From the Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania (E.E.L., T.C., J.K., A.N.); Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania (E.E.L., A.E.C., N.P., T.C., D.C., A.N.); Department of Emergency Medicine, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania (A.E.C.); and Department of Emergency Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania (N.P., N.R.J.).
Anesthesiology. 2016 Apr;124(4):870-7. doi: 10.1097/ALN.0000000000001032.
Bedside ultrasound has emerged as a rapid, noninvasive tool for assessment and monitoring of fluid status in children. The inferior vena cava (IVC) varies in size with changes in blood volume and intrathoracic pressure, but the magnitude of change to the IVC with inhalational anesthetic and positive-pressure ventilation (PPV) is unknown.
Prospective observational study of 24 healthy children aged 1 to 12 yr scheduled for elective surgery. Ultrasound images of the IVC and aorta were recorded at five time points: awake; spontaneous ventilation with sevoflurane by mask; intubated with peak inspiratory pressure/positive end-expiratory pressure of 15/0, 20/5, and 25/10 cm H2O. A blinded investigator measured IVC/aorta ratios (IVC/Ao) and changes in IVC diameter due to respiratory variation (IVC-RV) from the recorded videos.
Inhalational anesthetic decreased IVC/Ao (1.1 ± 0.3 vs. 0.6 ± 0.2; P < 0.001) but did not change IVC-RV (median, 43%; interquartile range [IQR], 36 to 58% vs. 46%; IQR, 36 to 66%; P > 0.99). The initiation of PPV increased IVC/Ao (0.64 ± 0.21 vs. 1.16 ± 0.27; P < 0.001) and decreased IVC-RV (median, 46%; IQR, 36 to 66% vs. 9%; IQR, 4 to 14%; P < 0.001). There was no change in either IVC/Ao or IVC-RV with subsequent incremental increases in peak inspiratory pressure/positive end-expiratory pressure (P > 0.99 for both).
Addition of inhalational anesthetic affects IVC/Ao but not IVC-RV, and significant changes in IVC/Ao and IVC-RV occur with initiation of PPV in healthy children. Clinicians should be aware of these expected vascular changes when managing patients. Establishing these IVC parameters will enable future studies to better evaluate these measurements as tools for diagnosing hypovolemia or predicting fluid responsiveness.
床边超声已成为一种快速、非侵入性的工具，可用于评估和监测儿童的液体状态。下腔静脉（IVC）的大小随血容量和胸腔内压力的变化而变化，但吸入麻醉和正压通气（PPV）对 IVC 的变化程度尚不清楚。
对 24 名 1 至 12 岁择期手术的健康儿童进行前瞻性观察研究。在五个时间点记录 IVC 和主动脉的超声图像：清醒；面罩下吸入七氟醚时自主呼吸；气管插管时吸气峰压/呼气末正压为 15/0、20/5 和 25/10 cm H2O。一位经过盲法训练的研究员从记录的视频中测量 IVC/主动脉比值（IVC/Ao）和 IVC 因呼吸变化而引起的直径变化（IVC-RV）。
吸入麻醉降低了 IVC/Ao（1.1 ± 0.3 比 0.6 ± 0.2；P < 0.001），但没有改变 IVC-RV（中位数，43%；四分位距 [IQR]，36 至 58% 比 46%；IQR，36 至 66%；P > 0.99）。开始使用 PPV 后，IVC/Ao 增加（0.64 ± 0.21 比 1.16 ± 0.27；P < 0.001），IVC-RV 降低（中位数，46%；IQR，36 至 66% 比 9%；IQR，4 至 14%；P < 0.001）。随着吸气峰压/呼气末正压的逐步增加，IVC/Ao 或 IVC-RV 均无变化（两者 P > 0.99）。
在健康儿童中，吸入麻醉会影响 IVC/Ao，但不会影响 IVC-RV，而在开始使用 PPV 时，IVC/Ao 和 IVC-RV 会发生显著变化。临床医生在管理患者时应注意这些预期的血管变化。确定这些 IVC 参数将使未来的研究能够更好地评估这些测量结果，将其作为诊断低血容量或预测液体反应性的工具。
