# Shortly after induction with succinylcholine and sevoflurane, an OR client develops masseter rigidity, rapid rise in end-tidal CO2 to 70, tachycardia, and temperature spike to 40°C. Which is the priority action?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=en  
> language: en  
> subject: Adverse Effects/Contraindications/Interactions  
> category: PPT

## Question

Shortly after induction with succinylcholine and sevoflurane, an OR client develops masseter rigidity, rapid rise in end-tidal CO2 to 70, tachycardia, and temperature spike to 40°C. Which is the priority action?

## Option

1. Stop triggering agents (succinylcholine, volatile gas), call for help, administer IV dantrolene 2.5 mg/kg, cool the client, hyperventilate with 100% O2, and treat hyperkalemia/acidosis **✔ Correct answer**
2. Switch to a different volatile gas
3. Give additional succinylcholine for relaxation
4. Increase anesthetic agent for deeper sedation

**Correct answer: 1**

## Explanation

Correct (2): Malignant hyperthermia — autosomal dominant ryanodine receptor disorder triggered by succinylcholine and volatile anesthetics. Hallmarks: masseter rigidity, rising EtCO2, hyperthermia, tachycardia, acidosis, rhabdomyolysis. Antidote: IV dantrolene 2.5 mg/kg immediately (repeat to max 10 mg/kg). Stop triggers, cool, treat hyperkalemia and acidosis. (1,3,4) Fatal.

## In-depth explanation

Memory Tip MH triggers = "Sux + Volatile gas (sevo/iso/des)." Dantrolene antidote. Family history → use non-triggering anesthetic. MHAUS hotline.

## Clinical scenario

Scenario 18-year-old undergoing elective surgery received succinylcholine + sevoflurane. New: masseter rigidity, EtCO2 70, HR 145, temp 40°C, mottled skin.

## Key concepts

- **Malignant hyperthermia** — Genetic hypermetabolic crisis triggered by succinylcholine and volatile anesthetics.
- **Dantrolene** — Skeletal muscle relaxant; blocks calcium release; MH antidote.
- **MH triggers** — Succinylcholine + volatile anesthetics (sevoflurane, isoflurane, desflurane).

## Related questions

- [A nurse is reviewing the morning lab results for an adult client receiving warfarin for at…](https://mymerci.kr/pages/nclex_q.php?qn_id=360515&lang=en)
- [A client is admitted to the emergency department after ingesting an unknown amount of acet…](https://mymerci.kr/pages/nclex_q.php?qn_id=362720&lang=en)
- [A client with chronic heart failure is prescribed metoprolol 25 mg orally twice daily. Bef…](https://mymerci.kr/pages/nclex_q.php?qn_id=362756&lang=en)
- [A 28-year-old client with type 1 diabetes receives regular insulin 6 units and NPH insulin…](https://mymerci.kr/pages/nclex_q.php?qn_id=362792&lang=en)
- [A client receives IV vancomycin 1 g every 12 hours for MRSA bacteremia. Before the next do…](https://mymerci.kr/pages/nclex_q.php?qn_id=362833&lang=en)
- [A client with bipolar disorder has been taking lithium carbonate 600 mg orally three times…](https://mymerci.kr/pages/nclex_q.php?qn_id=362894&lang=en)
- [An 80-year-old male with heart failure is prescribed digoxin 0.125 mg daily. During mornin…](https://mymerci.kr/pages/nclex_q.php?qn_id=372686&lang=en)
- [A 38-year-old female with rheumatoid arthritis is being discharged with a new prescription…](https://mymerci.kr/pages/nclex_q.php?qn_id=372687&lang=en)

## Read in another language

- [en](https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=en)
- [ko](https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=ko)
- [ja](https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=ja)
- [zh-TW](https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=zh-tw)
- [vi](https://mymerci.kr/pages/nclex_q.php?qn_id=391877&lang=vi)

---

More free questions: [NCLEX-RN Practice](https://mymerci.kr/pages/nclex_bank.php?lang=en)

_For study reference only. Always follow current clinical guidelines and your institution’s protocols._