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51 Cards in this Set
- Front
- Back
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ASA Patient Status Scale
ASA PS-I |
Normal patient
No organic, physiologic, or psychiatric disturbance Excludes the very young and very old |
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ASA Patient Status Scale
ASA PS-II |
Patients with mild systemic disease
No functional limitations Has a well-controlled disease of one body system (just focus on issue at hand) |
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ASA Patient Status Scale
ASA PS-III |
Patients with severe systemic disease
Some functional limitation Has a controlled disease of more than one body system or one major system No immediate danger of death (but KEEP EYE OPEN) |
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ASA PS-IV
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Patients with severe systemic disease that is a constant threat to life
Has at least one severe disease that is poorly controlled or at end stage Possible risk of death (BUT NEEDS SURGERY) |
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ASA PS-V
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Moribund patients who are not expected to survive without the operation
Not expected to survive > 24 hours without surgery Imminent risk of death |
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ASA PS-VI
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Declared brain-dead patient who organs are being removed for donor purposes
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ASA PS-#E
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Emergency status
Added to any PS code to designate emergency procedure (often with food in stomach--maybe add metaclopramide...) |
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Adjuncts to Anesthesia
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Relieve anxiety
Sedation Prevent allergic responses Prevent aspiration of stomach contents or postsurgical emesis Analgesia Prevent bradycardia and pulmonary fluid secretions Facilitation of intubation and relaxation |
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Adjuncts to Anesthesia
(secondary) general |
Relieve anxiety (drugs or talk)
Sedation (antihis say,allergy,sed, anxiety) Prevent allergic responses Prevent aspiration of stomach (metaclop...) contents or postsurgical emesis Analgesia (lot's of options, people have varied responses) Prevent bradycardia and pulmonary fluid secretions (atropine etc) Facilitation of intubation and relaxation (tuboc.. but watch His) |
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Ideal Anesthetic Provide.....
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Analgesia
Rapidly reversible depression of consciousness, circulation and respiration consistent with surgical needs Relaxation of skeletal muscle Reduction in reflex activity (not too far) Amnesia Safety in the operating room |
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Four Stages of Anesthesia
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1-Analgesia---at least 4numbing, no response
May also produce amnesia and loss of consciousness 2 Disinhibition Delirium and excitation common Amnesia is present, reflexes enhanced, and respiration irregular Nausea and vomiting possible(up as down)(loud drunk phase) 3 Surgical anesthesia Unconscious and no pain reflexes Autonomic signs are stable*****like deep sleep 4-Medullary depression-----(OD) Severe respiratory and cardiovascular depression Medical emergency |
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Surgical Anesthesia
phases |
Induction
Goal is to avoid excitatory phase Maintenance Surgical anesthesia maintained Vital functions monitored and stable Recovery Rapid emergence from anesthesia-----is ideal Must be conscious, alert and responsive |
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Two Theories for How Anesthetics Work
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Membrane expansion by 0.4% disrupts sodium channel function (locked into place turns and distorted---)
An anesthetic receptor exists that when activated interferes with sodium or chloride channel function GABA receptor may be a common target (strong evidence that all (except ketamine (sp?)) work here) |
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Fundamentals of Inhaled Anesthetics
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Primary site of action is the brain.
Anesthetic gas first goes to the alveoli, is removed to the blood until equilibrium is established. The reverse process occurs in the brain Essentially at equilibrium, the partial pressure in the alveoli is the same as the partial pressure in the brain. Henry’s Law |
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Henry’s Law
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At equilibrium, concentration of gas dissolved in liquid is proportional to partial pressure of gas and its affinity for the liquid
Gas molecules dissolve in blood until the blood exerts a tension equal to the alveolar partial pressure Brain concentrations can be controlled by alveolar concentrations |
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Minimum alveolar concentration
defined |
The alveolar concentration(in %) needed to prevent movement in 50% of experimental subjects with a standardized skin incision. (3/4 inch long)
Thus an ED50 value (WITH an efficacy component) due to standardized (?) some with high vs. low MAC (say nitrous----very high mac thus actually an anelgesic otherwise would need to be pressurized) MACs can be added for induction we use 1.3-1.7 times the mac (85% effective) then go back down to 1.1-1.2 |
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MAC values examples (no memmory)
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halothane .75
isoflurane 1.4 sevoflurane 2.0 nitrous >100 (can get there) For induction Multiply MAC by 1.3 to 1.5 MACs are additive |
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Factors Affecting Anesthetic Concentration
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Solubility of the gas
Blood/gas partition coefficient less soluble the gas, the faster the induction and emergence (blood needs to saturate before bubbling it out) Lung Inspired concentration Higher concentration, faster equilibrium Minute ventilation volume Deeper or faster inspirations = faster equilibrium Cardiac output Low CO slows delivery Blood and brain Blood equilibrates w/alveoli, brain equil. w/blood Concentration effect Higher inspired concentration, faster the equilibrium (too fast it will be harder to equil) Second gas effect Acceleration in alveolar transfer of an second gas may be accelerated by large uptake of a primary gas (two gases go in faster) Anesthetic apparatus. Specific for agent being used. 2 to 3 vaporizers per machine. Diffusion hypoxia. With nitrous oxide, when anesthetic is turned off, nitrous oxide rushes into alveolar spaces from blood displacing oxygen. Offset by 100% oxygen administration and maintaining normal ventilation. |
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Malignant Hyperthermia
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Most common with halogenated anesthetics or succinylcholine (DPNMB)(some genetic variability in processing)
Related to increased myoplasmic calcium levels and increased excitation-contraction coupling Treatment Withdrawal drug Cool patient Treat with dantrolene (decr ca mobilization from SarcoRetic |
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Halothane
actions |
(Fluothane)
Weak analgesic (common themes) Often used with analgesic adjuncts Muscle relaxant **Cardiovascular system Direct cardiac depressant Deep anesthesia may be associated with nodal rhythm No direct effect on sympathetic outflow but blocks sympathetic reflexes May stimulate vagal pathways ******Sensitizes myocardium to catecholamines***(THIS IS ITS DISTINGUISHING FEATURE**********(watch pheochromocytoma etc.) arrhythmogenic effects |
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Halothane
adv Rx |
*****Hepatic necrosis (aka halothane hepatitis)
May be a problem for anesthesiologist obtaining low level repeated exposures (use max and a scavenger system specific to anesthetic) ******Sensitizes myocardium to catecholamines***(THIS IS ITS DISTINGUISHING FEATURE**********(watch pheochromocytoma etc.) |
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Enflurane
actions |
Similar in anesthesia to halothane
Cardiovascular system Direct cardiac depressant (all ARE) No stimulation of sympathetic system Sensitizes myocardium to catecholamines BUT Less than halothane ***********Biotransformation product contains fluoride*******(THE DISTINGUISHING.....)** Watch renal function***very toxic to kidneys |
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Enflurane
adv RXs |
Seizures noted******PROBABLY ALSO THE FLOURINE
Muscle relaxation Uterine relaxation Contraindicated in labor |
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Isoflurane
Desflurane actions |
(Forane),(Suprane)
--Respiratory effects Some evidence for early stimulation of respiratory reflexes and secretions (DON't UP dose because you think induction is delayed!!could reach medullary depression) Cardiovascular system ********Cardiac output is maintained No cardiac sensitization to catecholamine Some hypotension due to peripheral vasodilation |
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Desflurane
considerations |
Fast induction and rapid adjustments in anesthetic depth possible.
Rapid changes in drug concentration may increase heart rate and blood pressure. *****Reacts with some dry adsorbents to form *****carbon monoxide**** and causes carboxyhemoglobinemia (HAS SPECIAL SCAVENGER)(FOR STAFF). |
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Nitrous Oxide
indications |
MAC is greater than 100%
******Not suitable as solo agent***** Good analgesic (ITS BASIC USE) No muscle relaxation noted Second anesthetic gas, Second gas effect Diffusion hypoxia |
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Nitrous Oxide
actions |
(not a solo DRUG)
Respiratory system No irritation or depression noted Will potentiate depression by other agents Cardiovascular system Direct cardiac depressant Blood pressure maintained as reflexes maintained or enhanced (THIS IS GOOD) |
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Sevoflurane
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(Ultane)
Non-irritating to airway Relatively fast induction and emergence Acceptable to pediatric***DOCish******patients Adverse effects Mild and transient Sinus bradycardia, sinus tachycardia, hypotension **Nephrotoxicity due to halogen (more long term) |
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Inhaled Anesthetics
specific agents........that.. Cardiac arrhythmias triggered by catecholamines and Cardiac output changes |
Halothane-High
Enflurane-moderate others low CO- all decrease (enflurone transient) |
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Inhaled Anesthetics that cause
Respiratory depression |
ALL but......
Isoflurane, Desflurane-Transient stimulation |
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Inhaled Anesthetics-that cause
Halogen toxicity (LIVER) kidney probs |
Halothane-HIGH RISK TO LIVER
Enflurane-Lower risk to liver, risk to kidney Isoflurane, Desflurane-no risk Nitrous Oxide-no risk Sevoflurane-Risk to kidney |
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Intravenous Anesthetics
general trends |
Injectable
Rapid in effect Provide analgesia Pleasant emergence as a rule(short-t1/2) |
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Intravenous Anesthetics
uptake and distribution |
Highly lipid soluble
Typical redistribution (THIS IS THE METHOD OF termination of drug effect)THUS WATCH OUT For vancomycin and the whole red man syndrome w/anesthesia scene inreased Histamine sensitivity) profile Blood, vessel rich group (heart, lung, brain, kidneys, liver), muscle, vessel poor group High cardiac output enhances effect Reduces dilution effect or extraction by muscle group don't count on kidney and liver |
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Ultra-short Acting Barbiturates
named |
Methohexital sodium (Brevital Sodium)
Thiopental sodium (Pentothal Sodium) Thiamylal sodium (Surital) T1/2 in minutes |
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Ultra-short Acting Barbiturates
actions |
No analgesia or muscle relaxation
(PROFOUND)Depression of respiratory and cardiovascular systems noted Major problem in elderly or infirm (can induce a coma (good and bad) *******Reduces intracranial pressure (come and go in fashion)(some LIKE it) |
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Ultra-short Acting Barbiturates
adv RXs |
Hypersensitivity reactions are major concern
Asthma Rashes(DISCONTINUE) Acute intermittent porphyria (NOT USED IN HEME PROBS---they are big time inducers) Poorly soluble at physiological pH (PUT it basic) |
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Ketamine
actions |
(Ketalar)(special k)
THE NON GABA GUY Dissociative anesthetic. Patient is in a trance-like state and may be aware of surrounding. Eyes may be open. Unable to respond. Mechanism likely antagonism of glutamate binding site on NMDA receptor Increase in muscle tone and maintenance of most reflexes******** Ideal for trauma patients. (NOT FOR head -----increase intracranial pressure Blood pressure may be unstable. (IM ROUTE ALMOST AS GOOD AS IV THUS ANIMAL DART---GOOD OPTION IF CAN'T FIND A VEIN SAY IN A BURN) |
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Ketamine
adv RXs |
Emergence characterized by excitement and hallucinations
Poor tolerance by adults Hallucinations can occur up to a year after use *****Always give benzodiazepines during use(TO AVOID FLASHBACKS-amnesia) Emergence should be in a low sensory stimulation environment *****Increases intraocular and intracerebral pressures**** |
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Midazolam
ACTIONS |
(IV)*****(THE ONE)Water-soluble benzodiazepine
Short half-life with no active metabolites Powerful amnestics No analgesia or muscle relaxation Antidote Flumazenil (Romazicon) is available (THIS MAKES IT POPULAR) |
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Etomidate
everything |
(IV)(Amidate)
No analgesia or muscle relaxation Respiratory and cardiovascular reflexes are intact Pain on injection Postoperative nausea and vomiting a problem **************May depress steroid production for 24 hours Inhibits 11-beta-hydroxylase********BAD FOR STRESS RESPONSE so for minor stuff |
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Propofol
everything |
(IV)(Diprivan)very popular drug maybe most in IV
********Lowers blood pressure Avoid use in patients with cardiac disease or peripheral vascular disease ********Low incidence of nausea and vomiting (may be antiemetic)*** Good for outpatient surgery (good emergence) May be antiemetic Transient apnea, respiratory depression, sinus bradycardia and tremors common problem |
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Fentanyl Remifentanil
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(Sublimaze)(Ultiva)
Potent synthetic opiate agonist Very lipid soluble Short duration of action Aids induction and maintenance of general anesthesia Attenuates hemodynamic responses Maintains cardiac stability Neuroleptanesthesia – a state of amnesia and analgesia when fentanyl used with droperidol and nitrous oxide ************Respiratory depression lasts longer than analgesia******use it before or in surgery |
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Local Anesthetics
general |
Low systemic toxicity
Fast onset of action Duration of action sufficient for indication Reversible (REDISTRIBUTION is the method again of term---thus the epinephrine scene v-constr to inc doA |
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Local Anesthetics
moA |
(SAME BUT LOCAL)
Distortion of membranes constricting or “plugging” sodium channels closed Especially likely for inactivated channels, inhibiting inward flux of sodium Elevates threshold Slows rate of depolarization Slows or stops conduction of action potential An anesthetic receptor exists that when activated interferes with sodium channel function |
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local anesthetic
Differential Blockade |
Smaller nerves are more sensitive
Sympathetic function lost first Pin-prick sensation Touch Temperature Motor function lost last Infiltration of trunk fibers Outer mantle first Core last Loss of anesthetic effect is reverse order |
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Local Anesthetics
General Pharmacology (vessel effects) |
Local anesthetics are vasodilators
Exception is cocaine Vasoconstrictors may be added to delay absorption of anesthetic from site of administration Epinephrine is commonly used Not to be used with terminal vascular beds (finger toe .....)may ischemic fall of nose in cocaine....... |
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Local Anesthetics
Ester-type Agents named doA scene |
(esters destroys by pseudoesterases (cholinesterase) thus don't go systemic much thus DOC in pregnancy but end product = PABA and many allergic---(are you sensetive to sulfonamides, thiazides, sun screen)
Cocaine Abuse potential Vasoconstrictor Benzocaine (probably most seen) Procaine (Novocain) Tetracaine (Pontocaine) Long-lasting*******************************(if prob hard to get out----plus can go systemic-then CARDiotoxic) |
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Amide-type Agents
named doA scenes |
Lidocaine (Xylocaine)
Prilocaine (Citanest) -------Bupivacaine (Marcaine, Sensorcaine) = Long-lasting Intravenous bupivacaine can cause severe cardiotoxicity (usually a tingle in phase or auditory scenes) they are all |
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Local anesthetics
pharmacokinetics |
Ester-type local anesthetics are hydrolyzed by pseudocholinesterases
Results in very short half-lives and low plasma levels Final product is PABA (allergy scene) Amide-type local anesthetics are biotransformed by liver microsomal enzymes. Slower elimination process. *********Placental transfer is certain. Fetal and maternal levels are almost same. Esters may be preferred during pregnancy because of lower plasma levels (but if paba sensitive....). |
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Local anesthetics
ADv Rxs |
Central nervous system stimulation at high doses
Medullary depression may produce lethal respiratory depression Cardiac toxicity due to depressed conduction Allergic reactions to ester-type agents Amides are nearly allergy-free ********Vasovagal syncope (pass out) usually the sight of procedure Circumoral tingling or tinnitus Major sign of vascular administration |
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Local anesthetics
uses |
Topical (dyphenhydramine is also local)
Relieves pain and itching Absorption through skin is slow Useful for procedures involving cornea, nasal, oral or mucous membranes -Infiltration Injection under skin or near site Useful for local procedures Care must be taken that contiguous areas are not stimulated Regional block Includes spinal and epidural anesthesia Injection near a nerve or nerve plexus proximal to surgical site Spinal anesthesia Injected directly into spinal fluid Results in a “reversible” cord transection Care must be taken to monitor sympathetic function and ensure that block is not too high on spine (CAN kill) |
