TABLE 2.

Equations for calculating renal metabolic and functional parameters

Outcome	Unit	Equation	Abbreviations
Arterial oxygen content	mLO2/L	$\left(Hb\times 2.4794\right)+(p{O}_{2arterial}\times K)$	Hb, hemoglobin content (mmol/L).2.4794 = arterial oxygen content in mLO2/dL and is calculated by 1.54 (mLO2/g Hb at 37 °C × (Hb [mmol/L] × 1.61) × 100 (= SO2 arterial) × 0.01.po2, partial oxygen pressure kPa).K, SO2, hemoglobin saturation (%).
Venous oxygen content	mLO2/L	$(0.024794\times Hb\times S{O}_{2venous}+\left(p{O}_{2venous}\times K\right))$	0.024794 = venous oxygen content in mLO2/dL and is calculated by 1.54 (mLO2/g Hb at 37 °C × (Hb [mmol/L] × 1.61) × SO2 venous × 0.01.Hb, hemoglobin content (mmol/L).po2, partial oxygen pressure (kPa).K, solubility constant of oxygen in water at 37 °C (0.0225 mLO2 per kPa).SO2, hemoglobin saturation (%).Bold part of the formula is canceled when no RBCs were used.
Oxygen consumption	mLO2/min/100 g	$\begin{array}{l}(arterialoxygencontent\left[\frac{mL{O}_2}{L}\right]\\ -venousoxygencontent\left[\frac{mL{O}_2}{L}\right])\times Q/g\times 100\end{array}$	Q, renal blood flow (L/min).g, kidney weight (g).
Fractional sodium excretion	%	$100\times \frac{U_{Na}\times P_{Cr}}{P_{Na}\times U_{Cr}}$	UNa, urine sodium concentration (mmol/L).PNa, perfusate sodium concentration (mmol/L).PCr, perfusate creatinine concentration (mmol/L).UCr, urine creatinine concentration (mmol/L).
Total sodium reabsorption	mmol/min/ 100 g	$\left(\frac{\left(CrCl\times P_{Na}\right)-(U_{Na}\times U)}{g}\right)\times 100$	CrCl, creatinine clearance (mL/min).PNa, perfusate sodium concentration (mmol/L).UNa, urine sodium concentration (mmol/L).U, urine production rate (mL/min).g, kidney weight (g).
Creatinine clearance	mL/min/100 g	$\left(\frac{\left(\frac{U_{Cr}\times U}{P_{Cr}}\right)}{g}\right)\times 100$	UCr, urine creatinine concentration (mmol/L).U, urine production rate (mL/min).PCr, perfusate creatinine concentration (mmol/L).g, kidney weight (g).
TBARS production	U/L	$\left(TBAR{S}_{urine}\times U\right)+\left(TBAR{S}_{perfusate}\times (P+I)\right)$	TBARSurine, concentration of TBARS in urine (µM).U, urine production rate (mL/min).TBARSperfusate, concentration of TBARS in the perfusate (µM).P, priming volume of the NMP setup (L).I, volume of infusion during NMP (L).

NMP, normothermic machine perfusion; TBARS, thiobarbituric acid-reactive substances.