As I understand it, the caffeine increases the chances of reflux (after surgery, I don't think that you'd be able to consume enough fast enough to give yourself a heart attack!). It is, of course, highly addictive. I was absolutely, absolutely addicted to it for many years. You'd never see me at the office or in front of a class without a bottle of Diet Pepsi in my hand. Never. Once I started down the surgery path in April last year, however, I started rotating a bottle of caffeine-free diet Pepsi into my daily mix of soda. This was a big deal. Over a month or 2, I weaned myself off of caffeine, just by slowly and deliberately adding another caffeine-free soda into my daily allowance until it was completely caffeine free.
I have some pretty strong compulsive behaviors, so I was still psychologically dependent on the soda. I don't have many demands in life, but the ones I do have are not negotiable. Soda preference was one of these. In the fall, we ran out of Caffeine Free Diet Pepsi in South Jersey. During the lockdown, at my house had developed the habit of stockpiling soda, diet ginger ale for her and Pepsi for me. We had piles of the stuff. And I was ok for about a month, but then I started not finding it at local stores and had to go farther and farther afield and still would come up short. This was just as people were becoming aware of supply chain problems. So, I made the hardest choice since Sophie's: I switched to caffeine free diet coke. Look, I worked in Atlanta, the home of Coca-Cola. Not only that, I worked at Georgia Tech, and my office was in the shadow of the Coca-Cola HQ:
You'll notice that my office is just north of the HQ, and some winter evenings when the sun was low, I was literally in the building's shadow. I still carried my Pepsi in my briefcase, however, even though I knew that if anyone saw me, I could be fired, beaten, and exiled from the city. I would die for Diet Pepsi. I would have killed for it if it had asked me to, but luckily it never did.
I switched over to caffeine free Diet Coke in early fall. Knowing that surgery was coming up, I started looking for a caffeine-free, sugar-free, alcohol-free, carbonation-free drink that would have to be my psychological crutch and constant companion. I settled on PowerAde Zero. Preferably the blue stuff. We have so much of the stuff downstairs, it's ridiculous.
Your life, going from the first consult with your surgeon through to surgery and beyond, is going to change radically. It's very important to embrace that change. Sugar free red bull may be a step-down from regular red bull. That's important. But I would approach it as a step on the way to other changes, weening yourself off of the caffeine, for instance. Eventually, you'll want to move away from carbonation, since that can apparently make you feel more full than you actually are when you need to be taking in protein. Knowing that I could go from caffeinated to decaf soda, and then to a different brand...those were psychological milestones that let me know that change was possible where previously it had been unthinkable ("....my precioussssssss"). There may well be a place for sugar-free red bull in your routine, but I'd recommend looking down the road and perhaps seeing it as a stepping stone instead of a destination.