NR 500 IMC STUDY GUIDE
Cardiac
Anatomy & Physiology – see power point
Hemodynamics – refers to fluid, dynamic state of the human cardiovascular
system
- Volume, pressure , perfusion, oxygen demand, oxygen delivery
- Cardiac output – SV X HR = CO
- Normal Ejection fraction for 60-70%
- In HF – less than 40% Ejection Fraction
Preload – Amount of stretch placed on a cardiac muscle fiber just before systole,
affected by the volume at the end of diastole, related to left ventricular end –
diastolic pressure.
- Decreased preload – s/sx – fluid volume deficit – Tachycardia,
tachypnea, poor urine output, Negative fluid balance, poor skin turgor,
increasing bun.
- Less volume = less O2 delivery to tissue.
Afterload – The force or pressure against which a cardiac chamber must eject
blood, affects stroke volume by increasing or decreasing the ease of emptying a
ventricle during systole.
- Factors that affect afterload include hypertension, vasoconstriction,
valvular disease, hypercoagulability, hyper/hypovolemia, pulmonary
hypertension, copd, mitral valve disease, cardiac tamponade, Right
ventricle can’t hand increase pressure.
Contractility – results from inotropic capabilities and cardiac workload. The
ability of the fibers to stretch and contract.
- The contractile force of the heart which is independent of preload and
afterload status, also known as the “pump”.
- What increases contractility – SNS stimulation, endocrine disorders,
early sepsis, sympathomimetic medications like epinephrine.
- What decreases contractility – low BP, low SPO2, low urine output, low
peripheral perfusion, high HR(trying to compensate), high respiratory
rate.
Ejection Fraction – the percent of blood in the ventricle that is ejected with each
systole- 60-70 Normal, for HF is less than 40%
Normal CVP and causes of high and low readings – Central venous pressure aka
Right atrial pressure.
- Normal 2 to 6mmHg
- Causes of high readings – right ventricle failure, mechanical ventilation,
fluid overload.
, - Causes of low readings – hypovolemic state, vasodilation like sepsis,
medications.
Pulse pressure - difference between the systolic and diastolic blood pressure
MAP –Mean arterial pressure for perfusion is minimum of 60.
- MAP = systolic BP + (2X diastolic BP) \ 3 or 1/3 pulse pressure +
diastolic pressure.
- MAP tells us organ perfusion if less than 60 brain, kidney, will be
effected.
ECG rhythms and normal measurements – see power point.
- P-R interval 0.12-0.20
- QRS interval <0.12
- QT interval <0.40
- U wave occasionally seen.
Shockable rhythms – VT, VFib, SVT,
Treatments for tachycardias and bradycardias
Tachycardia -
Patient Treatment
The patient's QRS Try vagal maneuvers. Give adenosine 6 mg rapid
is narrow and IV push. If patient does not convert, give
rhythm is regular. adenosine 12 mg rapid IV push. May repeat 12 mg
dose of adenosine once.
Does the patient's rhythm convert? If it does, it was probably reentry
supraventricular tachycardia. At this point you watch for a recurrence. If the
tachycardia resumes, treat with adenosine or longer-acting AV nodal blocking
agents, such as diltiazem or beta-blockers.
Patient Treatment
The patient's QRS Consider an expert consultation.
is narrow (< 0.12
sec).
The patient's Control patient's rate with diltiazem or beta-
rhythm is blockers. Use beta-blockers with caution for
irregular. patients with pulmonary disease or congestive
heart failure.
, If the rhythm pattern is irregular narrow-complex tachycardia, it is probably atrial
fibrillation, possible atrial flutter, or multi-focal atrial tachycardia.
Patient Treatment
Patient's rhythm has wide (> Expert consultation is advised.
0.12 sec) QRS complex AND
Patient's rhythm is regular.
Patient is in ventricular Amiodarone 150 mg IV over 10 min;
tachycardia or uncertain repeat as needed to maximum dose of
rhythm. 2.2 g in 24 hours. Prepare for elective
synchronized cardioversion.
Patient is in supraventricular Adenosine 6 mg rapid IV push If no
tachycardia with aberrancy. conversion, give adenosine 12 mg
rapid IV push; may repeat 12 mg dose
once.
Patient's rhythm has wide (> Seek expert consultation.
0.12) QRS complex AND
Patient's rhythm is irregular.
If pre-excited atrial Avoid AV nodal blocking agents such
fibrillation (Atrial fibrillation as adenosine, digoxin, diltiazem,
in Wolff-Parkinson-White verapamil. Consider amiodarone 150
Syndrome) mg IV over 10 min.
Patient has recurrent Seek expert consultation,
polymorphic VT
If patient has torsades de Give magnesium (load with 1-2 g over
pointes rhythm on ECG 5-60 min; then infuse.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Smartstudies. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $18.49. You're not tied to anything after your purchase.
