Cardiovascular Emergencies Flashcards
1. Explain concept related to the care of an ED patient experiencing a cardiovascular emergency. 2. Describe various patient presentations related to cardiovascular emergencies. 3. List interventions necessary for a patient presenting with a cardiovascular emergency.
cardiac output
SV x HR
SNS r/t HR
increases HR d/t:
- stress
- anxiety
- acute pain
- release of catecholamines
- hypotension
- drugs w/ + chronotropic effects
PNS r/t HR
decreases HR d/t:
- vagus nerve stimulation
- cardiac conduction abnormalities
- drugs with (-) chronotropic effects
heart rhythm r/t HR
some dysrhythmias can impair adequate filling of heart chambers or result in loss of atrial kick which contributes to 20-40% of ventricular filling in healthy adult
define stroke volume
amount of blood ejected from each ventricle per contraction
stroke volume overview
measured in ml/beat
amount ejected / ventricle is equal in healthy patient
positively influenced by preload and contractility
define contractility
strength of each myocardial contraction
contractility overview
significantly contributes to CO
affected by preload (Frank-Starling law), afterload, electrolyte status, myocardial oxygenation, amount of functional myocardium, and drugs with inotropic effects
define preload
volume of blood that results in pressure or stretch of the ventricles during diastole
affected by amount of venous return to heart
what increases preload?
peripheral venous constriction
alpha adrenergics (epi, norepi, dopamine)
what decreases preload?
decreased intravascular volume 2/2:
- hemorrhage
- diuresis
- v/d
- third spacing
- redistribution of blood flow
also vasodilators
define afterload
resistance to ventricular emptying during systole
negatively influences stroke volume
what increases afterload?
vasoconstriction or mechanical obstruction of ventricular outflow such as:
- aortic or pulmonic stenosis
- HTN
- hypothermia
- compensatory shock mechanisms
what decreases afterload?
- hyperthermia
- distributive shock
- vasodilators
increasing CO: adults vs children
adults: HR and SV
children: tachycardia (cannot increase SV)
define MAP
average pressure over entire cardiac cycle
(DBPx2 + SBP)/3
define pulse pressure
difference between systolic and diastolic BP
calculate via systemic or pulmonary pressure
low systemic pulse pressure
narrowing pulse pressure
decreased LV SV, blood loss, low stroke volume 2/2 shock or cardiac tamponade
high pulse pressure
widening pulse pressure
may be transient and normal effect of activity
caused by chronic or acute conditions
chronic causes of high pulse pressure
atherosclerosis
aortic regurg
acute causes of high pulse pressure
aortic aneurysm aortic dissection PDA endocarditis anxiety fever pregnancy
Cushing Triad
indicative of increased intracranial pressure
widening pulse pressure or HTN
bradycardia
irregular breathing pattern
chronotropes
affect HR (generation of electrical impulse) at SA node
inotropes
affect contractility