Anesthesia Questions

[chromuffin]

Wrong forum perhaps.

I'm in anesthesia right now, and I'm reading that continuous temp measurements aren't important under general anesthesia according to ASA standards. My question is why since volatile anesthetics can cause malignant hypertension? Is it simply because you could technically use IV anesthetics alone? And it would be essential for cases with gases (and succinylcholine)?

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[Mazshax]

I'll try to answer this one point at a time. First of all, ASA standards say we should continuously monitor oxygenation, ventilation, circulation, and temperature. Of these, temperature is optional and should be measured whenever large changes in temperature are anticipated. I usually monitor temperature on any case anticipated to last 45 minutes or longer, since the first hour under general anesthesia results in a predictable drop in core temperature.

Second, volatile anesthetics can incite malignant hyperthermia, not hypertension. I think you knew this since you're asking about temp monitoring, but I just wanted to clarify. So why not measure temperature any time we're using MH inciting agents? Well MH is a clinical syndrome that affects multiple body systems, and thus temperature increases are not the only way to detect it. Patients having an episode of MH will experience muscular rigidity, high peak airway pressures, hypercarbia, tachycardia, acidosis, and yes, hyperthermia.

Another thing to keep in mind is that MH episodes may not happen for several hours after exposure to inciting agents and may even happen AFTER they are fully recovered from anesthesia. Symptom onset is more commonly in the second or third hour of anesthesia than the first, which means that the cases when we are not monitoring temperature (short cases) are unlikely to see an intra-op episode of MH.

I hope this all makes sense.

 

[HooliganSnail]

There is a difference between not doing continuous temp measurements, and not measuring temp at all.

 

[chromuffin]

I'll try to answer this one point at a time. First of all, ASA standards say we should continuously monitor oxygenation, ventilation, circulation, and temperature. Of these, temperature is optional and should be measured whenever large changes in temperature are anticipated. I usually monitor temperature on any case anticipated to last 45 minutes or longer, since the first hour under general anesthesia results in a predictable drop in core temperature.

Second, volatile anesthetics can incite malignant hyperthermia, not hypertension. I think you knew this since you're asking about temp monitoring, but I just wanted to clarify. So why not measure temperature any time we're using MH inciting agents? Well MH is a clinical syndrome that affects multiple body systems, and thus temperature increases are not the only way to detect it. Patients having an episode of MH will experience muscular rigidity, high peak airway pressures, hypercarbia, tachycardia, acidosis, and yes, hyperthermia.

Another thing to keep in mind is that MH episodes may not happen for several hours after exposure to inciting agents and may even happen AFTER they are fully recovered from anesthesia. Symptom onset is more commonly in the second or third hour of anesthesia than the first, which means that the cases when we are not monitoring temperature (short cases) are unlikely to see an intra-op episode of MH.

I hope this all makes sense.

Thank you. It makes perfect sense. Yes I meant malignant hyperthermia, not HTN. I appreciate your insight.