To perform a meta-analysis of non-invasive brain edema dynamic monitor in diagnosis of acute brain injury and evaluate the diagnostic value of non-invasive brain edema dynamic monitor for intracerebral hemorrhage, brain trauma and cerebral infarction.

The literatures of the non-invasive brain edema dynamic monitor were retrieved using the Chinese Biomedical Literature Database, Wanfang Medical Database, Chinese Knowledge Network Journal Database, and the PubMed Database. The cerebral electrical impedance of the brain with healthy side in acute brain injury patients was treated as control. The quality of included literatures was assessed. The relevant data for research was extracted. Statistical analysis was performed Review Manager 5.4 software. The heterogeneity of the literature was tested. The sensitivity analysis was carried out by single literature exclusion method, and the OR value of disturbance coefficient of each subgroup was calculated by drawing forest map.

Eight studies with heterogeneity were included for subgroup analysis according to the onset type. The cerebral electrical impedance was significantly lower than that of healthy side after 1 d of intracerebral hemorrhage and brain trauma, the OR values were -2.57(95%CI: -3.01--2.13) and -0.83(95%CI: -1.02--0.63). The cerebral electrical impedance was significantly higher than that of healthy side after 3 and 7 d of intracerebral hemorrhage and brain trauma. The cerebral electrical impedance was significantly higher than that of healthy side after 1, 3 and 7 d of cerebral infarction, the OR values were 0.75(95%CI: 0.39-1.10), 0.61(95%CI: 0.32-0.90), 0.50(95%CI: 0.31-0.99). The variation amplitude of cerebral electrical impedance during 1-3 d in patients with intracerebral hemorrhage, cerebral infarction and brain trauma was significantly greater than that during 3-7 d after onset, the OR values were 3.30 (95%CI: 3.11-3.50), 1.03 (95%CI: 0.08-1.98), 2.23 (95%CI: 2.09-2.38).

The cerebral electrical impedance of non-invasive brain edema dynamic monitor in patients with acute brain injury accorded with the basic pathophysiological law of brain edema and reflected the dynamic process of changes in the severity of cerebral edema. It can be used as an auxiliary diagnostic method for patients with acute brain injury to help clinicians understand the situation of brain edema in patients at any time during treatment.