Conscious Sedation

Conscious Sedation

EDUCATIONAL MATERIAL AND EXAM FOR NON-ANESTHESIOLOGY PROVIDERS PERFORMING CONSCIOUS (MODERATE) SEDATION

Review of this educational material and completion of the exam is required of non-anesthesia physicians requesting (or renewing) the privilege to perform conscious sedation. This material is a guideline for educational purposes only. It is not designed to establish or reflect standards, nor is it intended to be used for legal purposes. Our goal in providing this material is to assure the same level of quality patient care by all individuals with delineated clinical privileges within medical staff departments and across all departments and services within the institution.

Patient Objectives

Sedation and analgesia (conscious sedation) may be administered to patients undergoing diagnostic or therapeutic procedures in a variety of clinical settings. Regardless of the setting, the same level of quality patient care must be ensured by the hospital.

St. Joseph Medical Center and St. Mary’s Medical Center have developed specific protocols for the care of patients receiving sedation and a credentialing process for physicians in order to maintain a uniform quality of care throughout our institution regarding sedation and analgesia.

Intravenous (IV) sedation and analgesia are produced by the administration of pharmacologic agents, which alone or in combination, produce a depressed level of consciousness and yet allow the patient to independently maintain a patent airway and respond appropriately to verbal and physical stimulation.

The objectives for the patient include:

  • Maintenance of consciousness
  • Cooperation
  • Elevation of pain threshold
  • Minimal variation of vital signs
  • Safe return to ambulation

The desired effects include:

  • Relaxation
  • Cooperation
  • Purposeful responses to verbal communication and tactile stimulation
  • Easy arousal from sleep

Undesirable effects of sedation and analgesia:

  • Deep and unarousable sleep
  • Hypotension
  • Bradycardia
  • Agitation and combativeness
  • Respiratory depression
  • Airway obstruction
  • Apnea

Sedation and analgesia (conscious sedation) as defined by the institution’s policy is a medically controlled state of depressed consciousness that allows protective reflexes to be maintained. Also, the patient’s ability to maintain a patent airway independently and continuously is retained and permits appropriate response by the patient to physical stimulation or verbal command. This is distinguished from premedication, which is defined as a single dose of medication, usually given either by mouth or intramuscularly (IM) prior to a procedure. This is also distinguished from postoperative pain management to include patient controlled analgesia (PCA). Premedication and post procedure pain management are not part of the policy regarding conscious. Premedication is not usually titrated to affect as are medications given for conscious sedation. Examples of premedication include: IM Valium, IM Demerol/Vistaril or chloral hydrate. The dosages and/or routes of administration of drugs used for premedication or for post procedure pain management are not considered to have a reasonable risk of causing loss of the patient’s protective airway reflexes. Therefore, similar medication(s) used for these purposes are not part of the policy on conscious sedation by non-anesthesiologists.

Sedation and analgesia (conscious sedation) must also be distinguished from deep sedation. Deep sedation is a controlled state of depressed consciousness from which the patient is not easily aroused and is unable to respond purposefully to physical stimulation or verbal command. This may be accompanied by partial or complete loss of protective reflexes and an inability to maintain a patent airway independently. Deep sedation should only be administered by an anesthesiologist. An exception would be in circumstances where a patient is already mechanically ventilated for medical reasons. Sedation of mechanically ventilated patients is not considered in this policy.

Minimal Sedation (Anxiolysis) is a drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular functions are unaffected.

Moderate Sedation/Analgesia ("Conscious Sedation") is a drug-induced depression of consciousness during which patients respond purposefully (Reflex withdrawal from a painful stimulus is NOT considered a purposeful response) to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained.

Deep Sedation/Analgesia is a drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully following repeated or painful stimulation. The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining a patent airway, and spontaneous ventilation may be inadequate. Cardiovascular function is usually maintained.

General Anesthesia is a drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation. The ability to independently maintain ventilatory function is often impaired. Patients often require assistance in maintaining a patent airway, and positive pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardiovascular function may be impaired.

This educational material will review some of the drugs which may be used for sedation and analgesia (see Hospital Conscious Sedation Policy), as defined above, as well as the personnel, monitoring and patient evaluation necessary for procedures requiring sedation and analgesia.

Pharmacologic Principles

Sedation and analgesia may be provided by a variety of drugs, which differ significantly in their pharmacologic classification and effects. The most widely used include the benzodiazepines and narcotics.

Benzodiazepines are often used for sedation and analgesia. They are considered to be sedatives/hypnotics or tranquilizers. They are used for anxiolysis, sedation and amnesia. The most widely used for sedation include diazepam (Valium), midazolam (Versed) and lorazepam (Ativan). Midazolam use has overtaken that of diazepam, due to a shorter duration of action and water solubility that helps to decrease the pain associated with injection.

The benzodiazepines produce a spectrum of effects, depending upon the dose. They range from tranquility and drowsiness to sedation, and ultimately, unconsciousness. Anterograde amnesia is associated with benzodiazepines. The most significant side effect of any of the benzodiazepines is severe respiratory depression, particularly when used in combination with other CNS depressants. Benzodiazepines cause minimal cardiac depression when used alone. However, when combined with other anesthetic agents, including narcotics, which by themselves are cardio stable drugs, cardiovascular depression may occur. A sedating dose of diazepam is 0.05-0.1 mg per kilo IV (see Hospital Conscious Sedation Policy). For midazolam, an initial dose of 0.01 mg per kilogram IV may be used. Lorazepam has a much longer clinical duration and is most useful as a premedication, given IM at a dose of .05 mg per kilo. These agents should be administered slowly due to the widely varied response from patient to patient. The dose should be lowered in the elderly or debilitated patient. The patient must be monitored by qualified personnel after administration of these agents.

Flumazenil (Romazicon), a benzodiazepine antagonist, can reverse the effects of the agents above. It should be used cautiously because it can precipitate acute withdrawal in patients who are chronically dependent on benzodiazepines. When given IV, the dose is 0.2 mg repeated at 1-minute intervals to a maximum of 1 mg (see Hospital Conscious Sedation Policy). The onset of action is usually within 2 minutes. While flumazenil reliably antagonizes the sedative effects of benzodiazepines, its antagonism of respiratory depression is not as reliable and should not be depended upon. Respiratory depression should be initially treated with supplemental oxygen, and if needed, positive pressure ventilation by a bag/valve/mask system. Furthermore, the duration of action of the benzodiazepine used may exceed that of flumazenil. Continued monitoring is essential even after flumazenil use.

Narcotics, which are routinely used for sedation and analgesia, act at a variety of different receptor sites. The use of narcotics serves to produce analgesia. In combination with the benzodiazepine, this provides sedation, anxiolysis and analgesia, which is the goal. In addition, a local anesthetic injection or topical anesthetic may also be used to provide anesthesia for a specific indication or site.

The narcotics can be divided into several classes. They include naturally occurring opioids, semisynthetic opioids and synthetic opioids. The potency and duration of action among these different classes vary considerably.

For analgesia, a mu receptor agonist is ideal. It acts centrally in pain suppressing areas of the brain and spinal cord. While narcotics may render a patient apneic and completely unresponsive to noxious stimulation, the patient may retain enough residual awareness to later recall the procedural events. For this reason, a narcotic is often given in combination with a benzodiazepine, which produces more reliable amnesia.

Widely used mu agonists include morphine sulphate, methadone, meperidine (Demerol), and fentanyl. Agonist-antagonist opioids are also used. They have different actions at different receptor sites, resulting in diverse pharmacologic effects. They may also precipitate withdrawal in narcotic addicted patients. Agents in this class include butorphanol (Stadol) and nalbuphine (Nubain).

The most common narcotic antagonist utilized is naloxone. Naloxone is a pure antagonist of all opioid effects and is used primarily to antagonize respiratory depression and acute opioid overdose. The duration of action of naloxone is about 20-30 minutes. It is important to recognize that the opioid-analgesia is antagonized like the respiratory depression. This antagonism can precipitate acute withdrawal in opioid-addicted patients. Rare, but potentially fatal, reactions to naloxone include pulmonary edema, seizures, hypertension, arrhythmias, and cardiovascular collapse. Careful titration (see Hospital Conscious Sedation Policy) and close monitoring are essential. Naloxone is administered in a dose of 2 to 5 micrograms per kilogram IV every 2 to 3 minutes up to a total of 10 micrograms per kilogram, or ¼ amp IV every 2 to 3 minutes up to 1 amp.

Preprocedural Evaluation

A physician administering sedation and analgesia (conscious sedation) should be familiar with relevant aspects of the patient’s medical history including major organ system abnormalities, previous experiences with analgesia/anesthesia, current medications and drug allergies, the time and nature of last oral intake, and history of alcohol, tobacco or substance abuse. The preprocedural examination should include a focused evaluation of the airway and the heart and lungs. The practitioner should be alerted to the possibility of difficult tracheal intubation in the obese patient and the patient with a short neck, small jaw or a receding mandible. Medical conditions such as rheumatoid arthritis or other conditions that limit range of motion of the neck or jaw may also present a challenge to tracheal intubation. Caution should be exercised; and based on the degree of airway abnormality, sedation of these patients may require consultation with the Anesthesiology Department.

For patients with significant cardiac, pulmonary, hepatic, renal, or CNS disease, morbid obesity, sleep apnea, or in certain selected classes of patients such as uncooperative patients, extremes of age (under 1 year or over 70 years of age), the pregnant patient, and drug/alcohol abusers, there is an increased risk of developing complications related to sedation and analgesia. This risk may be reduced by preprocedural consultation with appropriate specialists including, but not limited to, anesthesiologists, cardiologists or pulmonologists. For patients whose underlying medical condition presents significant risk or if it appears likely that sedation to the point of unresponsiveness or even general anesthesia may be necessary to obtain adequate conditions, the Department of Anesthesiology should be consulted prior to planning the procedure.

Monitoring and Equipment

The equipment necessary for use in any area where sedation and analgesia is administered is listed in the sedation and analgesia policy. The monitoring of level of consciousness, respiratory function, and hemodynamics reduces the risk of adverse outcomes. The frequency of monitoring necessary variables is noted in the sedation and analgesia policy. Responses of patients to verbal commands during a procedure performed with Conscious Sedation serve as a guide to their level of consciousness. An appropriate level of consciousness implies that patients will be able to control their own airways and take deep breaths, as necessary. Level of consciousness should be assessed frequently (1-minute intervals) during the onset of sedation and whenever medications are being titrated. Once an appropriately safe level of sedation is established, patients may be aroused less frequently, if this is necessary, to avoid interfering with the diagnostic or therapeutic procedure. With administration of sedative/analgesic medications, responses of patients to verbal commands are delayed and responses are frequently slowed or slurred. Light tactile stimulation may be required to get the patient’s attention. However, once aroused they should respond appropriately to verbal commands. In cases where verbal response is not possible, seek other indications of consciousness and response to verbal or tactile stimulation. Patients whose only response to verbal command is reflex withdrawal from painful stimuli are deeply sedated, approaching a state of general anesthesia. In the event this undesirable state is reached, these patients require special care to ensure the adequacy of pulmonary ventilation and hemodynamic stability. This is deep sedation, not conscious sedation.

Sedative and analgesic medications significantly depress both ventilatory drive and airway patency. Monitoring of pulmonary ventilation provides the earliest indication of inadequate air exchange that may subsequently lead to hypoventilation and hypoxemia. By appropriate intervention when airway obstruction, hypoventilation or apnea are first observed, the risk of adverse outcome may be significantly reduced. To ensure safety of the patient, a designated individual other than the physician performing the procedure should be continuously present to monitor the patient throughout the procedure. This individual may assist with only minor, interruptible tasks. This person should also understand the pharmacology of the agents administered as well as the role of antagonists. This person should also be able to recognize associated complications. At least one member of the care team should be capable of establishing a patent airway and providing positive pressure ventilation. There should also be a means for summoning additional assistance whenever sedation and analgesia are administered.

Hypoventilation, apnea, and/or airway obstruction may lead to adverse outcomes such as cerebral hypoxia, cardiac arrest and death. Clinical detection of cyanosis is unreliable, especially when lighting is suboptimal. A pulse oximeter is therefore required on a continuous basis to provide the earliest warning of hypoxemia. The pulse oximeter is a noninvasive device that measures a pulse and oxygen-hemoglobin saturation (SpO2). The operating principle of a pulse oximeter involves absorption of different wavelengths of red and infrared light by oxygenated and deoxygenated hemoglobin as it is transmitted through and reflected by a tissue bed. Pulse oximeters use the pulse to distinguish between blood and tissue absorption. The pulse oximeter uses two specific wavelengths of light: 660 nm and 940 nm. The pulse oximeter is subject to signal artifacts that may be due to ambient light, low perfusion and patient motion. It can also be affected by injected dyes such as methylene blue which have absorbencies similar to deoxygenated hemoglobin and can cause brief artefactual oxygen desaturation when administered by IV injection.

In addition to pulse oximetry, ventilatory functions should also be monitored by observation of spontaneous respiratory activity or continuous auscultation of breath sounds. This is especially important since a delay of a minute or more may occur between the onset of apnea and an initial decrease in the pulse oximetry reading.

Medications administered during sedation/analgesia may directly depress cardiac function. In addition, they may impair the ability of the autonomic nervous system to compensate for hemodynamic changes. Thus, patients who are dependent upon activation of the sympathetic nervous system to maintain hemodynamic stability (hypovolemia or underlying cardiac disease) are at an even greater risk to become hypotensive when sedative analgesics are administered. By monitoring blood pressure and heart rate at frequent intervals, especially during the onset of sedation/analgesia, these changes may be rapidly recognized and treated if necessary. The treatment of hypotension may include elevation of the legs, administration of IV fluids and, in some cases, administration of a short acting vasoconstrictor.

Some patients may be at increased risk for developing cardiac dysrhythmias during sedation/analgesia. Continuous electrocardiographic monitoring should be utilized for these patients which then allows the practitioner to rapidly detect and diagnose dysrhythmias and intervene as necessary in a timely manner. Patients at risk include those with underlying cardiovascular disease and in those patients with a known history of dysrhythmias. Other patients at risk include those patients undergoing procedures that are associated with an increased risk of dysrhythmia (those involving GI distention or cardiovascular manipulation), or in procedures where epinephrine is administered with local anesthetics.

Recovery and Discharge

Patients may continue to be at significant risk for complications after completion of a procedure. A lack of stimulation, prolonged drug absorption or post procedural hemorrhage may contribute to cardiorespiratory depression. After administration of sedation/analgesia, the patient should be observed until they are no longer at an increased risk for cardiorespiratory depression. The monitoring of patients after sedation and analgesia is described in the Conscious Sedation policy. The scoring system for discharge of the patient noted in the policy is utilized to clinically assess the physical status of patients recovering from sedation/analgesia. Requiring that patients meet the criteria as noted prior to discharge is necessary to minimize the risk of complications from the central nervous system and/or cardiorespiratory depression.

Adult Drug & Dosing Guidelines

Recommended doses and route of administration are included below. As individual circumstances vary, these guidelines may require modification based on the responsible physician's judgment, thus this information is included as a reference only and does not obligate the practitioner in any way. Although philosophies differ, when the I.V. route is chosen, the principle of "titration to desired effect" up to, but not exceeding, the maximum dose is recommended. With I.V. administered medications, the onset of action is more rapid than with other routes and onset of effect is typically seen quickly. It should be noted that some practitioners advocate a "bolus" of a pre-calculated total dose vs. "titration" of smaller, incremental doses up to a total dose. It is recommended that the "bolus" technique be reserved for those practitioners who have considerable experience with sedation techniques.

The recommended initial intravenous dosage for average adult patients is as follows for commonly administered medications. Note that other routes of administration (oral, intramuscular, intranasal, rectal) and other agents may be utilized to achieve sedation, but doses, time of onset and duration of action differ depending upon agent and selected route of administration. The following only applies to I.V. administration of commonly used agents.

Some general comments are in order. While many different types of drugs can and have been utilized to sedate patients, by and large the best results obtain from the combination of a benzodiazepine with a narcotic. The universal problems of peri-procedural anxiety coupled with pain or the anticipation of pain are best managed by the administration of a potent anxiolytic agent with a strong analgesic, or pain reliever.

Benzodiazepines, in addition to being very effective at reducing anxiety, also serve reliably as anterograde amnestic agents. It is important to remember, however, that benzodiazepines do not provide analgesia, or relief of pain. While narcotics are very helpful as general sedative drugs, their specific utility in this setting owes to their analgesic, or pain relieving, properties. Narcotics do NOT reliably confer any degree of amnesia.

In general, shorter acting agents should be chosen for procedural sedation since the duration of the beneficial effects will approximate the duration of most procedures. Likewise, use of shorter acting agents reduces the potential of producing sedation lasting beyond the time needed to perform the procedure.

It is occasionally necessary to "reverse" the effects of benzodiazepines and narcotics because a relative overdose of either (or both) has caused a greater depth of sedation or outright depression of ventilatory drive. Reversal agents should be used cautiously, however, titrating to desired effect. By using shorter acting agents, there will be less risk of prolonged over sedation and greater success at reversing their effects when required.

Benzodiazepines
NOTE: Risk of respiratory depression is dose dependent. When combined with narcotics, this risk is potentiated.

Midazolam (Versed)0.015 - 0.030 mg/kg
Diazepam (Valium) 0.05 - 0.1 mg/kg
Lorazepam (Ativan) 0.03 - 0.06 mg/kg

Narcotics
NOTE: Risk of respiratory depression is dose dependent. When combined with benzodiazepines, this risk is potentiated.

Morphine 0.03 - 0.06 mg/kg
Meperidine (Demerol) 0.15 - 0.20 mg/kg
Fentanyl (Sublimaze) 0.75 - 1.5 mcg/kg

Reversal agents

Benzodiazepines:

Flumazenil (Romazicon) 0.2 mg I.V. repeated at 1-minute intervals to a total of 1.0 mg. Onset of action is 1-3 minutes, with duration of action usually less than one hour. Reversal effects of flumazenil may wear off before effects of benzodiazepine subside.

Narcotics:

Naloxone (Narcan) 2-5 mcg/kg I.V. q 2 to 3 minutes up to a total of 10 mcg/kg. An easier way to remember is ¼ amp I.V. q 2 to 3 minutes up to 1 amp total.

Hospital Sedation Policy

Hospital Sedation Policy

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