“Night and day, you are the one” – Cycled light exposure in the NICU.


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Light influences the health and behavior of human beings. The effects of light on premature infants and particularly on those of very low birth weight have not yet been satisfactorily researched. On neonatal intensive care units (NICU) different types of light exposure have been and are being practiced: 1. Uninterrupted light exposure (UL), 2. Dimmed light (DL), 3. Near darkness (ND), and 4. Cycled light exposure (CL) – rotating light and darkness every twelve hours.

In the 1980s, bright UL of 600 to 1,000 lux was standard on NICUs. With improvements in the technical possibilities and new scientific findings, light management has changed considerably. Even in phases of brighter illumination today, the high lux values of the 1980s are no longer reached. In 1997, the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG) already issued a new recommendation with CL as the standard (1). The background of this recommendation was the appearance of studies from the mid-1980s which indicated that bright uninterrupted light is apparently damaging for preterm babies and is accompanied by stress manifestations such as increased activity levels, reduced sleep and bradydardia. Other studies also pointed to positive effects of CL related to weight, sleep (rhythm), activity, crying, and the length of time until a 24-hour rhythm is established. In addition to the possible effects on the premature infants, it also was assumed that the selected light exposure would have an influence on the medical personnel and the parents of the babies. Continuous half-light and continuous bright light could have negative effects on the hospital personnel and the parents and trigger disturbances in their circadian rhythms.

Light influences the health and behavior of human beings. The effects of light on premature infants and particularly on those of very low birth weight have not yet been satisfactorily researched. On neonatal intensive care units (NICU) different types of light exposure have been and are being practiced: 1. Uninterrupted light exposure (UL), 2. Dimmed light (DL), 3. Near darkness (ND), and 4. Cycled light exposure (CL) – rotating light and darkness every twelve hours.

In the 1980s, bright UL of 600 to 1,000 lux was standard on NICUs. With improvements in the technical possibilities and new scientific findings, light management has changed considerably. Even in phases of brighter illumination today, the high lux values of the 1980s are no longer reached. In 1997, the American Academy of Pediatrics (AAP) and the American College of Obstetricians and Gynecologists (ACOG) already issued a new recommendation with CL as the standard (1). The background of this recommendation was the appearance of studies from the mid-1980s which indicated that bright uninterrupted light is apparently damaging for preterm babies and is accompanied by stress manifestations such as increased activity levels, reduced sleep and bradydardia. Other studies also pointed to positive effects of CL related to weight, sleep (rhythm), activity, crying, and the length of time until a 24-hour rhythm is established. In addition to the possible effects on the premature infants, it also was assumed that the selected light exposure would have an influence on the medical personnel and the parents of the babies. Continuous half-light and continuous bright light could have negative effects on the hospital personnel and the parents and trigger disturbances in their circadian rhythms.

In earlier times when the technology was not as sophisticated, continuous bright light exposure was necessary because optical inspection of the infant was essential for diagnostic purposes. With the development of modern diagnostictechnology, the medical establishment distanced itself from the use of continuous bright illumination. The literature, however, also warns of the effects of too little sensory stimulation coming from continuous half-light. Even though dark surroundings are the natural physiological condition for the fetus, there are other factors which stimulate its neurosensory development that are missing outside of the mother’s body (4). Light exposure could presumably partially compensate for these factors in preterm newborns. As far as the commencement of cycled light exposure is concerned, different starting points are discussed. Because the neuronal system is still immature prior to the 32nd week, some researchers recommend that CL not be used for preterm newborns prior to this time. Only a few studies have looked at the direct comparison between the two light exposure options and there is insufficient evidence currently to confirm this recommendation. Entirely independent of what type of light management is used, premature infants sleep longer during the night and adjust sooner to a 24-hour sleep-wake cycle than full-term infants.

Cochrane Review evaluated the influence of cycled light exposure

The Cochrane Review published on the subject of “Cycled light in the intensive care unit for preterm and low birth weight infants” for the first time in 2011. In 2016, this review was updated and includes a literature evaluation from 1966 to 2016 (2). One of the studies that has now been included in the new review gives clear support to the supposition that CL shortens the time in hospital in comparison to UL and ND. In the current review, nine studies with 544 infants were included meeting the criteria of an RCT or quasi-RCT study with a satisfactory design. Six of these studies included data from a total of 424 infants and dealt with the varying effects of CL and ND (5), (6); (7); (8); (4); (1). The three additional studies were based on a collective cohort of 120 infants and investigated the effects of CL versus UL (9); (10); (11).

Results “cycled light exposure” compared to “near darkness”

Length of hospital stay: Two studies (7, 1) with a total of 77 infants (CL starting at the 32nd week) measured the length of hospital stay and described an overall significant reduction in length of stay in favor of the CL group versus ND with a mean difference of 13 days.  The researchers in one study (8) reference in the abstract their own earlier research results showing 39 infants with significantly shorter hospital stays.

Day-night activity: In one study (4) with 62 infants which studied the ratio of day-night activity until hospital discharge, there was a significant benefit for the CL group. 18 percent more daytime than nighttime activity was measured in the CL group.

Total number of movements: In the same study (4) where infants experienced CL starting from the 32nd gestational week, the total number of movements was measured using an actograph in various time frames: 10 – 0 days prior to discharge; 1 – 10 days after discharge; 11 – 20 days after discharge; and 21 – 30 days after discharge. The researchers found significant benefits in all time frames for the CL group.

Circadian rhythm: The same study (4) found a statistically significant difference in 51 infants in favor of CL for the adjustment to the circadian rhythm in the first ten days at home following discharge.

Days until first oral ingestion of nutrition: With CL from the 32nd gestational week, infants needed twelve days fewer on average until the first oral ingestion of nutrition in comparison to infants with ND light management (8). This result was also significant.

Frequency of crying: A study with a cohort of 37 infants described significantly less crying in the eleventh week (corrected age) in the CL group as compared with the ND group.

Retinopathy of prematurity: In two studies (5, 7) on retinopathy of prematurity (all stages) with CL since birth or since the 32nd gestational week in a total of 189 infants, the researchers found a positive, although not statistically significant difference between CL and ND in favor of CL.

 

Significant results “cycled light exposure” compared to “uninterrupted light exposure”

Length of hospital stay: In two studies with a total of 79 infants, a significantly shorter hospital stay was found in the CL group compared with the UL group (10, 11) with a mean difference of 16.5 days. No heterogenenity was found for either of the studies.

Hours of wakefulness: Another study with 41 infants (CL from the 32nd week) (9) showed a significantly lower median value in the hours of wakefulness for the children in the CL group over 24 hours at the calculated full-term birth date and at the sixth and twelfth week of corrected age.

Mean weight: The same study (9) found a significantly higher mean weight after six and twelve weeks corrected age for infants with CL care.

Hours of nutrition intake: The same study found a significantly lower mean number of hours of nutrition intake in the CL group over 24 hours in infants in the twelfth week of corrected age (9).

Days until first oral ingestion of nutrition: Another study (10) also with 41 children (CL since birth) reported a significantly shorter time until the first oral ingestion of nutrition which was seven days for the CL group.

Growth: The same study showed a significant benefit for the CL group, who gained on average 9.4 percent in weight in one week in comparison to infants in the UL group with an average gain of 7.4 percent (10).

Days requiring oxygen: This study also showed a significant benefit for the CL group in the number of days that oxygen therapy was required with a mean difference of 20.8 days.

Length of ventilation: The researchers of this same study (10) also reported a significantly shorter time of ventilation in the CL group compared with the UL group with a mean difference of 18.2 days.

Conclusions

The authors conclude that the evidence is currently too weak to provide a legitimate quantification of the risks and benefits of different light exposure regimens (CL, UL, ND) in the sense of evidence-based medicine. Nonetheless, several of the studies show significant results with benefits for cycled light exposure. The current work is not sufficient to provide strong evidence primarily due to the low number of patients in the individual studies and the fact that the question of the most favorable form of illumination can in general not be posed on a blind basis.  Other distorting factors in the included studies are unknown or are subject to a demonstrably high risk. According to the authors, further studies should be restricted to investigating the differences between CL and ND.

Active Versus Passive Cooling During Neonatal Transport.


BACKGROUND AND OBJECTIVE: Therapeutic hypothermia is now the standard of care for hypoxic-ischemic encephalopathy. Treatment should be started early, and it is often necessary to transfer the infant to a regional NICU for ongoing care. There are no large studies reporting outcomes from infants cooled passively compared with active (servo-controlled) cooling during transfer. Our goal was to review data from a regional transport service, comparing both methods of cooling.

METHODS: This was a retrospective observational study of 143 infants referred to a regional NICU for ongoing therapeutic hypothermia. Of the 134 infants transferred, the first 64 were cooled passively, and 70 were subsequently cooled after purchase of a servo-controlled mattress. Key outcome measures were time to arrival at the regional unit, temperature at referral and arrival at the regional unit, and temperature stability during transfer.

RESULTS: The age cooling was started was significantly shorter in the actively cooled group (46 [0–352] minutes vs 120 [0–502] minutes; P <.01). The median (range) stabilization time (153 [60–385] minutes vs 133 [45–505] minutes; P = .04) and age at arrival at the regional unit (504 [191–924] minutes vs 452 [225–1265]) minutes; P = .01) were significantly shorter in the actively cooled group. Only 39% of infants passively cooled were within the target temperature range at arrival to the regional unit compared with 100% actively cooled.

CONCLUSIONS: Servo-controlled active cooling has been shown to improve temperature stability and is associated with a reduction in transfer time.

Source: http://pediatrics.aappublications.org