The Fever Files: Knock ‘Em Down, Burn ‘Em Up
The Case
It’s a snowy evening and your critical care transport helicopter is a giant rock. The phone rings, and your dispatcher is sending you an hour away, maybe longer if the roads haven’t been plowed, to pick up a motor vehicle collision patient whose car slid into a bridge pillar at high speed. He’s alert, but a CT of his head showed intracranial bleeding.
You finally pull into a rural critical access hospital. No awning over the ER doors, let alone a dedicated ambulance garage. Freezing, you head into the building.
As you walk into the resuscitation area you hear a voice yell “Tubes in!” You pull back the curtains and see a patient with obvious head and extremity injuries having a tube taped to his mouth while a bag valve mask is attached to it. You pause so as not to interrupt tube confirmation, watching condensation come and go with each ventilation. The intubator seems satisfied as she replaces her stethoscope around her neck.
“Hey guys. Just intubated him with 100 of ketamine and 100 of sux. He tanked about 10 minutes ago; went from a GCS of 12 to 5 and blew a pupil.” She quickly lists off his extremity injuries—the open ankle fracture that she’s washed out and placed plaster on is the only one you really take interest in. “I’ve already hung a bag of mannitol; we don’t carry 3% saline,” she says with a tone equal parts annoyance and embarrassment.
She assures you the chest and pelvis CT were normal, and that his vitals have been rock solid the entire 90 minutes he’s been in the facility. She even proudly tells you the lab rushed his bloodwork and that his hemoglobin and blood gas are normal (along with his electrolyte panel, glucose, and ethanol).
A quick rapid trauma survey confirms the chest, abdomen, and pelvis are stable. With his acute deterioration, you decide to load-and-go and get a move on to the neurosurgical hospital 60 minutes away. Figuring the ketamine should be more than sufficient until you get your propofol infusion running and seeing how the patient is still strapped into a backboard, you decide to move quickly to the rig.
The back of the truck is freezing, and you crank up the heat. But as you settle in the jump seat to prepare your sedative infusion, you notice your temp probe is reading 39.8 C (103.6 F). You don’t recall hearing a temp inside, so you browse your monitor screen: the heart rate is up 25 points, now 135 beats per minute, and the blood pressure is 160/110. You assume the patient is regaining awareness and quickly push 100 mcg of fentanyl and 50mg of propofol, but the vitals don’t budge. You start the infusion and grab the handheld thermometer. You’re surprised when it comes back 40.4 C (104.7 F).
It's not uncommon for patients with intracranial bleeding to have fever. You look for lateralizing symptoms, but when you raise his arms, you feel rigidity bilaterally. As your brain comes to terms with what’s happening, your eyes widen and you gasp.
Critical Care Corner: Drugs That Cause Worrisome Fever
Lots of drugs can cause fevers. Ironically, antibiotics are one of the worst offenders for drug-induced fever in the critical care setting. But most drugs don’t cause life-threatening fever. Fortunately, the list of life-threatening drug reactions associated with high fever is short: serotonin syndrome and neuroleptic malignant syndrome, in which serotonergic and anti-dopamine medications respectively cause fever, present with classic toxidromes (even though you don’t need to ingest a toxic amount of drug to trigger fever). But one condition is of particular interest to our critical care crew: malignant hyperthermia.
Malignant hyperthermia is the result of an inherited disorder of skeletal muscle. Anesthetic agents, particularly succinylcholine, can trigger an attack characterized by hypermetabolism (fever, tachycardia, hypertension) and muscle rigidity. A mutation in the RYR1 skeletal muscle calcium channel is to blame; when triggered, calcium is released causing contractions and hypermetabolism, which leads to fever, acidosis, and rhabdomyolysis. It is usually fatal if patients don’t receive the antidote promptly.
Back to the Case
You realize that you are in dangerous territory with this rare presentation of malignant hyperthermia caused by succinylcholine. Despite its famously short half-life, you realize the drug’s presence doesn’t matter now that it’s triggered a chain reaction.
You are still 45 minutes away from your planned destination. You ask your partner to head to the closest hospital while you dial into your medical director, who affirms your choice to divert and suggests you double your propofol infusion and add a midazolam drip. You turn off the heater, rip off the patient’s blanket, slide the windows open, and crack every ice pack you can find. Despite the frigid air pouring into the compartment, you feel sweat drip down your face.
Having called ahead with your suspicion, the ER called the OR, and an anesthesiologist is waiting with the ER doc. She has a bunch of glass vials in her hand: dantrolene, the treatment for malignant hyperthermia. Thirty minutes later, the symptoms have abated, and you arrange to re-load the patient into your ambulance and carry on to the tertiary hospital.
Not a typical call, but in EMS, when is anything typical?
Citation:
https://www.bjaed.org/article/S2058-5349(17)30064-1/fulltext
