Chapters 19, 23, 24 (Learning Outcomes) Flashcards
What is the effect of anesthesia?
Loss of feeling or sensation
What is general anesthesia categorized by?
- State of unconsciousness
- Analgesia
- Amnesia
What is regional anesthesia?
When sensory transmission from a specific area/region of the body to the CNS is blocked
What is the effect of neuromuscular blocking agents?
Cause muscle paralysis (loss of motor function)
What two groups can neuromuscular blocking agents be broken down into?
- Depolarizing
2. Non-depolarizing
What is the prototype drug for inhaled anesthetics?
Isoflurane (Forane)
What is the prototype drug for regional anesthetics?
Lidocaine (Xylocaine)
What are the prototype drugs for neuromuscular blocking agents?
- Depolarizing = Succinylcholine
2. Non-depolarizing = Vecuronium
At the synaptic level, what is the action of anesthetics?
May provoke a decreased release of neurotransmitters or an increased re-uptake and inhibition of postsynapthic enzymes
How does local anesthesia act to stop nerve transmission?
Reversibly block all nerve impulses by disrupting membrane permeability to sodium during an action potential
- therefore stop the generation and propagation of the nerve impulse
Describe how Non-depolarizing drugs cause paralysis.
They are competitive antagonists that prevent the binding of Ach to the receptor, therefore, the end plate is unable to depolarize
Describe how depolarizing drugs cause paralysis.
Structurally similar to Ach, and cause continuous muscle depolarizing and prevent repolarization
- muscle is unable to repolarize as long as the drug continues to bind to the Ach receptor
What are the four LEVELS of sedation?
- Minimal sedation
- Moderate sedation and analgesia (conscious sedation)
- Deep sedation and analgesia
- Anesthesia
What are the four STAGES of anesthesia?
Stage 1 = analgesia
Stage 2 = Delirium/excitment
Stage 3 = Surgical Anesthesia
Stage 4 = Meduallary depression
What is occurring during Stage 1 analgesia?
Duration is from start of anesthesia to the loss of consciousness
What happens during Stage 2 (delirium/excitment)?
- systolic blood pressure rises
- may experience excitation, agitation, restlessness
- increased RR
What happens during Stage 3 (surgical anesthesia)?
- Begins with resumption of regular respiration
- beginning of muscle relaxation
- By plane IV, spontaneous respiration ceases
(there are four planes to stage 3)
What happens during Stage 4 (medullary depression)?
Respiratory and vasomotor centers are depressed
- spontaneous respiration has ceased
- marked hypotension with weak and irregular pulse
What are general anesthetics used for?
To induce and maintain anesthesia during surgery
What is Isoflurane used for?
To induce and maintain anesthesia
Describe the pharmacokinetics of isoflurane
Administered: Inhalation
Metabolism: 0.2% is taken up
Excreted: pulmonary
Onset: secs to mins
Describe the pharmacodynamics of Isoflurane
Exact mechanism is unknown
How can we minimize the adverse effects of Isoflurane?
Monitor blood pressure and temperature to detect residual hypotension
- possibility of malignant hyperthermia
- manage shivering and tremors
What happens when Isoflurane is mixed with a non-depolarizing muscle agent?
Prolongs the blockage and potentiates the effects
What is the most serious adverse effect of Isoflurane?
Respiratory depression
What are intravenous (IV) anesthetics also known as?
Induction agents
What class of IV anesthetic agents does Propofol fall into?
Non-barbiturate hypnotic agent
What are the 4 classess of intravenous anesthetic agents?
- Barbiturates
- Benzodiazepines
- Opiod analgesics
- Nonbarbiurate hypnotic agents
What is Propofol (Diprivan) used for?
Induction and maintenance of general anesthesia
- and maintenance of sedation in the ICU
Describe the pharmacokinetics of Propofol
Administered: Intravenously
Onset: 40 secs
Dur: 3 to 5 minutes
Metabolized: Hepatic and lung routes
What is the advantage of Propofol?
The rapid return of consciousness with minial psychomotor impairment
Describe the pharmacodynamics of Propofol
Cellular mechanism action is unknown
- thought to mediate activity of the inhibitory GABA receptors
What are three example of benzodiazepines?
- Diazepam
- Lorazepam
- Midazolam
What is Fentanyl?
Opioid analgesic
- used in general anesthesia and conscious sedation
What do you need to be aware of prior to administering Fentanyl?
Respiratory rate
- causes respiratory depression
How are local anesthetics divided into two classes? What are they?
Based on their chemical structure
- Esters
- Amides
How do local anesthetics produce local or regional anesthesia and analgesia?
By blocking electrical transmission of pain along nerve fibers and abolishing sensations in a limited and well-defined area of the body
- without loss of consciousness
What nerve function is affected first when local anesthetic is applied?
- Temperature
- Pain
- Touch
- Proprioception
- Skeletal muscle tone
What is the prototype drug of local anesthetics?
Lidocaine (Xylocaine)
When is lidocaine used?
- Regional blocks
- Peripheral nerve blocks
- Ophthalmic anesthesia
- Dental anesthesia
- Infiltration anesthesia
What addition can prolong the effect of Lidocaine?
Epinephrine slows the vascular absorption and prolongs its effects
True or False:
Lidocaine is susceptible to the first pass effect of the liver
True!
Describe the pharmacodynamics of Liodcaine
Produces its analgesic effects through a reversible nerve conduction blockade
- decreases the rate of membrane depolarization
In both depolarizing and non-depolarizing agents, where does the neuromuscular block occur?
At Ach receptor sites on the motor end plate
What is the prototype drug of Non-depolarizing neuromusclar blocking agent?
Vecuronium (Norcuron)
Describe the pharmacotherapeutics of Vecuronium
A non-depolarizing muscle relaxant
- used to provide skeletal muscle relaxation to facilitate intubation and mechanical ventilation
What route is Vecuronium available in?
IV use only
Describe the pharmacodynamics of Vecuronium
- anatgonists of Ach, compete with the neurotransmitter for the cholinergic receptor sites at the motor end plate
What is important to keep in mind if there is prolonged paralysis due to Vecuronium?
Change the patients position frequently to prevent venous stasis
How do depolarizing NMJ blockers work?
By causing the muscle cell membrane to depolarize or become excited
- causes muscle contraction
What is the prototype drug for depolarizing NMJ blockers?
Succinylcholine (Anectine)
What is succinylcholine primarily used for?
Rapid endotracheal intubation
- very short-acting paralytic
Describe the pharmacodynamics of Succinylcholine
Acts as an agonist at the cholinergic nicotinic receptors of the motor end plate
- depolarizes the postsynaptic membrane
- producing repetitive excitation of the motor end plate
What do patients commonly experience after receiving succinylcholine?
Muscle pain
- from rapid contraction followed by flaccid paralysis
What are the three types of drugs used to treat pain?
- Strong narcotics
- Mild narcotics
- Mixed agonist-antagonists
What is the prototype for strong narcotics?
Morphine
What is the prototype for mild narcotics?
Codeine
What is the prototype drug for mixed agonist-antagonist opioid?
Pentazocine
What is transduction?
Term used to describe the phenomena associated with the initiation of a pain signal
What do afferent nerves carry signals to?
To the CNS
What do efferent nerves carry signals to?
To the peripheral
What is nociceptic pain caused by?
Injury, disease or inflammation
- indicates real or potential tissue damage
How can nociceptic pain be categorized as?
Somatic
Visceral
What does somatic pain result from?
Ongoing activation of peripheral nociceptors found in bone, muscle or soft tissue
What does visceral pain result from?
Stimulation within the deep tissues or organs and surrounding structural tissues
What is neuropathic pain used to describe?
Pain in which the underlying pathology is abnormal processing of stimuli in the peripheral or CNS
What is acute pain?
Immediate phase of response to an insult or injury
How is chronic pain resolved?
With the healing of the underlying injury
What is chronic pain?
Pain that persists well beyond actual tissue injury and healing
What is easier to do, decrease pain or prevent pain?
Prevent pain
What are the two drug classifications that are normally used for pain management?
- Opioid analgesics
2. Non-steroidal anti-inflammatory (NSAIDs)
What are narcotics?
Opioids
What is the action on NSAIDS?
Work on the peripheral nervous system, preventing the transmission of the pain nerve impulse
What are adjunct analegsics?
Drugs that are used secondarily for pain relief
- anti-depressants
- corticosteriods
- antiepileptics
List the following drugs in order of strength: Morphine, Hydromorphone, Oxycodone, Fentanyl
- Fentanyl
- Hydromorphone
- Oxycodone
- Morphine
What is the prototype drug of a strong narcotic agonist?
Morphine
What is the drug that is the narcotic antagonist?
Naloxone
What does Morphine cause?
Respiratory depression
What are some examples of secondary pharamacologic actions of morphine (and other narcotics)?
- Respiratory depression
- Hypotension
- Euphoria
- N/V
- Itching, flushing, red eyes
- Abdominal pain/cramps
- Constipation
- Urinary retention
How can a morphine overdose be treated?
Naloxone (Narcan)
What should be assessed prior to administering Morphine?
- RR
- cardiac, renal, hepatic, pulmonary disease
- hypothyroidism
- addison disease
- prostatic hypertrophy
Define tolerance
Body has become accustomed to the effects of a substance
- patient must use more to achieve desired effect
Define physical dependence
A withdrawal when Morphine is discontinued
- an exaggerated rebound from its acute effects
Define addiction
Compulsive use of the drug for a secondary gain, not for pain control
What is breakthrough pain?
Transitory flare-ups of pain over baseline in a patient receiving opioid therapy
What is incidental pain?
Spontaneous or activity-related pain
- may be specific movement or all movements
What is the prototype for mild narcotic agonists?
Codeine
What does codeine do to your cough?
It suppresses it
How are fever, inflammation and pain commonly controlled by?
Salicylates
NSAIDs
Para-aminophenol derivative drugs
How are migraine headaches typically treated?
With Triptans
What fever-inducing substance causes fever?
Pyrogens
What are the classic signs of the inflammatory response?
Redness Warmth Swelling Pain Loss of function
What are salicylates used for?
Conditions ranging from simple headache to acute MI
What are NSAIDs primarily used for?
Anti-inflammatory drugs
- also analgesics
What is the prototype drug for salicylates?
Acetylsalicylic acid (Aspirin)
Other than pain reduction and inflammation, what is another use of Aspirin?
Antiplatelet
- helps to prevent transient ischemic attacks, MIs, and stokes
When is aspirin contraindicated?
Bleeding disorders
- anticoagulation
What are two adverse effects of aspirin therapy?
- Salicylism (mild aspirin toxicity)
2. Salicylate poisoning (life-threatening)
What are the most serious adverse effects of aspirin?
- renal impairment
- gastric ulceration
- GI bleeding
What is the prototype drug for NSAIDs?
Ibuprofen (Motrin, Advil)
What are the labeled uses of Ibuprofen?
- RA
- OA
- Mild to moderate pain
- Migraine headache
- Fever
- Menstrual cramps
What can chronic use of Ibuprofen result in?
- Gastritis
- Ulceration
- GI bleeding
How can you maximize the therapeutic effects of Aspirin?
Give with milk or food to decrease gastric distress
What is the only para-aminophenol derivative that is available in the US?
Acetaminophen (Tylenol)
What is oral acetaminophen indicated for treating?
Fever and mild pain
What is the maximum recommended dose in a 24 period for Tylenol?
4 grams
How does Acetaminophen’s antipyretic action work?
Results from inhibiting prostaglandin synthesis in the CNS
