EMT Lecture - AED

Understanding the Cardiac Conduction System

Overview of Cardiac Emergency Response

• The importance of rapid response in cardiac emergencies is emphasized, highlighting that cells begin to die within four to six minutes without intervention.

• The average emergency medical services (EMS) arrival time is noted as eleven and a half minutes, stressing the need for early CPR and defibrillation.

Anatomy of the Heart

• Introduction to the mediastinum, which is defined as the space where the heart sits between the lungs.

• Explanation of two phases of heart function: systole (contraction) and diastole (relaxation), referred to as systolic and diastolic pressures.

Key Concepts in Myocardium Function

• Automaticity is introduced as a unique property of myocardium, allowing it to generate electrical impulses independently.

• The SA node, located in the right atrium, initiates electrical impulses; its proper functioning indicates a normal sinus rhythm.

Understanding Sinus Rhythms

• Medical professionals refer to rhythms originating from the SA node as "sinus," indicating normal heart function.

• Different types of sinus rhythms are discussed: bradycardia (slow), tachycardia (fast), and arrest (no activity).

Backup Systems in Cardiac Conduction

• The AV node serves as a backup system if the SA node fails; it can generate impulses at rates typically between 40 and 60 beats per minute.

• If both SA and AV nodes fail, Purkinje fibers can take over but only maintain a very low rate of 20 to 40 beats per minute, indicating critical conditions.

Advanced Rhythm Considerations

• Junctional rhythms arise when impulses originate from the AV node due to failure or inactivity of the SA node.

• Discussion on accelerated junctional rhythms highlights their potential for higher rates while still being classified under junctional origins.

Clinical Implications

• Clarification on bradycardia types: sinus bradycardia originates from SA node while junctional bradycardia comes from AV node.

• Importance of understanding various cardiac measurements for accurate diagnosis during emergencies is emphasized.

Final Notes on Heart Functionality

Understanding AED and Cardiac Rhythms

Introduction to AED

• The Automated External Defibrillator (AED) is a crucial device in cardiac emergencies, designed to apply electric shocks to restore normal heart rhythm.

• Key terms: "automated" indicates the device operates automatically, "external" signifies it is used outside the body.

Fibrillation and Defibrillation

• Fibrillation refers to the quivering of the heart muscle; defibrillation aims to stop this quivering by delivering an electrical shock.

• An AED should be used when a patient is found unconscious, pulseless, and apneic (not breathing).

Recognizing Cardiac Rhythms

• Understanding EKG rhythms is essential; ventricular fibrillation (v-fib) appears as chaotic electrical activity on a monitor.

• V-fib is the most common rhythm seen immediately after cardiac arrest; another critical rhythm is pulseless ventricular tachycardia (v-tach).

Shockable vs. Non-Shockable Rhythms

• The AED can identify shockable rhythms like v-tach with or without a pulse but cannot determine if there’s a pulse itself.

• Asystole, or flatline, indicates no electrical activity in the heart; defibrillation cannot be performed in this state.

Importance of CPR and Monitoring

• If a medic observes pulseless electrical activity (PEA), they must check for a pulse before proceeding with further actions.

• Continuous CPR may be necessary until definitive signs of life are observed or until advanced medical help arrives.

Special Considerations During Defibrillation

• Ensure that the patient's chest is dry before applying pads; wet conditions can lead to ineffective shocks.

• Hypothermic patients require careful handling during defibrillation due to potential complications from repeated shocks.

Safety Precautions with Devices

• When dealing with patients who have pacemakers or implanted defibrillators, place AED pads away from these devices to avoid interference.

Challenges with Patient Conditions

How to Use a Defibrillator in Emergency Situations

Preparing for Defibrillation

• All clothing must be removed from the waist up, including undergarments, before using the defibrillator.

• The pads of the defibrillator are crucial; one pad is placed on the right upper quadrant and another on the left lower area, avoiding direct placement over the heart.

• Instructions for use are typically found on the back of the device, but time constraints may prevent reading them during an emergency.

Steps to Operate a Defibrillator

• Four universal steps should be memorized:

1. Switch on the defibrillator.

2. Apply pads to the patient's bare chest.

3. Follow audio prompts from the device.

4. Administer a shock if advised by the machine.

• It's important not to focus solely on the defibrillator; maintain awareness of patient status while preparing to deliver a shock.

Post-Shock Protocol

• After delivering a shock, immediately resume CPR unless the patient regains consciousness; perform 30 compressions before checking for responsiveness again.

• If no pulse or breathing is detected after applying an AED (Automated External Defibrillator), continue CPR and prepare for transport if advised by machine prompts.

Analyzing Patient Status

• After two minutes post-shock, check for pulse and breathing; if "no shock advised" appears, resume CPR immediately and initiate transport as necessary.

• Understanding that patients can transition between cardiac arrest states (e.g., v-fib to v-tach with pulse); follow machine guidance without delay.

Key Concepts in Defibrillation

• Joules measure energy delivered during shocks; understanding this metric is essential for effective treatment protocols in emergencies.