Patients who present with impaired consciousness could be suffering from a variety of serious conditions. Although computed tomography can identify most brain lesions, it does not identify metabolic and extrinsic brain dysfunctions. Ikeda and colleagues studied the ability of vital signs to differentiate patients with impaired consciousness who are likely to have an intracranial lesion from those who are not.

The study evaluated 529 consecutive patients 15 years or older who presented to a Japanese emergency department. Patients with head trauma were excluded from the study. The mean age of patients was 65 years. Some vital signs distinguished patients with brain lesions from those without lesions. Patients with lesions had significantly higher systolic and diastolic blood pressures and lower pulse rates. The diagnostic value of systolic blood pressure was significantly better than that of diastolic blood pressure or pulse rate. Likelihood ratios for systolic blood pressure lower than 90 mm Hg were less than 0.04; for systolic blood pressure greater than 170 mm Hg, likelihood ratios were more than 6.09.

The authors conclude that systolic blood pressure is the best vital sign for predicting whether impaired consciousness is due to a brain lesion.