Temperature & Vasomotor Tone During the First 5 Days in Preterms Less than 1000g

描述(申请人提供)：目的：这项研究将通过测量30名极低出生体重(ELBW)婴儿出生前5天的中心和外周体温与外周血流灌注的关系来检测血管运动张力的成熟度。我们将使用热敏电阻温度、外周血流指数和红外热成像来检测每个婴儿在腹部皮肤温度下降时表现出外周血管收缩的能力，以及保持腹部温度高于外周体温的能力。这项研究将提供数据，作为多中心研究的基础，以检验血管运动张力成熟与低出生体重儿发病率--脑室出血(IVH)和坏死性小肠结肠炎(NEC)--之间的关系。方法：婴儿出生前需征得父母同意。胎龄小于29周且出生体重小于1000克的极低出生体重儿将在NICU入院。生理变量将 在120小时内每分钟采样一次。腹部和外周体温将使用热敏电阻和数据记录器进行测量。外周血流量将使用Masimo Radus-7监护仪的外周血流灌流指数进行测量。将使用红外摄像机测量人体表面。 温度每天一次，通过适应热成像的保温箱罩。婴儿将在5天内连续录像，以捕捉可能使婴儿暴露在寒冷环境温度下的护理。婴儿的医疗记录将被审查，直到NICU出院。资料分析：采用SAS软件对数据进行分析，首先作为受试者内的个案研究，然后比较23-25、25 1/7-27、27 1/7-28 6/7周三个胎龄组之间的比较。时间序列分析和Logistic回归的状态空间方法将被用来确定每个婴儿的血管运动张力成熟时间和每个婴儿组的平均时间。血管运动成熟的时间将根据每个婴儿有能力将周围温度降低到低于腹温0.5-2℃的年龄来确定，以应对腹部温度降至37℃以下，以及婴儿能够持续保持腹部温度高于周围温度的年龄。临床护理事件将与体温下降和随后恢复到基线温度的关系进行分析。导致体内体温下降的事件可能包括吸痰、使用氧气袋进行通风或向脐带导管中注入液体。事件导致 外部环境温度的降低与打开孵化器的舷窗或门有关。所有事件都将根据视频数据进行编码，并使用生理变量进行分析。将使用交叉相关来比较外周温度、外周灌注量和内部孵化器温度。红外温度测量将与热敏电阻测量的体温进行比较，以评估热成像技术在整体体温和血流灌注方面的应用。IVH和NEC的发生将与每个婴儿的胎龄和出生后血管舒张性张力成熟有关。 与公共卫生相关：极早产儿在其生命的最初几天容易受到低温的影响。这些婴儿在此期间脑损伤的风险增加，这可能是由于血液流动调节不成熟，增加了他们的神经感觉、发育和身体风险。这项研究将提供证据，证明在极早产儿出生的第一周，控制流向脚部和返回大脑和心脏的血液的能力成熟的时间，从而可以开发干预措施来减少这些 发展风险。

DESCRIPTION (provided by applicant): Objective: This study will examine maturation of vasomotor tone by measuring central and peripheral body temperature of 30 extremely low birth weight (ELBW) infants in relationship to peripheral perfusion during the first 5 days of life. We will examine the ability of each infant to exhibit peripheral vasoconstriction in response to decreased abdominal skin temperature and to keep abdominal temperature higher than peripheral using thermistor temperatures, peripheral perfusion index and infrared thermal imaging. The study will provide data on which to base a multi-center study to examine the relationship between the maturation of vasomotor tone and morbidity--intraventricular hemorrhage (IVH) and necrotizing enterocolitis (NEC)--in ELBW infants. Methods: Consent will be obtained from parents prior to infant birth. ELBW infants less than 29 weeks gestation and less than 1000 gram birth-weight will be enrolled at NICU admission. Physiologic variables will be sampled every minute for 120 hours. Abdominal and peripheral body temperature will be measured using thermistors and data loggers. Peripheral blood flow will be measured using peripheral perfusion index from a Masimo Radical-7 monitor. An infrared camera will be used to measure body surface\ temperature once daily, through the incubator hood adapted for thermal imaging. Infants will be video-recorded continuously over the 5-days to capture care that may expose the infant to cold environmental temperatures. Infant medical records will be reviewed until NICU discharge. Data Analysis: Data will be analyzed using SAS software, first as case studies within-subjects, then with comparison between subjects in three gestational age groups: 23-25, 25 1/7-27, and 27 1/7-28 6/7 weeks. The State Space approach to time series analysis and logistic regression will be used to determine time of vasomotor tone maturity within each infant and average over each infant group. Time of vasomotor maturity will be determined as the age at which each infant has the ability to decrease peripheral temperature 0.5-2¿ C below abdominal temperature in response to a decrease in abdominal temperature below 37¿C and when the infant can consistently keep abdominal temperature greater than peripheral temperature. Clinical care events will be analyzed in relationship to decreases in body temperature and subsequent recovery to baseline temperature. Events causing decreased internal body temperatures may include suctioning, ventilation with an oxygen bag or infusion of fluids into umbilical catheters. Events causing decreases in external environmental temperature are related to opening the incubator portholes or doors. All events will be coded from video data and entered into analyses with physiological variables. Cross correlations will be used to compare peripheral temperature, peripheral perfusion and internal incubator temperature. Infrared thermal measurements will be compared to body temperature measured by thermistor to evaluate the use of thermal imaging for overall body temperature and perfusion. Occurrence of IVH and NEC will be related to each infant's gestational and postnatal age of vasomotor tone maturity. PUBLIC HEALTH RELEVANCE: Extremely premature infants are subject to low temperatures during their first few days of life. These infants have an increased risk for brain injury during this time that may be due to immature regulation of blood flow, increasing their neurosensory, developmental and physical risks. This study will provide evidence of the time when the ability to control blood flow to the feet and back to the brain and heart becomes mature in extremely premature infants during their first week of life, allowing interventions to be developed to decrease these developmental risks.