Drugs in the OR

General Anesthesia Pharmacology Overview for Clerks

Learning Objectives

List commonly used agents in the induction, maintenance, and emergence of general anesthesia
Understand the physiological effects of each agent on the cardiovascular, respiratory, and central nervous systems
Understand the indications and contraindications for each agent

Introduction: Drugs in Context

Goals of General Anesthesia

The five goals (or 5 A's) of general anesthesia (GA) are:

1. (Loss of) Awareness (sedation/hypnosis)

2. Amnesia (no memory)

3. Analgesia (no pain)

4. Akinesia (paralysis/neuromuscular block)

5. Autonomic block

In a course of general anesthesia, a combination of medications is used to achieve all five of these goals.

One class of drugs may achieve more than one of these goals. For example, opioids are sedative, analgesic, and blunt autonomic responses.

Phases of General Anesthesia

General anesthesia can be broken down into three phases:

1. Induction: Our main goal is to transition the patient from an awake to an anesthetized state (put them to "sleep") using a primary induction agent. Several adjuvant agents can then be added to achieve other desirable effects.

2. Maintenance: Next, the goal is to make sure the patient stays anesthetized throughout the procedure.

3. Emergence: Lastly, anesthesia is weened and the effects of adjuvant agents, such as neuromuscular blockade, are reversed or discontinued.

This module will take you through the agents used in a typical course of general anesthesia, starting from the induction phase all the way through to emergence.

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