Background

The invasive nature of the current methods for monitoring of intracranial pressure (ICP) has prevented their use in many clinical situations. Several attempts have been made to develop methods to monitor ICP non-invasively. The aim of this study is to assess the relationship between ultrasound-based non-invasive ICP (nICP) and invasive ICP measurement in neurocritical care patients.

Methods and findings

This was a prospective, single-cohort observational study of patients admitted to a tertiary neurocritical care unit. Patients with brain injury requiring invasive ICP monitoring were considered for inclusion. nICP was assessed using optic nerve sheath diameter (ONSD), venous transcranial Doppler (vTCD) of straight sinus systolic flow velocity (FV_sv), and methods derived from arterial transcranial Doppler (aTCD) on the middle cerebral artery (MCA): MCA pulsatility index (PI_a) and an estimator based on diastolic flow velocity (FV_d). A total of 445 ultrasound examinations from 64 patients performed from 1 January to 1 November 2016 were included. The median age of the patients was 53 years (range 37–64). Median Glasgow Coma Scale at admission was 7 (range 3–14), and median Glasgow Outcome Scale was 3 (range 1–5). The mortality rate was 20%. ONSD and FV_sv demonstrated the strongest correlation with ICP (R = 0.76 for ONSD versus ICP; R = 0.72 for FV_sv versus ICP), whereas PI_a and the estimator based on FV_d did not correlate with ICP significantly. Combining the 2 strongest nICP predictors (ONSD and FV_sv) resulted in an even stronger correlation with ICP (R = 0.80). The ability to detect intracranial hypertension (ICP ≥ 20 mm Hg) was highest for ONSD (area under the curve [AUC] 0.91, 95% CI 0.88–0.95). The combination of ONSD and FV_sv methods showed a statistically significant improvement of AUC values compared with the ONSD method alone (0.93, 95% CI 0.90–0.97, p = 0.01). Major limitations are the heterogeneity and small number of patients included in this study, the need for specialised training to perform and interpret the ultrasound tests, and the variability in performance among different ultrasound operators.

Conclusions

Of the studied ultrasound nICP methods, ONSD is the best estimator of ICP. The novel combination of ONSD ultrasonography and vTCD of the straight sinus is a promising and easily available technique for identifying critically ill patients with intracranial hypertension.

中文翻译：

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神经重症监护中颅内压的超声无创测量：一项前瞻性观察研究

背景

目前用于监测颅内压 (ICP) 的方法的侵入性使其无法在许多临床情况下使用。已经进行了几次尝试来开发非侵入性监测 ICP 的方法。本研究的目的是评估基于超声的非侵入性 ICP (nICP) 与神经重症监护患者的侵入性 ICP 测量之间的关系。

方法和发现

这是一项针对三级神经重症监护病房患者的前瞻性、单队列观察性研究。考虑纳入需要有创ICP监测的脑损伤患者。使用视神经鞘直径 (ONSD)、直窦收缩流速 (FV _sv ) 的静脉经颅多普勒 (vTCD) 和大脑中动脉 (MCA) 上的动脉经颅多普勒 (aTCD) 方法评估 nICP：MCA 搏动指数 (PI _a ) 和基于舒张期流速 (FV _{d ) 的估计量}）。包括 2016 年 1 月 1 日至 11 月 1 日期间对 64 名患者进行的总共 445 次超声检查。患者的中位年龄为 53 岁（范围 37-64）。入院时格拉斯哥昏迷量表中位数为 7（范围 3-14），格拉斯哥结局量表中位数为 3（范围 1-5）。死亡率为20%。ONSD 和 FV _sv与 ICP 的相关性最强（ ONSD 与 ICP 的R = 0.76； FV _{sv与 ICP 的}R = 0.72 ），而 PI _a和基于 FV _d的估计量与 ICP 没有显着相关性。结合 2 个最强的 nICP 预测因子（ONSD 和 FV _sv）导致与 ICP（R= 0.80）。ONSD 检测颅内高压（ICP ≥ 20 mm Hg）的能力最高（曲线下面积 [AUC] 0.91，95% CI 0.88–0.95）。与单独的 ONSD 方法相比，ONSD 和 FV _sv方法的组合显示出 AUC 值的统计学显着改善（0.93, 95% CI 0.90–0.97, p = 0.01）。主要限制是本研究中包含的异质性和少数患者，需要专门培训来执行和解释超声测试，以及不同超声操作者之间的表现差异。

结论

在所研究的超声 nICP 方法中，ONSD 是 ICP 的最佳估计方法。ONSD 超声和直窦 vTCD 的新组合是一种有前途且易于使用的技术，可用于识别患有颅内高压的危重患者。