Hypotension Shock

Introduction

Welcome to the QBankMD MCCQE1 preparation guide on Hypotension Shock. This comprehensive resource is tailored for Canadian medical students preparing for the Medical Council of Canada Qualifying Examination Part I (MCCQE1). Understanding hypotension and shock is crucial for success in the MCCQE1 and for your future practice in the Canadian healthcare system.

Definition and Types of Shock

Shock is a life-threatening condition characterized by inadequate tissue perfusion and cellular oxygenation. In the context of the Canadian healthcare system, early recognition and prompt management of shock are essential skills for medical practitioners.

There are four main types of shock:

1. Hypovolemic Shock
2. Cardiogenic Shock
3. Obstructive Shock
4. Distributive Shock

Pathophysiology of Shock

Understanding the pathophysiology of shock is crucial for MCCQE1 success. The key components include:

1. Inadequate Tissue Perfusion: Reduced blood flow to organs
2. Cellular Hypoxia: Insufficient oxygen delivery to cells
3. Metabolic Acidosis: Accumulation of lactic acid due to anaerobic metabolism
4. Multi-Organ Dysfunction: Progressive failure of organ systems

Clinical Presentation

Recognizing the signs and symptoms of shock is critical for Canadian healthcare providers. Key clinical features include:

• Hypotension (SBP <90 mmHg or 30 mmHg below baseline)
• Tachycardia
• Altered mental status
• Cool, clammy skin
• Decreased urine output (<0.5 mL/kg/hr)

Diagnostic Approach

For the MCCQE1, focus on the following diagnostic steps:

Management of Shock

The management of shock in the Canadian healthcare system follows evidence-based guidelines. Key principles include:

1. Airway, Breathing, Circulation (ABC) approach
2. Fluid resuscitation
3. Vasopressor therapy
4. Treating the underlying cause

Fluid Resuscitation

Initial Fluid Bolus = 20-30 mL/kg of crystalloid solution

Vasopressor Therapy

Canadian Guidelines for Shock Management

The Canadian Association of Emergency Physicians (CAEP) provides guidelines for the management of shock in the emergency department. Key recommendations include:

• Early recognition and rapid intervention
• Goal-directed therapy with specific targets for MAP, CVP, and ScvO2
• Use of balanced crystalloids for initial fluid resuscitation
• Consideration of blood products in hemorrhagic shock
• Early antibiotic administration in suspected septic shock

Key Points to Remember for MCCQE1

• Understand the four main types of shock and their pathophysiology
• Recognize the clinical signs of shock, including hypotension and organ dysfunction
• Know the initial management steps, including ABC approach and fluid resuscitation
• Familiarize yourself with Canadian-specific guidelines for shock management
• Understand the role of vasopressors and their indications
• Be aware of potential complications of shock and their management
• Consider special populations, such as Indigenous Canadians, in your approach to shock

Sample Question

A 68-year-old woman presents to the emergency department with a 2-day history of fever, chills, and dysuria. She appears confused and has a blood pressure of 80/50 mmHg, heart rate of 120 bpm, respiratory rate of 24 breaths/min, and temperature of 39.5°C. Which one of the following is the most appropriate initial management step?

• A. Administer broad-spectrum antibiotics
• B. Start norepinephrine infusion
• C. Obtain blood cultures
• D. Perform chest X-ray
• E. Administer intravenous fluid bolus

Explanation

The correct answer is:

• E. Administer intravenous fluid bolus

This patient is presenting with signs of septic shock, likely due to a urinary tract infection. The initial management step in shock, regardless of etiology, is to address circulation with fluid resuscitation. While all the other options are important in managing septic shock, the immediate priority is to improve tissue perfusion with an IV fluid bolus.

In the Canadian context, following the CAEP guidelines, the recommended initial fluid bolus is 20-30 mL/kg of balanced crystalloid solution. This should be followed by reassessment and further management, including antibiotic administration, vasopressor therapy if needed, and additional diagnostic tests.

References

1. Seymour CW, Rosengart MR. Septic Shock: Advances in Diagnosis and Treatment. JAMA. 2015;314(7):708-717.
2. Canadian Association of Emergency Physicians. Position Statement on Early Care of Patients with Sepsis (opens in a new tab)
3. Rhodes A, et al. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock: 2016. Intensive Care Med. 2017;43(3):304-377.
4. McIntyre WF, et al. Association of Vasopressin Plus Catecholamine Vasopressors vs Catecholamines Alone With Atrial Fibrillation in Patients With Distributive Shock: A Systematic Review and Meta-analysis. JAMA. 2018;319(18):1889-1900.