Alex Robertson

Recommended Permissible Noise Criteria for Occupied, Newly Constructed or Renovated Hospital Nurseries

OBJECTIVE:To base permissible noise criteria for occupied, new nurseries on research findings.STUDY DESIGN:An interdisciplinary group of clinicians reviewed the literature regarding the effect of sound on the fetus, newborn, and preterm infant and based recommended criteria on the best evidence. An external panel subsequently reviewed the criteria.RESULTS:The recommended criteria: Patient bed areas and the spaces opening onto them shall be designed to produce minimal ambient noise and to contain and absorb much of the transient noise that arises within the nursery. The overall, continuous sound in any bed space or patient care area shall not exceed: (1) an hourly Leq of 50 dB and (2) an hourly L10 of 55 dB, both A-weighted, slow response. The 1-second duration Lmax shall not exceed 70 dB, A-weighted, slow response.CONCLUSION: The permissible noise criteria will protect sleep, support stable vital signs, and improve speech intelligibility for many infants most of the time.

Improved transcutaneous bilirubinometry: comparison of SpectR(X) BiliCheck and Minolta Jaundice Meter JM-102 for estimating total serum bilirubin in a normal newborn population.

OBJECTIVE: To compare a new transcutaneous bilirubinometer, which uses multiple wavelength analysis of reflectance data (BiliCheck system), and the commonly used two-wavelength bilirubinometer (Jaundice Meter JM-102) to estimate serum bilirubin.STUDY DESIGN: Jaundiced newborn term infants (101 babies) had transcutaneous bilirubinometry (TCB) using each bilirubinometer, a determination of skin color using a skin color chart, and a total serum bilirubin determination.RESULTS: The variability of the BiliCheck system was less than the variability of the Jaundice Meter JM-102. The accuracy of the BiliCheck system was not affected by skin color, whereas the Jaundice Meter JM-102 was affected.CONCLUSION: Multiple wavelength analysis, as used in the BiliCheck system, is a significant improvement in TCB.

Bilirubin Displacing Effect of Drugs Used in Neonatology

In 1956, Silverman et al. (1 ) reported an increased incidence of kernicterus in premature infants receiving prophylactic penicillin and sulfisoxazole. In 1959, Ode11 (2) showed that sulfisoxazole competes with bilirubin for albumin binding and that this mechanism was the likely cause of kernicterus in the Silverman study. Since that time there have been no reported drug-related instances of kernicterus. The apparent absence of cases of iatrogenic kernicterus may result form the fact that few drugs compete strongly with bilirubin for albumin binding. Since Brodersen’s preliminary review of drug effects on bilirubin-albumin binding (3), only a few drugs have been added to the list of those which strongly interact with bilirubin. Another explanation which is more worrisome is that we cannot recognize kernicterus clinically in the very small, very sick premature infant, and, on follow-up of these babies, we cannot deduce which treatment or condition relates to a poor outcome. Therefore, we may be, unwittingly, causing adverse effects. For this reason, we believe every drug which may be used in newborn infants should be tested for its effect on bilirubin-albumin binding, as already suggested by Stern in 1972 (4). Every year additional drugs are introduced to clinical use in neonatal medicine. Many of these are not licensed for use in newborn infants but are prescribed by neonatologists. Even those licensed for use in newborn infants may not have been tested for their effect on bilirubin-albumin binding. Governmental authorities do not require such testing. In other cases the drugs may have been tested using inappropriate methods and reported, erroneously, to be safe or not safe. An approach to drug testing, which we believe is reasonable, has previously been developed (5). Using this approach we try to answer the following questions. 1) Which drugs, among those used in newborns, need testing? 2) What are the criteria for selecting available methods? 3) Which principles should the neonatologist apply when choosing drugs in order to avoid, as far as possible, the risk of bilirubin displacement? In addition, we present the results of testing most of the drugs used in neonatal medicine at this time.

Reflections on Errors in Neonatology: I. The “Hands-Off” Years, 1920 to 1950

This series discusses errors in neonatology since the 1920s. Three historical periods are defined: the “Hands-Off” years, 1920 to 1950; the “Heroic” years, 1950 to 1970; and the “Experienced” years, 1970 to 2000. In this article, the “Hands-Off” years, we discuss lowered thermal environment, supplemental oxygen, initial thirsting and starving, synthetic vitamin K, SMA formula, and diaper markings.

Reflections on errors in neonatology III. The "experienced" years, 1970 to 2000.

The first two articles of this series dealt with errors in neonatology, which occurred during the ‘‘Hands Off’’ years (1920 to 1950) and the ‘‘Heroic’’ years (1950 to 1970). From 1970 on, we call the ‘‘Experienced’’ years. This period is characterized by a refinement of the methods and treatments introduced in the earlier periods. The algorithms of neonatal intensive care become similar around the world. Some new treatments are studied before being generally accepted. Randomized controlled trials are more common. Organizations such as the FDA and committees of the American Academy of Pediatrics are more involved in assessing problems and making recommendations. Institutional research review boards become more authoritative, and there seem to be fewer errors. Perhaps we have learned from these past experiences. However, that may not be true. The increased complexity of our care and of our patients may simply make errors less apparent. In this article, we will discuss problems with infant formulas, ‘‘inactive’’ ingredients in drugs, erythromycin, steroids and conclude with an analysis of the causes of errors and ways to avoid errors in the future.

Sound transmission into incubators in the neonatal intensive care unit.

OBJECTIVE:To measure the attenuation of sound by modern incubators.STUDY DESIGN:LEQ, LMAX, LPEAK, and frequency distribution were measured simultaneously inside and outside two recent model incubators.RESULTS:The attenuation of sound (outside minus inside) was 15 to 18 dBA with the motor off and 4 to 8 dBA with the motor on. There was a significant difference between incubators in their attenuation of sound. Octave band analysis showed attenuation in frequency bands of >31.5 Hz with the motor off. With the motor on, the sound level inside the incubator was higher than outside at frequency bands of <250 Hz.CONCLUSION: Caring for infants inside modern incubators reduces “averaged” sound exposure to levels near those recommended for the neonatal intensive care unit. Lower frequency sounds are louder inside the incubator and arise from the incubator motor.

Effect of melanin, oxyhemoglobin and bilirubin on transcutaneous bilirubinometry

To determine the effect of skin pigments on transcutaneous bilirubinometer readings, we measured the effect of bilirubin, melanin, and oxyhemoglobin solutions on transcutaneous bilirubinometer readings in vitro. Our results showed that the variability of the readings in vitro was related to the instruments non‐linear response to bilirubin and melanin concentration and an inacurate oxyhemoglobin correction factor. These factors should be considered in developing a more accurate non‐invasive method of monitoring serum bilirubin concentration.

Reflections on Errors in Neonatology: II. The “Heroic” Years, 1950 to 1970

This series errors in neonatology since the 1920s. Three historical periods are defined: the “Hands-Off” years from 1920 to 1950, the “Heroic” years from 1950 to 1970, and the “Experienced” years from 1970 on. In this article, the “Heroic” years, we discuss the Blossom air lock, sulfisoxazole, chloramphenicol, novobiocin, hexachlorophene, Epsom salts enemas, feeding gastrostomy, diaper laundering, and equipment cleaning.

The Effect of Hydrocortisone, Thyroxine, and Phenobarbital on Diamine Oxidase Activity in Newborn Rat Intestine

ABSTRACT: There is a reported association between administration of prenatal glucocorticoids and a decreased incidence of necrotizing enterocolitis in human infants. In rats, the degree of ischemic bowel disease correlates negatively with intestinal diamine oxidase (E.C. 1.4.3.6) activity. Since the administration of hydrocortisone, thyroxine, or phenobarbital to newborn rat pups affects the development of intestinal enzymes, we were interested in knowing whether hydrocortisone, thyroxine, or phenobarbital specifically affect intestinal diamine oxidase activity. We injected rat pups with hydrocortisone sodium succinate, 1- thyroxine pentahydrate, sodium salt, sodium phenobarbital, or the control solution on days 4, 6, 8, or 10 of life (phenobarbital, days 3, 5, 7, or 9). Pups were injected 3 days consecutively (phenobarbital, 4 days), and all were sacrificed on days 7, 9, 11, and 13. Intestinal diamine oxidase and intestinal invertase (E.C. 3.2.1.26) activities were measured. Invertase was used as a control enzyme because it is known to be induced by glucocorticoid hormones. We found that the hydrocortisone-injected pups had 10-fold higher specific activity of invertase than the saline-injected animals. Diamine oxidase activity was significantly higher in the group receiving hydrocortisone and sacrificed on days 7, 9, and 11. Enzyme activity in both the hydrocortisone-injected and saline-injected groups was equal on day 13, as was enzyme activity on all days in the thyroxine-injected and sodium hydroxide-injected groups, and the phenobarbital-injected and the saline-injected groups. Our results suggest that diamine oxidase activity may be induced by hydrocortisone, but is not affected by thyroxine or phenobarbital.

Transmission Loss of Sound Into Incubators: Implications for Voice Perception by Infants

OBJECTIVE:To assess the transmission of sound into incubators as a function of talker position (i.e., standing or sitting), incubator port position (i.e., opened or closed), and center frequency (i.e., 125 to 10,000 Hz in one-third octave steps). The second objective was to estimate the audibility of the human voice inside the incubator.STUDY DESIGN: L eq measures of signal transmission loss and motor noise were obtained from two incubators.RESULTS:In general, signal transmission loss was greater for the standing-talker position, with front portholes closed, and for high-frequency spectra. Motor noise was greater with both front portholes closed and for lower-frequency spectra. The greatest signal delivery to an infant would be obtained when the speaker is sitting using a raised vocal effort while the incubator ports are opened.CONCLUSION:Measured signal transmission loss and motor noise characteristics of two incubators suggest that only mid-frequency speech spectra would be audible to infants and only at a speech-to-noise ratio of approximately 5 to 10 dB with a raised vocal effort.