Anesthesia Flashcards
As a PT, why should you care about anesthetics?
Pts have used anesthetics, and the effects can last days after surgery; PTs can administer anesthetics (phonophoresis, iontophoresis)
Patient is not conscious; Effect is on the whole body; Used for more extensive surgical procedures
General anesthesia
Patient is conscious; used in surgery of relatively small, well defined area or surgery where pt needs to remain conscious
Local anesthesia
Name 6 requirements that most general anesthetics meet
- Loss of consciousness and sensation
- Amnesia
- Skeletal muscle relaxation
- Inhibition of sensory and autonomic reflexes
- Minimum of toxic side effects
- Rapid onset, easy adjustment of dosage during use, and rapid, uneventful recovery
Name the four stages of anesthesia
- Analgesia
- Excitement (delirium)
- Surgical Anesthesia
- Medullary Paralysis
Loss of sensation of pain
Analgesia
Using too much anesthesia; results in loss of cardiac HR, decreased breathing, etc.
Medullary paralysis
What is the goal of anesthesia
To bring pt to stage III [surgical anesthesia] as quickly as possible
What are the administration techniques for anesthesia?
- Intravenous
- Inhalation
- Sequential combo of the two
What is an advantage to intravenous administration?
Quick onset
What is a problem with intravenous administration?
Lack of control if overdosed; once the drug is in the body, it cannot be removed quickly, so you must wait until the body metabolizes it
What is the advantage to inhalation administration?
Easy to adjust dose
What is the disadvantage to inhalation administration?
Slow onset
What is the currently used for inhaled anesthetics? What older anesthetics were used previously?
Nitrous oxide; Ether [explosive] or chloroform [toxic]
What are 5 IV anesthetics used?
- Barbiturates
- Benzodiazepines
- Etomidate
- Ketamine
- Propofol
General anesthetic that has fast onset; short-acting forms; relatively safe [respiratory and circulatory depressants, decrease intracranial pressure]; however little analgesic or muscle relaxant effect; Hepatic metabolism required for elimination (do not give to people with liver disease)
Barbiturates; Thiopental and methohexital
General anesthetic that has a slower onset than barbiturates; longer duration of action; more often used as premedication; prolongs recovery period but produces amnesia; used to get pt to relax before surgery
Benzodiazepines
Analgesics; usually not used alone to produce anesthesia but can produce anes. with higher doses; help maintain anes. at low doses; causes respiratory depression, post-op nausea and vomiting; can cause constipation, itching
Opioids
General anestesia; patient not fully awake or asleep [analgesia, retrograde amnesia]; short procedures requiring some pt cooperation
Neuroleptanesthesia
- neuroleptic drug AKA dopamine blocker = droperidol
- opioid analgesic = fentanyl
Induction of anesthesia (seconds); quick onset, quick recovery; combined with other drugs; adverse effects = no analgesic actions, involuntary movements, pain on injection, nausea and vomiting
Etomidate
Dissociative anesthetic [catatonia, amnesia, analgesia]; poor muscle relaxant; mostly for short procedures; increases muscle tone, BP, HR, breathing rate; increase salivary and bronchial secretions; hallucinations or disturbed dreams - reduced by diazepam
Ketamine
General anesthesia; Fast onset; antiemetic; lowers BP, ICP; little pain control, lethal metabolic acidosis and skeletal myopathy; dystonia and seizures
Propofol
Term meaning “stops vomiting”
Antiemetic
Term meaning “involuntary muscle contractions”
Dystonia
Drug used to treat dystonia; anticholinergic drug
Benzotropine
Prevents involuntary movements and make mechanical ventilation easier; block NMJ fxn
Neuromuscular blockers
Competitive antagonists of muscle nicotinic receptor; similar in structure to curare; no muscle movement
Non depolarizing blockers
Act like ACh ant NMJ, but not broken down; depolarized muscle is not responsive to further stimulation
Depolarizing blockers
What are 5 special concerns of general anesthesia?
- Drowsiness
- Confusion or delirium
- Weakness
- May last several days if a patient has difficulty eliminating the drug
- Lung concerns
Anesthetics decrease ______________ in airways, which increases risk of infection and atelectasis
Mucociliary clearance (move things out from lungs)
How can PTs help with residual lung concerns produced by using general anesthesia?
Encourage patients to cough and breath deeply to:
- Eliminate anesthesia
- Mobilize secretions
- Breathing exercises
- Postural drainage
Characterized by a loss of sensation in a specific body part or region
Local anesthesia
What two environments would you use local anesthetics?
- Surgery; no post op effects of general anes.; doesn’t interfere with CV, resp. or renal fxn
- Non-surgical; short- or long-term pain relief; block sympathetic pathways; iontophoresis or phonophoresis
Name 3 local anesthetics
- Benzocaine (Américaine)
- Lidocaine (Xylocaine)
- Procaine (Novocain)
What is local anesthetics often administered with? Why?
A vasoconstricting agent such as epinephrine; slows down removal of the drug and to reduce entering the bloodstream
How are anesthetics metabolized?
Hydrolysis by liver or enzymes in plasma
How are anesthetics excreted?
Metabolite secreted by kidneys
Local anesthetic applied directly to skin, mucous membranes, cornea, etc.; drug is for the thing its being applied to
Topical administration
Local anes. applied to skin, absorbed into underlying structures; iontophoresis, phonophoresis, transdermal patch
Transdermal administration
Local anes. injected into a region and saturates it; diffuses to sensory nerve endings; used in dental procedures
Infiltration anesthesia
Local anes. injected into a nerve trunk so that transmission in peripheral nerve is blocked; prolonged administration into skeletal m. can produce localized m. pain and necrosis
Peripheral nerve block
Local anes. injected into spaces surrounding the spinal cord; too high of dosage has a risk for neurotoxicity, resulting in nerve damage; used whenever anesthesia is needed for large region
Central neural blockade
Central neural blockade injected in space between vertebra and dura mater; safer and easier of the 2 blockades
Epidural nerve blockade
Central neural blockade injected in subarachnoid space (intrathecal anesthesia); faster and more effective, but higher risk for neurotoxicity
Spinal nerve blockade
Can occur during peripheral and central nerve blocks; can be used for specific treatment - CRPS; tend to work better in beginning of disorder rather than later
Sympathetic block
What is Complex Regional Pain Syndrome (CRPS)? How is a block used to treat this?
Affects a region of the body, thought to be due to dysfunction of symp. NS; injections into the region surrounding the sympathetic ganglion
Injected into peripheral vein; drug diffuses into body region; tourniquet restrict blood flow so anesthetic stays in the region
IV regional anesthesia
Inhibit of sodium ion channels [blocks action potential]; blockage at one point blocks all forward progression of action potential; smaller diameter axons affected the most
MOA (mechanism of action, inhibitor)
Drugs meant to have a local effect; if absorbed into general circulation, can affect nervous and CV systems; happens when a blood vessel is hit instead of a nerve
Systemic effects
What are anesthetic systemic effects of the CNS?
Initially stimulates the brane [somnolence, confusion, agitation, excitation, seizures]; followed by CNS depression [respiratory depression, cardiac depression]
What are anesthetic systemic effects of the cardiac system?
Decreased excitation, HR, force
What causes systemic actions due to anesthesia?
- Long-acting and excessive dose
- Increased absorption rate
- Injected into systemic circulation
