Hemodynamics Flashcards
The term used to describe the forces and mechanics of blood flow
Hemodynamics
The measurement and monitoring of the factors that influence circulation
Hemodynamic monitoring
Volume of blood ejected by the heart over 1 minute
Cardiac output (CO)
CO normal range
4-8 L/min
The volume of blood ejected from the ventricle with each beat of the heart
SV
What are the 3 components of stroke volume?
Preload, afterload, contractility
CO value adjusted for body size (BSA) that provides a more accurate measurement of adequacy of circulation
Cardiac Index (CI)
CI normal range
2.5-4 L/min m2
Equation for CI
CI = CO/patient’s BSA
BSA is calculated through what measurements?
Weight (Kg) and Height (cm)
Goal of hemodynamic monitoring
Tissue perfusion
To perfuse tissues and organs, several things must be done including
1) get O2 into lungs (ventilation), 2) get O2 from lungs into tissues (oxygenation), 3) get oxygenated blood to tissues (circulation), and 4) release O2 from blood into tissues
Factors that affect CO
Preload, afterload, contractility, and HR
Factors resulting in low cardiac output
Low SV, Low HR, or Both
Factors that decrease stroke volume
Low preload, high afterload, or decreased contractility
Component of stroke volume concerned with volume
Preload
Preload is associated with
Venous vasoconstriction or vasodilation
The initial stretching of cardiac myocytes prior to contraction
Preload
Preload is measured as ___ in the right ventricle and ___ in the left ventricle
CVP; PCWP/LVEDV
Factors that increase preload
Increased blood volume, pregnancy, exercise, HF, valve regurgitation, increased ventricular compliance
Factors that decrease preload
Drugs such as venous vasodilators and diuretics, loss of AV synchrony, increased HR
Volume of blood in the left ventricle at the end of diastole, as systole begins
LV end-diastolic volume
The ability of the heart and lungs to stretch
Compliance
How do venous vasodilators decrease preload?
Reduce blood return to the R side of the heart
How do diuretics decreased preload?
Reduce overall volume
Direct measure of preload
CVP
Premise that the greater the end-diastolic volume (preload), the greater the stretch of muscle cells, leading to greater stroke volume up to a point
Starling’s Law (Frank-Starling Curve)
Component of stroke volume associated with resistance
Afterload
Afterload is associated with
Arterial vasoconstriction or vasodilation
The pressure that must be overcome to push blood into the aorta or “what the heart has to work against”
Afterload
Factors that increase afterload
Vasoconstriction (medications with alpha 1 properties), hypothermia, SNS activation, aortic/pulmonic valve stenosis, HTN (systemic or pulmonary)
Factors that decrease afterload
Arterial vasodilation resulting from fever, exercise, inflammation/infection, or medications
Medications that cause arterial vasodilation (decreased afterload)
ACE inhibitors, ARBs, CCB, hydralazine (Apresoline), nipride, NTG
Afterload is measured through ___ in the right ventricle, and ___ in the left ventricle
CVP; PCWP
Explain resistance
The smaller the vessel the greater the resistance and vice versa; the greater the resistance, the harder the heart has to work to eject blood; increased resistance increases cardiac workload
Factors causing vasoconstriction
Decreased temperature, SNS activation, medications such as alpha — epi, phenylephrine, Levo (norepinephrine), vasopressin
Intervention to decrease afterload
Arterial vasodilators
Hormone that helps regulate BP by constricting blood vessels and triggering uptake of sodium and water
Angiotensin
Effects of increased afterload
Increased cardiac workload and oxygen
What should be administered to a smoker with HTN with narrowed, stiffened arteries?
Arterial vasodilator due to increased afterload
The force the heart can generate to eject blood, or the ability of the heart to overcome afterload
Contractility
Factors that increased contractility
SNS activation (catecholamine release), drugs
Factors that decrease contractility
PNS stimulation, hypoxia, ischemia/injury/infarction, acidosis, electrolyte imbalances
Irreversible tissue death from prolonged ischemia
Infarction
A patient with hypoxia and ischemic chest pain may have decreased
Contractility
Drugs that increase contractility
Digoxin, dopamine, dobutamine, epi
Drugs that decrease contractility
Negative inotropes such as beta blockers
The percentage of blood ejected from the ventricle
Ejection fraction (EF), or Left Ventricular Ejection Fraction (LVEF)
Ejection Fraction equation
EF = SV/LVEDP x 100
Normal EF
55-75%
Normal EF in women and men
Slightly higher for women (54-74%) than men (52-72%)
Low EF resulting in decreased ventricular function is associated with what conditions?
MI, CM, ischemia
Higher EF is associated with heart conditions like
Hypertrophic cardiomyopathy
EF less than 40% is generally considered
HF
Purpose of hemodynamic monitoring
Early detection, identification, and treatment of life-threatening conditions; evaluation of patient’s response to treatment; evaluate effectiveness of cardiovascular function
Indications for hemodynamic monitoring
Determine fluid volume status, measure CO, monitor/manage unstable patients, assess hemodynamic response to therapies, Dx primary pulmonary HTN, Dx shock states
Types of hemodynamic monitoring
Non-invasive, direct measurement of arterial pressure, invasive
Non-invasive hemodynamic monitoring includes
Clinical assessment and NBP
Non-invasive hemodynamic monitoring through clinical assessment
skin color/temp/mottling, HR, pulses, mental status, cap refill, UO, pulse ox, edema
Disadvantage of non-invasive hemodynamic monitoring
Susceptible to inaccuracy related to nature of measurements, impact of patient condition on results, etc.
Automated BP is less accurate during
Hypotension, arrythmias
Inaccurate pulse ox reading may be influenced by
Vasoconstriction, poor perfusion, cold extremities, skin pigmentation, motion artifact
A blood pressure cuff that is too small may yield a false _____ reading, while a blood pressure cuff that is too large may yield a false _____ reading
High; low
Indications for arterial BP monitoring
Frequent titration of vasoactive drips, unstable BP, frequent ABGs or lab draws, inability to obtain noninvasive BP
Sites for arterial BP monitoring
Radial, brachial, and femoral artery
Complications of arterial blood pressure monitoring
Hematoma, blood loss, thrombosis, distal ischemia, arterial injury, infection
Arterial line must remain level with patient’s
Phlebostatic axis (4th intercostal space, mid-axillary line)
An arterial line transducer that sits too low can result in a false _____ pressure, while a transducer that sits too high can result in a false _____ pressure
High; Low
Purpose of zeroing an arterial line transducer
Eliminates atmospheric pressure (0 mm Hg) ensuring that pressure measurements reflect only pressure values from the patient
Calculated pressure that closely estimates the perfusion pressure in the aorta representing average systemic arterial pressure during the entire cardiac cycle
Mean Arterial Pressure (MAP)
Normal MAP
70-100 mm Hg
MAP must be maintained above ___ mm Hg to preserve perfusion of major organs
60
Nursing implications for arterial line
Prevent/reduce potential complications, maintain 300 mm Hg on pressure bag, maintain continuous flow through tubing, aseptic dressing changes, sterile caps on openings
How often should arterial line tubing be changed?
Every 96 hrs or per facility protocol
How often should arterial line fluids be changed?
Every 24 hours (NS or heparin 1000 units/500 mL)
The nurse should hold the discontinued arterial line site for at least
5 min
Why does arterial line tubing need to be changed every 96 hrs?
To decrease opportunity for contamination of closed system
Why is heparin not commonly used in an arterial line?
Risk of HIT
Measurement of right atrial pressures reflecting preload to the right side of heart
Central Venous Pressure (CVP)
CVP assesses
Blood volume and RV function
CVP normal range
2-6 mm Hg
Causes of low CVP
Inadequate preload, hypovolemia (or bleeding), vasodilation
Causes of high CVP
Hypervolemia, RV failure, cardiac tamponade, tricuspid valve disease, pulmonary HTN, chronic LV failure, ventricular septal defect, constrictive pericarditis, PEEP > 10
CVC/PAC nursing care
Sterile insertion and dressing changes, hand hygiene, avoid kinking, periodic flushing for patency, maintain sterile port, prompt removal if no longer required, NOT routinely replaced, replace tubing every 96 hrs, monitor for infection
Hand hygiene is the most crucial step in nursing care for CVC to avoid
HAI such as CLABSI
Why are CVCs not routinely replaced?
Risk of complications and infections
CVC ports nursing care
Vigorous scrubbing before use (CHG, alcohol), use only sterile devices to access, lumens capped at all times
Placement of swan gang (pulmonary artery) catheter
Internal jugular vein, subclavian vein, femoral vein
What does a swan ganz catheter measure?
Pulmonary artery pressure (PAP), central venous pressure (CVP), core body temp, and allows for measurement of CO
Where does the tip of the swan ganz catheter lie?
Pulmonary artery
Indications for PA catheter
Dx and management of PAH, HF management, shock differentiation
Pulmonary artery pressure (PAP) normal range
20-30 / 6-12 mm Hg
Reasons for increased PAP
L-sided HF, increased pulmonary blood flow, increased pulmonary arteriolar resistance
Reasons for decreased PAP
Hypovolemia, increased pulmonary resistance (ex: pulmonary HTN)
Normal range for wedge pressure (PAWP/PCWP)
4-12 mm Hg
Indirect measure of left atrial filling pressure
Wedge pressure (PAWP/PCWP)
What does PAWP/PCWP indicate?
Intravascular fluid volume status
Wedge pressure should be roughly equal to
Left ventricular end diastolic pressure (LVEDP)
Why should PAP and PAWP be measured at end-expiration?
Respiratory pressure changes (ventilation) affect PAP and PAWP; intrathoracic pressure approaches atmospheric pressure and has the least effect on hemodynamic pressures at end-expiration
Swan and Wedge ports should be inflated with no more than ___ mL of air
1.5
How is wedge pressure measured?
By advancing a PA or swan ganz catheter in small branch of pulmonary artery
PA catheter puncture site complications
Infection, hematoma, bleeding, pneumothorax (IJ/SCV access)
PA catheter rhythm disorder complications
PAC/PVC, VT, VF
PA Catheter conduction disorders complications
Right bundle branch block (particularly danger in preexisting LBBB)
PA catheter complications
Damage to pulmonic or tricuspid valve (caused by pullback with inflated balloon), pulmonary artery rupture, pulmonary infarction/thromboembolism
Measures of preload
CVP, wedge pressure, PAD
Measures of afterload
ABP, SVR, PVR, valvular dysfunction
Measures of contractility
LVEF, RVEF
PAD can be a substitute measure for preload EXCEPT in patients with any degree of
Pulmonary hypertension (ex: smokers)
How does a defibrillator work?
randomized shock delivery to myocardium making all electrical activity stop. Goal is that patient’s own pacemaker will kick in and restore a normal rhythm
Defibrillators that decrease the amount of energy needed to convert rhythm resulting in less myocardial damage
Biphasic (150j - 200j)
Monophonic defibrillator range
200j - 360j
Shock synchronized with the patient’s R wave on EKG to avoid delivery of electricity during the refractory or repolarization phase
Cardioversion (synchronized shock)
Indications for cardioversion
Convert arrhythmias back to Sinus Rhythm, used for rapid rhythms WITH pulse (SVT, Afib, Aflutter, VT (pulse))
What causes ventricular tachycardia?
Low magnesium level
Preparing the patient for cardioversion
Ensure understanding, remove all metal objects from pt to prevent burns, do not shock over transdermal medication (remove or avoid), ensure pt and environment dry, remove hair from chest if necessary, confirm asystole in 2 leads; no need to turn to side
Defibrillator pad placement
To right of sternum just below clavicle, to left anterior axillary line 5th-6th intercostal space; NOT placed over permanent pacemaker
Additional patient preparation for cardioversion
Informed consent, time-out, obtain 12-lead EKG, NPO, supine position, remove dentures/partial plates, pre oxygenate and maintain oxygenation throughout procedure (NRB or oxymask; ambu-bag on standby), ensure suction set up, sedation and analgesia as prescribed, set defibrillator on “synchronize”
Synchronizing a defibrillator
Synchronized to R wave of patient’s EKG rhythm; marker indicates synchronization and beeping sound for each R wave (note: this procedure hurts!)
Post defibrillation care
Assess VS, LOC, pulmonary and cardiovascular status; antidysrhythmic meds if needed; evaluate for burns; emotional support
Treatment of choice for ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT)
Defibrillation
Synchronized v. Unsynchronized defibrillation for V -tach
Stable v. Unstable
Defibrillator strips for ventricular tachycardia vs. ventricular fibrillation
Monomorphic for VT and fine VF
Post unsynchronized shock monitoring and care
Evaluate LOC, VS, burns, and electrolytes; monitor airway (may be intubated during code), IV fluids (vasopressors for BP) antidysrhytmic medications (IV drip, amiodarone), consider possible causes
Defibrillation education
Explain S/S and problems associated with the dysrhythmia, discuss need for long term drug therapy, lifestyle changes, possible implanted cardiac defibrillator (ICD), need for an emergency communication system
Types of pacemakers
Transdermal, transvenous, epicardial, permanent
Transdermal pacemaker
Emergency, painful, very temporary
Transvenous pacemaker
Temporary, usually via IJ or femoral vein, sits in RV
Epicardial pacemaker
After cardiac surgery, use gloves to handle
What should patients with pacemakers avoid?
Strong magnets (turn off pacemaker and stop function), MRI
Permanent pacemaker
For complete heart block or other severe blocks, single/double/or triple chamber options, few restrictions after recovery (exercise, sexual activity, etc. are OK)
Permanent pacemaker post-procedure care
CXR, Monitor for bleeding/swelling at insertion site, pain/comfort, and assess EKG for appropriate function
Function of implantable cardiac defibrillator (ICD)
Shocks the patient internally for VT or VF
ICD education
OK to do chest compressions, magnet turns off defib (no MRI w/o consult), can have pacemaker and defib in one (most ICDs are also pacemakers), batteries replaced in several years (~10)
Where to listen during cardiac assessment
Aortic area, pulmonic area, Erb’s point, tricuspid area, mitral area/apex
Aortic area
2nd intercostal space, right sternal border
Pulmonic area
2nd intercostal space, left sternal border
Erb’s point
3rd intercostal space, left sternal border
Tricuspid area
4th intercostal space, left sternal border
Mitral area/Apex
5th intercostal space, midclavicular line
Area in which S2 (dub) sound is loudest
Aortic area
Area in which S1 (lub) sound in loudest
Mitral area
S2 (dub) sound is associated with
Closure of pulmonic and aortic valves
S1 (lub) sound is associated with
Closure of mitral and tricuspid valves
S3 heart sound
Follows S2, ventricular gallop (“Ken-tuck-y”), common in children, cardinal sign of HF, pulmonary edema, atrial septal defect
S4 heart sound
Occurs just before S1, Atrial gallop (“ten-nes-see”), indicates increased resistance to ventricular filling, MI after effect, elderly, HTN, aortic stenosis
Murmurs are caused by
Turbulent blood flow (d/t stenosis, regurgitation, structural defects such as septal defects, ruptured papillary muscle, etc.)
Assessment of abnormal or extra heart sounds
Location, degree (loudness), character, timing
Extra heart sounds
S3 and S4
Extra heart sounds indicate
Decreased ventricular compliance to filling
Extra heart sound associated with early diastole (passive filling phase)
S3
Extra heart sound associated with late diastole (caused by blood in active filling phase working against higher pressure (non-compliant LV))
S4
Best way to hear abnormal or extra heart sounds
With bell of stethoscope (low-pitched sound), patient on L side
Flow of blood through a valve that is supposed to be open, but is narrowed d/t calcium, clots, congenital defects, etc.
Stenosis
Backward flow of blood through a valve
Regurgitation
Regurgitation characteristics
Blowing, harsh, musical sound
S3 may be normal in patients…
Under 40 or some athletes (should disappear before middle age)
S4 is nearly always
Pathologic
Pulses to assess
Carotid, brachial, radial, ulnar, femoral, popliteal, posterior tibial, dorsalis pedis
Assessment of pulses
Note symmetry and strength, start distal and move up if not felt, if you think you feel it —> confirm w/ Doppler
Indications of poor CO and tissue perfusion
Cyanosis, pallor, cold skin
Characteristics of arterial insufficiency
Skin cool, pale, and shiny; ulcerations on toes and heels; foot usually turns deep red when dependent; nails may be thick and ridged
Characteristics of chronic venous insufficiency
Ulcerations around ankles, foot cyanosis when dependent, edema
Visible JVD can indicate
R-sided HF (occurs any time venous return is greater than hearts ability to pump the blood back out)
Partially occluded blood vessels
Bruits
Assessment of carotid artery bruit
Auscultate upper, middle, and lower carotid artery; have patient hold breath while auscultating each spot (eliminates high tracheal breath sounds)
Factors for monitoring perfusion
Noninvasive BP, HR, pulses, mental status, skin temp, mottling, cap refill, UO, pulse ox
Structures responsible for nutrient and oxygen delivery
Arteries and capillaries
Characteristics of ischemia
Blood is available but reduced (thrombus, stenosis, vasospasm), always results in hypoxia, leads to pain
Reduced oxygenation (turning blue) as a result of uncorrected ischemia
Hypoxia
Total lack of oxygen in body tissues resulting in cell death (infarction)
Anoxia
Insufficient flow of oxygenated blood to tissues that may result in hypoxia and subsequent cellular injury and death
Ischemia
The death of tissue with an inability to regenerate
Infarction
The death of an area of heart muscle or myocardium
Myocardial infarction
Chest pain assessment scale
APQRST: associated symptoms, palliative/provoking, quality (dull/sharp/crushing), radiate, severity (0-10), timing (before/after exercise, etc.)
Cardiac laboratory testing for diagnosis
Enzymes such as CK, CK-MB; troponin (elevation indicates MI/infarction); BNP (elevation indicates HF)
Laboratory tests for cardiac risk factors
Cholesterol/lipids (HDL/LDL), triglycerides
Cardiac enzyme that measure possible brain, heart, skeletal mm injury
CK
Cardiac enzyme specific to cardiac injury
CK-MB
Peptide that helps regulate circulation by promoting urine excretion, relaxing blood vessels, lowering BP, and reducing cardiac workload
BNP
