ENERGY EXPENDITURE, DIETARY INTAKE AND FEEDING PRACTICES FOR PRETERM INFANTS

该研究提出的问题是：考虑到婴儿特征、婴儿活动和食物不耐受，以及控制喂养方法（饮食的热量密度和随意或规定的喂养方案），能量消耗如何与饮食摄入和躯体生长相关？研究的具体目的如下：(1)确定三组早产儿在活动水平（从安静睡眠到剧烈活动，包括哭闹和喂养）期间的能量消耗；(2)考虑婴儿特征（出生体重、性别、种族、肺部疾病严重程度和能量消耗评估时的受孕后年龄）、婴儿活动和食物不耐受，并控制饮食和喂养方案的热量密度，确定能量消耗对这些婴儿的饮食摄入和躯体生长的贡献。采用2 × 2实验设计，随机分配婴儿进行自由或规定喂养，并在喂养实践中使用20或24卡路里/盎司的喂养物质。12名婴儿将被随机分配到四种喂养方式中的每一种。所有在新生儿重症监护病房（NICU）出生、妊娠少于35周、体重与胎龄相符、纯配方奶喂养或母乳喂养至少80%的婴儿都符合本研究的条件。研究婴儿不得有先天性或医学问题影响营养状况。婴儿可能已经从呼吸窘迫综合征（RDS）中恢复，或者患有轻度支气管肺发育不良（BPD）。四个研究组将根据以下可能的协变量进行平衡：(a)出生体重，(b)性别，(c)种族，(d)呼吸状态（RDS， BPD或无），以及(e)能量消耗评估时的受孕后年龄。将在第一天和第二天用间接呼吸量热法观察能量消耗，婴儿在餐后90分钟完全乳头喂养，每天90分钟，并在喂养期间使用平均心率。在72小时的研究期间，婴儿的6小时膳食摄入量和每日体重将作为以下措施的基础：(1)以cc/kg/天为单位的平均摄入量；(2)平均千卡/公斤/ 6小时摄入量；(3)平均g蛋白/kg/ 6小时摄入量。体重增加的平均克数/ 6小时内（体重增加的速度）除以当天的体重将是身体生长的量度。饮食摄入结果将根据以下协变量使用迭代广义最小二乘回归进行分析：(a)新生儿重症监护病房位置，(b)食物不耐受，(c)能量消耗，(d)肺部疾病严重程度，以及(e)喂养方法。体重增加的加权率将根据饮食摄入量和其他先前列出的协变量进行回归。将研究两个饲养实践因素（饲养方式和热量密度）的相互作用。

The question the proposed study addresses is: How is energy expenditure related to dietary intake and somatic growth, considering infant characteristics, infant activity, and food intolerance, and controlling feeding practice (caloric density of the diet and ad libitum or prescribed feeding regimen)? The specific aims of the study are as follows: (1) To determine the energy expenditure in the three groups of preterm infants during levels of activity, ranging from quiet sleep to vigorous activity with crying and including feeding; and (2) To determine the contribution energy expenditure makes to the dietary intake and somatic growth of these infants, taking infant characteristics (birthweight, gender, ethnicity, severity of lung disease, and postconceptional age at the time of energy expenditure assessment), infant activity, and food intolerance into account and controlling the caloric density of the diet and the feeding regimen. A 2 x 2 experimental design with random assignment of infants to either ad libitum or prescribed feeding, and, within the feeding practice, to 20- or 24-calorie/ounce feeding substance will be used. Twelve infants will be randomly assigned to each of the four feeding practices. All Infants admitted to the Neonatal Intensive Care Unit (NICU) born at less than 35 weeks gestation with weight that is appropriate for gestational age and who are exclusively formula fed or fed at least 80 percent breast milk will be eligible for this study. Study infants must not have congenital or medical problems interfering with nutritional status. Infants may have recovered from Respiratory Distress Syndrome (RDS) or have mild Bronchopulmonary Dysplasia (BPD). The four study arms will be balanced with respect to the following possible covariates: (a) birthweight, (b) gender, (c) ethnicity, (d) respiratory status (RDS, BPD, or none), and (e) post-conceptional age at the time of energy expenditure assessment. Energy expenditure will be observed with indirect respiratory calorimetry on the first and second day the infant is completely nipple fed at ninety minutes post-prandial for a ninety-minute period each day and with mean heart rate during feeding. The infant's six-hourly dietary intake and daily weight will be the basis for the following measures over the 72-hour study period: (1) mean volume in cc/kg/day of intake; (2) mean kcalories/kg/six-hours of intake; and (3) mean g protein/kg/six-hours of intake. Mean grams weight gain/six-hour period (rate of weight gain) divided by the weight that day will be the measure of somatic growth. Dietary intake outcomes will be analyzed using iterative generalized least-squares regression against the following covariates: (a) NICU location, (b) food intolerance, (c) energy expenditure, (d) severity of lung disease, and (e) feeding practice. The weighted rate of weight gain will be regressed against dietary intake and the other previously listed covariates. The interaction of the two feeding practice factors (feeding regimen and caloric density) will be examined.