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Anesthesia Alert
Keep Your Cool When the Temperature Rises
Henry Rosenberg
Publish Date: October 10, 2007   |  Tags:   Anesthesia

When you think of testing for malignant hyperthermia, you probably think of the pre-operative interview. It's standard to ask the patient about her history with anesthesia, follow with some questions about the family's experiences with anesthesia and determine whether there is a family history of unusual muscle disorders or malignant hyperthermia syndrome. This may catch the most obvious red flags, but for practical purposes, it's really not that effective for predicting a patient's risk for developing MH. Even patients who have low risk factors may later present with an MH episode.

Regardless of whether you're working in a hospital or a freestanding facility, if you're administering anesthesia you need a plan to recognize and treat this potentially fatal syndrome as quickly as possible. Here's what you and your staff should know about dealing with MH. The information provided has been developed over many years by those associated with the Malignant Hyperthermia Association of the United States, a not-for-profit patient advocacy group led by laypeople, physicians and scientists with an interest in MH and allied syndromes.

On the Web

Visit the Malignant Hyperthermia Association of the United States at writeOutLink("www.mhaus.org",1).

MHAUS's advice: Be prepared
Every minute counts during an MH episode as you and your team work to prevent a bad outcome, so the more preparation you've done in advance, the better. Training for MH is an important component. Everyone should be familiar with MH syndrome and the need for rapid and definitive action once it's diagnosed.

Some of the tasks you need to delegate include

  • obtaining and mixing dantrolene;
  • getting ice, hypothermia blankets and other devices to cool the patient;
  • drawing blood samples for arterial blood gas;
  • running electrolyte and coagulation tests; and
  • alerting the nearest hospital to expect a patient who is experiencing an MH episode.

MHAUS's professional advisory council has recommended that every facility using general anesthesia with potent volatile agents have a full supply of dantrolene immediately available stored with bacteriostatic water for mixing and a plan to handle the crisis.

To make sure everybody knows what to do, I suggest having a practice drill once a year. It's also wise to put the treatment plan in writing and post it near the ORs in case of an actual event. This will give everyone a quick reminder of what they have to do. You can include the MHAUS hotline number, (800) MH-HYPER (644-9737) if there is a suspicion that the patient may be experiencing an MH episode.

If you administer gas anesthetics such as sevoflurane or isoflurane or the muscle relaxant succinylcholine, be sure to keep a full supply of dantrolene available, along with bacteriostatic sterile water for mixing the powder. Having everything ready to mix lets your staff treat a patient with MH promptly, a valuable advantage, because every minute counts during an MH crisis.

Most offices and ASCs don't have the equipment to analyze arterial blood gases or electrolytes on-site; if that's the case in your facility, make sure you have arranged to rapidly transport specimens to an approved laboratory that reports results promptly.

It's also especially important for freestanding ASCs to have transfer policies and procedures to follow once a patient's condition is stabilized. In this context, stabilizing means administering enough dantrolene so that the patient isn't tachycardic, the end tidal carbon dioxide levels are declining to less than 50 mmHg or less, there is no rigidity and the core temperature is on the way down.

I also think that extra dantrolene (about 1 mg/kg), mixed and ready to use during the move, should be prepared. The receiving hospital should have dantrolene immediately available for administration upon the patient's arrival.

Intraop temperature
Except for very brief cases, you should monitor temperature during all general anesthetics. In many cases, temperature elevation is the confirmatory sign of MH, but it's usually a late symptom and, frighteningly, it doesn't present in all cases.

The rate of a temperature's rise often indicates the syndrome's severity. During an MH crisis, a person's body temperature can rise a degree every three to five minutes, so in a brief period of time, a patient can go from normothermia to 106'F. When temperature exceeds about 106'F, coagulation abnormalities often occur. If a patient develops such hyperthermically induced coagulopathy, the likelihood of mortality is high. On the other hand, overly aggressive cooling may lead to marked hypothermia, which can also have adverse consequences.

The anesthesia provider should have and be familiar with the equipment to measure and monitor body temperature continuously during anesthesia. Esophageal, nasopharyngeal or oral temperature monitoring is the ideal way to monitor temperature, but this isn't always possible. It's acceptable to measure rectal, bladder or axillary temperature. However, remember that axillary temperature is often one to two degrees less than core temperature. A patient's forehead skin temperature bears a very rough correlation to the core temperature, and it has the virtue of being non-invasive. If there is a significant change in skin temperature, a more accurate temperature monitor, such as esophageal, should be used.

Temperature monitoring, personnel training and preparedness may seem like a lot of work for what's essentially a rather rare event. It's very likely that the MH plan you make for your facility is rehearsed more often than it's actually used. However, over the course of an anesthesia provider's career he is likely to either detect an MH episode, assist in management of a case or deal with a patient with a family history of MH. Therefore, all anesthesia providers should be aware of the syndrome, and its symptoms, treatment and management. Without such preparation and training, an otherwise healthy patient may suffer needless morbidity or mortality. In other words, this knowledge may save a patient's life.