EDUCATIONAL MATERIALS MODERATE SEDATION/ANALGESIA
(CONSCIOUS SEDATION)
FOR
NON-ANESTHESIOLOGISTS
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 institution. Therefore, our institution has 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. The conscious sedation protocol (attached), this educational material, exam and credentials paperwork comprise the credentialing packet for sedation and analgesia (conscious sedation) by non-anesthesiologists.
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. Our goal in providing the physician with 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. The material in this handout 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.
The objectives for the patient include:
The desired effects include:
Undesirable effects of sedation and analgesia:
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 sedation and analgesia. Premedication is not usually titrated to affect as are medications given for sedation and analgesia. 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 sedation and analgesia 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 providers with deep sedation privileges. 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.
This educational handout will review some of the drugs which may be used for sedation and analgesia (see Appendix A - Hospital Sedation/Analgesia Policy), as defined above, as well as the personnel, monitoring and patient evaluation necessary for procedures requiring sedation and analgesia.
Pharmacologic Principles of Sedation and Analgesia
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 all of the 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 cardiostable drugs, cardiovascular depression may occur. A sedating dose of diazepam is 0.05-0.1 mg per kilo IV (see Appendix A - Hospital Sedation/Analgesia 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 Appendix A - Hospital Sedation/Analgesia 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 Appendix A - Hospital Sedation/Analgesia Policy) and close monitoring are essential.
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 preprocedure 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 for Sedation and Analgesia
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 sedation/analgesia 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 have an understanding of 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 artifactual 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 after Sedation/Analgesia (Conscious Sedation)
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/analgesia is described in the sedation and analgesia 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.