- Email: [email protected]
Shedding light on the very low birth weight infant
Shedding light on the very low birth weight infant In the study by Kennedy et al,1 reduced lighting via goggles from birth to 31 weeks’ postconceptional age (minimum of 4 weeks), did not improve medical outcomes; that is, the outcomes were similar in the group of very low birth weight (VLBW) infants who were exposed to continuous light. These data were secondary findings from the LIGHT-ROP Cooperative Group Study.2 Few areas in neonatology have remained as controversial as the design of neonatal intensive care nurseries, and particularly, the recommendation for lighting. Although developmental neurobiologists, health providers, neonatal care specialists, and nursery architects have generated many ideas about the types and patterns of environmental stimulation that may optimize the compromised development of preterm infants, there is no scientific consensus on what constitutes an “appropriate” environment. Some investigators favor natural day-night rhythm in the nursery,3 while others are in support of continuous dim light (“womb environment”).4 It is well known that VLBW preterm infants are at higher risk for blindness caused by retinopathy of prematurity (ROP). For many years, parents of children who have acquired blindness caused by ROP have blamed the chaotic lighting of the nursery. Glass et al5 raised the concern that the continuous light exposure in neonatal intensive care units (NICUs) may increase the incidence and severiReprint requests: Ronald L. Ariagno, MD, Department of Pediatrics, Stanford University School of Medicine, 750 Welch Rd, Suite 315, Palo Alto, CA 94304.
J Pediatr 2001;139:476-7. Copyright © 2001 by Mosby, Inc. 0022-3476/2001/$35.00 + 0 9/18/118879 doi:10.1067/mpd.2001.118879
476
ty of ROP. In response to these legitimate concerns about the potential adverse effects of light on retinal development, the National Institutes of Health supported a large multicenter trial to examine the effect of severe reduction of light on visual development from the moment of birth in VLBW preterm infants. The study showed no change in the incidence of ROP, blindness, or other major visual defects. 2 It is important to emphasize that the retina is indeed a part of the central nervous system (CNS). Developmental neurobiologists, for many years, have established a critical window for maturation in many CNS structures. During a critical period, the structure, for example, the retina and visual cortex, may be developmentally responsive or very vulnerable to environmental perturbation; however, at an earlier or later CNS NICU ROP VLBW
Central nervous system Neonatal intensive care Retinopathy of prematurity Very low birth weight
stage of development, there may be no or less effect on the CNS. The critical period for light stimulation in the human infant retina is not well studied (and we emphasize human, because the time course of CNS development in humans is unique and not comparable to that of any other mammals, including other primates). Although the rate of severe ROP is greater in the more immature infants (eg, 20% in infants <1000 g birth weight and <1% in infants >1500 g birth weight), both groups may experience chaotic lighting in the same nursery for several weeks. One can speculate that the window of retina sensitivity to environmental light may be longer or at least different in the infants with birth
weights of <1000 g. Many investigators have also argued that because they were not able to inhibit light immediately after birth, this may account for their negative results.1,2 We find this explanation very unlikely and probably less significant than other factors, such as the extracellular environment of the retina, its immaturity, and sensitivity to free radicals and toxic levels of amino acids.
See related article, p 527. Kennedy et al1 report that reduced lighting until 31 weeks’ postconceptional age had no effect on length of stay, growth, or duration of mechanical ventilation and supplemental oxygen. This prospective randomized study design had advantages over other environmental lighting interventions in previous reports in that the goggles were more effective in maintaining light reduction for the infant and eliminated the environmental lighting effect on the care givers. The investigators did not have funding to support evaluation of the long-term outcome of this unique randomized group (enrolled since 1995). This is unfortunate because a recent study from the Cryotherapy for Retinopathy of Prematurity Cooperative Group showed that the severity of ROP is predictive of neurodevelopmental outcome at 5.5 years of age.6 We agree with Kennedy et al1 that reduced lighting has no measurable clinical benefit7 and have presented arguments in favor of cycled lighting based on the available peer-reviewed literature.3 Thus, it is reasonable to make NICUs more developmentally appropriate through elimination of chaotic lighting and sound and by using a natural, gradual, dawn-and-
EDITORIALS
THE JOURNAL OF PEDIATRICS VOLUME 139, NUMBER 4 dusk transition of the light-dark cycle from the time of birth and admission to the NICU. Some investigators who propose a NIDCAP (Neonatal Individualized Developmental Care Assessment Program) intervention approach to preterm infant care believe that bundling infants in a dark, confined crib mimics an in utero condition. They have assumed that achieving a near-dark lighting environment is one of the most important factors; however, the biologic reality is that the intrauterine environment is a rhythmic environment highly controlled by interactions between maternal-fetal hypothalamus and placenta.3 For instance, maternal cortisol and melatonin convey information about the lightdark cycle to the fetus, thereby synchronizing the developing fetus’s biologic clock to the 24-hour cycle. These essential prenatal influences are largely underestimated and disregarded when a sign of “Do Not Disturb” is put
up on a crib in a continuously darkened room. The study by Kennedy et al1 provides important additional data that indicate that reduced lighting provides no measurable benefit. Ronald L. Ariagno, MD Department of Pediatrics Stanford University School of Medicine Palo Alto, CA 94304 Majid Mirmiran, MD, PhD Netherlands Institute for Brain Research 1105 AZ, Amsterdam The Netherlands
REFERENCES 1. Kennedy KA, Fielder AR, Hardy RJ, Tung B, Gordon DC, Reynolds JD. Reduced lighting does not improve medical outcomes in very low birth weight infants. J Pediatr 2001;139:···. 2. Reynolds JD, Hardy RJ, Kennedy KA, Spencer R, van Heuven WAJ, Fielder AR. Lack of efficacy of light reduction in preventing retinopathy of prematurity. N Engl J Med 1998; 338:1572-6.
3. Mirmiran M, Ariagno RL. Influence of light in the NICU on the development of circadian rhythms in preterm infants. Semin Perinatol 2000;24:247-57. 4. Als H, Lawhon G, Duffy FH, McAnulty GB, Gibes-Grossman R, Bickman JR. Individualized developmental care for very low birth weight infant: medical and neurofunctional effects. JAMA 1994;272:853-8. 5. Glass P, Avery GB, Subramanian KN, Keys MP, Sostek AM, Friendly DS. Effect of bright light in the hospital nursery on the incidence of retinopathy of prematurity. N Engl J Med 1985;313:401-4. 6. Msall ME, Phelps DL, DiGaudio KM, Dobson V, Tung B, McClead RE, et al. Severity of neonatal retinopathy of prematurity is predictive of neurodevelopmental functional outcome at age 5.5 years. Behalf of the Cryotherapy for Retinopathy of Prematurity Cooperative Group. Pediatrics 2000;106:998-1005. 7. Ariagno RL, Thoman EB, Boeddiker MA, Kugener B, Constantinou JC, Mirmiran M, et al. Developmental care does not alter sleep and development of premature infants. Pediatrics 1997;100:e9.
Access to The Journal of Pediatrics Online is reserved for print subscribers! Full-text access to The Journal of Pediatrics Online is available for all print subscribers. To activate your individual online subscription, please visit The Journal of Pediatrics Online, point your browser to http://www.mosby.com/jpeds, follow the prompts to activate online access here, and follow the instructions. To activate your account, you will need your subscriber account number, which you can find on your mailing label (note: the number of digits in your subscriber account number varies from 6 to 10). See the example below in which the subscriber account number has been circled: Sample mailing label
This is your subscription account number
**************************3-DIGIT 001 SJ P1 FEB00 J009 C: 1 1234567-89 U 05/00 Q: 1 J. H. DOE, MD 531 MAIN ST CENTER CITY, NY 10001-001
Personal subscriptions to The Journal of Pediatrics Online are for individual use only and may not be transferred. Use of The Journal of Pediatrics Online is subject to agreement to the terms and conditions as indicated online. 477
J Pediatr 2001;139:476-7. Copyright © 2001 by Mosby, Inc. 0022-3476/2001/$35.00 + 0 9/18/118879 doi:10.1067/mpd.2001.118879
476
ty of ROP. In response to these legitimate concerns about the potential adverse effects of light on retinal development, the National Institutes of Health supported a large multicenter trial to examine the effect of severe reduction of light on visual development from the moment of birth in VLBW preterm infants. The study showed no change in the incidence of ROP, blindness, or other major visual defects. 2 It is important to emphasize that the retina is indeed a part of the central nervous system (CNS). Developmental neurobiologists, for many years, have established a critical window for maturation in many CNS structures. During a critical period, the structure, for example, the retina and visual cortex, may be developmentally responsive or very vulnerable to environmental perturbation; however, at an earlier or later CNS NICU ROP VLBW
Central nervous system Neonatal intensive care Retinopathy of prematurity Very low birth weight
stage of development, there may be no or less effect on the CNS. The critical period for light stimulation in the human infant retina is not well studied (and we emphasize human, because the time course of CNS development in humans is unique and not comparable to that of any other mammals, including other primates). Although the rate of severe ROP is greater in the more immature infants (eg, 20% in infants <1000 g birth weight and <1% in infants >1500 g birth weight), both groups may experience chaotic lighting in the same nursery for several weeks. One can speculate that the window of retina sensitivity to environmental light may be longer or at least different in the infants with birth
weights of <1000 g. Many investigators have also argued that because they were not able to inhibit light immediately after birth, this may account for their negative results.1,2 We find this explanation very unlikely and probably less significant than other factors, such as the extracellular environment of the retina, its immaturity, and sensitivity to free radicals and toxic levels of amino acids.
See related article, p 527. Kennedy et al1 report that reduced lighting until 31 weeks’ postconceptional age had no effect on length of stay, growth, or duration of mechanical ventilation and supplemental oxygen. This prospective randomized study design had advantages over other environmental lighting interventions in previous reports in that the goggles were more effective in maintaining light reduction for the infant and eliminated the environmental lighting effect on the care givers. The investigators did not have funding to support evaluation of the long-term outcome of this unique randomized group (enrolled since 1995). This is unfortunate because a recent study from the Cryotherapy for Retinopathy of Prematurity Cooperative Group showed that the severity of ROP is predictive of neurodevelopmental outcome at 5.5 years of age.6 We agree with Kennedy et al1 that reduced lighting has no measurable clinical benefit7 and have presented arguments in favor of cycled lighting based on the available peer-reviewed literature.3 Thus, it is reasonable to make NICUs more developmentally appropriate through elimination of chaotic lighting and sound and by using a natural, gradual, dawn-and-
EDITORIALS
THE JOURNAL OF PEDIATRICS VOLUME 139, NUMBER 4 dusk transition of the light-dark cycle from the time of birth and admission to the NICU. Some investigators who propose a NIDCAP (Neonatal Individualized Developmental Care Assessment Program) intervention approach to preterm infant care believe that bundling infants in a dark, confined crib mimics an in utero condition. They have assumed that achieving a near-dark lighting environment is one of the most important factors; however, the biologic reality is that the intrauterine environment is a rhythmic environment highly controlled by interactions between maternal-fetal hypothalamus and placenta.3 For instance, maternal cortisol and melatonin convey information about the lightdark cycle to the fetus, thereby synchronizing the developing fetus’s biologic clock to the 24-hour cycle. These essential prenatal influences are largely underestimated and disregarded when a sign of “Do Not Disturb” is put
up on a crib in a continuously darkened room. The study by Kennedy et al1 provides important additional data that indicate that reduced lighting provides no measurable benefit. Ronald L. Ariagno, MD Department of Pediatrics Stanford University School of Medicine Palo Alto, CA 94304 Majid Mirmiran, MD, PhD Netherlands Institute for Brain Research 1105 AZ, Amsterdam The Netherlands
REFERENCES 1. Kennedy KA, Fielder AR, Hardy RJ, Tung B, Gordon DC, Reynolds JD. Reduced lighting does not improve medical outcomes in very low birth weight infants. J Pediatr 2001;139:···. 2. Reynolds JD, Hardy RJ, Kennedy KA, Spencer R, van Heuven WAJ, Fielder AR. Lack of efficacy of light reduction in preventing retinopathy of prematurity. N Engl J Med 1998; 338:1572-6.
3. Mirmiran M, Ariagno RL. Influence of light in the NICU on the development of circadian rhythms in preterm infants. Semin Perinatol 2000;24:247-57. 4. Als H, Lawhon G, Duffy FH, McAnulty GB, Gibes-Grossman R, Bickman JR. Individualized developmental care for very low birth weight infant: medical and neurofunctional effects. JAMA 1994;272:853-8. 5. Glass P, Avery GB, Subramanian KN, Keys MP, Sostek AM, Friendly DS. Effect of bright light in the hospital nursery on the incidence of retinopathy of prematurity. N Engl J Med 1985;313:401-4. 6. Msall ME, Phelps DL, DiGaudio KM, Dobson V, Tung B, McClead RE, et al. Severity of neonatal retinopathy of prematurity is predictive of neurodevelopmental functional outcome at age 5.5 years. Behalf of the Cryotherapy for Retinopathy of Prematurity Cooperative Group. Pediatrics 2000;106:998-1005. 7. Ariagno RL, Thoman EB, Boeddiker MA, Kugener B, Constantinou JC, Mirmiran M, et al. Developmental care does not alter sleep and development of premature infants. Pediatrics 1997;100:e9.
Access to The Journal of Pediatrics Online is reserved for print subscribers! Full-text access to The Journal of Pediatrics Online is available for all print subscribers. To activate your individual online subscription, please visit The Journal of Pediatrics Online, point your browser to http://www.mosby.com/jpeds, follow the prompts to activate online access here, and follow the instructions. To activate your account, you will need your subscriber account number, which you can find on your mailing label (note: the number of digits in your subscriber account number varies from 6 to 10). See the example below in which the subscriber account number has been circled: Sample mailing label
This is your subscription account number
**************************3-DIGIT 001 SJ P1 FEB00 J009 C: 1 1234567-89 U 05/00 Q: 1 J. H. DOE, MD 531 MAIN ST CENTER CITY, NY 10001-001
Personal subscriptions to The Journal of Pediatrics Online are for individual use only and may not be transferred. Use of The Journal of Pediatrics Online is subject to agreement to the terms and conditions as indicated online. 477