Test 2: 27 hypotension Flashcards
three things that control stroke volume
preload
contractility
afterload
arterial blood pressure= CO x —
systemic vascular resistance
need to keep a balance that ensures adequate blood flow
⍺1 and ⍺2 receptors cause
vasoconstriction
β2 receptors cause
vasodilation
what happens to Symp nervous system tone during anesthesia
decreased= vasodilation
anesthetic drugs can also directly cause vasodilation (volatile anesthetics, propofol, acepromazine, lidocaine)
what anesthetics cause an increase in SymNS
ketamine and tiletamine
what anesthetic drugs cause vasoconstriction
⍺ 2 agonists
* Xylazine
* Romifidine
* Detomidine
* Dexmedetomidine
sepsis and histamine will do what to systemic vascular resistance
will decrease SVR by causing vasodilation
what are some things that increase HR during surgery
β1 agonists, anticholinergics, fever, MH
what are some things that decrease HR during surgery
hypothermia, β blockers, opioids
sympathetic works on — receptors to increase HR
β1 ( and β2)
PARA symp slows the HR by
M2 cholinergic receptors
vagus nerve
what are some anesthetic drugs that decrease HR
– Volatile anesthetics
– Opioids
– Propofol, alfaxalone (cats)
– α2 agonists
– Lidocaine
– Cranial epidural with LAs (block cardiac accelerator n.)
what are some anesthetics that cause increased HR
Dissociative anesthetics: ketamine, tiletamine
Alfaxalone (dogs)
what are some things during surgery that can cause an increase in HR
- Pain/ Nociception
- Light anesthetic plane
- Reflex response to hypotension
- Hypercarbia
- Hypoxemia
- Hyperthermia
- Cardiac Pathologies
fluids and vasoconstiction will increase or decrease preload
increase
hypovolemia, hemorrhage
↑ intrathoracic pressure (PPV) will do what to preload
decrease
β1 agonists will — myocardial contractility
increase
ingalant anesthetics and sepsis will — myocardial contractility
decrease
hypothermia, β blockers and opioids will do what to HR
decrease
β1 agonists will do what to HR
increase
⍺ antagonists will increase or decrease SVR
decrease
inhalants, sepsis and endotoxemia will do what to SVR
decrease
⍺ agonists will do what to SVR
increase
why can’t you just keep giving fluids to improve BP
at a certain point will no longer increase venous return and will cause damage/edema
stay on steep part of curve, not in red area
what are some things that effect venous return
venous tone
blood volume
blood distribution
positive pressure ventilation (too high and you can collapse vessels)
what are some things that can cause decrease contractility
§ Inhalant anesthetics
§ Hypoxemia / anoxia
§ Acidosis / acidemia
§ Catecholamine depletion
§ Myocardial ischemia / infarction
§ Systolic dysfunction/ CHF
§ Hypocalcemia
contraction is impacted by β1 agonists and calcium handling
what are some things that increase afterload
everything that increases SVR
(ketamine and tiletamine that increase SNS, or alpha 2 agonists like xylazine and dex that cause vasoconstriction (initially))
aortic stenosis
pulmonic stenosis
1st step if pt is hypotensive during anesthetsia
check depth- turn down iso if possible
step 2 is pt is hypotensive
check HR and fluid status
if low HR < 50-80 (dog), < 100 (cat)
give anticholinergic
Glycopyrrolate or atropine (faster and shorter acting)
fluid challange
give small bolus to figure out where on curve you are, if BP increases with bolus good, if not can fluid overloaded
step 3 if pt is hypotensive
sympathomimetics
§ Naturally-occurring catecholamines
§ Synthetic catecholamines
§ Synthetic non-catecholamines
inotrope or vasopressors
β1 receptors work where and how
heart inotropic and chonotropic
increase HR and contractility
⍺1 and ⍺2 receptors work where and how
vascular smooth muscle (contraction)
β2 receptors work where and how
vascular smooth muscle
lungs (bronchial)
dilation/relaxation
goal of inotropes and vasopressors during hypotension is to
increase myocardial contractility
counteract vasodilation of inhalant anesthesia and sepis
counteract bronchospasm
treat allergic reactions
epi works on what receptors
α1,α2,β1,β2
Naturally-Occurring catecholamine → causes increased contractility, HR and cause vascular and bronchial smooth muscle dilation
epinephrine will cause
Naturally-Occurring catecholamine → causes increased contractility, HR and cause vascular and bronchial smooth muscle dilation
low dose epi- vasodilation ↓BP
high dose epi- vasoconstriction, inotropy = ↑ pulse pressure
works on α1,α2,β1,β2 receptors
epi is used clinically for
CPR
CRI to increase myocardial contractility
treat anaphylaxis
negative effects of EPI
increase arrhythmias
decrease renal blood flow
increase coronary blood flow
vasoconstriction: to skin, mucosa and hepatorenal circulation
vasodilation: skeletal muscle
norepinephrine works on what receptors
β1 and ⍺
(no β2 effect- no vasodilation)
norepinephrine is used for
used in refractory hypotension- septic shock
causes intense vasoconstriction- increase SBP, MBP and DBP
baroceptor mediated bradycardia with minimal change to CO
dopamine works on what receptors
low dose- D1
medium dose- β1 = increase inotropy and chronotropy
high dose- ⍺ - peripheral vasoconstriction
effects of dopamine
Increased CO, HR, BP & SVR
(β1= ↑CO, ↑HR. ⍺= ↑BP, ↑SVR)
Endogenous NE release→ can see arrhythmias
dobutamine works on what receptors
β(1+2) agonist
- increases contractility
- slight peripheral vasodilation (β2)
- increase CO by increasing HR
- high dose can cause tachycardia or arrhythmia
dobutamine causes
- increases contractility
- slight peripheral vasodilation (β2)
- increase CO by increasing HR
- high dose can cause tachycardia or arrhythmia
works on β 1+2 receptors
vasopressin works on — receptor
V1R
works on vascular smooth muscle
low dose: vasodilation
high dose: vasoconstriction
how does vasopressin work
works on vascular smooth muscle
low dose: vasodilation
high dose: vasoconstriction
works on V1R receptor
vasopressin can be used when
CPR
shock
works on vascular smooth muscle
low dose: vasodilation
high dose: vasoconstriction
