A 25-year-old trauma patient developed probable malignant hyperthermia presenting primarily with refractory hypotension and rising EtCO2 despite increased ventilation, which reversed rapidly after dantrolene administration.
Key Findings
Results
Malignant hyperthermia can present with refractory hypotension as a prominent early manifestation, preceding hyperthermia.
The patient developed refractory hypotension approximately 2.5 hours after exposure to succinylcholine and sevoflurane.
Hemodynamic instability was unresponsive to fluids and vasopressors.
Hyperthermia developed after the onset of hemodynamic instability, indicating hypotension was an early rather than late sign.
The patient was a 25-year-old trauma patient, representing a young otherwise healthy individual.
Results
Rising EtCO2 despite progressive increases in minute ventilation served as a critical diagnostic clue for malignant hyperthermia.
The patient showed rising end-tidal CO2 (EtCO2) despite progressive increases in minute ventilation.
The authors emphasize this finding as a critical diagnostic clue requiring prompt dantrolene administration.
This sign preceded or accompanied the hemodynamic instability in the clinical presentation.
Results
Dantrolene (Ryanodex) administration rapidly reversed the hemodynamic instability associated with probable malignant hyperthermia.
The hemodynamic instability that was unresponsive to fluids and vasopressors reversed rapidly after treatment with dantrolene (Ryanodex).
The case was classified as 'probable' malignant hyperthermia.
Malignant hyperthermia is described as caused by 'dysregulated skeletal muscle calcium homeostasis.'
Background
Triggering agents identified in this case were succinylcholine and sevoflurane, both known malignant hyperthermia triggers.
The patient was exposed to succinylcholine and sevoflurane prior to the MH episode.
Symptoms developed 2.5 hours after exposure to these agents.
Both succinylcholine (a depolarizing neuromuscular blocking agent) and sevoflurane (a volatile anesthetic) are recognized MH-triggering agents.
What This Means
This case report describes a 25-year-old trauma patient who developed a rare and dangerous reaction to anesthesia called malignant hyperthermia (MH). MH occurs when certain anesthetic drugs cause a severe, uncontrolled increase in muscle activity that can raise body temperature to dangerous levels and disrupt normal body chemistry. In this patient, the reaction appeared about 2.5 hours after receiving two common anesthetic drugs (succinylcholine and sevoflurane), and it initially looked like a cardiovascular problem — the patient's blood pressure dropped severely and did not respond to fluids or blood pressure medications.
What makes this case particularly notable is that the dangerous drop in blood pressure came before the expected fever, which is often considered the hallmark of MH. The medical team also observed that the patient's carbon dioxide levels kept rising even when they increased the breathing rate on the ventilator — a warning sign that the body was producing excessive CO2 due to hyperactive muscles. Once the team recognized these signs as probable MH and administered the specific treatment (dantrolene, brand name Ryanodex), the patient's blood pressure quickly stabilized.
This research suggests that malignant hyperthermia should be considered as a possible cause when a patient under anesthesia develops unexplained low blood pressure that does not respond to standard treatments, especially when combined with rising CO2 levels despite increased ventilation. Early recognition of these atypical signs and prompt treatment with dantrolene may be critical, as waiting for fever to develop could delay life-saving intervention.
Azar M, Azar J, Azar A. (2026). Probable Malignant Hyperthermia Presenting With Refractory Hypotension in a Young Trauma Patient: A Case Report.. A&A practice. https://doi.org/10.1213/XAA.0000000000002213