de Souza Tiago H, Giatti Marina P, Nogueira Roberto J N, Pereira Ricardo M, Soub Ana C S, Brandão Marcelo B
Pediatric Intensive Care Unit, Department of Pediatrics, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil.
Department of Pediatrics, School of Medicine São Leopoldo Mandic, Campinas, São Paulo, Brazil.
Pediatr Crit Care Med. 2020 Apr;21(4):e186-e191. doi: 10.1097/PCC.0000000000002240.
Inferior vena cava ultrasound has been used as a predictor of fluid responsiveness in children. Two ultrasonographic modes can be used to measure the respiratory variation of inferior vena cava diameter: M-mode and B-mode. Inconsistencies in measurements between the modes can result in inaccuracies in commonly used indices that assess fluid responsiveness. Our primary objective was to determine whether there are differences in the ultrasound-based measurements between these two modes of evaluation, which would impact respiratory variation of inferior vena cava diameter calculation. Our secondary objective was to assess inferior vena cava displacements during the respiratory cycle as a possible mechanism for measurement differences between the modes.
Prospective observational study.
PICU of a tertiary care teaching hospital.
Seventy-three children under controlled ventilation (median age of 16 mo and weight of 10 kg).
The inferior vena cava diameters were measured using a longitudinal view using B- and M-mode ultrasound. Two respiratory variation of inferior vena cava diameter indices were evaluated: distensibility and respiratory variation. Maximum craniocaudal and mediolateral displacements of the inferior vena cava were measured using the B-mode ultrasound.
Maximum diameters of the inferior vena cava were similar between the B- and M-modes (7.90 vs 7.90 mm, respectively; p = 0.326), but minimum diameters were smaller when measured by M-mode (6.36 vs 5.00 mm; p = 0.003). When calculated by data obtained from M-mode, respiratory variation of inferior vena cava diameter indices presented significantly higher values compared to B-mode measures (p ≤ 0.001, for both). Median inferior vena cava displacements were 5.00 mm (interquartile range, 3.68-6.26 mm) in the craniocaudal and 0.80 mm (interquartile range, 0.12-1.23 mm) in the mediolateral directions.
There is a significant difference between measurements of the minimum inferior vena cava diameter observed in M- and B-mode ultrasound during the respiratory cycle in children under controlled ventilation. This results in imprecise respiratory variation of inferior vena cava diameter indices. Displacements of the inferior vena cava during the respiratory cycle may influence the reliability of ultrasonographic measurements, particularly in M-mode.
下腔静脉超声已被用作预测儿童液体反应性的指标。两种超声模式可用于测量下腔静脉直径的呼吸变化：M 模式和 B 模式。这两种模式测量结果的不一致可能导致评估液体反应性的常用指标出现不准确情况。我们的主要目的是确定这两种评估模式基于超声的测量是否存在差异，这会影响下腔静脉直径呼吸变化的计算。我们的次要目的是评估呼吸周期中下腔静脉的位移，作为两种模式测量差异的可能机制。
前瞻性观察性研究。
一家三级护理教学医院的儿科重症监护病房。
73 名接受控制通气的儿童（中位年龄 16 个月，体重 10 千克）。
使用 B 模式和 M 模式超声通过纵向视图测量下腔静脉直径。评估了两个下腔静脉直径呼吸变化指标：扩张性和呼吸变化。使用 B 模式超声测量下腔静脉的最大头脚向和内外侧位移。
B 模式和 M 模式下下腔静脉的最大直径相似（分别为 7.90 毫米和 7.90 毫米；p = 0.326），但 M 模式测量的最小直径较小（6.36 毫米对 5.00 毫米；p = 0.003）。根据 M 模式获得的数据计算时，下腔静脉直径指数的呼吸变化值比 B 模式测量值显著更高（两者 p≤0.001）。下腔静脉的中位位移在头脚向为 5.00 毫米（四分位间距，3.68 - 6.26 毫米），在内外侧为 0.80 毫米（四分位间距，0.12 - 1.23 毫米）。
在接受控制通气的儿童呼吸周期中，M 模式和 B 模式超声观察到的下腔静脉最小直径测量存在显著差异。这导致下腔静脉直径指数的呼吸变化不准确。呼吸周期中下腔静脉的位移可能会影响超声测量的可靠性，尤其是在 M 模式下。
