Week 5 Chapter 10 Anxiety, Phobia, and Conscious Sedation Flashcards
analgesic
Analgesic medications are frequently used in combination with the antianxiety drugs for conscious sedation. By combining the opiate (narcotic) analgesics, a synergistic action takes place to relieve the painful anxiety caused by the procedure. Opiate analgesics stimulate central nervous system (CNS) receptors known as opioid receptors and cause a decrease in the perception of pain. Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
antianxiety
Antianxiety medications alleviate the anxiety that is secondary to claustrophobia when undergoing CT and MRI. These medications generally act on the limbic system in the brain by enhancing the effect of the sedative neurotransmitter gamma-aminobutyric acid (GABA) and by blocking stimulation in the limbic and cortical systems of the brain.
Analgesic medications are frequently used in combination with the antianxiety drugs for conscious sedation. By combining the opiate (narcotic) analgesics, a synergistic action takes place to relieve the painful anxiety caused by the procedure. Opiate analgesics stimulate central nervous system (CNS) receptors known as opioid receptors and cause a decrease in the perception of pain. Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
anxiety
Anxiety and phobia are important considerations in patients presenting to the radiology suite for computed tomography (CT) and magnetic resonance imaging (MRI) scans. Thus, a basic understanding of the following disorders will assist the imaging technologist in performing safe and accurate scanning:
*Anxiety may cause a patient to experience an unpleasant state of tension forewarning danger. This can be very painful and persistent if the cause is unknown.
*Panic disorder occurs as a sudden, unexpected, intense attack of apprehension sometimes accompanied by physical symptoms such as agitation, tachycardia, hypertension, cardiac dysrhythmias, and shortness of breath. There is a general feeling of impending doom even though the danger is not real.
*Phobia is a psychological condition that consists of irrational fear leading to avoidance. Claustrophobia, the fear of tight and enclosed spaces, is one example of such phobia.
Investigators studied the 4.3% of patients who experienced psychological distress severe enough to require halting an MRI procedure. The majority were found to have had similar minor anxiety reactions in the past. Symptoms included nervousness, fear, palpitations, choking sensations, and fear of dying. Less than 1% had a previous psychiatric illness, suggesting that a previous psychatric diagnosis is not required for a patient to experience this reaction.
Anxiety was precipitated by two major sources: (1) the physical conditions of the MRI and (2) emotional turmoil. The physical conditions were such that the patient was unable to see outside the tube or to move while in the tube. Equally distressing was the unbearable noise of “metal being crunched.” Emotional turmoil resulted from the fear of what the MRI might show (e.g., brain tumor, cancer). These anxiety reactions have also been described in other procedures, such as cardiac catheterization, gastroscopy, uroscopy, dental procedures, and intensive care unit stay.
barbiturate
AGENTS USED FOR CONSCIOUS SEDATION
Medications used in the radiology department for conscious sedation consist primarily of the barbiturate, benzodiazepine (antianxiety agents), and opiate analgesic classes of drugs
Antianxiety medications alleviate the anxiety that is secondary to claustrophobia when undergoing CT and MRI. These medications generally act on the limbic system in the brain by enhancing the effect of the sedative neurotransmitter gamma-aminobutyric acid (GABA) and by blocking stimulation in the limbic and cortical systems of the brain.
Analgesic medications are frequently used in combination with the antianxiety drugs for conscious sedation. By combining the opiate (narcotic) analgesics, a synergistic action takes place to relieve the painful anxiety caused by the procedure. Opiate analgesics stimulate central nervous system (CNS) receptors known as opioid receptors and cause a decrease in the perception of pain. Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
The combination of antianxiety and opiate medications is especially dangerous because of the synergistic effects on respiration. Respiratory depression can rapidly occur to the point of respiratory arrest if the dose of either of these agents is too great. Should a respiratory arrest occur, naloxone, 0.4 to 2 mg given intravenously (IV), intramuscularly (IM), or endotracheally, is the drug of choice to immediately reverse the respiratory depressant effects of the opiates. To reverse the effects of the antianxiety drugs, flumazenil, 0.2 to 1 mg given IV, is the drug of choice.
Mechanism of Action
Barbiturates include medications such as thiopental, methohexital, and phenobarbital. These agents decrease cortical brain activity by facilitating the inhibitory neurotransmitter GABA and depress cerebral cortex activity by blocking excitatory neurotransmitters such as glutamic acid and acetylcholine. The barbiturates are capable of producing all levels of anesthesia, from conscious sedation to complete anesthesia.
claustrophobia
Phobia is a psychological condition that consists of irrational fear leading to avoidance. Claustrophobia, the fear of tight and enclosed spaces, is one example of such phobia.
Antianxiety medications alleviate the anxiety that is secondary to claustrophobia when undergoing CT and MRI. These medications generally act on the limbic system in the brain by enhancing the effect of the sedative neurotransmitter gamma-aminobutyric acid (GABA) and by blocking stimulation in the limbic and cortical systems of the brain.
benzodiazepine
AGENTS USED FOR CONSCIOUS SEDATION
Mechanism of Action
All benzodiazepines have the propensity to be used used for conscious sedation. However, the one most frequently used in current practice is midazolam because of its rapid onset (2 to 15 minutes) and short duration of action (up to 90 minutes). Benzodiazepines cause selective CNS depression, muscle relaxation, antianxiety, anticonvulsant, and sedative-hypnotic activities. These agents also facilitate the inhibitory neurotransmitter GABA and block stimulation and arousal in the limbic and cortical systems of the brain. In addition, the benzodiazepines cause some amnesia surrounding the immediate events (antegrade amnesia) and block reflexes. These agents have excellent absorption through the entire GI tract. Benzodiazepines also have conscious sedation action that is longer acting than with the barbiturates; patients may feel a “hangover” effect after the procedure.
Adverse reactions.
As a class, the benzodiazepines can cause excessive drowsiness, hiccups (midazolam), lassitude, decreased dexterity, dry mouth, GI upset (nausea, vomiting, cramping, constipation), headache, blurred vision, amnesia, paradoxical excitation, hallucinations, and choreiform spasmodic movements. These agents can also cause severe respiratory depression from both CNS depression and weakness in the external skeletal muscles used for respiration. The benzodiazepines can lead to cardiovascular collapse secondary to extreme hypotension, third-degree heart block, and respiratory depression when administered too rapidly by the IV route; extreme caution is advised.
conscious sedation
Conscious sedation is a drug-induced relaxation allowing the patient to tolerate unpleasant procedures. The patient remains conscious, but sedated, and in some cases amnestic (loss of memory) at the time of the procedure. With the proper amount of sedation, the patient remains cooperative, is able to respond purposefully to verbal commands and tactile stimulus, maintains airway with adequate cardiorespiratory function, and has reduced anxiety and apprehension toward the procedure.
It is paramount the clinician realize that the only difference between conscious sedation and general anesthesia, requiring mechanical ventilation, is the dose of sedative. All the sedatives used for conscious sedation can completely incapacitate a patient’s own ability to breathe if the dose is too high.
The following should be performed before considering conscious sedation:
1.Obtain an accurate history, physical examination, height, and weight.
2.Assess heart and lungs and document airway patency.
3.Acquire a list of all the patient’s medications, including over-the-counter drugs, herbal medications, alcohol, and illicit drugs.
4.List all known allergies to food and medication.
5.Know when the patient’s last oral intake of medication, fluid, or food occurred.
6.List all known abnormalities of organ function.
Before administering any of the conscious sedation medications, the following should be available:
1.Oxygen source and pulse oximeter to monitor oxygen saturation throughout procedure.
2.Suction equipment.
3.Airway equipment and means for providing positive-pressure ventilation (e.g., bag mask, ventilator).
4.Emergency resuscitation equipment and medications.
5.Pharmacologic reversal agents, including flumazenil and naloxone.
6.Intravenous (IV) equipment to maintain IV access throughout procedure.
7.A cardiac monitor is strongly advised.
8.A crash cart generally has all that is required to complete 1 through 7 above.
fentanyl
Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
The three main opiates used for conscious sedation include morphine, meperidine, and fentanyl. Morphine is dosed 0.08 to 0.15 mg/kg IV in adults and 0.1 mg/kg IV in pediatric patients. Meperidine is dosed 1 to 3 mg/kg IV in adults and is not recommended for children. Fentanyl is dosed at 1 to 5 micrograms (μg)/kg IV in adults and 1 to 5 μg/kg IV in pediatric patients. Fentanyl may also be prescribed in children at 5 to 20 μg/kg transmucosally (oral route).
flumazenil
CONSCIOUS SEDATION
5.Pharmacologic reversal agents, including flumazenil and naloxone.
The combination of antianxiety and opiate medications is especially dangerous because of the synergistic effects on respiration. Respiratory depression can rapidly occur to the point of respiratory arrest if the dose of either of these agents is too great. Should a respiratory arrest occur, naloxone, 0.4 to 2 mg given intravenously (IV), intramuscularly (IM), or endotracheally, is the drug of choice to immediately reverse the respiratory depressant effects of the opiates. To reverse the effects of the antianxiety drugs, flumazenil, 0.2 to 1 mg given IV, is the drug of choice.
meperidine
AGENTS USED FOR CONSCIOUS SEDATION
Analgesic medications are frequently used in combination with the antianxiety drugs for conscious sedation. By combining the opiate (narcotic) analgesics, a synergistic action takes place to relieve the painful anxiety caused by the procedure. Opiate analgesics stimulate central nervous system (CNS) receptors known as opioid receptors and cause a decrease in the perception of pain. Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
Adverse reactions
As a class, the opiate analgesics can cause excessive drowsiness, GI upset (nausea, vomiting, constipation), urinary retention, dizziness, headache, lightheadedness, histamine release, confusion, hallucinations, hypotension, and respiratory depression. Generally, a lower dose can be used when antianxiety medications are used in conjunction with opiate analgesics.
The three main opiates used for conscious sedation include morphine, meperidine, and fentanyl. Morphine is dosed 0.08 to 0.15 mg/kg IV in adults and 0.1 mg/kg IV in pediatric patients. Meperidine is dosed 1 to 3 mg/kg IV in adults and is not recommended for children. Fentanyl is dosed at 1 to 5 micrograms (μg)/kg IV in adults and 1 to 5 μg/kg IV in pediatric patients. Fentanyl may also be prescribed in children at 5 to 20 μg/kg transmucosally (oral route).
general anesthesia
CONSCIOUS SEDATION
3.Understand the critical difference between conscious sedation and general anesthesia.
It is paramount the clinician realize that the only difference between conscious sedation and general anesthesia, requiring mechanical ventilation, is the dose of sedative. All the sedatives used for conscious sedation can completely incapacitate a patient’s own ability to breathe if the dose is too high.
methohexital
Barbiturates
Methohexital is extremely rapid in onset and very short in duration. It is used mostly for brief procedures, such as cardioversions and electroconvulsive therapy (ECT), and for anesthesia induction. Methohexital also is used as a rectal preparation for pediatric conscious sedation before CT studies. The dose for rectal use in pediatrics is 25 mg/kg 15 minutes before CT. The child will sleep for up to 90 minutes (range 20 to 90 minutes). The dose for adults undergoing these short procedures is 1 mg/kg IV (note that this drug has ultrashort action in adults and would not be a good choice for procedures requiring more than 5 minutes of sedation).
Major adverse effects mirror those of thiopental. Thus, the same monitoring parameters would apply
midazolam
Midazolam is probably the most widely used benzodiazepine for conscious sedation. It is very predictable and quick in onset with a short duration of action. It was shown to decrease anxiety and improve the outcome of MRI by decreasing motion artifact. Midazolam is given to pediatric patients by either the intranasal or the rectal route at 0.2 to 0.5 mg/kg (maximum 20 mg) 15 minutes before procedure. Likewise, the same dose can be swallowed by using midazolam syrup. For more intense procedures such as endoscopy or fluroscopy, midazolam can be given IV slowly, as follows:
morphine
AGENTS USED FOR CONSCIOUS SEDATION
OPIATE ANALGESICS
Opiate analgesics stimulate central nervous system (CNS) receptors known as opioid receptors and cause a decrease in the perception of pain. Examples of common narcotic medications used for conscious sedation include morphine, meperidine, and fentanyl.
Mechanism of Action
Opiate analgesic medications stimulate the CNS opioid receptors to decrease pain perception. When used in combination with the antianxiety medications (e.g., midazolam), the opiates (e.g., fentanyl, morphine, meperidine) allow for decreased pain and anxiety.
Adverse reactions
The three main opiates used for conscious sedation include morphine, meperidine, and fentanyl. Morphine is dosed 0.08 to 0.15 mg/kg IV in adults and 0.1 mg/kg IV in pediatric patients. Meperidine is dosed 1 to 3 mg/kg IV in adults and is not recommended for children. Fentanyl is dosed at 1 to 5 micrograms (μg)/kg IV in adults and 1 to 5 μg/kg IV in pediatric patients. Fentanyl may also be prescribed in children at 5 to 20 μg/kg transmucosally (oral route).
naloxone
CONSCIOUS SEDATION
CONSCIOUS SEDATION
5.Pharmacologic reversal agents, including flumazenil and naloxone.
The combination of antianxiety and opiate medications is especially dangerous because of the synergistic effects on respiration. Respiratory depression can rapidly occur to the point of respiratory arrest if the dose of either of these agents is too great. Should a respiratory arrest occur, naloxone, 0.4 to 2 mg given intravenously (IV), intramuscularly (IM), or endotracheally, is the drug of choice to immediately reverse the respiratory depressant effects of the opiates. To reverse the effects of the antianxiety drugs, flumazenil, 0.2 to 1 mg given IV, is the drug of choice.
