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What are the general goals with cardiovascular dz?
- maintain cardiac output
- maintain tissue perfusion
How does low HR and high HR affect CO?
- Low HR: decreases CO directly
- High HR: can also decrease CO b/c of decreased diastolic filling time, absence of atrial kick
How do low and high preload affect CO, and what causes each?
- Low preload: decreases CO; dehydration, shock, hemorrhage
- High preload: decreases CO; ventricular overdistension, systolic dysfunction
How do low and high afterload affect CO, and what causes each?
- Low afterload: increases CO; acepromazine, inhalants, propofol, alfaxalone [vasodilators]
- High afterload: decreases CO; alpha-2 agonists [increased SVR]
How do increased and decreased inotropy affect CO, and what causes each?
- Increased inotropy: increases CO; catecholamines, dobutamine, ketamine
- Decreased inotropy: decreases CO; cardiomyopathy, CHF, pericardial effusion, general anesthesia
What are anesthetic considerations for animals with volume overload (MV regurg, etc)? (4)
- promote forward flow of bloe
- avoid fluid overloading, which might reduce preload
- maintain HR (decreases time for regurgitant flow)
- decrease afterload (avoid alpha-2's, avoid stress)
What is the anesthetic plan for an animal at risk of volume overload?
- Pre-med: low dose acepromazine (vasodilator- decrease afterload) or benzodiazepine (minimal cardiac effects)
- Analgesia: opioids (minimal cardiac effects, may decrease HR, which can be treated with atropine)
- Induction: alfaxalone or propofol to effect (vasodilators); etomidate if CHF (no CVS effects)
- Lower fluids
- Inhalants at lowest possible concentration
What are special considerations for DCM?
- [decreased systolic function] be ready to treat tachyarrhythmias- lidocaine, procainamide
- positive inotropes- dobutamine, dopamine
Causes of volume overload.
- MV regurg/ insufficiency
Causes of pressure overload.
- subaortic stenosis
- pulmonic stenosis
What are anesthetic considerations and plan for animals with pressure overload (SAS, PS)?
- [poor ventricular compliance] maintain adequate preload while avoiding overload
- treat intra-op hypotension aggressively with volume (opposite of volume overload)
- avoid drastic increases in HR- premeds and opioids
What are causes of diastolic dysfunction?
- hypertrophic cardiomyopathy/ obstructive CM
- small end diastolic volumes
- stiff ventricle
What are anesthetic considerations for animals with HCM/ diastolic dysfunction?
- optimize diastolic filling
- maintain lower heart rates (more time for filling)
- avoid drugs that increase contractility (gets rid of more EDV, which is bad in this case)- ketamine, inotropes
- don't decrease afterload (may worsen situation)
What is the anesthetic plan for an animal with HCM?
- avoid ketamine
- low dose alpha-2 may be helpful (increases afterload--> some volume stays behind--> reduce outflow tract obstruction)
- maintain vascular tone for BP support- dopamine, phenylephrine [I thought we didn't want to increase inotropy???]
What is the treatment for Vtach?
IV lidocaine or procainamide
What are reasons to treat VCPs under anesthesia? (4)
- Vtach or runs
- multiform (coming from different foci)
- R on T phenomenon (R wave on top of previus T wave- Vtach)
- hemodynamic compromise (high HR, no atrial kick, poor perfusion)
What is the treatment for a fib?
What is the treatment for supraventricular tachycardia?
How do you treat bradycardia?
- correct any underlying cause (ex. electrolytes)
- parasympatholytic (atropine, glycopyrrolate)
- complete AV block may require pacemaker
What are anesthetic considerations for animals with upper respiratory disease?
- pre-oxygenate by mask (but don't stress them out! maybe premed first)
- adequate sedation- decrease stress, watch for worsening obstruction, avoid drugs that cause vomiting (alpha-2's, opioids)
- IV access as soon as possible
- rapid induction and intubation- airway airway airway
- use smaller tubes for brachys (brachy dz- small trachea)
- monitor SpO2 and EtCO2
- recovery in sternal recumbency, extubate as late as possible
If there is airway swelling/ obstruction after recovery (ex. brachycephalic dog), what do you do? (3)
- corticosteroids for acute airway tissue swelling
What are the components of brachycephalic disease? (4)
- elongated soft palate
- stenotic nares
- everted laryngeal saccules
- hypoplastic trachea
How is lower airway disease managed with anesthesia?
- similar to upper airway disease
- in cases of poor gas exchange after intubation and 100% FiO2, positive pressure ventilation +/- PEEP