Malignant hyperthermia upon re-exposure to sevoflurane after an uneventful identical anesthetic in a patient with negative RYR1 and CACNA1S genetic testing: a case report
This case report describes a patient who developed malignant hyperthermia upon re-exposure to sevoflurane after a prior uneventful anesthetic and with negative genetic testing, highlighting the critical need for immediate dantrolene availability and sustained vigilance even in atypical presentations.
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In the operating room, anesthesiologists act as guardians of the body's delicate balance, keeping a patient's breathing, heart rate, and temperature steady while they sleep through surgery. Occasionally, however, a rare and dangerous reaction can occur in susceptible individuals when they are exposed to common inhaled gases used to keep them unconscious. This reaction, known as malignant hyperthermia, causes the body's muscles to go into a state of extreme overdrive. Instead of relaxing, the muscles contract and generate heat at a frantic pace, causing body temperature to spike, breathing to become dangerously rapid, and the blood chemistry to turn acidic. Without immediate and specific treatment, this metabolic storm can be fatal. For decades, medical training has relied on the idea that if a patient has survived a previous surgery with these gases without issue, they are likely safe for future procedures. Similarly, doctors have often assumed that if a patient's genetic test comes back negative for the two most common genes linked to this condition, the risk is effectively gone.
A recent case report from a hospital in Shanghai challenges these long-held assumptions, telling the story of a man who survived a terrifying medical crisis that defied every standard expectation. The patient, a fifty-six-year-old man, had undergone a successful surgery four months earlier using the same inhaled anesthetic gas, sevoflurane, with no problems at all. When he returned for a second procedure to remove a recurring adrenal lesion, the team used the exact same medication plan. For the first two hours, everything proceeded smoothly. Then, the warning signs appeared. The patient's heart rate began to climb, and the carbon dioxide in his breath, which should have remained steady, started to rise sharply despite the ventilator working harder to push it out. His body temperature began to soar. By the time the medical team realized what was happening, the patient was in the midst of a full-blown hypermetabolic crisis. His core temperature had reached 40.5 degrees Celsius, his heart was racing at 165 beats per minute, and his blood pressure had dropped dangerously low.
The situation was complicated by two major factors that made survival uncertain. First, the crisis did not strike immediately after the anesthesia began, as is typical; it started two hours into the procedure, a delay that is highly unusual and often causes doctors to lower their guard. Second, the hospital did not have the only known drug that can stop this reaction, dantrolene, in its own pharmacy. The team had to wait two hours for the medication to be retrieved from an outside facility. While they waited, they fought the crisis with supportive measures: they switched the patient to intravenous anesthesia, replaced the breathing circuit, used ice packs and cooling blankets to lower his temperature, and gave fluids and medications to correct his blood chemistry. When the dantrolene finally arrived, it was administered, and the patient's condition began to stabilize. His carbon dioxide levels normalized, and his temperature slowly came down. He spent time in the intensive care unit but eventually recovered fully, with no lasting damage to his organs or brain.
What makes this case particularly significant is what the investigation revealed afterward. The medical team performed a detailed genetic search for the mutations known to cause this condition, specifically looking at the two genes responsible for the vast majority of cases. The results were completely negative; no genetic cause was found. Furthermore, the patient had previously undergone the same anesthetic without incident, which traditionally would have suggested he was not at risk. This combination of events—a delayed onset, a negative genetic test, and a prior uneventful exposure—proves that the standard safety checks are not foolproof. The authors of the report emphasize that a patient can carry this susceptibility without showing it in a previous surgery, and that the genetic test used in most hospitals misses a significant number of susceptible people.
The story of this patient serves as a stark reminder that vigilance must be maintained throughout the entire duration of a surgery, not just in the first hour. It demonstrates that a previous successful surgery does not guarantee safety, and that a negative genetic screen does not rule out the possibility of a reaction. The medical team's ability to manage the crisis with supportive care while waiting for the specific drug highlights the importance of having that life-saving medication available on-site at all times. Ultimately, this case suggests that the rules for identifying who is at risk need to be broader, and that anesthesiologists must remain alert to the signs of this reaction from the moment anesthesia begins until the patient is fully awake, regardless of how long the procedure lasts or what the test results say.
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