Table 1.

Definition of physiology, histology, biochemistry, and combined indexes.

Index	Number of parameters	Parameters (P)	time point (s) (min)	Equation
Physiology Index (PI)	7	PaCO2, PaO2, SaO2, VT, FiO2, CertSO2, and Cs	45-180	$PI=\frac{1}{7}\times {\displaystyle \sum _1^7}{(physiologyparameter)}^{\alpha }$
Histology Index (HI)	7	Alveolar wall thickening, alveolar wall breakage, blood cell infiltration, interstitial edema, vascular bed injury, alveolar wall flooding, and phospholipid in cells	180	$HI=\frac{1}{7}\times {\displaystyle \sum _1^7}(10-\overline{histologyparameterscore})$
Biochemistry Index (BI)	13	SP-A, SP-D, IL-1β and TNFα in tissue and lavage, SP-B in tissue, SP-B pro and SP-B dimer in lung, IgG heavy and light chains in tissue	180	$BI=\frac{1}{13}\times {\displaystyle \sum _1^{13}}{(\overline{biochemistryparameter})}^{\alpha }$
Combined Index (CI)	3	PI at 180 min, HI, and BI	180	$CI=\frac{PI(time=180)+HI+BI}{3}$

α = 1 if higher paramter value signifies an improvement.

α = −1 if higher parameter value signifies a deterioration.