Cardiovascular Complications Flashcards
what are the common complications related to:
- heart rate
- blood pressure
- volume
Heart rate:
- tachycardia
- bradycardia
- arrhythmias
Blood Pressure:
- hypertension
- hypotension
Volume:
- hypovolemia
- hypervolemia
what are some considerations with heart rate
- age of animal
- size/breed of animal
- resting HR
do adults or neonates have a higher HR and why
neonates:
- immature SNS
- increased metabolic rate
CO =
BP =
CO = HR x SV
BP = CO x SVR
what influences stroke volume
preload, afterload, contractility
what influences oxygen delivery
- cardiac output
- oxygen content
- also ETCO2 (indicates O2 consumption and CO2 production in tissues)
what is bradycardia
slow heart rate
what are the consequences of excessively low HR (bradycardia)
will directly lower CO and BP
(since co = HR x sv and bp = CO x svr)
bradycardia is a consequence of increased _____________ activity
parasympathetic
what are the 3 broad causes of increased parasympathetic tone (and thus bradycardia)
1) increased vagal tone
2) drug-induced
3) reflex mechanism due to hypertension
what are causes of:
1) increased vagal tone
2) drug induced bradycardia
3) reflex bradycardia from hypertension
1) oculocardiac reflex (eye surgery), GI pressure, during expiration
2) alpha-2 agonists, opioids
3) alpha-2 agonists, Cushing reflex (increased intracranial pressure), primary hypertension
besides increased parasympathetic tone, what are 3 other causes of bradycardia
1) hyperkalemia
2) hypothermia
3) cardiac disease (sick sinus syndrome)
when do we treat bradycardia
- if marked
- if hypotension or low CO is associated
- if markedly irregular and/or dysrhytmias are also present
how do we treat bradycardia caused by:
- increased vagal tone
- drug induced
- reflex mechanism for hypertension
- cardiac disease
- increased intracranial pressure
- hyperkalemia
- hypothermia
- increased vagal tone: ANTICHOLINERGIC
- drug-induced: REVERSAL, LIDOCAINE, ANTICHOLINERGIC (if not hypertensive)
- hypertension: CONTROL HYPERTENSION
- cardiac disease: ANTICHOLINERGICS, ISOPROTERENOL, PACEMAKER
- increased ICP: CONTROL ICP
- hyperkalemia: DECREASE K+, CALCIUM GLUCONATE
- hypothermia: WARM
what is tachycardia? what are the consequences
fast HR;
- increased CO
- increased BP
- decrease SV if too fast
- increased O2 consumption by myocardium can cause myocardial ischemia and arrhythmias
in general, tachycardia is caused by increased __________________ activity
sympathetic
what are examples of conditions that increase sympathetic activity, leading to tachycardia
- light anesthetic plane/pain
- hypotension/hypovolemia (reflex)
- hypercapnia/hyperthermia
- drug induced
- hypoxia/shock
- specific diseases
what are examples of drugs that cause tachycardia
ketamine, sympathomimetics, anticholinergics
what are examples of specific diseases that cause tachycardia
- pheochromocytoma
- hyperthyroidism
- heart disease
how do you treat tachycardia caused by the following:
- light anesthetic plane/pain
- hyperthermia/hypercapnia
- hypotension/hypovolemia
- hypoxia/shock
- specific diseases
- drugs
- light anesthetic plane/pain: CHECK DEPTH/ANALGESIA
- hyperthermia/hypercapnia: COOL DOWN/VENTILATE
- hypotension/hypovolemia: FLUIDS/SYMPATHOMIMETICS
- hypoxia/shock: FLUIDS, IONOTROPES
- specific diseases: ADDRESS
- drugs: STOP GIVING
what do we look for when diagnosing dysrhythmias
- all waves present (P, QRS, T)
- all P associated with a QRS
- note rhythm
- heart rate
what is by far the most common dysrhythmia diagnosed during anesthesia
AV block
what is going on during AV blocks
conduction from the atria to ventricles is impaired (P and QRS no longer associated)
what is commonly associated with AV blocks (tachycardia or bradycardia)
bradycardia
what is the difference between a Type 1 and Type 2 2nd degree AV block
Type 1: prolonged P-QRS and sometimes dropped QRS
Type 2: no prolonged P-QRS and sometimes dropped QRS (worse)
what are causes of AV blocks during anesthesia
- increased vagal tone
- drugs: (alpha-2, low dose anticholinergic)
- intrinsic cardiac disease
how do we treat AV blocks during anesthesia:
- reverse alpha-2
- anticholinergics (check bp first if on an alpha-2)
- isoproternol
- pacemaker if 3rd degree
what is a ventricular premature contraction (VPC)
spontaneous depolarization in the ventricle (ectopic focus in ventricle)
T/F VPCs are associated with atrial activity
F
what are signs of VPC
- no P wave
- premature
- fucked QRS
how can we diagnose a VPC without ECG signs and why does this happen?
pulse deficit; because the premature nature prevent adequate diastolic filling
what are causes of VPC
- cardiac disease
- catecholamine release
- myocardial hypoxia
- electrolyte imbalance (low Mg, low K, high Ca)
- myocardial depressant factors
- arrhythmogenic drugs
- irritation of ventricle (mechanically during surgery)
how do we decide whether to treat VPC or not
if BP and CO are affected, we treat; if not, we do not treat
how do we treat VPC
- oxygenation
- improve contractility
- control underlying cause (ex. electrolytes)
- drugs
what drugs can we use to control VPC
- lidocaine
- procainamide
- magnesium sulfate
- beta-blockers
- amiodarone (last resort)
what is ventricular tachycardia
more than 3 VPC in sequence with a high HR
why do you ALWAYS treat ventricular tachycardia when it occurs
it can progress to ventricular fibrillation
how do we treat ventricular tachycardia
usually same as VPC (ex. lidocaine bolus)
why is a low pressure bad
it may indicate inadequate perfusion to vital organs
what is an acceptable and optimal mean BP in:
- adults
- neonates
ADULTS:
Acceptable: 60
Optimal: 85
NEONATES:
Acceptable: 50
Optimal: 75
what is the most common cause of hypotension in healthy animals
excessive anesthetic depth
what are all the causes of hypotension
- excessive anesthetic depth
- hypovolemia
- peripheral vasodilation
- cardiac dysrhythmias
- decreased contractility
- bradycardia
- tachycardia (pumping nothing)
what are the 5 steps in a hypotension treatment plan
1) depth: check plane
2) dehydration/bleeding: correct fluid deficits
3) HR: tachycardia, bradycardia, treat dysrhythmias
4) increase contractility
5) increase vascular resistance to treat vasodilation
what is hypertension:
SAP
DAP
MAP
SAP > 180 (200)
DAP > 60 (100)
MAP > 100 (140)
what are causes of hypertension during anesthesia
- inadequate depth/analgesia
- drug induced
- hypercarbia
- hypoxia
- underlying disease
what is the relationship between hypovolemia and hypotension
a hypovolemic patient is expected to be hypotensive but a hypotensive patient is not always hypovolemic
T/F hypovolemia results in decreased blood flow and perfusion but hypotension does not always
T
what are the hallmarks of hypovolemia
- increased HR
- decreased CO
- decreased BP
- hemodilution (decreased PCV and TS)
what is the treatment for hypovolemia
replacement fluids or blood products
increase contractility (inotropes, balanced anesthesia)
T/F if you vasoconstrict a patient that is enough to treat hypotension
F; need to correct fluid deficits
