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RTT 214 - Ch. 16

Ch. 16 - Assessment of Hemodynamic Pressures

QuestionAnswer
why is invasive hemodynamic monitoring needed? clinical assessment alone may not accurately predict hemodynamics
what must be considered before a catheter is placed in a pt? risk-benefit ratio of invasive monitoring
what is hemodynamic monitoring performed to do? evaluate: intravascular fluid vol, cardiac/vascular function; identify sudden changes in hemodynamics
why is invasive monitoring needed? obtain an accurate evaluation of hemodynamics
what type of pt may a physician place an arterial catheter? significant hemodynamic instability or freq arterial blood draws
what conditions are likely candidates for arterial pressure monitoring? severe hypotension (shock) or HTN; respiratory failure
what pts may benefit from arterial pressure monitoring? pts in need of meds that affect BP (vasodilators/inotropic agents)
how many arterial catheter sizes are in common use and what is selection determined by? two; planned insertion site
where is the smaller catheter ideal for use? where is it not adequate? radial/small arteries; femoral/large arteries
how do arterial catheter walls compare with central venous catheters? thin and stiff
where is the arterial catheter usually placed? radial, ulnar, brachial, axillary, femoral
where is the arterial line most often placed and why? radial; readily accessable/adequate collateral circulation
the radial site is easy to _______ and what does it provide? monitor; stable site for blood withdrawal
what does the femoral artery provide? pressure measurements less affected by peripheral vasoconstriction; leakage of blood occurs
the _________ technique is used for most arterial catheter insertions. "Seldinger"
what should the arterial pressure waveform include? clear upstroke on left, w/ dicrotic notch (aortic valve closure) on downstoke to right
what happens if the dicrotic notch is not present? pressure tracing dampened, inaccurate; numbers are lower that actual pressure
the dicrotic notch disappears in some pts when the systolic pressure drops below __-__ mmHg. 50-60
the left side of the pressure wave may become straight and even pointed on the top when there is an increase in...? when else does this happen? circulating catecholamines that causes an increased inotropic response; stiff aorta
increases in HR and vascular resistance _______ diastolic pressure. increase
what can cause the diastolic pressure to drop? vasodilation that decreases vascular resistance
because approx ___% of coronary artery perfusion occurs during the diastolic phase, coronary arterial perfusion may be compromised if the diastolic pressure falls below ___ mmHg. 70%; 50
what must be considered when respiratory variation in the arterial pressure waveform is seen? cardiac tamponade or other causes of paradoxical pulse
when are increases in arterial pressure during inspiration seen? after heart surgery; pts w/ LV failure with MV and PEEP
what can cause variations in the height and shapes of the waveforms? dysrhythmias and pulsus alternans
what is the normal arterial pressure in the adult? 120/80 mmHg
what values are considered hypertensive? >160/90 mmHg
what values are considered hypotensive? <90/60 mmHg
arterial pressure is only a general sign of _________ status. circulatory
what is pressure the product of? flow and resistance
what is low blood pressure a late sign of? deficits in blood volume or cardiac function
what is earlier evidence of decreased blood volume or CO? cold, clammy extremities (caused by catecholamine-mediated peripheral vasoconstriction)
what are the causes of hypotension? low blood vol (bleeding), cardiac failure/shock (heart attack), vasodilation (sepsis)
during administration of what drugs should diastolic pressure be watched carefully? vasodilators such as sodium nitroprusside
what values of diastolic pressure may result in compromised coronary perfusion? diastolic pressures <50 mmHg; mean pressure <60 mmHg
what are the causes of hypertension? improvement in circulatory vol/function, sympathetic stimulation, vasoconstriction, vasopressors
administration of ________ _____ may or may not increase BP. inotropic agents
what inotropic agent can cause vasodilation? isoproterenol (isuprel)
besides systolic/diastolic pressures, what else does arterial pressure monitoring allow assessment of? pulse and mean arterial pressures
what is pulse pressure? and what is the normal? difference b/t systolic and diastolic pressure; 30-40 mmHg
what is pulse pressure reflection of? SV by the LV and arterial system compliance
what is a decreasing pulse pressure a sign of? low SV
what is an increasing SV in a pt receiving fluid therapy consistent with? improved preload
what is mean arterial pressure? avg of pressures pushing blood through the systemic circulation (most important of arterial pressures)
what is mean arterial pressure an indicator of? tissue perfusion
what is the normal MAP? 80-100 mmHg
what is the MAP calculation? systolic pressure + (diastolic pressure x 2)/3
when is circulation to the vital organs compromised? MAP <60 mmHg
what is elevated MAP associated with? increased risk of stroke and heart failure (need vasodilators or negative inotropics)
what is MAP use to calculate? SVR, LVSW, cardiac work
what is a major compication of direct arterial monitoring? ischemia resulting from embolism, thrombus, or arterial spasm
what is this complication evidenced by? pallor distal to the insertion site; pain and paresthesias
what can ischemia result in? tissue necrosis (if catheter is not repositioned or removed)
what is thrombosis prevented by? irrigation w/ diluted heparanized solution
__________ is possible if the line becomes disconnected or a stop cock is left open. hemorrhage
what else can occur at the insertion side especially if the catheter was placed through a needle? bleeding and hematoma
as with all invasive lines, the presence of an arterial catheter increases the risk of _________. infection
_______ in pts with invasive lines must trigger questions about the necessity of the lines and their role as a cause of the infection process. fever
_______ _______ ________ is the pressure of the blood in the RIGHT atrium or vena cava, where the blood is returned to the heart from the venous system. central venous pressure
what does CVP also represent? RVEDP and preload (filling vol) for RV
when is CVP monitoring indicated? assess circulating blood vol (filling pressures), degree of venous return, assess RV function
what pts need a CVP catheter? pts w/ major surgery or trauma, severe dehydration; pulmonary edema; pts with damage to RV from MI
what are the most common central venous catheters? 7-french, 3-lumen catheters w/ one distal port and two pots 3-4 cm from the distal end of catheter
what does the multiple-lumen catheter allow? infusion of blood samples and medications
what catheters are less commonly associated with infection? those impregnated with antibiotics
what are the common sites for introduction of central venous catheters? subclavian, internal jugular, femoral veins
what is an advantage of the subclavian vein approach? results in stable catheter after placement
what is a disadvantage of the subclavian vein approach? more difficult to find
what approach is easier because there is nearly a straight shot for the guidewire to reach the superior vena cava and less risk for pneumothorax and hematomas are easier to see and control? internal jugular vein approach
what are the disadvantages of the internal jugular vein approach? catheter less stable, subject to kinking, breakage, and accidental removal
what central venous catheters are the easiest to place and have the least risk for complications, but they provide less reliable hemodynamic info b/c the catheter tip is far from RA, pressure waveforms often dampened? femoral central venous catheters
what should be performed after subclavian or internal jugular central venous line insertion? CXR (ensure placement/rule out pneumothorax)
where is the subclavian vein entered? edge of the distal third of the clavicle
where is the internal jugular vein entered? head of the clavicle or a site behind the brachial artery
where is the femoral vein entered? just medial to the femoral artery in the groin
what is the only difference b/t these techniques? the head of the pt's bed is lowered for subclavian/internal jugular vein insertions
what does doing this cause? increases size of vein, making it easier; decreases risk of air embolism
what do CVP waveforms reflect? what is it equivalent too? pressure changes in the R atrium; PAWP (approximates L atrial pressure)
what do CVP and PAWP waveforms both include? three waves - a, c, v
what does the a wave result from and occur during? atrial contraction; ventricular diastole
when the atrium contracts against a closed valve, as occurs during atrioventricular dissociation or w/ some junctional or ventricular pacemaker rhythms, what occurs? large a waves called cannon waves
what does the downslope of the a wave (x descent) result from? decrease in atrial pressure
when does the c wave occur? AV valve closure; represents movement of AV valve back toward atrium during V contraction
what does the v wave result from? atrial filling while the AV valve is closed during ventricular systole
when does the downslope of the v wave occur? when tricuspid and mitral valves open and the ventricle begins to fill with blood
what is it referred to as when the AV valve does not close all the way and some of the blood is ejected backward into the atrium during systole? tricuspid regurgitation (exaggerated v waves and elevated CVP measurement)
what are the most likely causes of no respiratory artifact seen on the trace and the pt is not holding their breath? kink/air in tube, stopcoack turned in wrong direction, small clot/kink in catheter
what should happen to the waveform if the patient is asked to take a deep breath? fall below baseline as intrathoracic pressure falls w/ inspiration
when does CVP decrease and increase? d: spontaneous inspiration, i: MV
how can a mean venous pressure without resp artifact be obtained if spontaneously breathing? on MV? suspend breathing; disconnect ventilator
what are hte two ways CVP can be obtained? transducer system (mmHg) or a water manometer (cmH2O)
which method is more accurate assessment of mean CVP or right atrial pressure and also allows observation of the CVP waveform? transducer
what are the advantages of the water manometer? inexpensive, does not require electric equipment, easy to use
when is CVP ideally read and why? end of expiration, spontaneous inspiration causes pressure to fall and MV causes it to rise
what does the criteria for interpretation of CVP by water manometer include? 1. X-ray 2. IV fluid 3. ability to easily aspirate blood sample 4. rapidly falling H2O column 5. small oscillations at top of H2O column 6. larger oscillations w/ respiration
what does the comparison of water manometer methods w/ transduccer methods demonstrate? water manometer method usually overestimates transducer-determined mean RA pressure (CVP)
what CVP regulated by? balance b/t ability of heart to pump blood out of RA and V and amount of blood returned to the heart by venous system (venous return)
when the pumping ability of the right heart is increased, CVP ________; when pumping ability decreases, CVP _________. decreases; increases
what are 6 causes of increased CVP? fluid overload, R/L heart failure, pulmonary HTN, tricuspid valve stenosis, pulm embolism, increased venous return
what are 4 causes of decreased CVP? vasodilation, reduced circulating blood vol, leaks in pressure system/air bubbles, spontaneous inspiratino
what does the CVP reflect when a pt is hypovolemic but has pulmonary HTN with decreased RV function? elevated pressure from the loss of ventricular function, does not fall to level that are expected
when is this most commonly seen? cor pulmonale who become dehydrated and hypovolemic
when can CWP be used to estimate LV filling pressures and performance? pts w/ an EF >0.50, no cardiopulmonary disease
what is CVP a reasonable option for the management of? intraoperative fluid levels, postop fluid levels, vol replacement in young pts w/ no hx of heart disease or HTN
who may benefit from monitoring of both the left and right heart pressures? pulmonary HTN disease
what problems can placement of the catheter cause? bleeding, pneumothorax
when is bleeding more likely? when pt is taking heparin or low platelet count; subclavian artery penetrated
when can pneumothorax occur? catheter punctures the pleural lining
what is the most common complication associated with use of the catheter over time? what is a less common complication? infection; thrombus around the catheter
what can accidental opening of the central venous line stopcock allow and result in? air to enter vein, air embolus
what does the PAC allow the assessment of? filling pressures of the left side of the heart
what does the PAC allow the assessment of? LV filling pressures (via PADP/PCWP); PVR (via PA mean systolic pressures/PCWPs), SVR (via systemic arterial mean pressure/PAEDP); CO; arteriovenous O2 difference, mixed venous O2 levels
what is the only place w/ swan-ganz catheter to get the most accurate assessment of oxygenation? arteriovenous O2 difference; mixed venous O2 levels
PAC is more a risk than CVP because why? need for catheter to pass through the R side of the heart and into PA (may cause dysrhythmias or other complications)
what are common factors to consider when placing a PAC? experience of physician, availability of proper equipment/personnel, diagnosis, cardiac/pulm hx
what are the common situations in which PAC monitoring is considered? severe cardiogenic pulm edema; ARDS (hemodynamically unstable); major thoracic surgery; cardiogenic/septic shock pts
what are PACs also called? swan-ganz catheters
what is the balloon at the tip of the catheter used for? float the catheter into position (into the R side of heart and into PA) and obtain wedge pressure measurements
what is another name for the catheter? balloon-tipped, flow-directed catheter
what are the catheters available for children? what is most commonly used for adults? 4- and 5-french catheters w/ 2 or 3 lumens; 7-french w/ 3-lumens (air channel for balloon)
the distal lumen terminates at the tip of the catheter, what is it used for? measuring PA pressures, aspirating mized venous blood samples, injecting meds
what might the balloon help prevent? PVCs
what is the proximal port used for? aspirating blood samples, measuring CVP, injecting drugs, injecting thermal bolus used for thermodilution CO measurements
some catheters have 2 lumens ending in the RA, what are these used for? 1. routine infusion of drugs/continuous pressure monitoring 2. infusion of thermodilution materials/periodic injections
what are the most popular sites for PAC used in ICU? subclavian/internal jugular veins
the PAC can be positioned used __________, but is more often...? fluoroscopy; floated into place using pressure waveforms to indicate position
what is the insertion technique for PAC? 1. balloon inflated at superior vena cava or RA 2. catheter floats through R side, into PA 3. wedges into place, balloon deflated
what are seen as catheter passes through the RA, RV, PA, and into wedge position? distinctive waveforms
what is the normal pressure for RA? RV? PA? PCWP? RA: 2-6 mmHg; RV: 20-30/0-5 mmHg; PA: 20-30/6-15 mmHg (mean pressures: 10-20 mmHg); PCWP: 4-12 mmHg
in most adults, catheters inserted through the subclavian or jugular vein are positioned in the PA when approximately ___cm of catheter is inserted into the pt. 50
what is entry into the PA recognized by? change in the diastolic portion of the wavefomr
PA maintains pressure throughout the cardiac cycle so that the basline pressure usually increases to ___-___ mmHg over RV diastolic pressures. 8-15
PA _______ pressure is the highest pressure created when the RV ejects blood through the pulmonary valve and into the PA and lungs. systolic
what is normal PA systolic pressure? 20-30 mmHg
when does PA pressure decrease? increase? d: vol of blood from RV decreases, decreased PVR; i: pulm blood flow increases, PVR increases
what can resistance to pulmonary flow (increased PVR) be caused by? constriction, obstruction, or compression of the pulmonary vasculature or backpressure from the L heart
what conditions cause increased PVR? pulmonary emboli; acute/chronic lung disease; cardiac tamponade; L heart failure
what is the normal PA diastolic pressure? what does it reflect? 8-15 mmHg; pulm venous, LA, LVEDP
what is a PADP-PCWP gradient >5 mmHg a characteristic of? ARDS, sepsis, excessive PEEP, anything that increases PVR
what is normal PCWP? what is PCWP also called? and what is it used to monitor? 4-12 mmHg; pulmonary artery occlusion pressure; LV filling during diastole
what will hx of MI cause? stiff LV and lead to higher pressures
in the normal heart, optimal SV is obtained with a PCWP of ___-___ mmHg. in the pt with LV hypertrophy, a PCWP of ___ mmHg or higher may be needed to optimize SV. 10-12; 18
when does PCWP increase? LV failure (common cause); mitral valve regurgitation; pulm venous circulation obstructed w/ tumor
what is the most common cause of a decreased PCWP? what also decreases PCWP? hypovolemia; severe dehydration
what is zone I? no blood flow b/c alveolar pressure exceeds both pulmonary venous pressure and MAP
what is zone II? alveolar pressure exceeds venous pressure but is less than MAP
what is zone III? area of lung where both PA and venous pressures exceed alveolar pressure
what does the catheter in zone II measure? PAP w/ balloon deflated but reflects alveolar pressure when it is wedged
zone II conditions dominate in ________ pts. supine
to measure L heart pressure accurately, the catheter tip must be in zone ___. III
when can zone III areas convert to zone I or II? when intravascular vol decreases or alveolar pressure increases
alterations in ventilatory patterns cause fluctuations in __________ _______. intrapleural pressure
wedge pressure readings normally are about __ mmHg lower than pulmonary diastolic pressure readings b/c blood flows from high pressure to low pressure. 2
what is transmural pressure? the net distending pressure within the ventricle
how is the transmural pressure calculated? subtracting the pressure around the heart from the measure filling pressure of the heart
what is wedge pressure used to estimate? LV filling pressure inside the heart
what is used to approximate the pressure pushing on the heart from the outside? intrapleural or esophageal pressure
what are the 2 ways PEEP is subtracted from wedge pressures? 1. compliant lungs: 1/2 of PEEP from PCWP 2. noncompliant lungs: 1/4 of PEEP from PCWP
what complications of PA catherization is possible during cannulation of a central vein? pneumothorax; hydrothorax; hemothorax; air embolism; damage to the vein, arteries, nerves
what can movement of the catheter inside the heart trigger? bundle-branch block; supraventricular or ventricular dysrhythmia
constant movement of the catheter with heartbeat, breathing, and pt movement can result in ________ _________. catheter migration
_________ ___________ and even PA rupture can result from overfilling the balloon while obtaining a wedge pressure, as well as from catheter migration. pulmonary infarction
what should be immediately available at both insertion adn removal? lidocaine and emergency resuscitation equipment
what should be optimized to decrease the risk of dysrhythmia? blood gases and serum electrolytes
what is not normal and is an indication for obtaining a CXR to assess the cause? catheter resistance
Created by: christa_2008