Sound and the developing infant in the NICU: conclusions and recommendations for care.

OBJECTIVE: To present the conclusions and associated recommendations for care developed by the Physical and Developmental Environment of the High-Risk Infant Center, Study Group on Neonatal Intensive Care Unit (NICU) Sound, and the Expert Review Panel. STUDY DESIGN: A multidisciplinary group of clinicians and researchers reviewed the literature regarding the effect of sound on the fetus, newborn, and preterm infant and developed recommendations based on the best evidence. An Expert Review Panel reviewed the data and conclusions. RESULTS: The following recommendations are developed from the review of the literature and are clarified in the body of the article. (1) Women should avoid prolonged exposure to low-frequency sound levels (< 250 Hz) above 65 dB(A) during pregnancy. (2) Earphones or other devices for sound production should not be used directly attached to the pregnant woman's abdomen. (3) The voice of the mother during normal daily activities, along with the sounds produced by her body and those present in her usual surroundings, is sufficient for normal fetal auditory development. The fetus does not require supplemental stimulation. Programs to supplement the fetal auditory experience cannot be recommended. (4) Infant intensive care units should incorporate a system of regular noise assessment. (5) Sound limit recommendations are to maintain a nursery with an hourly Leq of 50 dB(A), an hourly L10 of 55 dB(A) and a 1-second Lmax of 70 dB(A), all A-weighted, slow response scale. (6) Infant intensive care units should develop and maintain a program of noise control and abatement in order to operate within the recommended permissible noise criteria. (7) Care practices must provide ample opportunity for the infant to hear parent voices live in interaction between parent and infant at the bedside. (8) Earphones and other devices attached to the infant's ears for sound transmission should not be used at any time. (9) There is little evidence to support the use of recorded music or speech in the environment of the high-risk infant. Audio recordings should not be used routinely or left unattended in the environment of the high-risk infant. CONCLUSION: The recommendations, if followed, should provide an environment that will protect sleep, support stable vital signs, improve speech intelligibility for the infant, and reduce potential adverse effects on auditory development.

Clinical research data illuminating the relationship between the physical environment & patient medical outcomes.

The past 8 to 10 years have produced a large amount of information on the sensory development of the preterm infant. As a result of this information, it is evident that many of the environmental factors and care practices in the NICU do have a significant impact on infant sensory development. The factors that relate to light and noise clearly can be technologically modified to adapt better to infants' needs. Lights can be individually controlled. Focused lighting with limited scatter can be used, and a variety of techniques are available to produce barriers between light and the infant. Sound reduction and noise control in the NICUs are a constant problem. Much of the noise is generated by personnel. Much of it, however, is not essential and can be controlled. While the sound levels of the nursery do not produce any form of hearing loss, as measured by traditional hearing tests, it is now clear that they have the capacity to interfere with frequency discrimination and pattern recognition. These effects have been demonstrated in a wide range of animals and are currently under study in humans. The problems of sleep deprivation are very much tied to care practices and NICU organization. Again, the evidence supports the need for extended periods of undisturbed sleep in infants at all levels of maturity. This requires active involvement of the staff and the development of care plans and practices that allow infants clear rest periods undisturbed.

Diagnosis of pediatric human immunodeficiency virus infection by means of a commercially available polymerase chain reaction gene amplification.

OBJECTIVE: To assess the sensitivity and specificity of polymerase chain reaction (PCR) in infants and children at risk for human immunodeficiency virus (HIV) infection. DESIGN: A prospective, blinded study of 286 HIV-seropositive infants and children. Infection was diagnosed by antibody detection after 18 months of age, two positive direct tests (p24 antigen and HIV culture), or the presence of an illness that defines the acquired immunodeficiency syndrome. SETTING: University of South Florida and All Children's Hospital, St Petersburg, inpatient and outpatient centers. PARTICIPANTS: Two hundred eighty-six infants and children seropositive for HIV who were examined between July 1988 and September 1992. MAIN OUTCOME MEASURES: Sensitivity, specificity, and predictive values of a commercially available PCR test. RESULTS: Five hundred sixty-seven PCR tests were performed on samples from 286 seropositive subjects followed up for a minimum of 16 months. Of the subjects, 105 were confirmed to be infected and 181 uninfected. Overall, 96 of 105 initial PCRs in infected subjects were positive (sensitivity, 91.4%; positive predictive value, 99%). If samples obtained during the first week of life are excluded, 95 to 100 samples were positive (sensitivity, 95%). Of 181 initial PCR tests from seropositive subjects who seroreverted, 180 were negative (specificity, 99.4%,; negative predictive value, 95.2%). The predictive value of a positive test was 90.9% and that of a negative test was 93.1% in the first month of life. All 145 initial samples obtained between 5 weeks and 12 months of age correctly predicted infection status (positive predictive value, 100%). CONCLUSIONS: Gene amplification by means of a commercially available PCR is useful in the diagnosis of HIV infection for infants born to seropositive mothers. Between day 7 through 1 year of age, HIV infection is accurately diagnosed by the PCR assay.

The high-risk infant environment. Part 2. The role of caregiving and the social environment.

Neonatal intensive care units are essential for the successful care of very immature and sick infants. The technology of NICUs has contributed significantly to the reduction of neonatal mortality and improvement of neonatal outcome. While the outcome for high-risk neonates has vastly improved over the past three decades, a number of infants sustain injuries and complications that result in long-term disabilities. It is now clear that some of the long-term problems of high-risk infants are a result of the environment and care practices and are not attributable to the original disease or condition that necessitated intensive care. There is accumulating evidence that environmental factors and care practices can interact with disease processes in ways that can increase morbidity, and possibly mortality. In addition to developmental and behavioral problems, there is growing evidence of effects on visual function and perhaps other sensory systems. Many of the environmental and care factors may cause delay in recovery and increase NICU time or unnecessary discomfort, yet not produce long-term disabilities or problems, as currently assessed. Many of the potential behavioral and developmental problems, as well as many of the potential problems with visual, auditory, and other modes of sensory discrimination, are not included in the usual follow-up assessments. The absence of data or the limitations of existing studies are not a cause for comfort or the assumption that the environment and care practices are safe or not harmful.(ABSTRACT TRUNCATED AT 250 WORDS)

The association of prenatal nutrition and educational services with low birth weight rates in a Florida program.

Nutrition services and education, provided as components of normal prenatal care, have a key role in preventing preterm delivery and low birth weight (LBW). To determine the influence of these components on a woman's risk of having a LBW infant, the authors examined groups of patients who were receiving the services. Bivariate analyses were made of 9,024 prenatal charts of single births. Most women received nutrition education, prescriptions for nutrient supplements, screenings for anemia, and dietary assessments. A greater proportion of the women at high risk received the interventions than did women at lower risk. The presence of educational components and assays for anemia were associated with a lower risk of a LBW delivery in the total group and in the high risk groups.

The sensitivity and specificity of a preterm risk score for various patient populations.

Scoring systems to identify women at high risk for delivering low birthweight infants are used to place high-risk women into special prenatal clinics. The March of Dimes Birth Defects Foundation scoring system was evaluated to determine its sensitivity, specificity, and positive predictive value at each cutoff point between 0 and 20 for various patient profiles when conducted before 29 weeks' gestation. In the present study, 9014 singleton births in 1985 and 1986 from nine Florida county health units were reviewed. Scores of 1, 5, 10, and 20 provided a sensitivity of 0.96, 0.66, 0.26, and 0.02, a specificity of 0.05, 0.44, 0.86, and 0.99, and a positive predictive power of 8.7, 10.1, 15.9, and 21.1, respectively. Differences in the sensitivity and specificity of the scores existed among subsets in the study population classified by gravida, age, race, and urban or rural county. Overall, the applicability was restricted, and the positive predictive value appeared best if a cutoff point of 15 was used, which represented the upper 5th percentile of the population. It was concluded that a greater emphasis was needed to designate scores for specific subpopulations and to give more consideration to psychosocial factors associated with having low birthweight infants.

Reducing infant mortality in rural America: evaluation of the Rural Infant Care Program.

The Rural Infant Care Program (RICP), initiated in 1979, was developed to improve perinatal health care in ten rural sites with histories of high infant mortality rates. Time-series regression models indicate that neonatal mortality rates were reduced, following program initiation, by 2.6 per 1,000 live births (p = .0002); black neonatal mortality rates were reduced by an estimated 4.5 per 1,000 (p = .0004). Three sets of comparison areas exhibited no significant changes in rates. Postneonatal mortality rates did not increase in the target areas following initiation of RICP, indicating that deaths were not merely being postponed. Nine of ten individual sites showed reductions in infant mortality following program initiation. Birthweight-specific mortality data indicated that the decline was due mainly to reductions in neonatal mortality among low-birthweight infants. No reductions in the incidence of low birthweight were observed in the target areas. Substantial gaps in the delivery of prenatal care remained due to the continuing poverty of the population and the resultant lack of financial coverage for health services. We conclude that improved perinatal medical care can reduce infant mortality in poor rural areas to average levels experienced in the United States, and that the high rates still observed in some rural counties are unnecessary.

Isolated, ventilated, perfused newborn rabbit lung preparation and its assessment.

To achieve an isolated, ventilated, perfused newborn rabbit lung preparation, newborn rabbits are anesthetized and ventilated. The pulmonary vasculature is perfused with a Krebs-Ringer bicarbonate solution containing glucose and plasma expanders, and the lungs are isolated in a 37 degrees C chamber at 100% humidity. The success of a perfusion is evaluated on three levels. 1) Visual. 2)mechanical: a, drop in flow of greater than 20% indicates failure; b, an increase of more than 25% of the initial lung weight indicates fluid accumulation and failure. 3) Biochemical: a, the endogenous ATP concentration after perfusion; b, the level of the enzyme choline phosphotransferase (CPT) after perfusion. Isolated, perfused, ventilated newborn rabbit lungs maintained for 4 h with no changes in the monitored physical and mechanical parameters have an endogenous ATP level of 1.06 +/- 0.06 (2 SD) mumol ATP/mg wet weight and a CPT level of 1.34 +/-0.15 (2 SD nmol [14C]CDP-choline per milligram protein in 30 min. These values are stable at a level lower than observed in intact, hypoxic, newborn rabbit's lungs. In constrast, if perfusion is maintained after any of the monitored criteria indicate failure, the endogenous ATP concentration and CPT activity are significantly depressed.

The growth and development of low birth weight infants receiving intensive neonatal care. Preliminary observations on 28 such infants.

This study reports the growth and development of 28 survivors who had a birth weight of less than or equal to 1,000 g and were cared for at a Regional Neonatal Intensive Care Unit. Only eight (30%) had neurologic abnormalities including spastic hemiparesis, retrolental fibroplasia, hydrocephalus, motor retardation, and some delay in language skills. The other survivors had normal physical examinations and developmental progress judged by a variety of screening examinations up to age four years, three months. The average caloric intake during the first week was 61 kg/da, although over half never reached that level until day 4. Nearly all the infants have had standard growth patterns thus far.

The use of amniotic fluid bubble stability, L/S ratio, and creatinine concentration in the assessment of fetal maturity.

Amniotic fluid bubble stability and creatinine concentration are analyzed in relation to the L/S ratio and clinical outcome. Bubble stability by the standard method showed 20.5 per cent (31/151) initial disagreement between two laboratories, 53.6 per cent (81/151) correlation with L/S ratio, and did not correlate well with patient outcome. However, a "foamy" test, i.e., foam noticeable at a distance, in both 1:1 and 1:2 dilutions, indicated an elevated L/S ratio and mature pulmonary outcome. Amniotic fluid creatinine levels showed an estimated 5 to 6 per cent risk for RDS at levels we formerly thought to be safe (greater than or equal to 2.0 mg. per 100 ml. with maternal serum less than or equal to 0.9 mg. per 100 ml.), and has many false-negative values. Fetal maturity can be estimated with clinical data and amniotic fluid analysis. Amniotic fluid sampling is necessary in all instances where the clinical data leave a reasonable doubt of actual gestational age and in all cases for elective preterm delivery. We recommend a sequential approach to amniotic fluid analysis. First a bubble stability test (a "foamy" at both 1:1 and 1:2 dilutions indicates pulmonary maturity). If the bubble stability test is not "foamy", an L/S ratio. The risk of RDS associated with creatinine concentration makes this test unacceptable in any case of elective delivery; however, it may be useful as a weighing factor in emergency situations where phospholipid analysis is unavailable.

Amniotic fluid lecithin to sphingomyelin ration of 3.5 and fetal pulmonary maturity.

The clinical outcome of 118 pregnancies assessed by amniotic fluid lecithin to sphingomyelin concentration (L/S) ratio within 2 days of delivery is presented. It has been observed that the critical L/S ratio for pulmonary function is 3.5 in that no infant born with an L/ S ratio greater than 3.5 has had respiratory distress syndrome (RDS). Below an L/S ratio of 3.5, the risk and severity of RDS is inversely related to the L/S ratio. An L/S ratio smaller than 3.5 has the same prognostic value in infants born between 30 and 34 weeks gestation as it has in infants born between 35 and 38 weeks gestation. Under these conditions the relation between L/S ratio and RDS is independent of gestational age.

Oxygen consumption in fetal rabbit ductus arteriosus (38590).

Oxygen consumption in fetal rabbit ductus arteriosus and descending aorta was studied after human umbilical artery tissue was used to standardize the technique. A steady state of oxygen consjmption persisted for 90-100 min after dissection, and a tissue dry weight of greater than 15 mg was necessary to obtain reliable data, necessitating pooling of rabbit fetal tissue from 25.75-26.5 day gestation had an oxygen consumption of 2.05 plus or minus 0.22 (4) mul oxygen/10 mg dry wt/hr, and at 27.5-29.5 it was 5.69 plus or minus 0.28 (7) (P less than 0.001). There was no change with gestational age in the oxygen consumption in the descending aorta (2.15 plus or minus 0.23 mul oxygen/10 mg dry wt/hr).