Copenhagen University Hospital-Rigshospitalet, Department of Neonatology, Blegdamsvej 9, Copenhagen 2100, DenmarkbUniversity of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3, Copenhagen 2200, Denmark.
Copenhagen University Hospital-Rigshospitalet, Department of Neonatology, Blegdamsvej 9, Copenhagen 2100, Denmark.
J Biomed Opt. 2017 Feb 1;22(2):25001. doi: 10.1117/1.JBO.22.2.025001.
Tissue oxygenation estimated by near-infrared spectroscopy (NIRS) is a volume-weighted mean of the arterial and venous hemoglobin oxygenation. In vivo validation assumes a fixed arterial-to-venous volume-ratio (AV-ratio). Regulatory cerebro-vascular mechanisms may change the AV-ratio. We used hypotension to investigate the influence of blood volume distribution on cerebral NIRS in a newborn piglet model. Hypotension was induced gradually by inflating a balloon-catheter in the inferior vena cava and the regional tissue oxygenation from NIRS ( rStO 2 , NIRS ) was then compared to a reference ( rStO 2 , COX ) calculated from superior sagittal sinus and aortic blood sample co-oximetry with a fixed AV-ratio. Apparent changes in the AV-ratio and cerebral blood volume (CBV) were also calculated. The mean arterial blood pressure (MABP) range was 14 to 82 mmHg. PaCO 2 and SaO 2 were stable during measurements. rStO 2 , NIRS mirrored only 25% (95% Cl: 21% to 28%, p < 0.001 ) of changes in rStO 2 , COX . Calculated AV-ratio increased with decreasing MABP (slope: ? 0.007 · mmHg ? 1
组织氧合的近红外光谱（NIRS）估计是动脉和静脉血红蛋白氧合的体积加权平均值。体内验证假设固定的动静脉容积比（AV 比）。调节性脑血管机制可能会改变 AV 比。我们使用低血压来研究血液体积分布对新生仔猪模型中脑 NIRS 的影响。通过在下腔静脉和区域组织氧饱和度（rStO 2 ，NIRS）中充气球囊导管逐渐诱导低血压，然后将其与从上矢状窦和主动脉血样 co-oximetry 计算的参考值（rStO 2 ，COX ）进行比较，该参考值使用固定的 AV 比计算。还计算了 AV 比和脑血容量（CBV）的明显变化。平均动脉血压（MABP）范围为 14 至 82 mmHg。在测量期间，PaCO 2 和 SaO 2 保持稳定。rStO 2 ，NIRS 仅反映 rStO 2 ，COX 变化的 25%（95%Cl：21%至 28%，p<0.001）。计算的 AV 比随 MABP 的降低而增加（斜率：？0.007·mmHg？1
