Fever And Hyperthermia

Introduction

Understanding fever and hyperthermia is crucial for success in the Medical Council of Canada Qualifying Examination Part I (MCCQE1). This comprehensive guide will help Canadian medical students prepare for questions related to these topics, with a focus on Canadian healthcare practices and guidelines.

Definitions and Pathophysiology

Fever

Fever is a regulated increase in body temperature in response to a pyrogen, typically as part of the immune response.

Hyperthermia

Hyperthermia is an uncontrolled increase in body temperature that exceeds the body's ability to lose heat.

Pathophysiology of Fever

Causes of Fever

1. Infections (bacterial, viral, fungal, parasitic)
2. Inflammatory conditions (e.g., rheumatoid arthritis)
3. Malignancies
4. Medications
5. Immunizations

Causes of Hyperthermia

1. Heat stroke
2. Malignant hyperthermia
3. Neuroleptic malignant syndrome
4. Serotonin syndrome
5. Thyroid storm

Clinical Presentation and Assessment

History Taking

• Duration and pattern of fever
• Associated symptoms
• Recent travel history (important for Canadian context, given diverse immigrant population)
• Medication history
• Immunization status

Physical Examination

• Vital signs (including temperature)
• General appearance
• Skin examination (rashes, petechiae)
• Lymph node palpation
• Systemic examination to identify source of fever

Diagnostic Approach

Laboratory Tests

1. Complete blood count (CBC)
2. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
3. Blood cultures
4. Urinalysis and urine culture
5. Liver function tests
6. Thyroid function tests (if thyroid storm suspected)

Imaging Studies

• Chest X-ray
• Abdominal ultrasound
• CT scan (if indicated)

Management

Fever

1. Treat underlying cause
2. Supportive care:
   • Hydration
   • Rest
   • Antipyretics (acetaminophen or ibuprofen)

Hyperthermia

1. Immediate cooling measures
2. Treat underlying cause
3. Supportive care and close monitoring

Canadian Guidelines and Considerations

1. Immunization Schedule: Familiarity with the Canadian Immunization Guide is crucial for MCCQE1 preparation. Fever is a common side effect of vaccinations.

2. Antimicrobial Stewardship: The Association of Medical Microbiology and Infectious Disease (AMMI) Canada provides guidelines on appropriate antibiotic use, which is relevant when managing fever due to bacterial infections.

3. Heat Alert and Response Systems: Health Canada has guidelines for managing heat-related illnesses, including hyperthermia, which are particularly relevant given Canada's diverse climate.

Key Points to Remember for MCCQE1

• Differentiate between fever and hyperthermia
• Understand the pathophysiology of fever
• Know the definition and approach to Fever of Unknown Origin (FUO)
• Recognize life-threatening causes of hyperthermia
• Familiarize yourself with Canadian immunization schedules and their relation to fever
• Understand the CanMEDS roles in managing patients with fever or hyperthermia

MCCQE1 Practice Question

Sample Question

A 28-year-old woman presents to the emergency department with a temperature of 39.5°C, severe headache, and neck stiffness. She returned from a backpacking trip across Southeast Asia two weeks ago. On examination, she appears ill and has a petechial rash on her trunk and extremities. Which one of the following is the most appropriate next step in management?

• A. Administer acetaminophen and discharge with follow-up
• B. Order blood cultures and start empiric antibiotics
• C. Perform a lumbar puncture
• D. Order a CT scan of the head
• E. Start antimalarial treatment

Explanation

The correct answer is:

• B. Order blood cultures and start empiric antibiotics

This patient presents with signs and symptoms suggestive of meningococcal meningitis, which is a medical emergency. The high fever, severe headache, neck stiffness, and petechial rash are classic signs. Given her recent travel history, this is a crucial differential to consider.

In the Canadian healthcare context, where meningococcal disease is a reportable illness, prompt recognition and treatment are essential. The most appropriate next step is to order blood cultures and start empiric antibiotics immediately. Delaying antibiotic treatment in suspected meningococcal disease can significantly increase morbidity and mortality.

While a lumbar puncture is important for diagnosis, it should not delay the initiation of antibiotics. A CT scan is not immediately necessary unless there are signs of increased intracranial pressure. Antimalarial treatment is not the first-line approach given the presenting symptoms, although malaria should be considered in the differential diagnosis.

This question tests the candidate's ability to recognize a medical emergency, prioritize management steps, and consider the patient's travel history - all crucial skills for Canadian medical practice and the MCCQE1 exam.

References

1. Public Health Agency of Canada. (2021). Canadian Immunization Guide. https://www.canada.ca/en/public-health/services/canadian-immunization-guide.html (opens in a new tab)

2. Association of Medical Microbiology and Infectious Disease Canada. (2020). Guidelines. https://www.ammi.ca/guidelines/ (opens in a new tab)

3. Health Canada. (2022). Extreme Heat: Heat Waves. https://www.canada.ca/en/health-canada/services/sun-safety/extreme-heat-heat-waves.html (opens in a new tab)

4. Unger, M., & Kariyawasam, D. (2019). Fever in the returning traveller. Canadian Family Physician, 65(4), 259-263.

5. National Institute for Health and Care Excellence. (2019). Fever in under 5s: assessment and initial management. https://www.nice.org.uk/guidance/ng143 (opens in a new tab)

6. Walter, E. J., Hanna-Jumma, S., Carraretto, M., & Forni, L. (2016). The pathophysiological basis and consequences of fever. Critical Care, 20(1), 200.