Exam 3 Flashcards
Factors that increase CVP
Hypervolemia (volume overload/perfusionist overfilling) Forced Exhalation Tension pneumo Heart failure Pleural effusion Decreased cardiac output cardiac tampenade Mechanical ventilation and the application of PEEP
Factors the decrease CVP
Hypovolemia (perfusionist underfilling)
Hypovolemia
Deep inhalation
shock
Six Factors Affecting Venous Return
- Musculovenous pump
- Decreased venous capacitance
- Respiratory pump
- Vena Cava Compression
- Gravity
- Pumping Action of the Heart
Musculovenous pump
Contraction of limb muscles during normal locomotion (walking, running, swimming) promotes venous return by the muscle pump mechanism (n/a on CPB)
Decreased venous capacitance
Sympathetic activation of veins decrease venous compliance, increase venous tone, increase CVP and venous return which increases blood flow through the circulatory system
Respiratory pump
during inspiration, the intrathoracic pressure is negative and abdominal pressure is positive
Vena Cava Compression
an increase in the resistance of the vena cava, when the thoracic vena cava becomes compressed decreases venous return
Gravity
the effects of gravity on venous return seem paradoxical, when a preson stands up hydrostatic forces cause the RAP to decrease and the venous pressure in the limbs to increase. This increases the pressure gradient for venous return from the dependent limbs to the right atrium; however, venous return decreases
Why do the effects of gravity cause venous return to DECREASE?
CO and arterial pressure decrease when standing (because RA pressure falls)
Flow decreases; arterial P falls more than RAP. Pressure gradient driving flow through the entire circulatory system is decreased.
(Orthostatic hypotension)
Pumping action of the heart
Atrial pressure changes alter CVP during cardiac cycle. CVP is altered because there is no valve between the heart’s atria nad veins. Atrial pressure changes venous pressure and therefore alters venous return
No valve; can assume pressures are equal
Subclavian vein & internal jugular vein insertion catheter length
20 cm
Femoral venous access catheter length
60cm
CVP Insertion Sites
Subclavian internal jugular external jugular femoral antecubital
Seldinger Technique
Catheter over guidewire
Do peds use swan ganz catheters?
No, they don’t make them small enough
Central Line Complications
Cardiac Tampenade Wire or catheter embolism Vascular injuries (non PA) -Hemothorax -Hydrothorax -Carotid artery injury -subclavian a. aneurysm Pulmonary artery rupture Pneumothorax Air Embolism Fluid extravasation
A Wave
Increased Atrial Pressure during right atrial contraction. Correlates with P wave on EKG
C Wave
Slight elevation of the tricuspid valve into the right atrium during early ventricular contraction. Correlates with QRS
Due to isovolumic RV contraction; closes tricuspid valve and causes it to bow back into RA
“tricuspid valve close and ventricular contraction”
X Wave
Downward movement of ventricle during systolic contraction. Before T wave on EKG.
Midsystolic Event
“Systolic collapse in atrial pressure”
V Wave
Pressure produced when blood filling the right atrium comes up against a closed tricuspid valve. Occurs as the T wave is ending on an EKG
Last atrial pressure increase caused by filling of the atrium with blood from the vena cava; late systole with tricuspid still closed
“venous filling of the atrium”
Y Wave
Tricuspid valve opening the diastole with blood flowing into the RV. Occurs before P wave on EKG
“Diastolic collapse in atrial pressure”
Decrease in atrial pressure as tricuspid open and blood flows from atrial to ventricle
What determines change in CVP?
CVP = V/ Compliance
What part of CVP waveform coincides with point of maximal filling of the right ventricle?
Peak of “a” wave
What part of CVP waveform should be used for measurement of RVEDP?
Peak of “a” wave
Should be measure at end-expiration; machines just “average” the measurement
Systolic Events of CVP waveform (ventricular events)
cxv
Diastolic events of CVP waveform (ventricular events)
ay
Tachycardia and CVP
Short PR interval can cause “a” and “c” waves to fuse
Reduces time spent in diastole causing short “y” descent
“V” and “A” may appear to merge
Bradycardia and CVP
Each wave becomes more distinct
“H” wave may become evident- plateau wave in mid or late diastole
“H” wave has little clinical significance
A Fib and CVP
“A” wave disappears (no atrial contraction)
“C” wave more prominent (atrial volume is higher at the beginning of systole because the atrium did not empty)
PVCs and CVP
Large a wave
a wave at expected time (not premature)
Tricuspid Regurgitation and CVP
RA gains volume during systole so “c” and “v” wave is much higher
RA sees RV pressure curve becomes “ventricularized”
Tricuspid Stenosis and CVP
Problem with atrial emptying and a barrier to ventricular filling on the right side of the heart
Mean CVP elevated
“a” wave usually prominent as it tries to overcome the barrier to emptying
“Y” descent muted as a result of decreased outflow from atrium to ventricle
Pericardial Constriction and CVP
Limited venous return to heart, elevated CVP, end diastolic pressure, equalization in all cardiac chambers
Prominent “a” and “v” waves; steep “x” and “y” descnets
Characteristic M or W pattern, dip and plateau (square root sign)
Cardiac Tampenade and CVP
Changes in atrial and ventricular volumes are coupled so total cardiac volume doesnt change
CVP monophasic with single, prominent “x” descent and a muted “y” descent
Similar to pericardial constriction but not exactly the same
CVP and Respiration
Increases during Expiration
Decreases during inspiration
What is CVP when on bypass?
0
If not zero, you’re not emptying; get better venous return!!
As you restrict your venous line, what is the relationship between arterial flow and venous return?
Arterial Flow > Venous Return
This will fill your heart. CVP rises (preloads RV); Pa Volume rises (preload LV) arterial P rises
Therefore, perfusionists control preload!!
Who invented the Swan Ganz catheter and in what year?
Dr. Jeremy Swan & Dr. William Ganz
Cedars-Sinai Medical Center
Invented in 1970
Fabricated by Edwards Laboratories
Indications for PAP Monitoring
- Management of cardiopulmonary pressures and flows
- Assess CV Function
- Perioperative monitoring in surgical pts
- Shock
- Assess pulmonary status
- Assess fluid requirements
- Assess obstetric pts
- Therapeutic & diagnostic indications
Indications for Swan-Ganz PA Catheter
Assessment of respiratory distress
Assessment of Shock
Assessment of Therapy
Assessment of fluid requirement in critically ill patients
Assessment postoperative in heart surgery pts
Assessment of valvular disease
Assess cardiac tamponade/constriction
What is the #1 use for a swan?
assess fluid requirement in critically ill patients
What types of things are we looking at when assessing therapy?
Afterload reduction
Vasopressors
Beta Blockers
Intra-aortic balloon counter-pulsation
What do we look at when we assess fluid requirement in critically ill patients?
Hemorrhage
Sepsis
ARF aka Acute kidney injury
Burns
What can a Swan-Ganz Catheter do and measure?
Preload Afterload SVR PVR Cardiac Output (thermal dilution) Cardiac Index Venous Sat (Oximetric Swan) Pacemaker (paceport swan)
Preload
Reflected by end-diastolic pressures of ventricles, as generate by volume of blood into ventricles just before next contraction
What measures RV preload?
CVP measures right filling pressures
What measures LV preload?
PAWP measures left ventricular filling pressures
Afterload
pressure the ventricles must pump against to eject blood; resistance to ventricular systole
