Objective    To evaluate the application of noninvasive cerebral electrical impedance (CEI) measurement in monitoring brain edema after subarachnoid hemorrhage (SAH).     Methods    CEI was measured in 46 SAH patients stimulated with an invariable secure current at a frequency of 50 kHz and an intensity of 0.1 mA within 3 d after onset of the disease. CEI was expressed as the perturbative index (PI). CEI was defined as abnormal when PI was over 9.5 or the difference in PI was over 0.3 for 3 or more 3 measurements of PI in foci and bilateral side.     Results    The CEI was significantly increased in 10 patients (21.7%) with their PI 9.5. Among the 10 patients

CT showed global cerebral edema in 7 and no cerebral edema in 3. The CEI was within the normal range in the remaining 36 patients with no obvious cerebral edema. The PI was significantly increased in 5 SAH patients with obvious cerebral edema in 3 d after onset of the disease.     Conclusion    CEI measurement can sensitively show cerebral edema in SAH patients

and judge the condition of patients and adjust their treatment.