III. GENERAL PRINCIPLES OF ANESTHESIA

LIGHT, MODERATE, AND DEEP SEDATION

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QUESTIONS

QUESTIONS

QUESTIONS

QUESTIONS

QUESTIONS

QUESTIONS

Light, Moderate, and Deep Sedation

STANDARDS OF PRACTICE

STANDARD 9

Monitor, evaluate, and document the patient’s physiologic condition as appropriate for the procedure and anesthetic technique. When a physiologic monitoring device is used, variable pitch and threshold alarms are turned on and audible. Document blood pressure, heart rate, and respiration at least every 5 minutes for all anesthetics.

PARAMETER

MODIFIER

OXYGENATION

Continuously monitor oxygenation by clinical observation and pulse oximetry. The surgical or procedural team communicates and collaborates to mitigate the risk of fire.

VENTILATION

Continuously monitor ventilation by clinical observation and confirmation of continuous expired carbon dioxide during moderate sedation, deep sedation, or general anesthesia. Verify intubation of the trachea or placement of other artificial airway device by auscultation chest excursion, and confirmation of expired carbon dioxide. Use ventilatory monitors as indicated.

CARDIOVASCULAR

Monitor and evaluate circulation to maintain patient’s hemodynamic status. Continuously monitor heart rate and cardiovascular status. Use invasive monitoring as indicated.

THERMOREGULATION

When clinically significant changes in body temperature are intended, anticipated, or suspected, monitor body temperature. Use active measures to facilitate normothermia. When malignant hyperthermia (MH) triggering agent are used, monitor temperature and recognize signs and symptoms to immediately initiate appropriate treatment and management of MH.

NEUROMUSCULAR

When neuromuscular blocking agents are administered, monitor neuromuscular response to assess depth of blockade and degree of recovery.

Scope and Standards for Nurse Anesthesia Practice, 2019. American Association of Nurse Anesthetists.

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CONTINUOUS DEPTH OF SEDATION

 

LIGHT SEDATION

MODERATE SEDATION

DEEP SEDATION

GENERAL ANESTHESIA

RESPONSIVENESS

Normal response to verbal stimulation

Purposeful response to verbal or tactile stimulation

Purposeful response following repeated or painful stimulation

Unarousable, even with a painful stimulus

AIRWAY

Unaffected

No intervention required

Intervention may be required

Intervention often required

SPONTANEOUS VENTILATION

Unaffected

Adequate

May be inadequate

Frequently inadequate

CARDIOVASCULAR FUNCTION

Unaffected

Usually maintained

Usually maintained

May be impaired

REFERENCE: Barash Clinical Anesthesia 9th edition, page 800

ASSESSMENT OF SEDATION

ASA CONTINUUM OF DEPTH OF SEDATION

MODIFIED RAMSAY SEDATION SCALE

Light sedation (anxiolysis): normal response to verbal stimulation

1.     Awake and alert, minimal or no cognitive impairment

Moderate sedation/analgesia (“conscious sedation”): purposeful response to verbal or tactile stimulation

2.     Awake but tranquil, purposeful response to verbal commands at conversational level.

3.     Appears asleep, purposeful responses to verbal commands at conversational level

4.     Appears asleep, purposeful responses to verbal commands but at louder than usual conversational level, requiring light glabellar tap, or both

Deep sedation/analgesia: purposeful response following repeated or painful stimulation

5.     Asleep, sluggish purposeful responses only to loud verbal commands, strong glabellar tap, or both

6.     Asleep, sluggish purposeful responses only to painful stimuli

7.     Asleep, reflex withdrawal to painful stimuli only (no purposeful responses)

General anesthesia: unarousable even with painful stimulus

8.     Unresponsive to external stimuli, including pain

REFERENCE: Barash Clinical Anesthesia 9th edition, page 801

  • Oxygen delivery during a MAC case is mandated by the AANA. According to the Standards of Practice, oxygenation is to be monitored and the team will collaborate on fire risk. Moderate sedation, deep sedation, and general anesthesia require end-tidal carbon dioxide monitoring.
  • Benzodiazepines should be used with caution in the elderly, especially during MAC cases. These medications can increase inspiratory subglottic airway resistance by 3-4x.
  • The most common cause of death during MAC cases is excessive sedation.
  • The most important component of monitored anesthesia care procedures is the close monitoring and contact of the patient by the anesthetist.
  • A potential mild complication during conscious sedation is a dysphoric reaction.
  • The main goal of MAC cases in adults with cardiac disease is to preserve steady hemodynamics.
  • The CRNA must always be ready to convert from MAC to general.
    • Most common reasons:
      • Failed neuraxial or regional anesthesia
      • Patient inability to tolerate MAC
      • Hypoxia or airway obstruction
    • Obese patients have an increased risk of conversion due to sleep apnea, airway obstruction, and hypoxia.