Central Hemodynamics, Augmentation index and Microcirculation after Phlebotomy

Our principal aim is to assess the effects of phlebotomy on aortic augmentation (AIx) and central BP in supine position and after standing, second, to assess the effects of counter manoeuvres (leg crossing and thigh compression) on aortic augmentation (AIx) and central BP before and after phlebotomy while standing and third, the difference between viscosity change and volume depletion on aortic augmentation (AIx) and central BP.The burden of this study consists of one visit, with a duration of approximately one hour. The patients will be assigned a group (volume replacement or no volume replacement) depending on the regular receiving care; when a patient experienced negative effects after phlebotomy (such as dizziness, light headedness, weakness and/or collapse), the patient is assigned to receive volume replacement by their attending physician. The techniques used are the Nexfin, the Arteriograph and the MicroScan Video Microscope which will measure central BP, MAP, AIx, stroke volume, heart rate, systemic vascular resistance, forward and backward waves, cardiac output, pulse pressure, baroreflex and objectify microcirculation in supine and standing position with and without counter manoeuvres before and after phlebotomy. Furthermore a short questionnaire will be taken to assess record patients’ age, gender, medical history, demographic variables, medication use and co-morbidity. Also length, weight and waist circumference will be measured. Finally a blood sample will be taken before and after the phlebotomy for hemoglobin, plasma viscosity and hematocrit.

Recently it has been demonstrated that upon standing wave reflection and central blood pressure (BP) decrease despite an increase in systemic vascular resistance. The decrease in central aortic augmentation and central BP can be attenuated by unilateral leg compression. This suggests that aortic augmentation (AIx) and central BP are sensitive to alterations in venous return. Our principal aim is to assess whether changes in volume status affect aortic augmentation (AIx) and central BP in patients receiving regular phlebotomy while supine and after standing. Because changes in blood viscosity may influence AIx, BP and cardiac output, the current study also aims to assess the difference of BP and AIx in patient who receive volume replacement after.

A total of six measurement moments are done with the arteriograph: in supine position (t=10), in standing position (t=15) and with countermanouevres (t=20) before the intervention (phlebotomy). After the phlebotomy the same measurement regime is done (t=35, t=40 and t=45, respectively). At the same time a continuous measurement is done with the nexfin (before and after intervention). Objectified parameters are: central BP, AIx, PWV, stroke volume, heart rate, systemic vascular resistance, cardiac output, pulse pressure, baroreflex and MAP. At t=0 and again at t=55 microcirculation is objectified with a SDF-camera. Blood samples (Hb, ht and plasma viscocity) will be collected before (t=25) and after phlebotomy (t=50).

Phlebotomy with or without volume replacement. Each patient serves as his or her own control. The hemodynamic measurements from before the phlebotomy (500ml) are compared to the hemodynamic measurements after phlebotomy.