Custom Search

Thursday, January 3, 2008

What’s the Best Anesthestic for Colonoscopy?

Anesthesia for Colonoscopy

Note: The Colonoscopy Chronicles attempts to provide information that is as accurate as possible. It is not intended as medical advice. You should consult your personal physician regarding your own medical condition.

Most patients are, predictably, worried about whether the colonoscopy will be painful. Virtually every colonoscopy done these days is performed under anesthesia to make the procedure comfortable. There are several types of anesthesia available. It is advisable to have a frank discussion with the physician performing the colonoscopy to be sure you understand this important aspect of the procedure, and to make sure you have realistic expectations of the anesthesia. For the sake of simplicity, I’ll break them down into two main categories:
1) Conscious sedation
2) Monitored Anesthesia Care(MAC)

Conscious Sedation

The vast majority of anesthesia used for colonoscopy is conscious sedation. This is generally administered by the physician doing the colonoscopy. Usually, it takes the form of two different medications, given into an intravenous line that has been inserted into the patient’s vein prior to the procedure. The two medications normally given are 1)a narcotic analgesic(painkiller)-usually Demerol(meperidine) or Sublimaze(fentanyl) 2)a benzodiazepine(sedative/hypnotic)-usually Versed(midazolam) or Valium(diazepam).

The physician generally gives a small starting dose, then small subsequent doses until the patient is sufficiently sedated. Then the physician will start the colonoscopy, giving repeated doses of the medicine as necessary during the procedure. The vast majority of physicians who perform colonoscopy are experienced administering conscious sedation, and know what it takes to keep the patient comfortable and safe during the procedure. These medications can provide extremely effective, safe sedation for colonoscopy, but must be administered by a physician who is well trained in their use. The most common serious adverse effect is respiratory depression(decreased breathing). Changes in blood pressure, heart rate, and heart rhythm can occur as well. In most centers, patients are closely monitored before, during, and after the anesthesia-using monitors that check the pulse rate, heart rhythm, oxygen level, and blood pressure. Reversal agents-drugs that can reverse the effect of the anesthetic drug-exist for meperidine, fentanyl, and versed. These are generally only given if the patient experiences a significant, persistent decrease in breathing or blood pressure that is felt to be anesthetic related. This is relatively rare. Most physicians advise that, following conscious sedation, the patient be accompanied home, and they may not drive until the following day. Your physician should give you specific instructions regarding restrictions of your activity following the anesthetic.

There are several issues regarding conscious sedation that bear discussing:

· Because this form of anesthesia is not deep anesthesia or general anesthesia, it is possible that the patient may have some discomfort during the procedure-usually quite minor, although in rare cases it can be severe. I try to be quite honest with my patients: There is about a 95-99% chance they will be totally comfortable throughout the procedure-but I cannot give them an ironclad guarantee. If they expect and demand a virtually 100% guarantee then I suggest they consider MAC anesthesia(discussed below).
· Versed, which is commonly given, can cause transient amnesia. The main practical consequence of this is that patients often forget the conversation with the physician in the recovery area after the procedure. It is a good idea to ask ahead of time that the physician write down the findings, and also discuss them with the person accompanying them to the procedure.
· It is sometimes difficult to achieve adequate sedation in certain patients-including those who are unusually anxious, or are on certain medications, such as narcotic painkillers, medication for anxiety, sleeping pills, or those who have a history of being difficult to sedate for other procedures in the past. Again, these are situations where MAC anesthesia may be considered.

Monitored Anesthesia Care(MAC)

MAC anesthesia is a somewhat generic term, but basically describes anesthesia services that are under the supervision of an anesthesiologist or registered nurse anesthetist. As you recall, I mentioned that in conscious sedation, the physician performing the procedure also supervises the sedation. In contrast, with MAC anesthesia, there is a separate physician or nurse whose sole job is to administer and monitor the anesthesia. The anesthesiologist may choose to use the same drugs that I mentioned in the section on conscious sedation. In addition, they have a wide variety of other medications available which they are trained to give. One of the most commonly used medications used in MAC anesthesia for colonoscopy is called Diprivan(propofol). Propofol is well suited to colonoscopy due to its rapid onset of action, and short duration. It can be given alone, or in combination with a painkiller and/or sedative-depending on the preference of the anesthesiologist. Like the medications mentioned above, propofol can decrease the breathing, and patients receiving it must be carefully monitored by the anesthesia specialist during the procedure. Depending on the amount given, patients can go into deep sedation or even general anesthesia from propofol. MAC anesthesia has the advantage of being more effective for the “hard-to-sedate” patients, and also allows the physician performing the colonoscopy to focus on the procedure and not the anesthesia.

There is currently some controversy about who is qualified to use propofol as an anesthetic agent. Some feel that only those trained specifically in anesthesia-such as anesthesiologist and registered nurse anesthetists-should give propofol. Others feel that Gastroenterologists and other physicians who perform colonoscopy can-with proper training-safely give the medication.
I, personally, do not administer propofol, but commonly have an anesthesiologist or nurse anesthetist available to administer it to my patients.

A few things to mention about MAC anesthesia.

· Because an anesthesia specialist will be used, there will be an additional fee involved. Your insurance company may or may not cover this fee-depending on your particular policy, and the details of your case. You may want to clarify this in advance if MAC anesthesia will be used.
· Anesthesia specialists may not be available at the particular center where your colonoscopy will be performed. If MAC anesthesia is something your physician deems necessary, he or she may have to schedule it at a particular center or hospital where an anesthesia specialist is available.


Colonoscopy is safer, and more comfortable than ever. Physicians performing the procedure generally take great care to make it a pleasant and safe experience for patients. Don’t let fear of being uncomfortable stop you from having this important test. Be a good consumer, and make sure to discuss any questions or concerns you have with your physician prior to the colonoscopy.