Thursday, March 30, 2006

Wait after general anesthesia before diving?

Question:
How long should a patient that was under general anesthesia (knocked out) wait before diving?

Answer:
To some extent, the ability to dive will depend on the diagnosis for which the anesthetic was given and the disability from the surgical procedure will determine when to dive. If one were being put to sleep for some non-debilitating diagnosis (such as dental), my guess would be that there should be no diving for at least 24 hours. Longer periods of diving cessation may be recommended depending on the procedure performed and the presence of complications.

There have been reported long term effects of a general anesthetic decreasing the cognition patients lasting up to 3-4 months postoperatively. This is seen mostly in the elderly (over 60). Studies on rats fail to show any reduction in longevity. However, there are no studies that I can find concerning how soon the patient recovers completely from the blunted sensorium that occurs with every general anesthetic. This would be highly variable and would depend on the length of the operation, intraoperative medications and recovery room problems

Another variable would be the type of preanesthetic medication given and the type of inhalation anesthetic chosen for the procedure. Whether or not becoming saturated with nitrogen (as occurs with most deep dives) would increase the residual effects of the anesthetic is not known, at least I cannot find any studies on this particular situation.

A good thing to do would be to take the recommendations of the US Department of Transportation for driving after an anesthetic and substitute the word dive for drive. These recommendations can be seen at this web site: http://snipurl.com/oeu9 .

Dr.Richard Moon, Duke Anesthesiologist, says that diving should be safe after 48 hours provided the patient is not taking any sedatives (including opiate analgesics). The cause of postoperative cognitive effects is not known, but could be due to the inflammatory response rather than the anesthesia per se.

However, the major determinant is not the anesthetic, but rather the reason for the anesthetic. Diving is a bad idea immediately after surgery irrespective of the anesthetic.

Another anesthesiologist says "all of the modern anesthetics are relatively insoluble and one would expect them to be largely eliminated within minutes after their cessation. This might not be the case with some of the older anesthetics such as diethyl ether which is roughly ten times more soluable in blood. In that case, if diving soon after an anesthetic - one could imagine a diver at depth becoming re-anesthetized. This would likely be facilitated by any concomitant narcotic usage as well."

So, to summarize - return to diving depends mainly on the type of surgery, the restrictions placed on the patient from the surgical procedure, medications required by the diver and there probably should be a wait between 24-48 hours after the procedure.