Table 1. Demographic characteristics of both groups

Demographic characteristic	Non-rebreathing oxygen mask (n=223)	OxyMask (n=237)	P-value
Age (years)	60.6±17.3	62.3±15.4	0.275
Sex (M/F)	91/132	105/132	0.448
Height (cm)	160.6±9.9	162.2±9.1	0.064
Weight (kg)	60.6±11.9	63.4±11.0	0.010
BMI (kg/m2)	23.5±3.8	24.1±3.7	0.073
ASA physical classification (1/2/3/4)	41/137/45/0	27/154/55/1	0.141
Pulmonary disease (yes/no)	28/195	39/198	0.236
Operation time (min)	167.9±125.2	192.9±139.8	0.044
Anesthesia time (min)	215.4±130.3	237.8±141.8	0.079

Values are presented as mean±SDs.
The Student t-test was performed for continuous variables and the chi-square test for categorical variables.
P<0.05 is regarded as indicating statistical significance.
BMI, body mass index; ASA, American Society of Anesthesiologists.