Re: interview questions about anesthetics

Wide and interesting question!

In the future, I believe anesthesia will focus on prevention of two categories of events:
- First, prevention of cardiovascular events (e.g. myocardial infarction) by improving the knowledge of a patient's status. For example, an 60 years old diabetic male will appear fit for "standard" anesthesia while comprehensive evaluation of his heart will highlight a compensated cardiac insufficiency. The challenge will be to optimize during the peri operative period (and specially during anesthesia)his heart function, avoiding to let him loose too much fluid (his bloodpressure will drop)as well as getting too much fluid loading, leading to pulmonary edema. For this purpose, small and accurate ultrasonographic devices will be of utmost interest, allowing us to monitor heart function during anesthesia.
- Second, prevention of all these "little pitfalls" such as nausea/vomiting, wich appear to be side effects of pain control, for example. Ten years ago, people admitted to be vomiting during post- operative course (the price to pay not to suffer....). Nowadays, people ask for analgesia without post-operative nausea or vomiting.

Anesthetics work by receptor activation. Three major categories can be described:
- morphine and morphinics (sufentanyl, alfentanyl) activate receptors located in the spinal cord and brain, leading to analgesia (they block the message that, when reaching the brain, gives you the feeling of pain)
- neuro muscular blocking agents (such as curare) stop the passage of nervous influx from nerve to muscle, leading to muscular hypotonia (areversible paralysis)
- hypnotics activate, through receptors, the reticula a zone in the brain that "puts you asleep".

Regarding biodisponibility, two major categories are to be considered:
- I.V. anesthetics go into the blood stream, and "hook" to the receptors, mainly in brain and spinal cord, but are partially stored in fazt as well. This explains what we name "secondary action", in a few words you wake up but are potentially prone to delayed decrease in you level of vigilance, and therefore subject to hypoventilation and potential hazards. This is the reason why you go in the recovery room for a certain amount of time before going back to you room.
- Volatile anesthetics go through lungs into the bloodstream, and there behave as above.

You can find a lot of information regarding volatile anesthesia on: http://vam.anest.ufl.edu/simulations/simulationportfolio.php(formerly vam.anest.ufl.edu/instructorsims/simulationportfolio.php).

Hope this helps.
Luc

Luc Ronchi, MD
pediatric anesthesia
Hopital de St-Nazaire (France)