Feasibility of using ultrasound to measure preterm body composition and to assess macronutrient influences on tissue accretion rates

Point of care ultrasonography of quadriceps femoris muscle thickness for assessing nutritional status in critically ill children

Muscle wasting occurs early during critical illness. It is associated with poor PICU outcomes. Ultrasonography can detect muscle thickness in critically ill children. Study quadriceps muscle thickness to assess the nutritional status on admission and follow the muscle thickness change throughout the first week of admission in PICU using point-of-care ultrasonography. This cohort study was conducted on 55 critically ill mechanically ventilated children aged between 2 months and 14 years. Serial measurements of quadriceps muscle thickness were done by ultrasound, during the first week of admission. Quadriceps muscle thickness decreased by 16.4% over the 1st week of admission. The muscle wasting was significantly correlated with STRONGkids score, the inability to achieve target caloric requirements during the 1st week of admission, duration of ventilation, PRISM score, and mortality. Point of care ultrasonography is an easy tool for assessing PICU muscle wasting. Loss of muscle mass during the first week of PICU admission is correlated to mortality, thus it can be utilized in predicting PICU outcomes.

Utilizing preterm infant body composition assessments to guide neonatal nutrition

PURPOSE OF REVIEW

The use of body composition to assess the quality of infant growth may add valuable information to pediatric clinical care. Preterm infants have differences in their fat and muscle mass development compared with infants born at term, which may be related to their early nutritional exposures. This review focuses on recent studies examining early nutrition in preterm infants and related body composition outcomes in the newborn period and beyond.

RECENT FINDINGS

Overall, the evidence shows that early nutrient delivery in parenteral nutrition and through formula supplementation or human milk fortification is associated with increased fat-free mass or lean mass in early life. However, future research is needed to fully understand the link between these body composition changes and longitudinal outcomes in preterm infants.

SUMMARY

Inclusion of body composition assessments in preterm infant nutrition research is critical to understand the factors associated with differences in adiposity and lean mass development in preterm infants. Medical fragility in preterm infants limits the routine use of body composition assessment tools which are currently validated, and additional studies are needed to thoroughly assess other methods which may be more feasible to integrate into bedside routine.

Body Composition in Preterm Infants: Current Insights and Emerging Perspectives

In recent years, significant advancements in respiratory and nutritional care have markedly improved the survival rates of preterm infants and enhanced long-term health outcomes. Despite these improvements, emerging research highlights the lasting impacts of early growth patterns on an individual's health trajectory. Adults born prematurely face a higher incidence of health issues related to their early birth. The American Academy of Pediatrics recommends that preterm infants should achieve growth rates similar to those of fetuses, with clinicians emphasizing nutrition delivery to help these infants reach their expected weight for gestational age. However, this approach often results in altered body composition, characterized by increased fat mass and decreased fat-free mass compared to full-term infants. Air displacement plethysmography stands out as a highly reliable method for measuring preterm body composition, while DEXA scans, despite their reliability, tend to overestimate body fat. Other methods include bioelectric impedance, isotope dilution, MRI, ultrasound, and skinfold thickness, each with its own strengths and limitations. In this paper, we aim to raise awareness among neonatal clinicians about the importance of achieving acceptable neonatal body composition. We discuss the pros and cons of different body composition measurement methods, the impact of nutrition and other factors on body composition in preterm infants, long-term follow-up data, and the potential use of body composition data to tailor nutritional interventions in NICU and post-discharge settings. This comprehensive approach is designed to optimize health outcomes for preterm newborns by focusing on their body composition from an early stage.

Ultrasound for assessing paediatric body composition and nutritional status: Scoping review and future directions

AIM

This scoping review aims to assess the utility of ultrasound as a prospective tool in measuring body composition and nutritional status in the paediatric population. We provide a comprehensive summary of the existing literature, identify gaps, and propose future research directions.

METHODS

We conducted a systematic scoping review following the PRISMA Extension for Scoping Reviews guidelines. This involved screening titles and abstracts of relevant studies, followed by a detailed full-text review and extraction of pertinent data.

RESULTS

We identified and synthesised 34 articles. The review revealed that while ultrasound has been used to assess body composition and bone properties in children, significant gaps remain in the literature. These include limited studies on ultrasound performance, insufficient attention to relevant sample characteristics, reliance on manual image measurements, and limited sample diversity.

CONCLUSION

Point-of-care ultrasound shows significant promise for assessing paediatric body composition and nutritional status. To validate and enhance its effectiveness, further research is needed. Future studies should include larger and more diverse patient cohorts and conduct longitudinal investigations to evaluate nutritional interventions. Additionally, developing artificial intelligence (AI) for standardising and automating data interpretation will be crucial in improving the accuracy and efficiency of ultrasound assessments.

Establishing feasibility and reliability of subcutaneous fat measurements by ultrasound in very preterm infants

BACKGROUND

Regional fat distribution may be a marker of metabolic health and brain growth in preterm infants. Point of care ultrasound has been used to assess regional fat in term infants but has not been used widely in preterm infants.

OBJECTIVE

To longitudinally quantify changes in body composition metrics using bedside ultrasound in very preterm infants.

STUDY DESIGN

Very preterm infants (N = 69) were enrolled after birth and body composition assessments were done through 36 completed weeks' postmenstrual age (PMA). Linear mixed effects regression was used to model change in body composition assessments over time.

RESULTS

There was an average increase across PMA for each body composition outcome. Biceps ultrasound subcutaneous fat (SQF) thickness increased by 0.11 mm (95% CI: 0.09, 0.13) each postmenstrual week. Triceps, subscapular, and abdominal ultrasound SQF remained constant through 28 weeks' PMA, then increased each week through 36 completed weeks' PMA. The inter-rater and intra-rater intraclass correlation coefficients for the ultrasound SQF measures ranged from 85.8 to 99.9.

CONCLUSION

Use of ultrasound as a novel method to assess regional fat distribution in very preterm infants is feasible and reliable.

IMPACT

Regional fat distribution may be a marker of metabolic health and brain growth in preterm infants. Gold standard body composition assessments may not be feasible in medically fragile very preterm infants. This study assesses longitudinally changes in regional adiposity development using bedside ultrasound techniques in a multicenter cohort of very preterm infants. Results of this study show that bedside ultrasound as a novel method to assess regional subcutaneous fat distribution and development in very preterm infants is both feasible and reliable.

Body composition in preterm infants: a systematic review on measurement methods

BACKGROUND

There are several methods to measure body composition in preterm infants. Yet, there is no agreement on which method should be preferred.

METHODS

PubMed, Embase.com, Wiley/Cochrane Library, and Google Scholar were searched for studies that reported on the predictive value or validity of body composition measurements in preterms, up to 6 months corrected age.

RESULTS

Nineteen out of 1884 identified studies were included. Predictive equations based on weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound did not show agreement with body composition measured with air displacement plethysmography (ADP), dual-energy x-ray absorptiometry (DXA), magnetic resonance imaging (MRI), or isotope dilution. ADP agreed well with fat mass density measured by isotope dilution (bias -0.002 g/ml, limits of agreement ±0.012 g/ml, n = 14). Fat mass percentage measured with ADP did not agree well with fat mass percentage measured by isotope dilution (limits of agreement up to ±5.8%) and the bias between measurements was up to 2.2%. DXA, MRI, and isotope dilution were not compared to another reference method in preterms.

CONCLUSIONS

DXA, ADP, and isotope dilution methods are considered trustworthy validated techniques. Nevertheless, this review showed that these methods may not yield comparable results.

IMPACT

Based on validation studies that were conducted in a limited number of study subjects, weight and length indices, body area circumferences, skinfold thickness, bioelectrical impedance, and ultrasound seem to be a poor representation of body composition in preterm infants. DXA, ADP, and isotope dilution methods are considered trustworthy and validated techniques. Nevertheless, these methods may not yield comparable results.

Human Milk Macronutrients and Bioactive Molecules and Development of Regional Fat Depots in Western Australian Infants during the First 12 Months of Lactation

We investigated associations between intakes of human milk (HM) components (macronutrients and biologically active molecules) and regional fat depots development in healthy term infants (n = 20) across the first year of lactation. Infant limb (mid-arm and mid-thigh) lean and fat areas were assessed by ultrasound imaging at 2, 5, 9 and 12 months of age. Concentrations of HM total protein, whey protein, casein, adiponectin, leptin, lysozyme, lactoferrin, secretory IGA, total carbohydrates, lactose, HM oligosaccharides (total HMO, calculated) and infant 24-h milk intake were measured, and infant calculated daily intakes (CDI) of HM components were determined. This pilot study shows higher 24-h milk intake was associated with a larger mid-arm fat area (p = 0.024), higher breastfeeding frequency was associated with larger mid-arm (p = 0.008) and mid-thigh (p < 0.001) fat areas. Lysozyme (p = 0.001) and HMO CDI (p = 0.004) were time-dependently associated with the mid-arm fat area. Intakes of HM components and breastfeeding parameters may modulate infant limb fat depots development during the first year of age and potentially promote favorable developmental programming of infant body composition; however, further studies are needed to confirm these findings.

Development of Visceral and Subcutaneous-Abdominal Adipose Tissue in Breastfed Infants during First Year of Lactation

This study aimed to investigate relationships between infant abdominal visceral and subcutaneous adiposity and human milk (HM) components and maternal body composition (BC) during first year of lactation. Subcutaneous-abdominal depth (SAD), subcutaneous-abdominal fat area (SFA), visceral depth (VD) and preperitoneal fat area of 20 breastfed infants were assessed at 2, 5, 9 and 12 months using ultrasound. Maternal BC was determined with bioimpedance spectroscopy. HM macronutrients and bioactive components concentrations and infant 24-h milk intake were measured and calculated daily intakes (CDI) determined. Maternal adiposity associated with infant SFA (negatively at 2, 5, 12, positively at 9 months, all overall p < 0.05). 24-h milk intake positively associated with infant SAD (p = 0.007) and VD (p = 0.013). CDI of total protein (p = 0.013), total carbohydrates (p = 0.004) and lactose (p = 0.013) positively associated with SFA. Lactoferrin concentration associated with infant VD (negatively at 2, 12, positively at 5, 9 months, overall p = 0.003). CDI of HM components and maternal adiposity have differential effects on development of infant visceral and subcutaneous abdominal adiposity. Maintaining healthy maternal BC and continuing breastfeeding to 12 months and beyond may facilitate favourable BC development reducing risk of obesity.

25 Years of Research in Human Lactation: From Discovery to Translation

Researchers have recently called for human lactation research to be conceptualized as a biological framework where maternal and infant factors impacting human milk, in terms of composition, volume and energy content are studied along with relationships to infant growth, development and health. This approach allows for the development of evidence-based interventions that are more likely to support breastfeeding and lactation in pursuit of global breastfeeding goals. Here we summarize the seminal findings of our research programme using a biological systems approach traversing breast anatomy, milk secretion, physiology of milk removal with respect to breastfeeding and expression, milk composition and infant intake, and infant gastric emptying, culminating in the exploration of relationships with infant growth, development of body composition, and health. This approach has allowed the translation of the findings with respect to education, and clinical practice. It also sets a foundation for improved study design for future investigations in human lactation.

Serum ghrelin is associated with early feeding readiness but not growth in premature infants

BACKGROUND

Feeding tolerance among premature infants is unpredictable using clinical parameters. Ghrelin, a peptide hormone, acts on the hypothalamus to increase hunger and gut motility. It is present in fetal tissues, promotes intestinal maturation, and is secreted in milk. We hypothesized that higher serum ghrelin levels on days 0-7 are associated with improved feeding tolerance and growth in premature infants.

METHODS

Infants (<  1500 g birth weight, n = 36) were recruited on day (D) 0-7. Serum ghrelin was measured by ELISA on D 0-7, D 10-14, and D 24-32, and milk ghrelin in a feeding concurrent with each serum sample. Feeding tolerance was assessed as days to first and full enteral feeds. Growth was quantified as both weight and adipose and muscle deposition by ultrasound.

RESULTS

Mean serum ghrelin levels decreased from D 0-7 to D 24-32. Higher ghrelin levels on D 0-7 were correlated with shorter time to first enteral feeding, but not with time to full enteral feeds, rate of weight gain, or rate of accretion of muscle or adipose tissue. Milk ghrelin was not related to serum ghrelin or growth. Abdominal and suprascapular muscle and adipose increased during the first month, but weight gain correlated only with the rate of accretion of abdominal adipose.

CONCLUSIONS

Elevated serum ghrelin in the first days of life may contribute to gut motility and readiness to feed. Weight gain in premature infants may primarily indicate abdominal fat accumulation, suggesting that ultrasound measurement of muscle accretion is a better marker for lean body growth.

Infant body composition assessment in the neonatal intensive care unit (NICU) using air displacement plethysmography: Strategies for implementation into clinical workflow

Nutritional management is integral to infant care in the neonatal intensive care unit (NICU). Recent research on body composition that specifically evaluated fat and fat-free mass has improved our understanding of infant growth and nutritional requirements. The need for body composition monitoring in infants is increasingly recognized as changes in fat mass and fat-free mass associated with early growth can impact clinical outcomes. With the availability of air displacement plethysmography (ADP) as a noninvasive method for assessing infant body composition and published normative gestational age- and sex-specific body composition curves, it is justifiable to integrate this innovation into routine clinical care. Here we describe our experiences in implementing body composition measurement using ADP in routine clinical care in different NICU settings.

Reliability of bedside ultrasound of limb and diaphragm muscle thickness in critically ill children

INTRODUCTION

We evaluated the reliability of measuring muscle thickness with ultrasound in limbs and diaphragms of critically ill children and determined the sensitivity of these measures to quantitate muscle atrophy over time.

METHODS

An expert and trained novice sonographers prospectively measured limb and diaphragm muscle thickness in 33 critically ill children.

RESULTS

Expert and novice intrarater and interrater reliability were similar. Intraclass correlations (ICC) and coefficients of variation (CoV) were better in limbs (ICC > 0.9; CoV 3.57%-5.40%) than in diaphragm (ICC > 0.8; CoV novice 11.88%, expert, 12.28%). Mean relative difference in all muscles was small (1%-8%). Limits of agreement of the relative difference were smaller in limb (<13%-18%) than in diaphragm (<38%) muscles.

DISCUSSION

Muscle thickness is reliably measured with ultrasound by trained examiners in critically ill children. Our approach detects atrophy >13% in limb and >38% in diaphragm muscles. The smaller detectable change in limb muscles is likely due to their greater thickness. Muscle Nerve 59:88-94, 2019.

Relationships between Breastfeeding Patterns and Maternal and Infant Body Composition over the First 12 Months of Lactation

Breastfeeding has been implicated in the establishment of infant appetite regulation, feeding patterns and body composition (BC). A holistic approach is required to elucidate relationships between infant and maternal BC and contributing factors, such as breastfeeding parameters. Associations between maternal and breastfed term infant BC (n = 20) and feeding parameters during first 12 months of lactation were investigated. BC was measured at 2, 5, 9 and/or 12 months postpartum with ultrasound skinfolds (US; infants only) and bioimpedance spectroscopy (infants and mothers). 24-h milk intake (MI) and feeding frequency (FFQ) were measured. Higher FFQ was associated with larger 24-h MI (p ≤ 0.003). Higher 24-h MI was associated with larger infant fat mass (FM) (US: p ≤ 0.002), greater percentage FM (US: p ≤ 0.008), greater FM index (FMI) (US: p ≤ 0.001) and lower fat-free mass index (FFMI) (US: p = 0.015). Lower FFQ was associated with both larger FFM (US: p ≤ 0.001) and FFMI (US: p < 0.001). Greater maternal adiposity was associated with smaller infant FFM measured with US (BMI: p < 0.010; %FM: p = 0.004; FMI: p < 0.011). Maternal BC was not associated with FFQ or 24-h MI. These results reinforce that early life is a critical window for infant programming and that breastfeeding may influence risk of later disease via modulation of BC.

Thigh Ultrasound Monitoring Identifies Decreases in Quadriceps Femoris Thickness as a Frequent Observation in Critically Ill Children

OBJECTIVES

Significant muscle wasting develops in critically ill adults, with subsequent worse outcomes. In the pediatric setting, occurrence and effects of muscle wasting are undescribed; this is in part due to a lack of validated, objective methods for assessing muscle wasting. A single measurement of quadriceps femoris thickness has failed to show consistent reproducibility. We hypothesized that averaging repeated measurements could afford good reproducibility to allow for quadriceps femoris thickness decline detection and monitoring.

DESIGN

A prospective bedside observational study.

SETTING

Two PICUs.

PATIENTS

Mechanically ventilated critically ill children were 15 years and younger.

INTERVENTIONS

Transverse and longitudinal axis measurements of quadriceps femoris anterior thickness were undertaken using bedside ultrasound. The average of four measurement values was recorded. The location of measurement was marked for consistency within subsequent measurements by the same or another trained operator, to assess intra- and interoperator repeatability and reproducibility of the technique. Where feasible, serial measurements were undertaken until the time of extubation in a group of children with prolonged PICU stay (> 5 d).

MEASUREMENTS AND MAIN RESULTS

Seventy-three children were enrolled to assess intra- and interoperator ultrasound reliability. Their median (25-75 interquartile range) age and weight were 30 months (4.5-96) and 10 kg (5-23.5). In the intraoperator repeatability study, mean relative difference in quadriceps femoris muscle thickness was 0.36% ± 2.5% (lower and upper limits of agreement: -4.5/+5.2%). In the interoperator reproducibility study, intraclass correlation coefficient was 0.998. In the 17 children monitored over their PICU stay, quadriceps femoris thickness significantly decreased at day 5 by 9.8% (p = 0.006) and by 13.3% (< 0.001) at the last performed measurement.

CONCLUSIONS

Quadriceps femoris thickness decrease, proposed as a surrogate for muscle mass, is an early, frequent, and intense phenomenon in PICU. Quadriceps femoris ultrasonography is a reliable technique to monitor this process and in future could help to guide rehabilitation and nutrition interventions.

Assessing the growth of preterm infants using detailed anthropometry

AIM

Preterm infants display altered body composition compared to term infants, and weight gain is a crude indicator body composition. Childhood mid-upper arm circumference (MUAC) is a measure of nutritional status. This study investigates MUAC and mid-thigh circumference (MTC) to monitor growth in preterm infants.

METHODS

Preterm infants (<30-week gestation) were recruited. MUAC, MTC, weight, length and head circumference (HC) were measured at recruitment and weekly intervals until discharge. Descriptive, correlation and regression analyses were used.

RESULTS

Ninety-three infants were recruited. Median measurement duration was eight weeks (1-19). Median gestational age was 27 weeks (23-29). Analysis by curve estimation displayed a mean increase of 2.58 mm/week (left MUAC) (p ≤ 0.0001), 2.56 mm/week (right MUAC) (p ≤ 0.0001), 4.16 mm/week (left MTC) (p ≤ 0.0001), 4.20 mm/week (right MTC) (p ≤ 0.0001). Coefficients of determination (R² ) were calculated using a growth regression model for MUAC and MTC (0.866-0.917); measures were comparable to growth modelling of weight (0.913), length (0.945) and HC (0.928). High concordance between left and right MUAC and MTC generated a Pearson's correlation coefficient of 0.999 (MUAC) (p ≤ 0.001) and 0.994 (MTC) (p ≤ 0.001).

CONCLUSION

Data demonstrate the potential utility of MUAC and MTC as additional measures of growth in preterm infants that are reproducible over time. There is potential to gain insights to improve lean-mass accretion in preterm infants.

Determinants of body composition in breastfed infants using bioimpedance spectroscopy and ultrasound skinfolds-methods comparison

BACKGROUND

Accurate, noninvasive, and inexpensive methods are required to measure infant body composition. Ultrasound (US) and bioimpedance spectroscopy (BIS) have been validated in adults and introduced in pediatric populations. The aim of this study was to evaluate the performance of both methods in determining percentage fat mass (%FM) in breastfed infants.

METHODS

%FM of 2, 5, 9, and 12 mo-old healthy, breastfed term infants (n = 58) was calculated using BIS-derived total body water equations and skinfold equations then compared with reference models. Skinfolds were measured with US at two and four sites (biceps, suprailiac and/or triceps, and subscapular).

RESULTS

%FM differed widely within and between methods, with the degree of variation affected by infant age/sex. Not a single method/equation was consistent with the distributions of appropriate reference values for all age/sex groups. Moderate number of matches with references values (13-24 out of 36) was seen for both types of equations. High number of matches (25-36) was seen for US skinfold-based equations. %FM values calculated from US and BIS were not significantly different (P = 0.35).

CONCLUSION

Both BIS and US are practical for predicting %FM in infants. BIS calculations are highly dependent upon an appropriate set of validated age-matched equations.

Comparing different methods of human breast milk fortification using measured v. assumed macronutrient composition to target reference growth: a randomised controlled trial

The variable content of human breast milk suggests that its routine fortification may result in sub-optimal nutritional intakes and growth. In a pragmatic trial, we randomised infants born below 30 weeks of gestation to either the intervention (Igp) of fortifying milk on measured composition according to birth weight criteria and postmenstrual age (PMA) or our routine practice (RPgp) of fortifying on assumed milk composition to target 3·8-4·4 g protein/kg per d and 545-629 kJ/kg per d. Milk composition was measured using the MIRIS® Human Milk Analyser. Percentage fat mass (%FM) was measured using PEA POD (COSMED). The effects of macronutrient intakes and clinical variables on growth were assessed using mixed model analysis. Mean measured protein content (1·6 g/100 ml) was higher than the assumed value (1·4 g/100 ml), often leading to lower amounts of fortifier added to the milk of intervention infants. At discharge (Igp v. RPgp), total protein (3·2 (SD 0·3) v. 3·4 (SD 0·4) g; P=0·067) and energy (456 (SD 39) v. 481 (SD 48) kJ; P=0·079) intakes from all nutrition sources, weight gain velocity (11·4 (SD 1·4) v. 12·1 (SD 1·6) g/kg per d; P=0·135) and %FM (13·7 (SD 3·6) v.13·6 (SD 3·5) %; P=0·984) did not significantly differ between groups. A protein intake >3·4 g/kg per d reduced %FM by 2%. Nutrition and growth was not improved by targeting milk fortification according to birth weight criteria and PMA using measured milk composition, compared with routine practice. Targeting fortification on measured composition is labour intensive, requiring frequent milk sampling and precision measuring equipment, perhaps reasons for its limited practice. Guidance around safe upper levels of milk fortification is needed.

Feasibility study: Assessing the influence of macronutrient intakes on preterm body composition, using air displacement plethysmography

AIM

Preterm nutrition guidelines target nutrient accretion and growth at intrauterine rates, yet at term equivalent age, the phenotype of the preterm infant differs from that of term infants. Monitoring early changes in preterm body composition (BC) in response to macronutrient intakes may facilitate our understanding of how best to meet preterm nutrition and growth targets.

METHOD

Macronutrient intakes based on milk analysis were calculated from birth for infants born <33 weeks gestation. BC was measured in the PEA POD when infants were thermodynamically stable, free of intravenous lines and independent of respiratory support. Subsequent BC measurements were taken at least fortnightly until term age. Regression analysis was used to assess macronutrient influences on changes in BC.

RESULTS

Median (range) gestation and birthweight of preterm infants (n = 27) were 29 (25-32) weeks and 1395 (560-2148) g, respectively. The youngest corrected gestational and postnatal ages that infants qualified for a PEA POD measurement were 31.86 and 1.43 weeks, respectively. Fat and total energy intakes were positively associated with increasing fat mass. Protein (with carbohydrate) intake was positively associated with increasing fat-free mass.

CONCLUSION

Preterm infants can be measured in the PEA POD as early as 31 weeks corrected gestational age and the method appears sufficiently sensitive to detect influences of macronutrient intake on changes in BC.