Early Prediction of Sepsis Based on Machine Learning Algorithm

Table 5

Time window structure of different variables.

Variables	Time window length	Feature descriptions
HR, MAP, O2Sat, Resp, SBP	2 hours	Calculate the difference between values when ICULOS = t or ICULOS = t-2
WBC, Temp, MAP, SBP, Creatinine, Platelets, FiO2, SaO2, PTT, BUN, Calcium, Phosphate, Hct, Lactate, Alkalinephos, Glucose, Hgb	12 hours	Calculate maximum, minimum, and the time range from ICULOS = t-12 and t-24 to ICULOS = t
	24 hours

Note: (1) when the length of the time window is 2 h, if the current time t < 2, the feature value is nan, and the missing position is filled with the median of the column data; (2) when the length of time windows is 12 h/24 h, if the current time t < 12/24, the time window will change into time from ICULOS = 1 to the current time ICULOS = t to construct features.