Induction of General Anesthesia

Introduction

The start of a case represents one of the highest risk periods in the operation.

After a surgical time-out, the tools required for a safe induction can be remembered with the MDSOLES acronym:

  • Monitors
  • Drugs
    • IV access
    • induction agents
    • resuscitation medications (vasopressors, reversal agents)
  • Suction
  • Oxygen (primary and alternative source)
  • Laryngoscope
  • ETT
  • Stylet

Goals of Induction

Loss of consciousness

Anesthetic agents are administered until the patient loses consciousness. The speed at which anesthesia is induced is often guided by the clinical scenario and patient comorbidities (see Rapid Sequence InductionRapid Sequence Induction
What is a Rapid Sequence Induction (RSI)? 1

General anesthesia usually involves impairment of airway reflexes, thereby increasing aspiration risk
If patients who require general anesthesia are...)

Tests of loss of consciousness:

  • loss of verbal or pain response
  • loss of eyelash reflex
  • apnea (often used when using PropofolPropofol
    What is Propofol? 12

    Sedative agent for induction and maintenance of anesthesia.
    Rapid redistribution allows brief, deep sedation (e.g., joint reductions, cardioversions, ECT).


    Mechanism of ...     or other apnea-inducing agents)

Hemodynamic Stability

There are many factors that contribute to hemodynamic depression and elevation. Hypotension is a common side effect of anesthetic agents and should be expected and counteracted. Similarly, laryngoscopy can be quite stimulating and achieving sympathetic blockade with narcotics or other medications is standard.

Factors causing hypotension:

  • anesthetic agents & analgesics
  • administration of positive pressure ventilation (due to reducing preload)
  • patient positioning (head up reduces preload, head down will augment preload)

Factors causing hypertension

  • jaw thrust
  • laryngoscopy
  • surgical incision

Facilitation of Airway Management

Depending on the desired airway, there are a variety of medications that can assist in placement of an airway device. See Airway DevicesAirway Devices
Bag Mask Ventilation
BMV Basics
Anesthetic machines come with several elements

Mask - forms a seal on the mouth. A good seal allows accurate reading of ETCO2 and ETO2 (to assess pre-oxygenation)...

Endotracheal Tube

  • Paralysis with SuccinylcholineSuccinylcholine
    What is Succinylcholine? 1

    A depolarizing neuromuscular blocking drug
    Commonly used for rapid sequence induction and intubation due to its rapid onset and ultra-short duration of action.
    Suc...     or RocuroniumRocuronium
    What is Rocuronium? 1

    An intermediate-acting non-depolarizing neuromuscular blocking drug (NDMR) used for rapid induction and intubation.
    Popular for short and intermediate procedures due to i...     is common
  • Narcotics like RemifentanilRemifentanil
    What is Remifentanil? 1

    Ultra-short-acting synthetic opioid analgesic.
    Used for pain management and as an adjunct to anesthesia.
    Rapid onset and short duration of action.


    Mechanism of Acti...     or FentanylFentanyl
    What is Fentanyl? 12

    Potent, synthetic opioid with rapid acting analgesic and sedative properties.
    Can be administered intravenously, intramuscularly, transdermally, transmucosally, or intrath...     can improve the grade of the view during laryngoscopy and prevent the hemodynamic impact of laryngoscopy
  • Adequate depth of anesthetic can facilitate intubation

Supraglottic Airway

  • Depth of anesthetic is important for placement of an SGA
  • Paralysis and narcotics can be used to facilitate SGA placement but paralysis is often unnecessary