If you buy a device and put it into service this calendar year (2018), you can deduct the full amount that you financed on that equipment, regardless if you don't start making payments till next year. That reduces how much you will be paying in tax next spring.
At this time of year, we sell a lot of ABIs and ANS devices. It takes 2 ABIs a month for you to break even on the equipment and most of my primary care doctors are doing 1 to 2 a day - so they are making $4K a month net profit. It only takes 4 ANS tests a month to break even and that usually brings in another $8K a month net profit.
Don't wait till January if you are looking for ways to reduce your taxes and increase your clinic income - while helping your patients. It doesn't make sense that you're sending patients to other doctors so the other doctors get to make the $48K a year or $96K a year profit.