# During general anesthesia with sevoflurane after succinylcholine, a client develops a rapidly rising end-tidal CO₂ from 38 to 72 mm Hg despite increased ventilation, generalized muscle rigidity, sinus tachycardia, mixed acidosis, and potassium 6.1 mEq/L. Core temperature is 38.1°C (100.6°F). Complete the bowtie by selecting the condition, two actions the nurse should take, and two parameters the nurse should monitor.

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=604460&lang=en  
> language: en  
> subject: Postsurgical Complications  
> category: ROR

## Question

During general anesthesia with sevoflurane after succinylcholine, a client develops a rapidly rising end-tidal CO₂ from 38 to 72 mm Hg despite increased ventilation, generalized muscle rigidity, sinus tachycardia, mixed acidosis, and potassium 6.1 mEq/L. Core temperature is 38.1°C (100.6°F). Complete the bowtie by selecting the condition, two actions the nurse should take, and two parameters the nurse should monitor.

Condition

Select 1
Perioperative anaphylaxis
Thyroid storm
Malignant hyperthermia
Septic shock

Actions to take

Select 2
Deepen the volatile anesthetic while treating the tachycardia
Stop triggering agents and hyperventilate with 100% oxygen using a clean circuit or charcoal filters
Obtain the malignant-hyperthermia cart and give IV dantrolene promptly
Complete surface cooling before administering dantrolene
Give a calcium-channel blocker for the tachycardia and hyperkalemia

Parameters to monitor

Select 2
End-tidal CO₂, minute ventilation requirement, heart rate, and muscle rigidity
Thyroid-stimulating hormone and free thyroxine every hour
Core temperature, potassium, creatine kinase, urine output, and urine myoglobin
International normalized ratio after anticoagulant therapy
Fever response to acetaminophen as the primary marker of crisis control

## Explanation

Rapid unexplained hypercarbia, rigidity, acidosis, hyperkalemia, and tachycardia after triggering anesthetics indicate malignant hyperthermia even before marked fever. Stop triggers, use 100% oxygen, and give dantrolene promptly; monitor hypermetabolism, temperature, electrolytes, muscle injury, and renal effects.

## In-depth explanation

Correct answer
Malignant hyperthermia; stop triggers with 100% oxygen; give IV dantrolene; monitor hypermetabolism and muscle-injury complications.
Why it fits
A rapid unexplained rise in end-tidal carbon dioxide with rigidity, acidosis, hyperkalemia, and tachycardia after sevoflurane and succinylcholine is characteristic of malignant hyperthermia. High fever is not required before treatment.
Action rationale
Triggering agents are stopped immediately, the client is hyperventilated with 100% oxygen, and dantrolene is administered promptly. Cooling or diagnostic confirmation must not delay dantrolene.
Monitoring rationale
Falling end-tidal carbon dioxide, heart rate, and rigidity indicate crisis control. Core temperature, potassium, creatine kinase, urine output, and urine myoglobin detect ongoing hypermetabolism and muscle breakdown.
NCLEX rule
When a trigger-specific emergency has a definitive antidote, remove the trigger and give the antidote while monitoring both response and life-threatening complications.
Why the alternatives fail
Continuing volatile anesthesia, delaying dantrolene for cooling, and using calcium-channel blockers are unsafe. Thyroid tests, INR, and antipyretic response do not show control of malignant hyperthermia.
**Sources**
- MHAUS — Emergency Treatment for an Acute MH Event

- MHAUS — Dantrolene Administration After an MH Event

## Key concepts

- **Malignant hyperthermia** — A life-threatening hypermetabolic skeletal-muscle reaction triggered by susceptible anesthetic agents.
- **Dantrolene** — The specific treatment used promptly to control a malignant-hyperthermia crisis.

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