Anesthesiologist Questions Anesthesia

How long does anesthesia stay in the blood?

My son is 6 years old and was administered mild anesthesia for a CT scan. I would like to know for how long will the anesthesia be present in his blood stream?

11 Answers

Typically not long but to answer this correctly it would be helpful to know what anesthesia agent was utilized. For short procedures such as a CT scan most anesthesiologists will use a very short acting agent and the child therefore would not have a long effect from the sedation.
It will depend on what medications your son was given during and after the scan. If your son has normal kidney and liver function, there will be no anesthesia medications left in his blood after 24-48 hours.
Half lives for usual sedative drugs are 4 hours. So effects for no more than half a day
Easily Less than a day
The answer depends on several factors. First is the choice of anesthetic or sedative agent. Some medicines last longer than others and are chosen to be appropriate for the procedure. Second is the dose of the anesthetic used. Higher doses will last longer, but may be necessary to assure a successful procedure. Some medications can be "reversed" by other medications if necessary.The goal is to prevent anxiety and allow the child to remain still during the procedure. Otherwise, the scans are blurry and unusable. All of this should be explained to you and your questions should be answered before the procedures. Most facilities provide written instructions for reference. Most current anesthetic agents and techniques are selected to allow for a rapid recovery after the procedure. Some locations use older protocols which do not involve utilizing specialized anesthesia providers and use older medications, which may result in longer recovery times afterwards. Another factor is the general health of your child. Some medical conditions and concurrent medications may slow the elimination of the sedative medications, which are typically eliminated by the liver and kidneys in the case of intravenous medications, or simply exhaled in the case of inhaled anesthetic agents. For most adult and pediatric patients, we often use the 24-hour rule, which states that although many agents are out of their system much faster (2-4 hours or 6-8 hours for most medications) than 24 hours, resuming "normal" activity is a matter of concern until a day has passed. If your child becomes more sedated or does not appear to be progressing, you may need to contact your care team or initiate a medical emergency if conditions seem to warrant that (examples would be respiratory difficulty or increasing lethargy).
Although many anesthetic drugs persist in the blood stream for several hours after surgery, their effect on the brain (to produce sedation) dissipates in a matter of minutes. As long as benzodiazepines and opioids are avoided, propofol sedation dissipates in minutes after discontinuation, an effect of redistribution in other body tissues.
It depends on the anesthetic used, but generally, effects wear off in 30-90 minutes and completely leaves the system in 1-3 days.

Boris Yaguda, M.D.
Hi,

Depending on what medications were used and assuming normal metabolism, the medications should be cleared from his system between 16 and 25 hours.

Dr Ketch
Depending upon what medications were given and the route of administration. Most of the medications stay roughly 48-72 hours in the system. Drink more fluids to get rid of it. Thanks.
It depends on the actual agent used, but most anesthesitics will have breakdown products that can be active for a few hours.
Paul Hubbell
phubbell@bellsouth.net
Usually, oral sedatives such as midazolam are used for short, outpatient pediatric procedures. The sedative properties should not last more than 8-12 hours. 
Benjamin Taimoorazy, MD FAHSDABPM DAAPM UCNS