Considering open heart surgery and triple bypass but concerned as a spoker about oxygen use?

It's a Problem. Smoking up until the time of CABG will cause more secretions in your lungs. You might end up going home on oxygen for a short time after surgery. Best to commit to quitting for good.
Stop smoking... Chances are that after bypass surgery you will not need oxygen at home. But that being said, stopping smoking is an absolute necessity. All the pain and suffering you will go through with the surgery will basically be wasted if you keep smoking. Smoking will cause the bypasses to stop working much much sooner than they would in a nonsmoker. Do your health a favor and stop before your surgery.