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Conscious Sedation


Some of you say that religion makes people happy. So does laughing gas. Clarence Darrow

The ability to understand and administer conscious sedation to perform invasive procedures is a necessity for the practicing surgeon. It is no longer solely the role of the anesthesiologist to provide sedation and analgesia for patients undergoing less complex but still painful or stimulating procedures. A surgeon must be familiar with the pharmacology, physiology, and techniques necessary to safely deliver sedation.

I

Introduction

A

Definition

  • 1.

    Sedation is “a minimally depressed level of consciousness that retains the patient’s ability to independently and continuously maintain an airway and respond appropriately to physical stimulation and verbal commands” (American Dental Association Council on Education).

  • 2.

    Sedation comprises a continuum from minimal sedation to general anesthesia (American Society of Anesthesiologists Guidelines) ( Table 8.1 ).

    TABLE 8.1
    Sedation Guidelines
    Data from document developed by the American Society of Anesthesiologists (ASA); approved by the ASA House of Delegates, October 13, 1999.
    Minimal Sedation (Anxiolysis) Moderate Sedation/Analgesia (Conscious Sedation) Deep Sedation/Analgesia General Anesthesia
    Responsiveness Normal response to verbal stimulation Purposeful a response to verbal or tactile stimulation Purposeful a response after repeated or painful stimulation Unarousable, even with 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

    a Because sedation is a continuum, it is not always possible to predict how an individual patient will respond. Hence practitioners intending to produce a given level of sedation should be able to rescue patients whose level of sedation becomes deeper than initially intended.

B

Applications (Selected)

  • 1.

    Intensive care unit (ICU)/emergency department procedures

  • 2.

    Central venous line insertions

  • 3.

    Chest tube insertions

  • 4.

    Endoscopic procedures

  • 5.

    Hernia reductions

  • 6.

    Patients with extensive burns

II

Preprocedural Evaluation

A

History

  • 1.

    General history and review of systems, including tobacco, alcohol, and drug use history

  • 2.

    Previous anesthetics and any adverse outcomes

  • 3.

    Airway abnormalities (e.g., obstructive sleep apnea, severe snoring, stridor, and previous tracheostomy)

  • 4.

    Chromosomal abnormalities and/or syndromes (e.g., Down syndrome)

  • 5.

    Gastroesophageal reflux disease/hiatal hernia

  • 6.

    Obesity

  • 7.

    Adequate intravenous (IV) access in situ

  • 8.

    Last meal (food and drink) (see Section II.C)

B

Airway Examination

  • 1.

    General assessment of patient (e.g., body habitus, presence of cervical collar)

  • 2.

    Mallampati examination ( Fig. 8.1 )

    FIG. 8.1, Mallampati classification: class I—faucial pillars, soft palate, and uvula are visible; class II—faucial pillars and soft palate are visible, and uvula view is obstructed by base of tongue; class III—only soft and hard palates are visible; and class IV—only hard palate is visible.

  • 3.

    Mouth opening (adults should have 3- to 4-cm distance between upper and lower incisors)

  • 4.

    Thyromental distance (distance from thyroid cartilage to mandible; should be at least 5 cm in adults)

  • 5.

    Neck extension

  • 6.

    Assessment for any cervical spine abnormalities or disorders associated with atlantooccipital instability

  • 7.

    Lack of extension or significantly reduced extension may indicate difficulty with direct laryngoscopy

  • 8.

    Any craniofacial/bony abnormalities

    • a.

      Receding mandible

    • b.

      High, arched palate

    • c.

      Syndromes (e.g., Pierre Robin, Treacher Collins)

  • 9.

    Dentition

  • 10.

    Facial hair (presence of a beard or other significant facial hair may signal difficult mask ventilation)

C

American Society of Anesthesiologists Fasting Guidelines ( Table 8.2 )

  • 1.

    Need to follow for all elective procedures

    TABLE 8.2
    Summary of Fasting Recommendations to Reduce the Risk for Pulmonary Aspiration a
    Ingested Material Minimum Fasting Period (h) b
    Clear liquids c 2
    Breast milk 4
    Infant formula 6
    Nonhuman milk d 6
    Light meal e 6

    a These recommendations apply to healthy patients who are undergoing elective procedures. They are not intended for women in labor. Following the guidelines does not guarantee complete gastric emptying.

    b The fasting periods noted apply to all ages.

    c Examples of clear liquids include water, fruit juices without pulp, carbonated beverages, clear tea, and black coffee.

    d Because nonhuman milk is similar to solids in gastric emptying time, the amount ingested must be considered when determining an appropriate fasting period.

    e A light meal typically consists of toast and clear liquids. Meals that include fried or fatty foods or meat may prolong gastric emptying time. Both the amount and types of foods ingested must be considered when determining an appropriate fasting period.

  • 2.

    May be modified in emergency situations at discretion of practitioner

III

Monitoring

A

Best Achieved by Someone Other than Person Performing Procedure

B

Preprocedure

  • 1.

    Vital signs

  • 2.

    SpO 2

  • 3.

    Places supplemental oxygen

C

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