roll and a postural support nappy demonstrated improved hip posture to term equivalent age compared with infants nursed with either a postural support roll only, or a postural support nappy only. Infants nursed with a postural support roll either with or without a postural support nappy demonstrated improved shoulder posture to term equivalent age.

CONCLUSIONS

Combined use of a postural support roll and a postural support nappy while very preterm infants are nursed prone improves hip posture up to term postmenstrual age. Use of a postural support roll improves shoulder posture up to term equivalent age.

Human milk improves cognitive and motor development of premature infants during infancy

Thirty-nine premature infants, 29 of whom received human milk (HMG) and 10 of whom received formula only (FG), were enrolled in a study examining the effect of human milk on cognitive and motor development. Infants were assessed at 3, 7, and 12 months corrected ages; the Peabody Picture Vocabulary Test was administered to their mothers. HMG infants had higher motor scores than FG infants at 3 months (48 +/- 20 vs 35 +/- 12, P = .05) and 12 months (63 +/- 20 vs 46 +/- 15, P < .05) and higher cognitive scores at 12 months corrected age (101 +/- 11 vs 90 +/- 9, P < .05). HMG infants had higher scores (motor R2 = 0.2, cognitive R2 = 0.3; P < .05) adjusting for oxygen requirement and maternal vocabulary score. Human milk is associated with improved development of premature infants at 3 and 12 months corrected age in this sample.

Neuromotor development and the physiologic effects of positioning in very low birth weight infants

OBJECTIVE

To provide a comprehensive literature review of neuromotor development and related physiologic effects of positioning in very low birth weight infants.

DATA SOURCES

MEDLINE, CINHAL, Health Star, Current Contents, and the Australian Medical Index (1966-2000) databases were searched. Unpublished studies (e.g., dissertations, conference proceedings) and all relevant references listed in articles also were examined.

STUDY SELECTION

One hundred and eighty theoretical writings, research studies, and clinical papers related to neuromotor development, the physiologic effects of positioning, and interventions to minimize or prevent short- and long-term effects of positioning in very low birth weight infants were reviewed.

DATA EXTRACTION

Studies were assessed for scientific rigor, evidence of theoretical foundation, and clinical relevance. Comparisons were made across data sources to determine the most reliable, valid, and consistent findings.

DATA SYNTHESIS

Three compelling results emerged: (a) The development of posture and mobility in newborn infants requires an optimal balance between active and passive muscle tone, (b) the prone position is physiologically more beneficial for the preterm infant than supine and lateral positions, and (c) the prone position can lead to short- and long-term postural and associated developmental problems.

CONCLUSION

Use of empirically tested postural interventions appropriate for an infant's gestational age, health status, and overall organizational capacity is recommended.

A quantitative use of the NIDCAP tool. The effect of gender and race on very preterm neonates' behavior

The purpose of this study was to demonstrate how the check sheet of the Newborn Individualized Developmental Care and Assessment Program (NIDCAP) can be quantified and used in research. Using the quantified NIDCAP measures, the hypothesis that Caucasian male infants are less behaviorally competent while in a neonatal intensive care unit (NICU) was explored. Participants included 42 very preterm NICU infants. Eighty-five NIDCAP behaviors were quantified into scores ranging from 0 to 1, indicating the percentage of time each behavior was observed. Multivariate analyses were used in grouping the 85 NIDCAP behaviors into three subsystems of functioning. The hypothesis that Caucasian male infants were less competent was not supported; neither were gender differences found. Contrary to this hypothesis, African American infants were identified as more vulnerable on several behaviors. NIDCAP assessments were easily quantified. Once the entire NIDCAP exam has been quantified, practice applications may involve automated development of individualized care plans.

The outcome of extreme prematurity

Significant advances in perinatology and neonatology in the last decade have resulted in increased survival of extremely premature infants. Survival rates for infants born in tertiary perinatal and neonatal care centers in the United States in the 1990s increase with each week of gestational age from 22 through 26 weeks. Reported survival rates at 22 weeks range from 0% to 21% in the few reporting studies. Reported survival rates at 23 and 24 weeks range from 5% to 46% and from 40% to 59%, respectively. These may not be the maximum survival rates possible because at these gestational ages information is either insufficient to determine that obstetric and neonatal intensive care strategies to maximize neonatal survival were used or it is specified that such strategies were not used. Reported survival rates at 25 and 26 weeks range from 60% to 82% and from from 75% to 93%, respectively. The literature regarding the prevalence of major neurodevelopmental disabilities among extremely premature survivors in the last 25 years is heteogeneous, and the reported prevalances of major disability vary much more than do survival rates. However, the majority of extremely premature infants who survive will be free of major disability. Overall, approximately one fifth to one quarter of survivors have at least one major disability-impaired mental development, cerebral palsy, blindness, or deafness. Impaired mental development is the most prevalent disability (17%-21% [95% CI] of survivors affected), followed by cerebral palsy (12%-15% of survivors affected). Blindness and deafness are less common (5% to 8% and 3% to 5% of survivors affected, respectively). Approximately one half of disabled survivors have more than one major disability. Based on studies of infants less than 750 to 1,000 grams birth weight, it can be anticipated that approximately another half of all extremely premature survivors will have one or more subtle neurodevelopmental disabilities in the school and teenage years. There is little evidence to suggest that long-term neurodevelopmental outcome has changed from the late 1970s to the early 1990s or with increasing survival. Survival of individual extremely premature infants cannot be accurately predicted in the immediate perinatal period. Major disability cannot be accurately predicted for individual survivors during the course in the newborn intensive care unit.

Extreme prematurity and school outcomes

The purpose of this study was to assess the impact of extreme prematurity on three global measures of school outcomes. Using a matched cohort design, exposed infants comprised all surviving singleton infants < or = 28 weeks gestation born at one regional neonatal intensive care hospital between 1983 and 1986 (n = 132). Unexposed infants comprised randomly selected full-term infants (> or = 37 weeks gestation) frequency matched on date of birth, zip code and health insurance. All children were selected from a regional tertiary children's centre serving western New York population. Standardised telephone interviews elicited information on grade repetition, special education placement and use of school-based services. Unconditional logistic regression was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI) adjusted for potential confounders for children without major handicaps. Extreme prematurity was associated with a significant increase in risk of grade repetition (OR = 3.22; 95% CI = 1.63, 6.34), special education placement (OR = 3.16; 95% CI = 1.14, 8.76) and use of school-based services (OR = 4.56; 95% CI = 1.82, 11.42) in comparison with children born at term, even after controlling for age, race, maternal education, foster care placement and the matching factors. These findings suggest that survivors of extreme prematurity remain at risk of educational underachievement.

Outcomes of children of extremely low birthweight and gestational age in the 1990s

Advances in perinatal care have improved the chances for survival of extremely low birthweight (<800 grams) and gestational age (<26 weeks) infants. A review of the world literature reveals that among regional populations, survival at 23 weeks' gestation ranges from 2 to 35%, at 24 weeks' gestation 17 to 62% and at 25 weeks' gestation 35 to 72%. These wide variations may be accounted for by differences in population descriptors, in the criteria used for starting or withdrawing treatment, in the reported duration of survival and differences in care. Major neonatal morbidity increases with decreasing gestational age and birthweight. At 23 weeks' gestation, chronic lung disease occurs in 57 to 86% of survivors, at 24 weeks in 33 to 89% and at 25 weeks' gestation in 16 to 71% of survivors. The rates of severe cerebral ultrasound abnormality range from 10 to 83% at 23 weeks' gestation, 9 to 64% at 24 weeks and 7 to 22% at 25 weeks' gestation Of 77 survivors at 23 weeks' gestation, 26 (34%) have severe disability (defined as subnormal cognitive function, cerebral palsy, blindness and/or deafness). At 24 weeks' gestation, the rates of severe neurodevelopmental disability range from 22 to 45%, and at 25 weeks' gestation 12 to 35%. When compared with children born prior to the 1990s, the rates of neurodevelopmental disability have, in general, remained unchanged. We conclude that, with current methods of care, the limits of viability have been reached. The continuing toll of major neonatal morbidity and neurodevelopmental handicap are of serious concern.

Outcomes of children of extremely low birthweight and gestational age in the 1990's

Advances in perinatal care have improved the chances for survival of extremely low birthweight (< 800 g) and gestational age (< 26 weeks) infants. A review of the world literature and our own experience reveals that at 23 weeks gestation survival ranges from 2% to 35%. At 24 weeks gestation the range is 17% to 58%, and at 25 weeks gestation 35% to 85%. Differences in population descriptors, in the initiation and withdrawal of treatment and the duration of survival considered may account for the wide variations in the reported ranges of survival. Major neonatal morbidity increases with decreasing gestational age and birthweight. The rates of severe cerebral ultrasound abnormality range at 23 weeks gestation from 10% to 83%, at 24 weeks from 17% to 64% and at 25 weeks gestation from 10% to 22%. At 23 weeks gestation, chronic lung disease occurs in 57% to 70% of survivors, at 24 weeks in 33% to 89%, and at 25 weeks gestation in 16% to 71% of survivors. When compared to children born prior to the 1990's, the rates of neurodevelopmental disability have, in general, remained unchanged. Of 30 survivors reported at 23 weeks gestation nine (30%) are severely disabled. At 24 weeks gestation the rates of severe neurodevelopmental disability (including subnormal cognitive function, cerebral palsy, blindness and deafness) range from 17% to 45%, and at 25 weeks gestation 12% to 35% are similarly affected. In Cleveland, Ohio, we compared the outcomes of 114 children with birthweight 500-749 g born 1990-1992 to 112 infants born 1993-1995. Twenty month survival was similar (43% vs 38%). The use of antenatal and postnatal steroids increased (10% vs 54% and 43% vs 84%, respectively, P< 0.001), however the rates of chronic lung disease increased from 41% to 63% (P = 0.06). There was a significant increase in the rate of subnormal cognitive function at 20 months corrected age (20% vs 48%, P < 0.02) and a trend to an increase in the rate of cerebral palsy (10% vs 16%) and neurodevelopmental impairment. We conclude that, with current methods of care, the limits of viability have been reached. The continuing toll of major neonatal morbidity and neurodevelopmental handicap are of serious concern.

Weight-bearing patterns on the knees of preterm infants

In this study we present a method of monitoring the forces under the knees of preterm infants lying in the prone position. Dual force sensing resistor transducers, connected to optically-isolated amplifiers, were used to monitor the forces. A thermistor airflow sensor was used for the parallel monitoring of the respiratory signal. The measurements were made on ten preterm infants. The average forces were 0.51 and 0.50 N for the left and right knees, respectively. In the frequency domain, the basic harmonic of the force traces was 1.27 Hz approximately, corresponding to the respiratory rhythm. Additional, smaller harmonics, were detected in the force traces at 2.54 and 3.81 Hz. A rather notable power signal could also be seen around 0.1 Hz. The results obtained indicate that the system developed is highly sensitive for providing data on the amplitudes, periods and sequences of oscillations and symmetry of load bearing in preterm infants. Knowledge of the normal and abnormal reaction force patterns may assist in the early diagnosis of abnormal neurodevelopment.

Environmental impact of the NICU on developmental outcomes

The neonate, especially the premature one, is both dependent on and vulnerable to the intensive care environment to support physiologic and neurobehavioral organization. Concerns about this environment have led to suggestions that it may be a major contributing factor in the persistent incidence of behavioral and learning problems among preterm infants. By modifying the neonatal intensive care environment to provide a more developmentally supportive milieu, we can better meet the infant's physiologic and neurobehavioral needs, support the infant's emerging organization, and foster growth and development.

Neuropsychological and functional outcomes of very low birth weight infants

Advances in perinatal and neonatal management have resulted in a significant increase in the survival of fragile extremely low birth weight (ELBW) infants > 1,000 g at birth. The evaluation and reporting of the outcome of these infants aids in assessing the efficacy of interventions, provides data to aid in policy decisions, and provides critical information for parents and primary care providers. Comprehensive assessment of multiple domains including neurologic/neurosensory, developmental-cognitive, visual perceptual, speech/language, motor, functional skills for daily living, and Kindergarten readiness permit a total view of the child within the context of the family. Survival of VLBW infants < 800 g has steadily improved from 0% (1943 to 1945) to 49% to 70% (1994 to 1995). Rates of cerebral palsy, mental retardation, blindness, and deafness have remained stable in the 1980s and 1990s. There is evidence, however, that the percent of functional limitations may be increasing. A requirement for Special Education Resources among VLBW infants remains high at 44% to 56%. As increasing numbers of infants at the limits of viability survive, the medical community must remain vigilant in its surveillance and advocate both humanistically and scientifically for comprehensive strategies that optimize long-term functional, academic, and family outcomes.

Postnatal weight velocity patterns in very low birthweight infants

The care of very-low-birth-weight infants has improved over the years with continuing changes in medical and nutritional management. In view of these changes, there is a need to study the pattern of postnatal weight gain. Postnatal weight gain patterns of 32 very-low-birth-weight infants were examined during the first two months of life. Their mean gestational age was 29.5 +/- 2.3 weeks and mean birth weight was 1255 +/- 258 grams. The babies were weighed daily and weight changes were expressed in gram/day. All data were accurately recorded. When mean weight gain profiles were obtained by computing increments at 1, 3, 7 and 14 day intervals, the babies weight gain showed a non-linear pulsatile pattern which did not change even after full enteral nutrition had been established. This study demonstrates that weight velocity profile in very-low-birth-weight infants is not linear as expected from available standard curves and these data might therefore be considered while monitoring the adequacy of the increments of the weight gain of the individual subjects.

Problems of preterm infants after discharge

Preterm infants often experience continuing health problems after discharge and have a higher rate of readmittance to the hospital during the first year. These infants also are at risk for neurodevelopmental problems, such as language, learning, and school difficulties. The continuing health and developmental problems of preterm infants creates stress for the family. Nurses caring for these infants in hospital settings must understand the problems for which preterm infants are at risk after discharge as a basis for appropriate discharge planning and teaching. A similar knowledge base will help nurses working in community settings in assessment and interventions with infants and their families after discharge.