Sedation for colonoscopy – do it yourself

Adults over age 50 should be screened for colon cancer. Although “virtual colonoscopy” is an appealing alternative, a “real” colonoscopy is still the gold standard. This involves a large black hosepipe-sized endoscope being inserted where the sun never shines, so its perhaps not surprising that colon cancer screening rates aren’t what they should be.

In most cases, colonoscopy isn’t extremely painful but it is uncomfortable and certainly not much fun; most patients in the United States receive some form of sedation for it. There is lots of controversy over who provides this sedation and what is given. A form of self-administered sedation creates new options.

A common recipe for colonoscopy sedation is midazolam (Versed) plus an opioid like meperidine (pethidine, Demerol) or fentanyl. The most troublesome side-effect of this drug combination is the suppression of breathing which sometimes requires “rescue” to prevent serious harm. Blood pressure can drop too. A small but vocal minority of patients believe that Versed (midazolam) causes unpleasant short and long term psychological side-effects, and even post-traumatic stress disorder, although this is not supported by scientific study. They argue that an amnestic (memory-suppressive) drug like midazolam is simply a cover-up for an extremely painful, torture-like experience that a patient endures but cannot subsequently remember. Despite this conspiracy view, midazolam has been used successfully, and most would contend, safely, in millions of sedation procedures around the world.

Much of the controversy centers around propofol (Diprivan) sedation with which is associated with the highest levels of patient satisfaction, along with rapid recovery, and even, in at least one study, higher rates of polyp detection. Unfortunately there aren’t enough professional anesthesia providers available for everyone to get this form of sedation. Many gastroenterologists believe that propofol sedation is so safe for the average patient that is should be available for administration by non-anesthesia providers. Some insurance companies, believing this too, have stopped payment for anesthesia for colonoscopy. Anesthesiologists on the other hand argue that propofol is too dangerous to be given by non-anesthesia providers. They say they are needed for these procedures because of their skill and experience, particularly in rescuing patients who become oversedated, and that safety should not be compromised for economic reasons.

Along comes an attractive alternative to conventional sedation, PCS – Patient-controlled Sedation. Using PCS, you, the patient, are in charge. You press a button that operates a special syringe pump to administer small doses of intravenous sedation, until you are adequately sedated. You press it again if and when you start to experience discomfort. The effect of the drug comes on rapidly. It’s the same approach commonly used to treat postoperative pain – known as PCA – (Patient-controlled nalgesia). The benefit is that you are unlikely to overdose because you have to be awake enough to press the button, and because the machine is set to prevent subsequent doses for a defined lockout period, although some studies of PCA have shown this technique isn’t nearly as safe as it should be in theory. Of course you still need monitoring, by machines and humans, and the administration of oxygen.

The Study

A study just published in the journal Anesthesia & Analgesia shows that patients can recover remarkably quickly from PCS, using a mixture of propofol plus an ultra-short acting opioid called remifentanil. These patients also spent an average of only 5 minutes in the recovery room and could walk without assistance within an average of 9 minutes.

With this PCS technique, colon cancer screening can be done with apparently high levels of patient satisfaction. Rapid recovery may allow more patients to get screened per day, with fewer nurses needed to staff recovery areas.

So how safe is this technique? Two patients out of 25 who got the propofol-remifentanil mix needed breathing assistance from an anesthesiologist, available at the location. The study wasn’t big enough to detect any statistically significant difference in side-effects between the propofol mix and a comparison midazolam-fentanyl combo.

In many respects this is the ideal setup. Patients deliver their own sedation and feel satisfied with the results. Recovery is extremely rapid. An anesthesiologist is available at short notice to rescue.

Unfortunately, anesthesiologists on standby don’t come cheap, and the study wasn’t large enough to determine the safety of PCS. A 4% incidence of the need for rescue isn’t that encouraging. And it seems likely that some patients just won’t go for the notion of do-it-yourself anesthesia.

What you can do

It would appear that PCS is not really “in production” outside research settings in the US, but might be available elsewhere. Both drugs described here – propofol and remifentanil – are in widespread use, so some anesthesia providers might consider using this technique while carefully supervising it. Patients who dislike Versed, for whatever reason, could find this technique rather appealing and would therefore offer a ready “market” for propofol-remifentanil PCS.

Reference:

Mandel JE. A Randomized, Controlled, Double-Blind Trial of Patient-Controlled Sedation with Propofol/Remifentanil Versus Midazolam/Fentanyl for Colonoscopy. Anesth Analg 2008;106:434 –9.

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One Response to Sedation for colonoscopy – do it yourself

  1. Scheduled for colonoscopy on 27 August at VA Bay Pines and found this information useful. I will discuss on the 18th, particularly the anesthesia to be used.

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