Antihypertensives/Beta Blockers Flashcards
In anesthesia, before treating hypertension, what should you do?
determine why the patient is hypertensive in the first place!!!! figure out what the cause is before giving an antihypertensive/BB
What could be some potential causes of hypertension in a patient receiving anesthesia?
- pain (give opioids)
- hypothermia (bair hugger)
- anxiety (give anxiolytic)
- increased ICP (give propofol)
- bladder distension (cath)
- poorly controlled HTN (CAREFULLY give antihypertensive/BB)
- lack of anesthesia (turn your gas on!!)
T/F: hypertension under anesthesia should always be treated with an antihypertensive or beta blocker
FALSE
- many times you can treat the cause of HTN and BP will decrease
- use antihypertensives sparingly
What is the MOA of labetalol?
- NONSELECTIVE beta antagonist
- SELECTIVE alpha1 antagonist
- blocking beta1: decrease HR and contractility
- blocking beta2: vasodilation
- blocking alpha1: arteriolar vasodilation
What is the ratio of alpha to beta blockade with labetalol?
1 (a) to 7 (b) blockade
1:7 ratio
What is labetalol used used for?
- acute and chronic HTN in pregnant patients
- treat increases in BP and HR from stimulation (like intubation)
When is labetalol contraindicated?
- bronchospastic disease
- impaired cardiac conduction
- underlying resting bradycardia
How do we achieve BP reduction with labetalol use?
- decreased PVR, which can depress cardiac contractility
- essentially unchanged CO
T/F: Labetalol can significantly affect CO
false
- per Barash, CO is essentially unchanged
T/F: labetalol has profound affects in CBF and ICP
false
- only causes minimal affects in CBF and ICP
Labetalol Dosing
5-20 mg boluses IV
- less is more!!! use with caution
Labetalol onset and duration
Onset: 1-2 min
Duration: up to 6 hours
Why is labetalol contraindicated in bronchospastic disease?
a potential side effect of labetalol is bronchoconstriction
What is the MOA of esmolol?
SELECTIVE beta1 antagonist
- directly only works on the heart
Does esmolol have rapid or slow onset?
esmolol has rapid onset
Is esmolol short acting or long acting?
short acting
When would esmolol be used?
- perioperative tachycardia
- pretreatment during intubation/extubation
What cardiac effects do we see with esmolol?
- decrease in HR, contractility, and CP
- some decrease in BP with no rebound effects
When is esmolol contraindicated?
- bradycardia
- heart block
- cardiogenic shock
- heart failure
Esmolol Dosing
- 10 mg boluses IV
- 50 mcg/kg/min infusion after a 0.5 mg/kg bolus
Esmolol onset and duration
Onset: rapid
Duration: 10-15 min
How is esmolol metabolized?
plasma esterases
What is the reasoning behind esmolol’s short duration?
metabolism by plasma esterases
An infusion of esmolol at __________ should be started after a _________ bolus is given
- 50 mcg/kg/min infusion
- 0.5 mg/kg bolus
What is the MOA of propranolol?
NONSELECTIVE beta1 and beta2 antagonist
Due to propranaolol’s beta2 antagonist effect, what should be our concern?
- risk of bronchoconstriction
- careful with use in bronchospastic disease
when is propranolol contraindicated?
- bronchospastic disease
- AV block
- bradycardia
When would propranolol be used?
- HTN
- angina
- acute MI
- pheochromocytoma
- anxiety/panic attacks
How does propranolol achieve decreased BP?
decrease in contractility, HR, and CO, therefore causing decrease in myocardial oxygen demand
Propranolol Dosing
1 - 3 mg IV
- no more than 1 mg/min
- titrated to effect
Propranolol onset and duration
Onset: 2-3 min
Duration: up to 4-6 hours
What is the MOA of metoprolol?
- SELECTIVE beta1 adrenergic receptor antagonist
- prevents inotropic and chonotropic responses to beta stimulation
When would metoprolol be used?
- rapid HR and contractility control
- treatment for MI
Metoprolol Dosing
1-5 mg IV; up to 15 mg
- best to give 1 mg at a time
What is the half-life of metoprolol?
3-4 hours
What is the action of vasopressin in the body?
- antidiuretic hormone via increasing water reabsorption in the kidneys
- released by the posterior pituitary
When is vasopressin used?
- cardiac arrest (but removed from ACLS algorithm)
- sepsis
- shock
- hypotension secondary to ACE inhibitors refractory to catecholamines or sympathomimetics
What are the sites of action of vasopressin and what are their effects?
V1: CV effects
V2: renal effects
V3: pituitary effects
Vasopressin Dosing
1-2 unit bolus
How is vasopressin diluted for safe administration?
10/20 units/1mL in a 10/20 mL syringe to get 1 unit/mL concentration
Vasopressin is a potent _____________ in what two locations?
- potent vasoconstrictor
- arterial
- mesenteric
Knowing that vasopressin is a potent vasoconstrictor, what should we consider when giving this during/after a surgery?
- vasoconstriction can potentially cause necrosis in the surgical site
When would hydralazine be used?
- HTN
- heart failure
- eclampsia
What is the MOA of hydralazine?
- direct systemic arterial vasodilator
- blocks Ca++ release from sarcoplasmic reticulum
- causes relaxation of arterial smooth muscle
What are the cardiac effects seen with hydralazine administration?
- decreased BP
- increased HR, SV, CO
When is hydralazine contraindicated?
- coronary artery disease (CAD)
- increased ICP
What effect does hydralazine potentially have on ICP?
potentialy increased ICP
Hydralazine Dosing
2.5-5 mg IV
- titrated q 20-30 min
Hydralazine onset and duration
Onset: 15-30 min
Duration: 4-6 hours
How often is hydralazine titrated?
every 20-30 minutes
Nitroglycerine
Nipride
