Definitions of Sedation

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Levels of Sedation

The transition from mild to moderate sedation and from moderate to deep sedation is on a continuum. This transition can be difficult to predict and must be anticipated whenever sedation is administered. The definitions of mild sedation, moderate sedation, deep sedation and general anesthesia are defined below.

Mild Sedation (anxiolysis)

Mild sedation exists when a patient can provide appropriate response to all physical and verbal stimulation with no loss of airway control or cardiovascular function. There is no loss or minimal loss of ventilatory responsiveness. The patient is attentive to environmental stimuli with no change or minimal change in orientation to person and place. There may, however, be minimal to mild alteration in gross motor function.

Moderate Sedation

Moderate sedation exists when a patient has blunted response to light tactile, physical and/or verbal stimulation, is able to handle secretions without aspiration and can maintain a patent airway independently. There may be minimal to mild alterations in ventilatory responsiveness, and cardiovascular function is usually maintained. There is significant loss of orientation to environment, with mild to moderate impairment of gross motor function.

Deep Sedation

Deep sedation exists when the patient can provide only blunted response to painful physical stimulation. Moderate loss of ventilatory responsiveness may occur. Spontaneous ventilation may be inadequate, with potential for partial or complete loss of protective airway reflexes, and cardiovascular function may be depressed. There is moderate impairment in gross motor function, with diminished muscle tone.

General Anesthesia

General anesthesia exists when the patient is unarousable even with painful stimulus and the ability to independently maintain ventilatory and cardiovascular function is impaired. Patients require assistance in maintaining an adequate airway, and positive pressure ventilation may be required because of depressed ventilatory drive or drug-induced depression of neuromuscular function, including airway control. Only anesthesiologists are credentialed to administer and/or supervise planned general anesthesia care. Supervised residents and supervised clinical anesthetists are authorized to administer general anesthesia under the medical direction of an anesthesiologist.

Below is a table summarizing sedation levels and the pediatric sedation score:

Sedation Levels

Parameter Mild Moderate Deep

Airway Control

No loss of airway control.

Able to handle secretions without aspiration and maintain a patent airway independently.

No to minimal loss of airway protection.

Able to handle secretions without aspiration and can maintain a patent airway independently.

Potential for partial or complete loss of protective airway reflexes.

May lose the ability to handle secretions without aspiration or to maintain a patent airway independently (intervention may be required).

Respiratory Responsiveness

No to minimal loss of ventilatory responsiveness.

No to minimal change in oxygen saturation from baseline.

Minimal to mild alteration in ventilatory responsiveness.

May experience no more than a 5% reduction in oxygen saturation from baseline.

Moderate alteration in ventilatory responsiveness.

>5% decrease in oxygen saturation.

Gross Motor

Minimal to mild alteration in gross motor function.

Mild to moderate impairment in gross motor function.

May be unable to sit independently.

Moderate impairment in gross motor function.

Diminished muscle tone.

Level of Awareness

Attentive to environment/appropriate interactiveness.

No change in orientation to person or place.

Significant loss of orientation to environment and impaired ability to interact with the environment.

May fall asleep.

Loss of orientation.

Does not interact with environment.

Responsiveness to Stimuli

Appropriate response to all physical and verbal stimulation.

Blunted response to light tactile, physical and/or verbal stimulation.

Blunted response to painful physical stimulation.

Desired Sedation Score**

3, calm

4, drowsy

5, asleep

Cardiovascular function is generally not affected during mild to deep sedation but must be monitored and continually assessed.

The Pediatric Sedation Score is an abbreviated sedation scale that broadly defines the sedation level in terms of arousal. A Pediatric Sedation Score of 3 (Calm) generally describes Mild Sedation whereas scores of 4 (Drowsy) and 5 (Asleep) typify Moderate and Deep Levels respectfully.

Below is a table summarizing sedation levels and the pediatric sedation score:

Pediatric Sedation Score

Sedation Score Patient Reaction
1 = Agitated Clinging and/or drowsy
2 = Alert Awake, not clinging; may whimper but not cry
3 = Calm Lying comfortably with eyes spontaneously open
4 = Drowsy Lying comfortably with eyes spontaneously closed, but responds to mild stimulation
5 = Asleep Eyes closed, does not respond to mild stimulation

Physicians credentialed in moderate sedation must be able to rescue and resuscitate patients who progress to a deeper level of sedation, including deep sedation and general anesthesia.

Sedation Continuum

It is important to appreciate the transition to a deeper level of sedation along the sedation continuum. If the transition to a deeper level of sedation is not appreciated and appropriate interventions are not taken immediately, the patient’s condition can deteriorate rapidly, resulting in hypoxemia, respiratory arrest, bradycardia or cardiopulmonary arrest. Close monitoring and frequent reassessment of the patient’s condition facilitate prompt determination of when the desired level of sedation is achieved and early recognition of adverse events. The transition along the sedation continuum may be particularly difficult to assess in infants, young children and children with developmental disabilities.

Sedation Drugs

Sedative drugs are medications that result in central nervous system depression. Use of these drugs may result in loss of protective reflexes, with subsequent respiratory and/or cardiac dysfunction.

Many of the clinical effects of medications administered to achieve sedation are dose-related and must be assessed individually for each child. Sedative drugs may be administered orally, intranasally, rectally, parenterally or by inhalation. Specific types of sedatives can be further defined by their characteristic or predominant clinical effect. Some of the more common definitions include:

  • Sedative: A sedative decreases activity, moderates excitement and calms the patient.
  • Hypnotic: A hypnotic produces drowsiness and facilitates the onset and maintenance of sleep.
  • Analgesic: An analgesic relieves pain by altering perception of nociceptive stimuli.
  • Anxiolytic: An anxiolytic relieves apprehension and fear due to an anticipated act or illness.
  • Amnesic (antegrade): An amnestic agent affects memory incorporation such that the patient is unable to recall events following delivery of the drug.

Patient Physical Status Classification

American Society of Anesthesia (ASA) Definitions

Class Class Definition
I A normally healthy patient
II A patient with mild systemic disease with no functional limitation
III A patient with severe systemic disease and clearly defined functional limitation
IV A patient with severe systemic disease that is a constant threat to life

Sedation Risk: ASA Class I and II patients are generally considered low-risk candidates for moderate sedation. Class III patients are considered moderate to high sedation risk and in the pediatric population have a higher frequency of adverse events. Class IV patients are very high sedation risk.