Anesthetics Flashcards
What are the four types of Anesthesia?
General Anesthesia (this is a drug induced loss of consciousness of the entire body where patients are not able to feel any pain) Usually they are used in conjunction with neuromuscular blockades.
Neuraxial Anesthesia - injection of anesthetic with an opioid around the nerves. This can be split into two main types of anesthesia.
Epidural - (single dose or continuous infusion) this is when the anesthesia is injected outside the dura (skin like covering around the spinal cord) into the epidural space.Gives more of a local effect. You can also administer this type of anesthesia as an analgesic for post treatment recovery.
Subarachnoid - (single dose) this is when it is injected into the dura, directly into the spinal cord. This will provide waist down numbing of pain and areflexia.
Regional Anesthesia- Is an injection of an anesthetic around a specific nerve to block sensation of pain to an ENTIRE limb. Examples include an arm/leg or for the teeth during dental work.
Local Anesthesia: injection of anesthetics in the area of surgery rather than around a specific nerve. Often used for very minor surgeries. For example, a mole removal or skin tag.
What are the goals of Anesthesia?
Amnesia - provide of sedation
Areflexia - (prevent reflexes from moving) for example: coughing, muscle tension, and cardiovascular reflexes like increased BP
Analgesia - inability to feel pain
What are the two types of intravenous anesthetic agents?
Propofol and Ketamine.
How does Propofol work?
They increase the GABA in the body, hence providing sedation.
What can Propofol not do?
Propofol cannot provide analgesic affects alone, and hence must be used in conjunction with an analgesic.
They can provide amnesia and the maintenance.
What are the side effects of Propofol?
Respiratory depression and potential hypotension.
How does Ketamine work?
It interacts with NDMA receptors as an antagonist.
This anesthetic can be given intravenously or intramuscularly.
What effects does Ketamine provide?
They have both amnestic and analgesic properties.
In high does they work for amnesia (dissociative), and low doses they have pain management.
What are the side effects of Ketamine?
Increased sympathetic nervous system activity, hallucinations (this is why its used recreationally) and minimal respiratory depression (this drug helps maintain muscle tone and keep BP stable).
What are volatile anesthetic agents?
Anesthetics that are delivered through inhalation, and are ether based compounds.
How are they delivered?
Through an anesthetic mask or a endotracheal tube.
What are the most common drugs names?
Desflurane and Sevoflurane.
What is the mechanism of action?
Increases GABA agonism, but the full mechanism is unclear.
What effects to volatile agents provide?
Amnesia and Areflexia in the spinal cord.
What are the side effects of volatile agents?
Hypotension, mild respiratory depression, nausea/vomiting, and Malignant hyperthermia.
What is malignant hyperthermia? CFAM
rare clinical condition of hyper metabolism that leads to fever, muscle breakdown, acidosis and cardiovascular collapse. This can result in death is not promptly treated.
What are muscle relaxants?
Medications that cause paralysis of skeletal muscles that are used to facilitate surgery and endotracheal intubation.
What effects do they produce?
They are areflexia agents but they do not provide analgesic, amnestic, or hypnotic properties.
What are the two broad categories for muscle relaxants?
Depolarizing agents, and non-depolarizing agents.
What are depolarizing muscle relaxants?
IHM^2
Drug name: Succinylcholine
What this drug does is binds to the ACh receptor as an agonist. Acetylcholine is a neurotransmitter that sends signals that causes skeletal muscle fibers to be unresponsive. By binding and increasing the affinity, the muscles can be relaxed for a period of time. This causes a prolonged depolarization period.
How long does Succinylcholine last?
Up to 10 mins
Is there a reversal agent?
No
What are the side effects?
Hyperkalemia (increased K+), Myalgia (muscle pain), Malignant Hyperthermia and increased intraocular and cranial pressure.
Who shouldn’t use this drug?
Those who are prone or have history with Malignant Hyperthermia or those at risk of developing Hyperkalemia (prior strokes, burns, multiple sclerosis)
What is the name of the non-depolarizing agent?
Rocuronium
How does it work?
It has higher affinity for the ACh receptors as an antaognist
How long does it last? Does it have a reversal agent?
Up to one hour. If treatment is fast, you can use Neostigmine to reverse the effects.
Can you use this drug if you have Malignant Hyperthermia?
yes
What does Neostigmine do?
It inhibits the Acetylcholinesterase from breaking down ACh. This gives it the overpowering effect to partially blockade Rocuronium.
What are the two symptoms people like to avoid post surgery?
Pain and Postoperative nausea and vomiting.
What is PONV?
Postoperative nausea and vomiting within the first 24 hours after surgery.
What are major risk factors for PONV?
- female gender
- non-smoking status
- history of PONV or motion sickness
- need for postoperative opioids
How to reduce PONV?
- Avoid volatile anesthesia
- Use neuraxial (spinal or epidural) or regional instead of general anesthesia
- minimize use of opioid medications
- administer PONV prevention medications
Examples of PONV medications (all also used for chemotherapy induced vomiting)
Dexamethasone, Ondansetron, and Droperidol
Dexamethasone
- steroid
- MOA: unclear
- side effect: confusion, increased blood glucose
Ondansetron
- anti-emetic
- serotonin receptor antagonist in brain and GI tract
- side effect: constipation, headache, QTc prolongation
- contraindication: migraines
Droperidol
- typical antipsychotic
- Dopamine D2 receptor antagonist
- used also for excessive pregnancy nausea and vomiting
- QTc prolongation, extra-pyramidal symptoms
- contraindication: parkinsons disease
Why should postoperative pain be taken care of?
Increased pain can lead to increased sympathetic activity, hence potentially increasing heart rate and blood pressure which can cause myocardial ischemia (blood cannot get to the heart).
Additionally it can cause impaired respiratory function which can increase the risk of pneumonia.
Surgical pain may also lead to chronic pain when not treated.
What happens when pain is assessed?
it is documented, managed, and is done to ensure adequate breathing, coughing, mobilization and sleep are taking place.
What are the two main types of local anesthetics and which type of anesthesia uses them?
Amide type: Lidocaine, Bupivacaine
Ester Type: Cocaine
Usually local anesthetics is used for local anesthesia, regional, and neuraxial (spinal and epidural).
What do local anesthetics do to prevent pain?
Since local anesthetics are weak bases, they can enter the membrane and are lipophilic in nature. Due to the lower intracellular pH, it becomes protonated. In doing so, it can block the Na+ channel from sending action potential. Keep in mind that the Na+ channel must be open for nerve transmissions to be sent and recognized.
How come patients vital signs and consciousness need to be monitored?
When administering a local anesthetic, it is possible for it to have a toxic effect. There are two main forms of toxicity: cardiotoxicity (cardiac arrest) and neurotoxicity (numbness, dizziness, decreased consciousness, blurred vision and seizures).
How do they determine dosage so it is not toxic?
They determine is by the patients weight
What forms of medications can be taken for pain management?
Acetaminophen, NSAIDS, and opioids.
What does Acetaminophen do?
A good analgesic drug but does have strict regulations of use. The MOA is unclear but it is thought to be due to its ability to inhibit the COX enzyme.
What do the NSAIDS do?
- they have anti-inflammatory, analgesic, and anti-pyretic properties.
- they exert their analgesic properties on peripheral tissues, by inhibiting the COX enzyme.
How many COX enzymes are there?
Two. COX-1 is present in most tissues, and is responsible for normal cellular function including kidney, gastric, and platelet aggregation function.
COX-2 expression is usually increased with tissue injury and inflammation. NSAIDS are said to work by inhibiting COX-2, hence providing their analgesic properties.
What do opioids do?
These are exogenous substances that bind to opioid receptors (Mu, Kappa, and Delta) in the brain and the spinal cord.
How are opioids administered in the hospital setting?
enteral: orally, rectally, sublingually
parenteral: intravenous, subcutaneous
intrathecal (through spine)
topical: transdermal
What is a PCA pump?
Patient controlled anesthetic pump. They can administer intermittent doses every 6 minutes to a specific max dose.
Why is it important for patients to be monitored closely after receiving opioids?
They have to check for side effects: CRINDDS
Constipation, respiratory depression, itchiness, nausea, delirium, dependency and sedation
What is important for physicians to do before patients are discharged?
Wean off their opioids
