Hemodynamics Flashcards
what is hemodynamic monitoring?
monitoring of tissue perfusion
what is cardiac output a good indicator of?
best indicator of the heart’s contractile or inotropic ability
what are the meanings of + & - inotropes?
+ inotropic = better contraction (squeeze)
- inotropic = less forceful contraction
what is the definition of cardiac output?
volume of blood ejected by the heart in 1 minute into the systemic circuit
what is normal cardiac output amount per minute & at rest?
4-8 L of blood per minute (4-6 L at rest)
does CO equate for differences in body size?
No!
what is cardiac index?
the CO divided by an individual’s body surface area
what is considered a normal CI range?
2.2 - 4.0
if CI drops below 2.2, what is usually used to help get more blood ejected systemically?
a + inotrope
what is the formula for cardiac output?
CO = SV x HR
what is stroke volume?
volume of blood ejected by the left ventricle during each systole
what is the normal SV range?
60-100 ml
what 3 factors is SV affected by?
- preload
- afterload
- contractility
how does increased preload affect stroke volume, ventricular work & myocardial O2 requirements?
increases all of them!
what are some assessment findings w a right-sided elevated preload? list 3
- JVD
- edema
- Hepato-jugular reflux (HJR) (when pressing on the liver, jugular veins begin to bulge)
what are some assessment findings w left-sided elevated preload? list 5
- Orthopnea (trouble breathing when lying down)
- Dyspnea
- cough
- crackles
- S3 (indicates severe HF, mitral regurgitation, low EF, etc.)
what types of medications are given to reduce preload? name 2
- Diuretics (directly reduce blood volume)
- Nitrates (promote vasodilation; decreases pressure esp on venous side)
give an example of a nitrate med
Nitroglycerin
how should a patient w a high preload be positioned?
semi-fowler’s / high-fowlers position
what are some things that can cause a decreased preload? name 5
- hypovolemia
- hemorrhage
- third spacing (capillaries become more permeable so fluid begins to leak from the intravascular space into the interstitial space)
- diuresis (peeing off all volume decreasing preload)
- vasodilation (SHOCK)
what are some assessment findings associated w a decreased preload? name 6
- tachycardia / hypotension (compensation)
- dry, cool skin
- dry mucous membranes
- poor skin turgor
- alteration in LOC
- decrease urine output / vital organ perfusion
what are the hemodynamic parameters for right sided preload? where are they inserted?
CVP (inserted into the intra jugular or subclavian vein)
what are the hemodynamic parameters for left sided preload? where are they inserted? list 2
- PAWP (wedge pressure)
- pulmonary artery occlusive pressure (PAOP)
catheter goes through right side of the heart & sits on the pulmonary artery
what is used as an estimate if we can’t get physical wedge pressures?
pulmonary artery diastolic pressure (PADP)
how do we increase preload on a patient? list 4 ways & specific conditions they are commonly used for
- crystalloids (often used for dehydration) (NS, LR)
- Colloids (often used for third spacing)
- PRBC (for hemorrhages)
- modified tredelenburg / supine w legs raised positionings
what is afterload?
increased ventricular wall tension or stress during systolic ejection (pressure that the ventricle has to over come to eject blood into circulation during systole)
what is the most crucial factor for determining afterload?
systemic vascular resistance (SVR)
what are 3 ways to measure afterload?
- MAP (measures tissue perfusion)
- SVR (specific to left ventricle)
- pulmonary vascular resistance (PVR) (specific to right ventricle)
what type of catheter is needed to calculate SVR & what must you know to calculate it?
invasive one that goes into the pulmonary artery
must know cardiac output
what conditions are commonly seen w a high PVR
pulmonary embolism or severe pulmonary hypertension
what are some things that cause an elevated afterload? list 5
- vasoconstriction (increased SVR)
- meds (alpha 1 agonists) Epi, Norepi
- catecholamine releases or compensatory mechanisms (hypovolemia, pain, hypoxia, SHOCK, hypothermia)
- hypertension
- increased aortic impedance (EX: aortic stenosis)
which 4 classes of meds are used to reduce afterload?
- vasodilators (EX: nitroprusside or Nipride)
- Ca channel blockers (EX: Nicardiopine)
- ACE-Inhibitors (prils)
- angiotension receptor blockers (sartans)
what are some things that cause a decreased afterload? list 4
- vasodilation (decreased SVR) from meds or shock states
- inadequate aortic valve function (aortic valve regurgitation or back flow)
- inflammatory response
- hyperthermia
which meds are used to increase afterload? give examples
vasopressors e.g. adrenergic stimulants (Norepi, Phenylphrine, Dopamine & vasopressin)
what is important to know about vasopressin for increasing afterload?
it’s used as an augumenting therapy so the pt will already be on norepi, phenylphrine or dopamine before they are on this med
what is contractility?
the inotropic action of the heart during systole or the force of each ventricular contraction
what factors influence contractility? list 6
- intracellular Ca & ATP (Ca chloride is sometimes pushed during code situations)
- coronary artery perfusion
- cardiac O2 supply / demand balance
- HR
- BP
- valve competence
what are some assessment findings w low contractility? list 5
- tachycardia (compensation)
- cool, pale skin
- decreased urine output (body is trying to hold onto more fluid –> RAAS system)
- mental status changes
- poor peripheral circulation
what are 3 ways we measure contracility?
- CO (measured w pulmonary artery or PA cath)
- CI (pulmonary artery or PA cath)
- ejection fraction (measured w an echo)
what is a normal ejection fraction?
around 70% but anything above 50% is appropriate (100% is not normal!)
what are ways we can increase contracility? list 2
- increasing the preload = volume expansion, increasing stretch
- positive inotropic agents (Dopamine, Digoxin, Milirinone) all affect Beta 1 receptors
how do we decrease the contractility or workload of the heart? give examples
Negative inotropic agents (Beta blockers & Ca channel blockers that block beta 1 receptors)
what are the meanings of + & - chronotropes?
+ = increasing the HR
- = decreasing the HR
what does dromotropic mean & which meds affect this?
rate of electrical conduction; affected by meds like Digoxin or Ca channel blockers
name two meds that are beta 1 agonists
Dobutamine & Digoxin
name a med that is considered a beta 1 antagonist
Metoprolol
name a med that is an example if a beta 2 agonist. what does it produce?
Epinephrine; produces vasodilation for asthma or anyone w broncho constriction or in anaphylactic shock
what is an example of a nonselective beta blocker?
Labetalol
what do alpha 1 receptors produce & how do they affect the SVR?
vasoconstriction; they increase the SVR
what type of response does the PNS create & what does it produce?
cholinergic response; it produces acetylcholine & produces negative dromotrophic & chronotropic effects on the heart
which nerve innervates the PNS w the heart?
vagus nerve (people passing out)
what do arterial lines monitor?
continuous BP monitoring & ABGS
what does CVP monitoring show?
right sided preload
what does a PA cath monitor show?
shows all hemodynamic parameters EXCEPT a systemic BP
name the 3 arterial line sites
- radial (most common)
- femoral
- brachial
what must be done to monitoring systems at each HOB change up to 60 degrees supine?
leveling the stopcock (air/fluid interface) of transducer to phlebostatic level
what is part of the initial assessment with monitors?
zeroing the balance of the transducer
what is the phlebostatic axis?
rough height of the atrium & reference level for placement of the transducer to ensure accuracy of measurements
the phlebostatic axis is located at the intersection of which two reference lines?
4th ICS at sternum & mid-axillary line
when looking at the arterial pressure monitoring, what does the systolic wave represent?
represents ejection phase of left ventricular systole; it’s the highest point recorded at peak of waveform
when is the diastolic wave measured in arterial pressure monitoring?
measured at end-diastole just prior to the next systolic pressure
what is the normal MAP range?
70 - 90 mm Hg
describe the Allen’s test & when it must be done
occluding the radial artery to make sure there is still perfusion to the fingers; must be done prior to placing an arterial line
If a pt’s BP changes quickly on an arterial line monitor, what should you do?
check pt, connections & level of transducer!!
what does CVP measure?
pressure in the right atrium or vena cava & provides info regarding intravascular volume
where is a central venous cath inserted into?
vena cava
how many mm of mercury is the invasive catheter bag pumped up to?
300
what are some complications related to CVP monitoring? name 5
- infection
- dislodgement
- pneumothorax
- thrombosis
- air embolism (can happen esp when catheter is being removed)
when removing a central venous cath, what instructions will you give to the pt?
lie them flat & have them hold their breath when removing to create positive pressure
what is the PA cath also known as?
Swan-Ganz Catheter
With a PA cath, why is there always just an estimated wedge pressure on the left?
if the cath were to cross over to the left side, it would hit the lungs
what was a CV wave form look like on a monitor?
squiggly line when it reaches the right atrium
what does a PA cath wave form look like on a monitor?
wedge wave form
explain the thermodilution CO method
injection of 10 ml of room temp solution, subsequent change in core blood temp at the distal end of catheter sensed by thermistor; computer calculates CO
what are some complications with a PA cath? name 5
- pneomothorax
- infection
- ventricular dysrhymias (passing through the right atrium & right ventricle)
- pulmonary artery rupture or perforation (internal bleeding)
- air embolus (esp during removal)
if a clot is present in a line, what should you do before flushing it?
aspirate
what factors determine cardiac output?
stroke volume & HR
what is preload?
the mount of stretch placed on cardiac muscle fibers just before systole / volume (intravascular space or within the vesicles) of blood in the ventricle at the end of diastole
what does the volume of blood in preload create?
a filling pressure
what are some things that cause an elevated preload? name 4
- volume overload
- left & right ventricular dysfunction (both affect that inotropic action of the heart)
- valvular defects (stenosis or insufficiency)
- cardiac tamponade (fluid fills up pericardial space affecting the overall stretch leading to a less forceful contraction)
what parameters are measured w a PA cath?
CVP & pulmonary artery pressures
