Procedures that can be done for pain management are expansive. There are so many interventions that can be done to help with pain. They range from a simple knee injection to minimally invasive spinal decompression or spinal cord stimulator implants. Some of the more advanced procedures, like the decompression and stimulator implant mentioned above are typically done under general anesthesia and will be ignored in this post. Today, we are looking specifically at monitored anesthesia care (MAC), which is, “Planned procedure during which the patient undergoes local anesthesia together with sedation and analgesia,” per the American Society of Anesthesiologists (ASA).
What does MAC mean for you, the patient? It means that you will likely take a small nap and will have you pain controlled during the procedure. This makes for an extremely comfortable setting. None of the procedures require sedation, it is an option for those who don’t want to feel the procedure, have anxiety, dislike needles, or who are worried that moving during the procedure. There are requirements to get sedation. The day of the procedure, the patient should be fasting with no food intake for 8 hours. Liquids are often told to be stopped at the same time but clear liquids (water, black coffee, sport drinks, soda) would technically be allowed up to two hours prior. The risk that is run with intake of food and drink is aspiration. This is when food or drink enters into the windpipe and lungs. This is dangerous. Having an empty stomach prevents this as there is little to be aspirated. Even though clear liquids are allowed up to 2 hours prior, a large intake of clear liquid does increase the risk for aspiration. To make it less confusing, most patients are told nothing to eat or drink after midnight.
No sedation is the same. By that I mean that the medications used vary from institution to institution as well as varying by the anesthesiologist that is administering the anesthesia. Multiple medications can be used for light sedation or even a deeper monitored anesthesia care. The medications include Midazolam (for anxiety, sedation, and amnesia) Fentanyl (for pain), Ketamine (for pain and sedation), Propofol (for sedation), or Nitrous Oxide (for pain and sedation).
The key to a great sedation is a watchful and attentive anesthesiologist and appropriate use of monitors. In nearly every case of a bad outcome with MAC for pain cases, the anesthetist didn’t use the standard ASA monitors, but only used a pulse oximeter to check for oxygen in the blood and a blood pressure cuff. These monitors are necessary but are later to show signs of a non-breathing patient. The use of a special nasal cannula (that will supply oxygen to the patient) with a sampling line that gives capnography (displays a waveform of exhaled CO2) shows an apneic patient early, which means intervention can be applied earlier too. The key takeaway for sedation, no matter what medications are used, but especially if Propofol is used, make sure that the anesthesiologist uses a nasal cannula and a monitor that can measure End-Tidal CO2. I’m sad to say that there are lots of clinics and outpatient treatment centers that do not have this necessary equipment because they wanted to save money.
I am a board certified anesthesiologist so please take this advice; if you are getting your injections at a location without these monitoring equipment, please cancel your appointment until they have the necessary equipment or see another specialist.