With low-flow oxygen administration, one of the methods of oxygen therapy, the concentration of oxygen depends on the flow rate and on the tidal volume of the patient. It is often casually referred to as 100% oxygen, though in fact it is usually 30-60%, and rarely exceeds 70%. A patient who receiving 6l/min of oxygen flow by nasal cannula is receiving an FiO2 of 44%, nasal cannula with more than 6l flow does little to increase inspired oxygen concentrations. Patients in control group received 0.11/min/kg of oxygen flow by modified T-piece in PAR,in low flow group received 0.11/min/kg of oxygen flow and in high group received 0.2Vmin/kg of oxygen flow. Blood pressure,heart rate, ABGA, SaO2, PAR score were measured in PAR with 5 minutes interval. PaO2 and SaO2 of low flow group were significantly (p<0.05) lower than control group with 5 of PAR score, PaO2 of low flow group was significantly (p<0.05) lower than control group with 10 of PAR score and PaO2 and SaO2 of high flow group were significantly (p<0.05) higher than low flow group with 10 of PAR score. These result suggest that patient who were taken Ravitch's operation receive a higher oxygen flow than others who were taken operation except Ravitch's operation for the same effect of oxygen therapy.