pre quiz notes Flashcards
does ace lower the seizure threshold?
no
How does ketamine act with ICP?
Ketamine will increase ICP at large doses with CSF outflow tract obstruction
ketamine can control seizures (it is anti-epileptic)
KETAMINE INCREASES SEIZURE THRESHOLD AND ICP
your p is getting 1L.min O2 from your machine, raising this flow rate to 2L/min will do what to FIO2?
no effect; fracture of inspired O2
O2 1L/min (98%)
ISO 2% = 100%
or O2 2L/min (98%)
ISO 2%
= 100%
but what if….
O2 2L/min (99%)
but ISO is 1%? –? 1%
then O2 is 99%
doppler vs. oscillating BP
Both provide systolic blood pressure and heart rate; Oscillometric also provides diastolic and mean arterial pressures
Doppler is indirect and oscillometric is Direct
using buprenorphine before surgery means the amount of any full mu agonist administered during anesthesia in surgery will need to be
Increased
T/F hypotension usually occurs due to premeds and induction agents
False, the inhalant drug
How do you tx VPC’s?
Lidocaine (only if a run/triad)
What is metabolic acidosis? Respiratory acidosis?
meta- decreased HCO3-
Resp. increased PaCO2
what is metabolic alkalosis? Resp. alkalosis?
meta- increased HCO3-
resp- decreased PaCO2
what is metabolic alkalosis? Resp. alkalosis?
meta- increased HCO3-
resp- decreased PaCO2
What premeds reduce insulin release and cause hyperglycemia as a result?
alpha 2 agonists
How long do alpha-2 drugs work?
30 mins to 1 hour
what receptor is responsible for surgical and ortho pain in mammals?
mu receptors
why do we not want to give lrg animals full mu opioids?
slows GI motility
how long does fent last?
15-30 mins
how long does methadone last?
2-4 hours
What drug is a kappa agonist and mu antagonist and is poor for pain control?
butorphanol
what drug is an antitussive?
butorphanol
what drug for pain is most likely to cause histamine release so we do not want it for MCT p?
morphine
benzos are DEA class ____ and cause muscle relaxation, anti seizures, decreases MAC, but no pain control
class 4
what is the reversal for benzos (mid and diazepam)
flumazenil
___ is water soluble but ____ is lipid soluble and cannot give IM
midazolam; diazepam
what drug is a D2 dopamine antagonist without analgesia but sedation?
Acepromazine (which is a phenothiazine)
what drug can be dangerous in boxers?
Acepromazine
What heart condition do boxers usually get?
Boxer arrhythmogenic right ventricular cardiomyopathy
what drug is GOOD in DCM but BAD in HCM?
dissociative which are NMDA antagonists (like ketamine)
what drug combats SLUDGE and increases HR and can cause 2nd degree AV blocks?
anticholinergics (atropine or glycopyrrolate)
what are the C/I of epidural/local anesth?
cannot ID landmarks (severely obese)
in shock/hypotensive
abscess/infection
neoplasia
blood disorder
sepsis
if P is too cold, what can we use to increase HR?
norepinephrine
Low CO2 =
high pH= resp. alkalosis
High CO2=
Low pH= resp. acidosis
high bicarb (HCO3-)=
high pH= metabolic alkalosis
low bicarb (HCO3-)=
Low pH= metabolic acidosis
PaCO2 less than ___ mmHg means resp. alkalosis
35mmHg
why is PaCO2 more than ETCO2?
bc there is alveolar dead space in the tube that dilutes the CO2 in the ET Tube
AG more than 12=
gap acidosis due to loss of bicarb (HCO3-) and increase of Chloride (Cl-) or due to increased acids or hypoalbuminemia
what are the 5 causes of hypoxemia?
LOW FIO2
HYPOVENTILATION
DIFFUSION IMPAIRMENT
SHUNTING- RIGHT TO LEFT
V/Q MISMATCH (Atelctasis, pulm. edema, pneumonias)
v= ventilation
p= perfusion
what neuromuscular drug blocks acetylcholine? how do you test when p is paralyzed?
Atracurium; you have to use a nerve stimulator
evidence is whether or not p can buck ventilator, heart rate jumping up, hypertension
What is the last thing in the body to become paralyzed with a neuromuscular blocker agent?
the diaphragm (fine motor goes first)
What is the reversal for neuromuscular blocking agents?
Neostigime which inhibits acetylcholine breakdown, an acetylcholinesterase inhibitor, ach build up and kicks out the nerve blocking agent and muscle will begin contracting again
make sure to give glyco or atropine before reversing
What are the causes of hypoxemia?
- V/Q (ventilation/flow) mismatch
- R to L shunt
- Hypoventilation
- Low inspired O2
- Diffusion impairment
- decreased CO
What are the Side effects of Dexmed?
Vasoconstriction, second degree AV block, brady
what is the MOA of atropine?
acetylcholine antagonist at the muscarinic receptor
low dose vs high dose dopamine:
low dose- increasing HR and CP and renal vasodilation
High dose- alpha 1 increasing SVR and BP (vasoconstriction)
What is the MOA for anticholinergic agents?
Competitive antagonism of acetylcholine at the parasympathetic muscarinic cholinergic receptors
what effects do anticholinergic agents have on the body??
increased HR, decreased secretions, bromchodilation, decreased GI motility
which anticholinergic agent crosses the BBB and placenta?
atropine
Which anticholinergic agent is more likely to cause tachycardia and maybe some arrhythmias?
Atropine
what is the onset of glyco? How long does it last?
onset is about 10 mins and lasts for 30-45 mins IV
What is the class of acepromazine?
Phenothiazine (used to smooth induction and recovery)
what effects does acepromazine have on the body?
Tranq, vasodilation, leading to hypotension
what are the C/I for using ace?
C/I in hypovolemic shock bc atangonizes peripheral alpha-1 and prevents the vasoconstrictive responses needed to respond to shock (and be carefulll in stallions and Boxers- can cause brady in Boxers)
MOA of benzos
Gaba agonists
in what p are benzos MOST LIKELY to cause dysphoria?
in healthy p
What alpha-2 agonists were discussed in class?
- xylazine
- detomidine
- dexmedetomidine
- romifidine
What animals should alpha-2 agonists be avoided in? Why? What is the exception to this?
animals with cardiovascular compromise (exception: can work for cats with HCM) - these agents commonly cause profound bradycardia and 2nd degree AV blocks
Why is the use of anticholinergics with alpha-2 agonists not recommended?
The hypertension caused by alpha-2 agonists is compounded by the tachycardic effects of anticholinergics, leading to myocardial oxygenation compromise and increased incidence of ventricular arrhythmias
Which opioid is most likely to cause histamine release? What can this lead to?
Morphine; histamine release causes hypotension secondary to vasodilation
this is why we give abx and morphine slowww
what premed agents are DEA scheduled?
Benzos, opioids, some dissociative (ketamine and telazol)
Give some examples of full (mu) agonist opioids
Morphine, hydromorphone, fentanyl, methadone
Butorphanol is a kappa ___ and Mu ___
agonist; antagonist
What are the critical mean arterial pressures that describe the upper and lower limits of autoregulation of tissue blood flow?
60-160 mmHg
Why is mean arterial pressure not necessarily a good indicator of tissue perfusion?
A high MAP could potentially be due to vasoconstriction or even a high vascular volume, but not necessarily due to adequate blood volume
Why do we need to administer 3-4 times more isotonic crystalloid than you would whole blood in the face of acute hemorrhage?
Isotonic crystalloids have a large volume of distribution in the body, so up to 75-80% will leave the vascular space and enter the interstitial space in 30-45 minutes
Why is administration of IV crystalloid fluids necessary following administration of hypertonic saline?
Hypertonic saline pulls water from the interstitial space into the vascular space, so an isotonic crystalloid must be given to replace the fluids taken from the interstitial space
Both inotropes and pressors have the potential to raise blood pressure in hypotensive anesthetized patients, but inotropes are generally preferred. Why?
Inotropes improve perfusion and blood pressure by increasing the contractility of the heart, whereas pressors increase blood pressure by increasing vascular resistance, which doesn’t necessarily improve perfusion
What is the intravascular residence time for isotonic crystalloid solutions like plasmalyte or LRS???
30 minutes
The intravascular residence time for isotonic colloids is…
24 hours
what is the relationship b/t arterial, alveolar, and end tidal CO2???
ETCO2 < PAO2 < PaO2
PaCO2 more than ___ is hypoventilation
45 mmHg
Why are alpha-2 agonists not particularly good agents in neonatal and pediatric patients?
Due to weak myocardial contractility and inability to maintain cardiac output against an increase in afterload
You are going to administer the alpha-2 adrenergic agonist, xylazine, to a colt as a premed. Which of the following statements regarding this drug is most accurate?
The drug will cause peripheral vasoconstriction and bradycardia
sevoflurane is slightly less soluble in blood than is isoflurane; therefore, onset and recovery times are slightly_____ with sevoflurane than iso
faster!!!!
Speed of onset and recovery of inhalational anesthetic drugs is inversely proportional to which of the following properties?
Solubility
What does this capnograph trace indicate? What are the differentials?
it looks like a shark fine with exp. on the left being gradual to a point then inspiration drops straight down
Expiratory resistance:
- obstructed endotracheal tube
- bronchospasm
- expiratory valve malfunction
Will atropine work on ruminants to decrease their saliva??
Nah
Which fluid type is contraindicated in liver disease due to hepatic metabolism?
LRS fluid
Which preanesthetic drugs should not be used in cases of hepatic encephalopathy? Why?
Benzodiazepines - the benzodiazepine reversal agent, Flumazenil, is the mainstay of treatment for hepatic encephalopathy
Which pre-med/induction agents are best to use if the liver function is compromised?
- opioids
- etomidate
- propofol
- inhalants
What is the reversal agent for alpha-2 agonists?
Atipamezole
What is the reversal agent for benzos?
Flumazenil
What is the Cushing reflex?
Increased ICP causes sympathetically mediated increases in blood pressure (hypertension) with reflex bradycardia - may indicate imminent brain herniation
What anesthetic drugs could increase cerebral blood flow, therefore increasing intracranial pressure?
Atipamezole, inhalants, ketamine
Although Ketamine can cause an increase in cerebral blood flow and therefore, intracranial pressure, it is not contraindicated in neuro patients. Why?
The increase in CBF/ICP can be eliminated by administering a GABA agonist, such as propofol or benzodiazepines, and Ketamine has a neuroprotective effect to prevent ischemic injury to a reduction of glutamate neurotoxicity
What is the mechanism of action of atracurium?
It is a competitive nondepolarizing neuromuscular blocking agent that has a competitive affinity for acetylcholine receptors, but does not activate it, therefore it blocks it, leading to neuromuscular blockade and paralysis
Which of the following are not DEA controlled substances?
- Fentanyl
- Morphine
- Dexmedetomidine
- Lidocaine
- Buprenorphine
- Bupivicaine
- Acepromazine
- Tramadol
- Butorphanol
- Glycopyrrolate
- Propofol
- Alfaxalone
- Dexmedetomidine
- Lidocaine
- Bupivacaine
- Acepromazine
- Glycopyrrolate
- Propofol
does ace lower seizure threshold?
No
Does ketamine increase ICP and lower seizure threshold?
No, it does not lower seizure threshold but it dose raise ICP
An animal has been given buprenorphine prior to surgery. The amount of any full-mu agonist administered during surgery for analgesia will be:
a. increased
b. decreased
c. remain the same
a. increased
Why do patients undergoing a laparoscopic abdominal surgery need to be on a ventilator?
the pressure on the abdomen and CO2 absorbing into the blood stream during procedure can make these patients not breathe well
What are your primary concerns with pediatric patients?
Hypoglycemia and they rely on heart rate to maintain adequate blood pressure
What fluid solution is atracurium incompatible with?
LRS solution
How can you distinguish between VPCs and 2nd degree type 1 blocks without using an ECG (only your senses)?
2nd degree: no beat on auscultation and no pulse
VPC: apex beat on auscultation but missing pulse
What occurs when you combine an alpha-2 and an opioid in horses?
Produces a standing chemical restraint - horse may plant itself before you have it where you want it to go (give opiate after getting the horse where it needs to be)
Ideal MAP is __-___
60-160
F circuit vs bain circuit
F circuit is circle circuit for animals more than 9kgs and bain is smaller non rebreathing circuit on a bain block for smaller p less than 9kg
Hyperventilation is defined as….
low PaCO2
Know all capnograph stuff
///
All about anticholinergic drugs (atropine and glyco)
MOA: competitive antagonism of acetylcholine at the parasymp. muscarinic cholinergic receptors
S/E tachy, decreased resp. and salivary secretions, bronchodilation, decreased GI motility, can lead to secondary AV block
C/I in animals with pre-existing tachyarrhythmias
All about alpha 2 agonists
MOA: central presynaptic inhibition of norepi release, peripheral activation of post synaptic alpha receptors (these receptors are like everywhereee)
effects- sedation, analgesia, muscle relax, bradycardia, peripheral vasoconstriction, insulin inhibition, resp. depression, mild hypertension followed by hypotension, decreased CO
indications- preanesthetic sedatives, analgesia, sedation
C/I- avoid in p with AV block or arrythmias, avoid in DCM dogs, avoid in highly stress p because can make them more excited, may increase risk of abortions in cattle, not rec. in p with anticholinergics on board already
Opioids, all about it
MOA: binding to specific opiate receptors (mu, kappa, delta) in the brain, SC, and peripheral sites to prevent the transmission of nociceptive information
side effects- analgesia, resp. depression, hypoventilation ad bradycardia, cough suppression, dysphoria, sedation
indications- preanesth for sedation, analgesia, reduction of anesth. meds, minimal CV compromise, but may cause vagally mediated brady which can be tx with glyco or atropine
C/I- can cause histamine release if given fast IV, avoid using without traq in cats and horses bc causes dysphoria, avoid in p w head injuries when CSF pressure is questionable
Why are opioids used cautiously or not at all in CSF pressure status being unknown?
Because opioids can cause hypoventilation which may cause an increase in CO2 which will then cause cerebral vasodilation and further increase the CFS pressure
Dissociatives and all the information about them:
MOA: interference with transmission of nervous impulses of brain leading to dissociation between subconscious and conscious systems
Indications: best with combo of other drugs, premed IM or add to prop or alfax
S/E- increase symp and muscle tone, increased intracranial and intraocular pressures, DO NOT GIVE TO HORSES IM, may cause excessive salivation, can cause increased HR, contractility, BP, CO, and myocardial O2 demand
class 3 controlled substance
no reversal
C/I- IM in horses, HCM, DCM
these drugs are ketamine, tiletamine (Telazol)
___ does not cross BBB but __ does and placenta but no affect on fetus :)
glycopyrrolate; atropine
