INTRACRANIAL HYPERTENSION AND NEUROSURGERY

Mean arterial pressure and systolic blood pressure for detection of hypotension during hemapheresis: implications for patients with baseline hypertension

Mean arterial pressure (MAP) has been characterized as a more sensitive and physiologically appropriate hemodynamic parameter in the detection of hemapheresis-related hypotension, resulting in a much closer correlation with the presence of symptomatic hypotension. Patients were enrolled over a 12-month period and data collected on any previous diagnosis of hypertension, antihypertensive therapy used, indication for apheresis, age decile, and gender. Baseline vital signs, any hypotensive signs or symptoms observed, and the patient's vital signs at the time of any hypotensive episode were recorded. Patients were assigned to a subgroup, sensitivity and specificity analysis performed, positive likelihood ratios calculated, receiver operating characteristic curves constructed, and ideal cutoff values identified. The incidence of hypotension among our study population was found to be 6.8%. Over all procedures, systolic blood pressure (SBP) was determined to be a "poor" test for detecting hypotension, while MAP demonstrated a "fair" capacity. A downward normalization was evident in the ideal cutoff value based upon a patient's hypertensive history. The currently accepted SBP less than 80 mmHg cutoff failed to detect hypotensive episodes among baseline hypertensive patients, raising questions about its sensitivity. Based upon physiologic principles and study findings, a MAP-based criterion is preferable in the diagnosis of hypotension during hemapheresis.