Preanesthetic period & anesthetic agents

pre-anesthetic agents

-calm or sedate a vicious animal -reduce noxious side effects from anesthesia -reduce amount of general anesthetic used -decrease pain or discomfort -smoother the induction, smoother the recovery -pain meds are more effective before painful event -multimodol= multiple attacks (balanced anesthesia)

halothane

-high vapor pressure -low solubility -moderate MAC -cam odic arrhythmias, brachycardia, & vasodilation -may cause respiratory depression -little analgesia -may cause malignant hyperthermia (spike a fever, especially in pigs) -not as safe as isoflurane or sevoflurane

vapor pressure

-high vapor pressure (volatile) = evaporates easily, requires a vaporizer -low vapor pressure = doesn't evaporate easily, doesn't require a vaporizer

tranquilizers and sedatives: benzodiazepines

-valium (diazepam) (propylene glycol based-only given IV) -midazolam (water based; can be given IV, IM, SQ)

properties of inhalants

-vapor pressure -solubility -mac

fluid rates

3 ml fluids given for every 1ml of blood lost -hospitalized pt-focus on dehydration, on-going fluid loss (vomiting/diarrhea), fluid volume maintenance

using IPPV, the rate to ventilate a pt under general anesthesia is

8 to 12 breaths per minute

what breed or species must be watched especially closely during any anesthetic procedure to ensure a patent airway?

brachiocephalic breeds

respiratory acidosis is an acid-base disturbance where the blood gas analysis reveals

increase CO2, decrease pH

Most preanesthetics will not cross the placental barrier.

false

An anesthetic agent that has a low blood-gas partition coefficient will result in __________ induction and recovery time.

fast

compared to methoxyflurane, isoflurance is considered to have a

higher vapor pressure

pure mo agonists

morphine, meperidine, hydromorphone

which of the following drugs may cause histamine release when administered IV?

morphine, meperidinr

anticholinergic drugs such as atropine block the release of acetylcholine at the

muscarinic receptors of the parasympathetic system

tissue necrosis will occur if _____ is administered perivascularly

thiopental

propofol sometimes causes transient apnea. to avoid this, the anesthetist should:

titrate this drug in several boluses

High doses of opioids can cause bradycardia and respiratory depression.

true

it is recommended that atropine not be given to an animal that has tachycardia

true

one of the disadvantages of the drug methohexital is that animals that are anesthetized w/ it may demonstrate excitement during recovery

true

Urine SG

urine subspecific gravity; cat= 1.035-1.055; dog= 1.025-1.035

AZO stick

measures BUN

MAC will vary with:

-Body temperature of the patient -Age of the patient -Concurrent use of other drugs -Anesthetic agent

Diagnostics

-CBC (complete blood count) -blood chemistry (organ function) -blood gases (arterial blood levels, CO2 + O2); mainly in cardiac pt -radiography (sometimes required) -ECG/EKG (cardiac pt, older pt) -blood clotting tests (history of bleeding, breed, not routine, not fancy testing)

general guidelines about body fluids in a normal adult animal

-about 2/3 of the total body water is inside the cells -blood plasma makes up about 5% of the total body weight -dogs have a larger total blood volume than cats

pre-anesthetics: tranquilizers

-acepromazine -chlorpromazine -valium -xylazine -medtomidine

tranquilizers and sedatives: phenothiazines

-acepromazine (intimation sickness, yellow) -chlorpromazine

pre-anesthetic: anticholinergics

-atropine (prevents bradycardia, decrease salivation -glycopyrrolate (longer duration, more $)

injectable anesthetics

-barbiturates -cyclohexamines -neuroleptanalgesics -propofol -etomidate

nitrous oxide

-blue -use in conjunction w/ other gas anesthetics -high MAC -low solubility -wide safety margin -good analgesia -can cause hypoxia -competes w/ hemoglobin for oxygen

Patient Status Classification

-class 1 = minimal risk- normal, healthy pt (ex. castration, ovariohysterectomy) -class 2 = slight risk- mild systemic disturbances (ex. ruptured cruciate ligament, neonate, geriatric pt) -class 3 = moderate risk- moderate systemic disturbances or disease w/ mild clinical signs (ex. anemia, fever, heart murmur, moderate dehydration) -class 4 = high risk- severe systemic disturbances that are life threatening (ex. shock, severe dehydration, fever, gastric torsion w/ arrhythmias) -class 5 = extreme risk/ moribund- submitted for surgery desperation but little chance of survival. pt not expected to live 24 hr (ex. advanced multiple organ failure, shock, severe trauma)

Benzodiazepines

-controlled -anti-anxiety & calming behavior -skeletal muscle relaxation -anti-convulsant activity -minimal adverse effects -no analgesia -minimum cardia +respiratory depression -can be given rectally (absorbed well) -appetite stimulant in cats (IV) -often used w/ ketamine (IV) as induction agent -very rarely used as tab form

cyclohexamines

-controlled -dissociative drug (mind separate of body) -awake, but not aware of surroundings -increases reflexes & sensitization to light & sound -rigidity & stiffness - no visceral analgesia (guts) -tissue irritation -ketamine can cause tachycardia (ketamine=winds them up, cause eyes to point forward) -giving ketamine + valium helps body rigidity & muscle relaxation -ex. ketamine (stings), tiletamine (telazol & zolazepam) -ketamine - valium = telazol

Effects that atropine may have on the body include:

-decreased salivation -decreased GI motility -mydriasis

IV fluids: colloid solutions

-dextrans -hetastarch (most common) -oxyglobin -plasma *colloid: huge molecules w/ lg osmotic pull, doesn't leave blood stream, maintains blood volume

statements regarding electrolyte composition of fluids:

-extracellular fluid contains more sodium than intracellular fluid -intracellular fluid contains more potassium than intravascular fluid -osmolarity of intracellular fluid is similar to that of extracellular fluid

inhalation agents

-halothane -isoflurane -sevoflurane -nirtrous oxide

isoflurane

-high vapor pressure -low solubility -high MAC -few adverse side effects -may cause respiratory depression -little analgesia -inexpensive, irritating/noxious smell)

Effects that are commonly seen after administration of a dissociative include:

-increase BP -increase HR -increased CSF pressure -increased intraocular pressure

anticholinergics (parasympathetic)

-inhibits acetycholine -causes tachycardia -reduces salivation -reduces GI activity -inhibits vomiting & diarrhea -makes pupil dilate -no systemic analgesia -blocks/prevents sympathetic -mimetic=stimulates sympathetic -lytic=blocks parasympathetic

MAC (minimum alveolar concentration)

-lowest concentration at which 50% of patients show no response to painful stimulus -indicates the strength of an inhalant -the lower the MAC the more potent the inhalant

Solubiliy

-measure of tendency of the anesthetic to exist as a gas or to dissolve in blood -LOW solubility= remains as gas in alveoli, builds up quickly, fast induction & recovery -HIGH solubility= induction is less rapid, slower recovery

pre-anesthetics: opioids

-morphine -butorphanol (torb/torbusejic) -oxymorphone -hydromorphone -buprenophine (buprenex) -simbadol

characteristic effects of the benzodiazepines

-muscle relaxation -minimal effect on the cardiovascular system

Sevoflurane

-must use a different vaporizer than halothane or isoflurane -lower solubility -higher MAC -cardiovascular depression -fast & smooth recovery -no analgesia -less stimulating to mucus membranes -not as noxious/irritating smell -fast response—go down or go up

opioids

-narcotics-controlled -can be used & a pre-anesthetic, induction & analgesic agent -sedation & analgesia -causes respiratory depression -reversible (naloxone, butorphanol) -ex. morphine, butorphanol, oxymorphone

signs of fluid overload

-ocular & nasal discharge -increase lung sounds & RR -dyspnea

neuroloeptanglesics

-opioid + tranquilizer -ex. ace + hydro -ex. zylazene + torb -not always used as premed

factors that may affect the speed of anesthetic induction w/ a volatile gaseous anesthetic include:

-partition coefficient of the agent -vaporizer setting

Patient Evaluation

-patient history -physical examination -appropriate diagnostics -patient status and anesthetic risk -will depend on what precautions to take prior to anesthesia (pre-meds, blood work)

The concentration of barbiturate entering the brain is affected by a variety of factors such as:

-perfusion of the brain -lipid solubility of the drug -plasma protein levels -blood pH

benefits of IV catheters

-perivascular irritation -multiple drugs -emergencies -fluid therapy -bigger the catheter the better

thiazine derivatives

-provides sedation & analgesia -profound cardiovascular changes -respiratory effects -vomiting -abdominal -reversible (yohimbine (reversal for rompan) ,antisedan (only IM) -excitement w/ dex -antisedan stays attached to domitor receptors than domitor lives

patient history

-procedure -age -previous illness -signs of illness w/in past 24 hrs -exercise tolerance -allergies or drug reactions -current medications -vaccination history -reproductive status -any serious clinical signs

IV fluids: crystalloid solutions

-saline -lactated ringers -dextrose -normosol *crystalloid: electrolyte composition to plasma/blood

phenothiazines

-sedative -anti-emetic effect -antihistamine effect -peripheral vasodilation (decrease crt) -reduction of seizure threshold -effects on personality (can make aggressive dogs more so, some dogs fight it) -no signs of suppression on heart or lungs -no analgesia -antianxiety properties w/ some muscle relaxation -always ask for previous seizure history

etomidate

-short duration -mild respiratory depressant -minimal cardiovascular effects -wide margin of safety -phlebitis (inflammation of veins)

physical exam

-signalment (breed, age, sex) -disposition (temperament) -activity level -examination of organ systems (liver, kidneys, heart (perfusion), & lungs (respiratory) most important)

barbiturates

-ultra short acting -brief recovery -dont use in slighthounds -perivascular sloughing -excitement -respiratory depression -decrease cardiac function -ex. thiopental sodium, pentobarbital (seizures)

propofol

-white milky appearance -iv only -rapid & smooth recovery -short duration of action -open bottle can only be used for a short period of time -causes apnea -amount may depend on premeds -TIVA- total intravenous anesthesia (short procedures -not an analgesia agent or sedative -used for unconscious state -alfaxolone=agent similar to propofol

pre-anesthetic pt care

-withhold food (NPO) -fix pre-existing problems -have IV catheter (maintain organ blood flows, limit to kidneys can led to renal failure) -fluids -K+ affects the heart, sodium potassium pump affects the heart -pt assessment before hand minimizes risks

alpha 2 agonist examples

-xylazine -dexmedetomidine

tranquilizers and sedatives: thiazine derivatives

-xylazine (rompan) -medetomidine (domitor)

As a rough guideline, to safely maintain a surgical plane of anesthesia, the vaporizer should be set at about:

1.5 X MAC

fluid infusion rate

100ml/hr

fluid rates: anesthesia

10ml/kg/hr

max halogenated anesthesia agent dose per day (ppm) according to the occupational safety and health administration (OSHA) is:

2 ppm

fluid rates: maintenance

2-4 ml/kg/hr

fluid rates: shock

50-90 ml/kg/hr

The delivery rate of a microdrip administration set is:

60 gtt/ml

albumin

A serum protein, made in the liver, that transports free fatty acids from one body tissue to another.

Atipamezole is a reversal agent for?

Dexmedetomidine

which of the following drugs will precipitate out when mixed w/ other drugs or solution?

Diazepam

example of a dissociative anesthetic

Ketamine hydrochloride

regarding fluid infusion rates

Surgery patients with blood loss may require colloids instead of crystalloids

example of a pt who may receive an anticholinergic as part of the preanesthetic protocol?

a 2 yr old st. bernard that will be having hernia repair surgrey

a tranquilizer &/or sedative combined w/ an opioid or an alpha 2 agonist is called

a neuroleptanalgesic

the importance of an ____ will significantly affect a its physiological signs (HR & BP) and pathological effects (tissue healing)

algesia

a neuroleptanalegsic is a combo of

an opioid and a tranquilizer

preanesthetic drugs are commonly used for:

analgesia, sedation, & safe handling

a ______ monitor is a device that measures end-tidal CO2

capnograph

all anesthetic gases suppress _______ and _______ depression

cardiovascular, respiratory

Using the ASA Physical Status Classification system, a patient that is moderately anemic or moderately dehydrated would be classified as:

class P3

adverse effects common w/ isoflurane include

depression of respiratory

the component that is color code and fitted w/ noninterchangeable, gas-specific connectors on an anesthesia machine is termed the:

diameter indexed safety system

One problem frequently associated with recovery from tiletamine-zolazepam in dogs is:

excitement

what sign of disease in a calm canine patient would be most significant in terms of the potential to increase the risk of anesthesia

increase respiratory effort

the fluid type more appropriate to replace moderate losses from dehydration would be

isotonic crystalloids

severe brachycardia caused by dexmedetomidine is best treated w/ the following drug:

naloxone

what class of drugs acts peripherally by reducing the prostaglandin production in the area of tissue damage?

non steroidal antiinflammatories

flow of O2 under anesthesia

oxygen—vaporizer—anesthetic mixed w/ oxygen—delivered to pt—into airways diffuses into blood stream—to the brain inducing anesthesia in the pt

PCV

packed cell volume (hematocrit)

which of the following drugs can be used as a sedative, induction agent, and maintenance anesthetic?

propofol

an anesthesia machine flush valve does not:

relieve pressure within the breathing systems

Etomidate is particularly well suited for induction of dogs with which of the following problems?

severe cardiac disease

which of the following has a lowest blood-gas partition coefficient

sevoflurane

during which stage of analgesia do delirium or excitement or loss of consciousness occur?

stage 2

TP

total protein; test to measure dissolved substances in the plasma

classification of drug that calms an anxious pt but will not necessarily reduce awareness

tranquilizer

what can be done to reduce WAG exposure in the environment?

use a scavenging system to capture waste gas, leak-test machine prior to each use, annual preventative maintenance