GSTM1 and anemia (phenotype): The hemogram data before extubation showed that the Hb concentrations were significantly lower in the M_aET group than in the S_aET group (p = 0.006), and moderate-to-severe anemia was identified in 81.8% of patients in the M_aET group and 33% of patients in the S_aET group (p = 0.002).