GSTM1 and anemia: The latest hemogram before intubation showed that the Hb concentrations were significantly lower in patients in the M_dMV group than those in the S_dMV group (p <0.001), and moderate-to-severe anemia was identified in 61.5% of the patients in the M_dMV group and 21.6% of those in the S_dMV group (p <0.001).