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Long-range correlations in rectal temperature fluctuations of healthy infants during maturation.

Stern G, Beel J, Suki B, Silverman M, Westaway J, Cernelc M, Baldwin D, Frey U - PLoS ONE (2009)

Bottom Line: We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (T(rec)) patterns in maturing infants.The effects of maturation, room temperature, and immunization on the strength of correlation were investigated.A significant increase in alpha with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. alpha was not associated with mean room temperature or influenced by immunization This study shows that the quantification of long-range correlations using alpha derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time T(rec) pattern in young infants, reflective of maturation of the autonomic system.

View Article: PubMed Central - PubMed

Affiliation: Division of Respiratory Medicine, Department of Pediatrics, Inselspital and University of Bern, Bern, Switzerland. georgette.stern@insel.ch

ABSTRACT

Background: Control of breathing, heart rate, and body temperature are interdependent in infants, where instabilities in thermoregulation can contribute to apneas or even life-threatening events. Identifying abnormalities in thermoregulation is particularly important in the first 6 months of life, where autonomic regulation undergoes critical development. Fluctuations in body temperature have been shown to be sensitive to maturational stage as well as system failure in critically ill patients. We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (T(rec)) patterns in maturing infants.

Methodology/principal findings: We measured T(rec) fluctuations in infants every 4 weeks from 4 to 20 weeks of age and before and after immunization. Long-range correlations in the temperature series were quantified by the correlation exponent, alpha using detrended fluctuation analysis. The effects of maturation, room temperature, and immunization on the strength of correlation were investigated. We found that T(rec) fluctuations exhibit fractal long-range correlations with a mean (SD) alpha of 1.51 (0.11), indicating that T(rec) is regulated in a highly correlated and hence deterministic manner. A significant increase in alpha with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. alpha was not associated with mean room temperature or influenced by immunization

Conclusions: This study shows that the quantification of long-range correlations using alpha derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time T(rec) pattern in young infants, reflective of maturation of the autonomic system. Detrended fluctuation analysis may prove useful for characterizing thermoregulation in premature and other infants at risk for life-threatening events.

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Change in α with age.a) Longitudinal measurements in infants with at least 3 measurements (solid lines). One infant had acceptable data from all 5 stages, 7 infants had acceptable data from 4 stages, and 10 from 3 stages. There is individual variability in the change in α with age, but there is an overall increase in α of 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001) (dotted line). b) A box plot of α in all included infants grouped by age at 4, 8, 12, 16, and 20 weeks. The boundary of the box closest to zero indicates the 25th percentile, the line within the box marks the median, the black dots are the outliers, and the boundary of the box farthest from zero indicates the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles.
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pone-0006431-g003: Change in α with age.a) Longitudinal measurements in infants with at least 3 measurements (solid lines). One infant had acceptable data from all 5 stages, 7 infants had acceptable data from 4 stages, and 10 from 3 stages. There is individual variability in the change in α with age, but there is an overall increase in α of 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001) (dotted line). b) A box plot of α in all included infants grouped by age at 4, 8, 12, 16, and 20 weeks. The boundary of the box closest to zero indicates the 25th percentile, the line within the box marks the median, the black dots are the outliers, and the boundary of the box farthest from zero indicates the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles.

Mentions: The scaling exponent α was normally distributed in all age groups (Table 1). α calculated from temperature time series of subjects which had at least three longitudinal measurements (n = 18) can be seen in Figure 3a. A box plot of α for all of the included infants stratified by age group is shown in Figure 3b. There was a small significant drop in mean Trec between the age groups starting at around 12 weeks of −0.021°C per week of age (95%CI −0.028 to −0.013, p<0.001). All three methods of analyzing the age effect on α showed a significant increase of α with age. Longitudinal data in a subgroup of 23 infants showed that α values at 4–8 weeks (mean (SD) 1.44 (0.08)) were significantly lower than those at 12–20 weeks (1.58 (0.10), p<0.001). Regression analysis of all 95 time series using random-effects model showed a significant increase in long-range correlations with age of α = 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001), adjusted for weight and sex of the infant. If only infants with 3 or more longitudinal measurements were included in the regression, there was a slightly higher increase in alpha with age of α = 0.015 per week (95%CI 0.007 to 0.024, p<0.001). Of the 95 acceptable datasets, 31 of these were determined to have an immature (n = 13) or mature (n = 18) night time Trec patterns (Table 1). An indeterminate group of 61 datasets in which a clear pattern was not identifiable was excluded. Of those with immature or mature night time temperature patterns, it was found that there was a mean increase in α of 0.17 in the mature group compared with the immature group, (95%CI 0.12 to 0.22, p<0.001).


Long-range correlations in rectal temperature fluctuations of healthy infants during maturation.

Stern G, Beel J, Suki B, Silverman M, Westaway J, Cernelc M, Baldwin D, Frey U - PLoS ONE (2009)

Change in α with age.a) Longitudinal measurements in infants with at least 3 measurements (solid lines). One infant had acceptable data from all 5 stages, 7 infants had acceptable data from 4 stages, and 10 from 3 stages. There is individual variability in the change in α with age, but there is an overall increase in α of 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001) (dotted line). b) A box plot of α in all included infants grouped by age at 4, 8, 12, 16, and 20 weeks. The boundary of the box closest to zero indicates the 25th percentile, the line within the box marks the median, the black dots are the outliers, and the boundary of the box farthest from zero indicates the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2713399&req=5

pone-0006431-g003: Change in α with age.a) Longitudinal measurements in infants with at least 3 measurements (solid lines). One infant had acceptable data from all 5 stages, 7 infants had acceptable data from 4 stages, and 10 from 3 stages. There is individual variability in the change in α with age, but there is an overall increase in α of 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001) (dotted line). b) A box plot of α in all included infants grouped by age at 4, 8, 12, 16, and 20 weeks. The boundary of the box closest to zero indicates the 25th percentile, the line within the box marks the median, the black dots are the outliers, and the boundary of the box farthest from zero indicates the 75th percentile. Error bars above and below the box indicate the 90th and 10th percentiles.
Mentions: The scaling exponent α was normally distributed in all age groups (Table 1). α calculated from temperature time series of subjects which had at least three longitudinal measurements (n = 18) can be seen in Figure 3a. A box plot of α for all of the included infants stratified by age group is shown in Figure 3b. There was a small significant drop in mean Trec between the age groups starting at around 12 weeks of −0.021°C per week of age (95%CI −0.028 to −0.013, p<0.001). All three methods of analyzing the age effect on α showed a significant increase of α with age. Longitudinal data in a subgroup of 23 infants showed that α values at 4–8 weeks (mean (SD) 1.44 (0.08)) were significantly lower than those at 12–20 weeks (1.58 (0.10), p<0.001). Regression analysis of all 95 time series using random-effects model showed a significant increase in long-range correlations with age of α = 0.012 per week of age (95%CI 0.005 to 0.019, p = 0.001), adjusted for weight and sex of the infant. If only infants with 3 or more longitudinal measurements were included in the regression, there was a slightly higher increase in alpha with age of α = 0.015 per week (95%CI 0.007 to 0.024, p<0.001). Of the 95 acceptable datasets, 31 of these were determined to have an immature (n = 13) or mature (n = 18) night time Trec patterns (Table 1). An indeterminate group of 61 datasets in which a clear pattern was not identifiable was excluded. Of those with immature or mature night time temperature patterns, it was found that there was a mean increase in α of 0.17 in the mature group compared with the immature group, (95%CI 0.12 to 0.22, p<0.001).

Bottom Line: We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (T(rec)) patterns in maturing infants.The effects of maturation, room temperature, and immunization on the strength of correlation were investigated.A significant increase in alpha with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. alpha was not associated with mean room temperature or influenced by immunization This study shows that the quantification of long-range correlations using alpha derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time T(rec) pattern in young infants, reflective of maturation of the autonomic system.

View Article: PubMed Central - PubMed

Affiliation: Division of Respiratory Medicine, Department of Pediatrics, Inselspital and University of Bern, Bern, Switzerland. georgette.stern@insel.ch

ABSTRACT

Background: Control of breathing, heart rate, and body temperature are interdependent in infants, where instabilities in thermoregulation can contribute to apneas or even life-threatening events. Identifying abnormalities in thermoregulation is particularly important in the first 6 months of life, where autonomic regulation undergoes critical development. Fluctuations in body temperature have been shown to be sensitive to maturational stage as well as system failure in critically ill patients. We thus aimed to investigate the existence of fractal-like long-range correlations, indicative of temperature control, in night time rectal temperature (T(rec)) patterns in maturing infants.

Methodology/principal findings: We measured T(rec) fluctuations in infants every 4 weeks from 4 to 20 weeks of age and before and after immunization. Long-range correlations in the temperature series were quantified by the correlation exponent, alpha using detrended fluctuation analysis. The effects of maturation, room temperature, and immunization on the strength of correlation were investigated. We found that T(rec) fluctuations exhibit fractal long-range correlations with a mean (SD) alpha of 1.51 (0.11), indicating that T(rec) is regulated in a highly correlated and hence deterministic manner. A significant increase in alpha with age from 1.42 (0.07) at 4 weeks to 1.58 (0.04) at 20 weeks reflects a change in long-range correlation behavior with maturation towards a smoother and more deterministic temperature regulation, potentially due to the decrease in surface area to body weight ratio in the maturing infant. alpha was not associated with mean room temperature or influenced by immunization

Conclusions: This study shows that the quantification of long-range correlations using alpha derived from detrended fluctuation analysis is an observer-independent tool which can distinguish developmental stages of night time T(rec) pattern in young infants, reflective of maturation of the autonomic system. Detrended fluctuation analysis may prove useful for characterizing thermoregulation in premature and other infants at risk for life-threatening events.

Show MeSH
Related in: MedlinePlus