Department of Medicine, Hôpital du Sacré-Coeur de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Nord-de-l'Ile-de-Montréal, 5400 Boul Gouin O, Montréal, Québec, H4J 1C5, Canada.
Research Center, Hôpital du Sacré-Coeur de Montréal, Centre intégré universitaire de santé et de services sociaux (CIUSSS) du Nord-de-l'Ile-de-Montréal, Montréal, Canada.
Neurocrit Care. 2020 Apr;32(2):486-491. doi: 10.1007/s12028-019-00763-y.
Brain tissue oxygenation (PbtO) in traumatic brain injury (TBI) is known to be dependent on cerebral blood flow (CBF) which remains difficult to assess during the very early phase of TBI management. This study evaluates if blood flow velocity measurement with 2D color-coded transcranial Doppler (TCD) can predict cerebral hypoxic episodes in moderate-to-severe TBI measured with a PbtO probe.
This is a prospective observational study of serial TCD measurements to assess blood flow velocity and its association with PbtO. Measurements were done bilaterally on the middle cerebral artery (MCA) early after the insertion of PbtO monitoring, daily for 5 days and during dynamic challenge tests. Physiological parameters affecting PbtO and Doppler velocities were collected simultaneously (PaO, PaCO, hemoglobin [Hb] level, intracranial pressure, and cerebral perfusion pressure [CPP]).
We enrolled 17 consecutive patients with a total of 85 TCD studies. Using 2D color-coded TCD, signal acquisition was successful in 96% of the cases. Twenty-nine (34%) TCD measures were performed during an episode of cerebral hypoxia (PbtO ≤ 20 mmHg). For early episodes of cerebral hypoxia (occurring ≤ 24 h from trauma), all Vmean < 40 cm/s were associated with an ipsilateral PbtO ≤ 20 mmHg (positive predictive value 100%). However, when considering all readings over the course of the study, however, we found no correlation between PbtO and MCA's mean blood flow velocity (Vmean). Vmean is also positively correlated with PaCO, whereas PbtO2 is also correlated with PaO, CPP, and Hb level.
Early TCD measurements compatible with low CBF (mean velocity < 40 cm/s) detect brain tissue hypoxia early after TBI (≤ 24 h) and could potentially be used as a screening tool before invasive monitoring insertion to help minimize time-sensitive secondary injury. Various factors influence the relationship between Vmean and PbtO, affecting interpretation of their interaction after 24 h.
已知创伤性脑损伤 (TBI) 中的脑组织氧合 (PbtO) 依赖于脑血流 (CBF)，而在 TBI 管理的早期阶段，CBF 仍然难以评估。本研究评估使用二维彩色经颅多普勒 (TCD) 测量血流速度是否可以预测使用 PbtO 探头测量的中重度 TBI 中的脑缺氧发作。
这是一项前瞻性观察性研究，对 TCD 测量结果进行了连续评估，以评估血流速度及其与 PbtO 的关系。在插入 PbtO 监测后早期，每天在大脑中动脉 (MCA) 双侧进行测量，共进行 5 天，并进行动态挑战测试。同时收集影响 PbtO 和多普勒速度的生理参数 (PaO、PaCO、血红蛋白 [Hb] 水平、颅内压和脑灌注压 [CPP])。
我们纳入了 17 例连续患者，共进行了 85 次 TCD 研究。使用二维彩色 TCD，成功采集了 96%的信号。29 次 (34%) TCD 测量是在脑缺氧发作期间进行的 (PbtO≤20mmHg)。对于早期脑缺氧发作 (创伤后≤24 小时发生)，所有 Vmean<40cm/s 均与同侧 PbtO≤20mmHg 相关 (阳性预测值 100%)。然而，当考虑整个研究过程中的所有读数时，我们发现 PbtO 与 MCA 的平均血流速度 (Vmean) 之间没有相关性。Vmean 与 PaCO 呈正相关，而 PbtO2 与 PaO、CPP 和 Hb 水平呈正相关。
早期 TCD 测量结果与低 CBF 相符 (平均速度<40cm/s) 可早期检测 TBI 后 (≤24 小时) 的脑缺氧，并可作为侵入性监测插入前的筛查工具，有助于尽量减少时间敏感的继发性损伤。各种因素影响 Vmean 和 PbtO 之间的关系，影响 24 小时后两者相互作用的解释。
