Nursing care
Rising temperature and rigidity in surgery: priority actions for malignant hyperthermia
Written and reviewed by Nicole Ramirez, BSN, RN, CMSRN · 4 min read · Updated November 2026
Short answer
The priority nursing intervention for malignant hyperthermia is to stop the trigger and start treatment at once: the volatile anesthetic and succinylcholine are stopped, help and the MH cart are called, and dantrolene is given IV while the client breathes 100 percent oxygen. Temperature is a late sign; rising end-tidal carbon dioxide and jaw rigidity usually come first.
Why temperature is not the first clue
Malignant hyperthermia is an inherited muscle reaction to potent volatile anesthetic gases and succinylcholine. MSD Manuals describes jaw rigidity and a rising end-tidal carbon dioxide as early signs, followed by a fast heart rate and fast breathing, within minutes to hours of induction. The muscle is burning energy out of control, and the carbon dioxide climbs before the thermometer does.
By the time temperature is rising, the crisis is already well underway. MSD Manuals notes that temperature can go above 40 degrees C. A question that describes rising temperature and rigidity in an anesthetized client is describing a late picture, which raises the urgency rather than lowering it.
The first actions, in order
The MHAUS crisis steps begin with telling the surgeon to stop the procedure as soon as possible and stopping the volatile agent and succinylcholine. At the same moment, someone brings the MH cart with dantrolene and calls for extra help. MHAUS also runs a 24-hour hotline, 1-800-644-9737, for guidance during an event.
The anesthesia provider hyperventilates the client with 100 percent oxygen at high flow to flush out the anesthetic gas, and dantrolene is given rapidly IV and repeated as needed. Dantrolene works inside the muscle to stop the runaway calcium release. The circulating nurse's role is fetching and preparing the drug, adding staff and keeping time, not starting with a cooling blanket.
Cooling, potassium and urine: the problems that follow
Cooling matters, but it supports the treatment rather than leading it. MHAUS advises cooling until core temperature is below 38 degrees C. An antipyretic will not help, because the heat comes from muscle, not from a reset temperature point in the brain.
Breaking muscle releases potassium, creatine kinase and myoglobin. MSD Manuals lists high potassium, very high CK, dark brown urine from myoglobin, acidosis and clotting problems. MHAUS recommends treating hyperkalemia and keeping urine output at least 1 mL per kg per hour to protect the kidneys. High potassium with ECG changes is the lab finding to report first, because it can cause a fatal rhythm.
Risk, history and what happens after the crisis
MSD Manuals describes the susceptibility as autosomal dominant, most often linked to the ryanodine receptor gene that controls calcium in skeletal muscle. The preoperative history question that matters is whether the client or any blood relative had a problem with anesthesia, such as an unexplained high fever or death during surgery.
Once stable, MHAUS describes signs of control as falling end-tidal carbon dioxide, a settling heart rate, resolving fever and loosening muscles, followed by ICU monitoring for at least 24 hours because the reaction can return. The client and family need to know that relatives may share the risk. For telling this crisis apart from neuroleptic malignant syndrome, use the comparison page linked below.
Hypothetical practice scenario
Hypothetical scenario, not a real exam item: during a laparoscopic surgery under a volatile anesthetic, the client's end-tidal carbon dioxide has climbed steadily, the jaw is rigid, heart rate is 136, and temperature has risen from 37.0 to 38.6 degrees C. Which action should the circulating nurse take first: apply a cooling blanket, give the prescribed acetaminophen, draw a potassium level, or bring the MH cart and dantrolene and call for help?
Bringing the MH cart and dantrolene and calling for help comes first, alongside the anesthesia provider stopping the trigger. Cooling treats the heat but not the muscle reaction driving it. Acetaminophen targets fever from the brain, which this is not. The potassium level is needed, but drawing labs before getting the antidote moving delays the one drug that reverses the crisis.
Sources and further reading
MSD Manual Professional Version: Malignant Hyperthermia. Triggers, early jaw rigidity and rising end-tidal CO2, later temperature above 40 C, high potassium, CK, myoglobinuria, acidosis, clotting problems, treatment with dantrolene, oxygen and cooling, autosomal dominant inheritance and ryanodine receptor.
MHAUS: Managing a Crisis. Crisis steps: stop procedure and triggers, MH cart and hotline, hyperventilate with 100 percent oxygen, rapid IV dantrolene, cool to below 38 C, treat hyperkalemia, urine output at least 1 mL/kg/h, signs of control and 24-hour ICU monitoring.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our med-surg practice questions are the closest set to what this page covers.
One question from the med-surg set
A client with chronic obstructive pulmonary disease has an oxygen saturation of 88% on 2 L/min via nasal cannula and is alert with no distress. What should the nurse do first?
Rationale
In COPD a saturation of 88–92% is the therapeutic target, not an emergency, and this client is alert with no distress. The first action is the independent nursing intervention that is least invasive and most likely to help: sit them up and reassess. Turning the oxygen up to 6 L/min risks blunting the hypoxic drive, and calling rapid response or drawing an ABG escalates ahead of an assessment you have not finished.
Answer: B
Common questions
What is the priority nursing intervention for malignant hyperthermia?
Stop the triggering anesthetic and succinylcholine, call for help and the MH cart, and get IV dantrolene started while the client is hyperventilated with 100 percent oxygen. Cooling and treating high potassium follow.
What is the earliest sign of malignant hyperthermia?
A rising end-tidal carbon dioxide that does not respond to usual adjustments, often with jaw or muscle rigidity and a fast heart rate. A high temperature usually comes later in the reaction.
Which lab finding should the nurse report first in malignant hyperthermia?
High potassium, especially with ECG changes, because it can trigger a dangerous heart rhythm. Rising CK, acidosis and dark brown urine from myoglobin also need prompt reporting.
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