Math for calculating PD, PDE and acPED.docx

We prospectively studied patients undergoing total knee arthroplasty (TKA). As part of a revised GDT (revGDT) protocol, the mini volume loading test (mVLT) was applied before induction of anaesthesia and surgery (pre-operative) and also 24-h later (post-operative). The mVLT implies mini fluid challenges. They consisted of acetated Ringer’s boluses followed by 5-min periods without fluids. Three 5 mL kg^-1 boluses were used in mVLT for 36 TKA patients, and six 2.5 mL kg^-1 boluses in other 48 TKA patients. Haemoglobin, invasive and non-invasive, stroke volume (SV) deviation from baseline (%), perfusion index (PI) and its deviation from baseline (PID), mean arterial pressure (MAP) were measured before and after each mini fluid challenge. We present our records and the math for calculating plasma dilution (PD), plasma dilution efficacy (PDE), as well as relative difference between the paired invasive and non-invasive haemoglobin measurements (RD) and absolute RD (ARD).