How safe is sedation?
Sedation can be performed safely and effectively by dentists with proper training. Most dental therapy can be accomplished on phobic patients using local anesthesia and sedation. Therefore, adequate use of local anesthesia must be considered as the first step of not only pain control but also anxiety control. Many central nervous system (CNS) depressants can alter the level of consciousness. Most of these can produce a hypnotic state if given in high enough doses, but only a select few can actually produce a complete state of general anesthesia. However, the potential for complications is not limited to the general anesthetic state; it may accompany any degree of drug-induced CNS depression. Respiratory and cardiovascular depression are the most feared complications. Respiratory depression represents the principal negative variable introduced with conscious sedation and, left unrecognized and untreated, is the cause of most serious complications.
Further complicating the question, To Sedate or Not To Sedate? is that fact that nearly all dentistry is elective. It is very rare to face the situation where a life will be lost if treatment is not instituted. A nerve may die, a tooth may be lost... all the teeth may be lost ... but the patient will still be alive and reasonably healthy. It is very difficult to accept a dental procedure where there is even a slight risk of death.
This is not to say that there is not a very slight risk to even the simplest procedures. Even administration of local anesthesia has resulted in death. For this reason, the safety of a sedative system is of the utmost importance. Sedation, deep sedation/general anesthesia, has a remarkable safety record; however, there have been studies showing that the deeper the sedation, particularly when administered to medically compromised patients, the very young and the elderly, the greater the risk over other procedures. Dione reported that overall mortality in the U.S. associated with general anesthesia, based on self-report of oral surgeons, has ranged from 1:860,000 to 1:349,000; however, self-reportings are usually given little credence due to a strong negative biases. A more credible study came out of records from the United Kingdom where the overall mortality risk was 1:248,000 for general anesthesia and 1:1,000,000 for conscious sedation (one patient died in a motorcycle accident later in the day of sedation). Only very low risk could be determined for local anesthesia.
The risk of sedation and anesthesia can be dramatically decreased with modern monitoring devices and the use of persons trained in monitoring and administration of anesthesia. It has been shown that the risk of anesthesia is dramatically reduced when a separate practitioner trained in general anesthesia administers and controls the sedation/anesthesia. In the case of two-operator administered anesthesia, the risk went from 1:248,000 to 1:598,000 This is particularly true when treating patients with underlying medical problems.
A problem that was unique to dentistry but is now affecting our medical colleagues who use day surgery is the need for rapid ambulation. We need to get our patients back to a state that allows them to leave the office in a timely manner. Their reflexes need to be such that they can walk unassisted, although I insist that another adult take their arm for additional support. They should not drive, undertake any task that might be hazardous, be placed in a position of responsibility (i.e. taking care of children) or make important decisions; even climbing stairs should be avoided. They need to be accompanied and supervised by a responsible adult for the rest of the day, during which time their activities should be limited to watching TV, and operating the remote control is about as complex a cognitive activity as they should attempt. It should be stressed to the patient that although they may feel normal, their reflexes may still be depressed. They need to take the rest of the day off.
It should be mentioned that some of the benzodiazepine drugs are initially bound to plasma proteins. This binding tends to reverse about 6 hours after administration. This phenomenon is known as a "second peak effect". When using most benzodiazepines, it is necessary to inform our patients that they will experience an increase in sedation about 5-8 hours after leaving the office. Interestingly, even after this time, blood concentrations of active drug have been reported to be close to 50% of what they were during sedation. For this reason, it is imperative that they not undertake any activity requiring cognitive or coordination skills the rest of the day. Because of the long half-life of diazepam, some practitioners felt there was reason for some concern even the next day.
Our choice of drugs is guided by consideration of elimination, half-lifes and side effects:
-Brevital (methylhexital sodium), an ultra short acting barbiturate when given intravenously, can take a conscious patient to a patient under surgical general anesthesia and back to consciousness often in less than 5 minutes total time.
-Diazepam, on the other hand, had a secondary half life of 20 to 50 hours. We must worry about patients who have had diazepam driving, taking alcohol and performing hazardous activities, not only the day of treatment but possibly for several days after sedation.
-Nitrous oxide is so completely eliminated, patients can drive after a relatively short recovery time. When we examine sedative systems we find a continuum of effects from slightly noticeable changes through more profound sedation to general anesthesia - eventually leading to death, if enough drug is administered. "General anesthesia is less safe than conscious sedation, which is less safe than local anesthesia."
It is our goal to chose a sedation system with a very wide difference between desired effect and death in a very broad range of patients. It is ideal if the effects of the drugs can be reversed at will if our system seems to be getting out of control.
It is also our goal to create a state of tranquility that will allow the patient to comfortably undergo the needed procedure. A pain-free state can always be achieved by rendering the patient unconscious, but with a much greater risk of serious complications. I try to keep the patient conscious and treat their apprehension as opposed to rendering them unaware. If I can alleviate apprehension without changing any other of the patient's parameters, I have achieved success. In fact, we always cause some change in our patients' physiology; however, with modern drugs these changes are much less hazardous than was accepted a few years ago.
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