Prognostic value of hemodynamic findings from impedance cardiography in hypertensive stroke

Abstract

Impedance cardiography (ICG), a noninvasive method of hemodynamic monitoring, is a useful tool in the care of critically ill patients. Use of this technology shows promise in the hemodynamic assessment of hypertensive stroke patients. This study describes the different ICG findings of patients with hypertensive stroke and correlates parameters with patient outcome. Adult patients with stroke admitted to the intensive care unit (ICU) who were on antihypertensive medications or had hypertensive blood pressure (BP) levels at the time of admission were included. Patients were classified as having ischemic or hemorrhagic stroke on the basis of imaging studies. The ICG was done in the initial 24 h of admission using the BioZ Cardiac Output Monitor (CardioDynamics, Inc., San Diego, CA) and 18 hemodynamic parameters were analyzed. Statistical analysis was performed to assess correlation of hemodynamic findings with the type of stroke and survival to hospital discharge. Fifty-two adult patients with a mean age of 60.5 +/- 12.4 years were included. Of this population, 29 had ischemic stroke and 23 had hemorrhagic stroke. Seventeen patients died during hospital stay. Overall, noninvasive hemodynamic parameters of stroke patients showed a high systemic vascular resistance index (SVRI) and systemic vascular resistance (SVR), and decreased cardiac output (CO), stroke index (SI), and stroke volume (SV). Among the ischemic stroke group, nonsurvivors had a significantly higher mean SVRI and mean SVR compared to the survivors. In contrast, among the hemorrhagic stroke patients, nonsurvivors had a significantly lower mean SVRI and SVR compared to survivors. Except for SI and BP, there was no difference in the noninvasive hemodynamic parameters between the ischemic stroke group and the hemorrhagic stroke group. In this population of hypertensive stroke patients admitted to the ICU, ICG showed an elevated SVRI and SVR and depressed CO, SV, and SI. In the ischemic stroke group, higher SVR and SVRI were associated with in-hospital death, whereas in the hemorrhagic stroke group, lower SVR and SVRI were associated with in-hospital death. The ICG may provide significant prognostic information in patients admitted with hypertensive stroke.