Panerai R B, Kerins V, Fan L, Yeoman P M, Hope T, Evans D H
Department of Cardiovascular Sciences, Faculty of Medicine, University of Leicester, Leicester Royal Infirmary, Leicester, UK.
Br J Neurosurg. 2004 Oct;18(5):471-9. doi: 10.1080/02688690400012343.
The objective of the study was to test the hypothesis that dynamic cerebral pressure-autoregulation is associated with the outcome of patients with severe head injury and to derive optimal criteria for future studies on the predictive value of autoregulation indices. Repeated measurements were performed on 32 patients with severe head injury. Arterial blood pressure (ABP) was measured continuously with an intravascular catheter, intracranial pressure (ICP) was recorded with a subdural semiconductor transducer and cerebral blood flow velocity (CBFV) was measured with Doppler ultrasound in the middle cerebral artery. Transfer function analysis was performed on mean beat-to-beat values, using ABP or CBFV as input variables and CBFV or ICP as the output variables. A dynamic index of autoregulation (ARI) ranging between 0 and 9 was extracted from the CBFV step response for a change in ABP. No significant differences between survivors and non-survivors were found due to mean values of ICP, ABP, CPP, CBFV, pCO2, GCS, age or heart rate. The transfer functions between ABP-ICP and CBFV-ICP did not show any significant differences either. The median [lower, upper quartiles] ARI was significantly lower for non-survivors compared with survivors [4.8 (0.0, 5.9) v. 6.9 (5.9, 7.4), p= 0.004]. The correlation between ARI and GOS was also significant (r=0.464, p=0.011). Cohen's coefficient was optimal for a threshold of ARI= 5.86 (kappa 0.51, p=0.0036), leading to a sensitivity for death of 75%, specificity=76.5%, odds ratio =9.75 and overall precision = 75.8%. The difference in ARI values between survivors and non-survivors persisted when results were adjusted for GCS (p = 0.028). A similar analysis for the Marshall CT scale did not reach significance (p = 0.072). A logistic regression analysis confirmed that apart from the ARI, no other variables had a significant contribution to predict outcome. In this group of patients, death following severe head injury could not be explained by traditional indices of risk, but was strongly correlated to indices of dynamic cerebral pressure-autoregulation extracted by means of transfer function analysis. Future studies using a prospective design are needed to validate the predictive value of the ARI index, as estimated by transfer function analysis, in relation to death and other unfavourable outcomes.
本研究的目的是检验动态脑压自动调节与重度颅脑损伤患者预后相关这一假设，并得出关于自动调节指数预测价值的未来研究的最佳标准。对32例重度颅脑损伤患者进行了重复测量。使用血管内导管连续测量动脉血压（ABP），用硬膜下半导体传感器记录颅内压（ICP），并用多普勒超声测量大脑中动脉的脑血流速度（CBFV）。以ABP或CBFV作为输入变量，CBFV或ICP作为输出变量，对平均逐搏值进行传递函数分析。从ABP变化时的CBFV阶跃响应中提取范围在0至9之间的自动调节动态指数（ARI）。在ICP、ABP、脑灌注压（CPP）、CBFV、二氧化碳分压（pCO2）、格拉斯哥昏迷量表（GCS）、年龄或心率的平均值方面，幸存者和非幸存者之间未发现显著差异。ABP-ICP和CBFV-ICP之间的传递函数也未显示出任何显著差异。与幸存者相比，非幸存者的ARI中位数[下四分位数，上四分位数]显著更低[4.8（0.0，5.9）对6.9（5.9，7.4），p = 0.004]。ARI与格拉斯哥预后评分（GOS）之间的相关性也很显著（r = 0.464，p = 0.011）。对于ARI = 5.86的阈值，科恩系数最佳（kappa 0.51，p = 0.0036），导致死亡的敏感性为75%，特异性 = 76.5%，优势比 = 9.75，总体精度 = 75.8%。当结果根据GCS进行调整时，幸存者和非幸存者之间的ARI值差异仍然存在（p = 0.028）。对马歇尔CT分级的类似分析未达到显著水平（p = 0.072）。逻辑回归分析证实，除ARI外，没有其他变量对预测预后有显著贡献。在这组患者中，重度颅脑损伤后的死亡不能用传统风险指标来解释，而是与通过传递函数分析提取的动态脑压自动调节指标密切相关。需要采用前瞻性设计的未来研究来验证通过传递函数分析估计的ARI指数与死亡及其他不良预后相关的预测价值。
