Data from our prospective observational clinical study using mini volume loading test (mVLT) using 2.5 ml kg-1 boluses of crystalloid for indication of perioperative changes in patient's hydration level

We prospectively collected data in 48 adult ASA II physical state patients who had elective primary total knee arthroplasty (TKA). As part of a larger RCT, with an aim to evaluate peri-operative changes in patients' hydration level, the mini volume loading test (mVLT) was applied before induction of spinal anaesthesia (pre-operative) and also 24-h later (post-operative). The mVLT protocol implied mini fluid challenges consisting of Ringer’s acetate boluses followed by 5 min periods without fluid loading. Six 2.5 ml kg^-1 boluses were infused. Haemoglobins - invasive (aHb, arterial) and non-invasive (SpHb or cHb, capillary), cardiac stroke volume (SV) deviation (%), perfusion index (PI) and its deviation from baseline (PID) were measured before and after each mini fluid challenge and also 20 min after the last bolus. We present our data. Several variables were obtained by mathematically processing haemoglobin values: plasma dilution (PD), plasma dilution efficacy (PDE), arterio-capillary plasma dilution efficacy difference (acPED) as well as relative difference between the paired invasive and non-invasive haemoglobin measurements (RD) and absolute RD (ARD). We post the related math, too.