A 40-year-old female is scheduled for parotid surgery and is administered general Anaesthesia. Approximately 10 minutes into the procedure, the following findings are noted:  • Rise in end-tidal CO₂ (EtCO₂)  • Temperature: 104°F (40°C)  • Heart rate: 150 bpm  • Blood pressure: 180/110 mmHg What is the most likely diagnosis?

1. A

   A. Heat stroke

2. B

   B. Malignant hyperthermia

3. C

   C. Heat cramps

4. D

   D. Heat pyrexia

Appeared in: INI-CET EXAM -2026

Explanation

• The combination of symptoms—a sudden rise in end-tidal CO2, tachycardia, hypertension, and hyperthermia—occurring shortly after induction of general anesthesia is the classic presentation of Malignant Hyperthermia (MH).
• MH is a pharmacogenetic disorder of skeletal muscle that triggers a hypermetabolic state when exposed to certain anesthetic agents.
• An unexplained rise in end-tidal CO2 (hypercapnia) is the earliest and most sensitive indicator of an MH crisis.
• While the high temperature is a hallmark sign, it often develops after the initial respiratory and cardiovascular changes.

Why Other Options Were Wrong

• Option A: Heat stroke is caused by prolonged exposure to high environmental temperatures, which is not the context of a typically cool operating room. Also, a sudden rise in EtCO2 is not a primary feature of heat stroke.
• Option C: Heat cramps are painful, involuntary muscle spasms that occur during or after intense exercise in hot weather. They are a localized issue and do not cause the severe systemic symptoms (high fever, extreme tachycardia, hypertension, respiratory changes) seen in this patient.
• Option D: Heat pyrexia is a general term for fever (pyrexia) caused by heat. Malignant hyperthermia is a specific, life-threatening syndrome of hypermetabolism triggered by drugs, not just a fever from external heat. The underlying pathophysiology is different.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Recognition and initial management of Malignant Hyperthermia (MH) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Early recognition of MH by the entire perioperative team, including nurses, is critical to prevent mortality, which can be as high as 70% if untreated but falls to less than 10% with prompt action.
• A key nursing role in the preoperative phase is to assess for risk factors, including a personal or family history of problems with anesthesia, which could indicate susceptibility to MH.
• Every operating room must have a dedicated Malignant Hyperthermia cart with dantrolene, sterile water for injection, syringes, and protocols for immediate access.

How to Approach the Question

• First, analyze the clinical setting: The patient is in an operating room under general anesthesia. This immediately raises suspicion for anesthesia-related complications.
• Next, identify the cluster of symptoms: The patient has acute respiratory (rise in EtCO2), cardiovascular (tachycardia, hypertension), and thermoregulatory (high fever) problems.
• Look for the most specific sign. The sudden, unexplained rise in end-tidal CO2 is the most unique and earliest sign presented in this scenario.
• Evaluate the options in the context of the setting and key sign. Heat stroke, cramps, and pyrexia are all related to environmental heat and do not explain the rapid rise in EtCO2 as a primary event triggered by anesthesia.
• Conclude that the constellation of findings is classic for Malignant Hyperthermia, a known and feared complication of general anesthesia.

Concept Tested & Keywords

• Concept Tested: Recognition and initial management of Malignant Hyperthermia (MH).
• Stem keywords: general Anaesthesia, Rise in end-tidal CO2, Temperature: 104°F, Heart rate: 150 bpm, Blood pressure: 180/110 mmHg
• Lead-in keywords: most likely diagnosis
• Clinical cues: Patient under general anesthesia
• Clinical cues: Sudden onset of symptoms 10 minutes into procedure

Question ID

Q_CfjHGXGVSVUdPIeBMA7d

Copy ID

Reference Book

E6 Nursing Brunner Adult Health 3SA Vol 1 Part 1 p. 105-107

E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 12-14