ASSESSING GUT OXYGENATION IN PREMATURE INFANTS USING NEAR INFRARED SPECTROMET

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 肠道氧合指标较低的婴儿（与大脑相比）更有可能患坏死性小肠结肠炎（NEC）或其他肠道疾病，并有喂养不耐受。 本项目的主要目的是建立早产儿近红外光谱测量正常值的基线，并确定存在什么变化，如果喂养。 由于NEC的发病率在该患者人群中约为5%，因此我们将能够生成一些关于NIRS在预测NEC中的有用性的试验数据。 具体目标 I. 在体重750至1500 g的新生儿中获得“正常”肠组织氧化指数值（TOI）。 2. 获得每名儿童的内脏氧合率（CSOR），以比较不同时间点（出生后1、2、3和4周）的值。 3. 将CSOR和TOI降低与NEC或其他肠道疾病（如果发生）的发生联系起来。 4. 获得出生后1、2、3、4周喂养期间肠道TOI增加的“正常”值。 5. 如果发生喂养不耐受，将喂养引起的肠道TOI增加与喂养不耐受的发生相关联。 早产儿有多种原因导致神经发育不良结局的风险，包括分娩过程中的缺氧缺血性损伤、呼吸窘迫综合征、脑室内出血、镇静和镇痛药物以及呼吸暂停/心动过缓。 此外，早产儿经常发生坏死性小肠结肠炎（NEC），其病因尚不清楚，但可能与肠道灌注减少有关。 近红外光谱（NIRS）测量大脑和躯体的氧合与两个波长的光，其中氧和脱氧血红蛋白具有不同的吸收特性。 测量氧合血红蛋白和总血红蛋白信号，并计算局部脑或肠氧合血红蛋白饱和率（组织氧化指数或TOI）。 低肠道TOI可能有助于解释该人群中坏死性小肠结肠炎的高发病率。 脑灌注是自动调节的，因此，内脏：脑灌注比在正常情况下应保持恒定，但在低血压或缺血期间应预期下降。 最近发表的一项研究显示，NEC/急腹症新生儿与非NEC/急腹症新生儿之间TOI的脑/肠比存在显著差异。 然而，没有数据证明下降的比率预测这些问题（即，肠道灌注的减少是疾病过程的结果，还是疾病过程是由于肠道灌注的减少？ 正如我们的具体目标中所提到的，获得正常值对未来的研究至关重要。 在没有任何数据的情况下，很难进行推测，但理想的临床情况将是建立一个“截止”点。 换句话说，我们希望我们能找到一个数字来定义异常的肠道灌注，并预测喂养不耐受。 这些数字将显示为真实的值，机器将其表示为StO 2百分比。 该值表示氧合血红蛋白除以总血红蛋白的百分比。 由于该值是在毛细血管床的静脉侧测量的，因此它反映了组织氧提取后的血氧状态。 将StO 2（5）与外周脉搏血氧仪（外周毛细血管床的动脉侧）的SPO 2（%）以及按照标准治疗（如有）采集的任何ABG进行比较。 将检查这些值的经口进食、呼吸频率以及任何氧合和灌注合并症。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Infants who have lower measures of gut oxygenation (compared to brain) are more likely to develop Necrotizing enterocolitis (NEC) or other intestinal disease and to have feeding intolerance. The primary objective of this project is to establish a baseline for normal values of NIRS measurements in premature infants and to establish what changes exist, if any with feeding. Because the incidence of NEC is around 5% in this patient population, we will be able to generate some pilot data on the usefulness of NIRS in predicting NEC. SPECIFIC AIMS I. To obtain "normal" intestinal tissue oxidation index values (TOI) in newborns weighing 750 to 1500g. 2. To obtain a cerebro-splanchnic oxgenation ration (CSOR) for each child in order to compare values at separate time points (at 1,2,3, and 4 weeks after birth). 3. To correlate decreasing CSOR and TOI with the development of NEC or other intestinal disease, if it occurs. 4. To obtain "normal" values of increased intestinal TOI during feeding at 1,2,3, and 4 weeks after birth. 5. To correlate a blunted intestinal TOI increase with feeding with the onset of feeding intolerance, if it occurs. Premature infants are at risk for neurodevelopmental adverse outcomes from a number of causes, including hypotoxic-ischemic insults from the delivery process, respiratory distress syndrome, intraventricular hemorrhage, sedative and analgesic drugs, and apnea/bradycardia. In addition, premature infants frequently develop necrotizing enterocolitis (NEC), the etiology of which is still unclear, but may be related to decreased gut perfusion. Near-infrared spectroscopy (NIRS) measures cerebral and somatic oxygenation with two wavelengths of light to which oxy-and deoxyhemoglobin have distinct absorption characteristics. The oxyhemoglobin and total hemoglobin signals are measured, and a regional cerebral or intestinal oxyhemoglobin saturation ratio is calculated (tissue oxidation index, or TOI). Low intestinal TOI may help explain the high incidence of necrotizing enterocolitis in this population. Cerebral perfusion is autoregulated, therefore, a splanchnic: cerebral perfusion ratio should remain constant under normal conditions, but should be expected to fall during hypotension or sschemia. A recently published study showed a significant difference between the brain/gut ratio of TOI between neonates with NEC/acute abdomen and those without. However, there is no data to prove that a decreasing ration predicts these problems (i.e., is the decrease in gut perfusion as a result of the disease process, or is the disease process due to the decrease in gut perfusion?). As mentioned in our specific aims, obtaining normal values are critical for future studies. Without any data, it is difficult to speculate, but the ideal clinical situation would be to establish a "cut off" point. Put in different terms, what we hope we will find is a number that defines abnormal gut perfusion and predicts feeding intolerance. The numbers will be presented as real values, which the machine expresses as percentage StO2. This value represents the percentage of oxygenated hemoglobin divided by the total hemoglobin. As this value is measured on the venous side of the capillary bed, it reflects blood oxygenation status after tissue oxygen extraction. The StO2 (5) will be compared to SPO2 (%) of the peripheral pulse oximeter (arterial side of peripheral capillary bed), as well as any ABGs that have been drawn per standard of care (if any). These vlaues will be examined with respect to oral feeds, respiratory rate, and any oxygenation and perfusion co-morbidities.