Ch 9 PA pressure monitoring Flashcards
CVP =
Right Heart Filling Pressures
LVEDP =
Left Heart Filling Pressures
Left atrial pressure waveforms have essentially the same form as what?
right atrial waveforms
PROBLEM: It is physically difficult to insert a catheter for the measurement of _____ ?
left atrial pressure.
A catheter fitted with an inflatable balloon (Swan Ganz catheter) is passed from a
vein, through the right side of the heart into the pulmonary artery.
With the balloon inflated the catheter is allowed to wedge into a pulmonary arterial side branch. Once wedged (there is zero flow in the pulmonary artery which is wedged) the pressure recorded via this catheter reflects the left atrial pressure, albeit giving a damped (smoothed) pressure waveform.
left atrial pressure, albeit or although giving a damped (smoothed) pressure waveform.
Nevertheless this pressure, termed the pulmonary artery wedge pressure (PAWP) or the pulmonary artery occlusion pressure, provides what ?
mean left atrial pressure values comparable to those measured in the left atrium.
PA catheter insertion steps?
IJ, SVC, RA, Tricuspid valve, RV, Pulmonic valve, and finally the PA.
On the PAWP waveform, what are the wave points in order?
a, x , v, and y
On the PAWP waveform, what does the “a” wave represent? what it a normal value?
Atrial Contraction
4-15 mmHg
On the PAWP waveform, what does the “x” wave represent?
Atrial Diastole
On the PAWP waveform, what does the “v” wave represent? What it a normal value?
Passive Atrial Filling
4 - 15 mmHg
On the PAWP waveform, what does the “y” wave represent?
Atrial Emptying
What can cause a confusing PA pressure and PAWP?
Mitral Valve Insufficiency
What are the Indications Pulmonary artery catheterization ?
√ Acute MI with hemodynamic
instability
√ Severe hypotension of
unknown etiology,
specially if the response to
initial therapy is inadequate
(eg, volume loading)
√ selected cases of septic
shock
√ ARDS, to confirm the
diagnosis of noncardiogenic
√ pulmonary edema
(normal "wedge" pressure)
and to aid in subsequent
fluid and ventilator
managementCVP should correlate with what pressure ?
PA
Indications Pulmonary artery catheterization continued. .
√ poss cardiac tamponade,
√ suspected papillary muscle rupture
√ poss VSD or ASD post MI
√ CHF responding poorly to diuretics, especially when intravascular volume status is uncertain
√ intraoperative monitoring of patients undergoing open heart surgery, particularly coronary artery bypass procedures involving multiple vessels; patients undergoing AAA repair may also benefit from PA catheterization perioperatively
ASD
Atrial Septal Defect
VSD
Ventricular Septal Defect
Swan-Ganz catheterization may also be useful in the following scenarios:
√ heroin, aspirin OD
√ exacerbations of COPD requiring intubation; hemodynamic monitoring may detect occult or
√ superimposed causes of respiratory failure not suspected clinically (eg, left ventricular dysfunction)
√ end-stage liver failure with deteriorating renal function
√ suspected cases of pulmonary hypertension
Contraindications for Swan-Ganz catheterization ?
- Severe, uncorrectable coagulopathy
- LBBB
- local infection at the skin
insertion site - severe hypothermia
- inadequate monitoring equipment
- patient refusal
If an underlying LBBB is present during placement of a right heart catheter may lead to what ?
complete heart block (A-V dissociation)
Severe hypothermia during placement of a right heart catheter may lead to what ?
malignant arrhythmias induced by the catheter due to the myocardium being highly irritable.
Would you insert a PA catheter in a patient who overdose with heroin or ASA?
No, the risk of acute lung damage is very high, this would cause enough bleeding for the patient to drown with their own blood.
Complications with PA catheter fill in the blanks?
- ) Balloon Rupture
2. ) 0-5% infection.
New RBBB complication with PA catheter insertion percentage?
New RBBB = 5%
VT & V-Fib complication with PA catheter insertion percentage?
VT = 3% V-Fib = 2%
Common complications with PA catheter insertion ?
1-4.) PI, PE, PAP, PAR
- ) Hemothorax
- ) Valvular trauma
- ) Retroperitoneal bleed
- ) Disappearenace of introducer
Inadvertent arterial puncture complication with PA catheter insertion percentage?
6%
Pneumothorax /Tension Pneumothorax complications with PA catheter insertion percentage?
0-6%
Thrombosis of a blood vessel for example (superior vena cava syndrome) complications with PA catheter insertion percentage?
1-2%
Natural curve of the PA catheter should be directed toward what ?
The Heart to facilitate entry
Normal CVP ?
1-6 mmHg
Special Considerations for PA catheterization.
Prosthetic Right Heart Valve.
Endocardial Pacemaker
Pulmonary HTN
PA catheter features.
Length = 60-110 cm Caliber = 4-8 Fr Inflation Volume = 0.5 - 1.5 ml Balloon Diameter = 8 - 13 ml Material = Polyvinyl Chloride 1 Black band = 10 cm
What does the Thermistor Wire on the Swan-Ganz measure?
CO
What do the fiberoptics on the Swan-Ganz measure?
Oxygen saturation in the PA (Mixed venous blood)
What do the 2 intracardiac electrodes with a rapid response Thermistor on the Swan-Ganz measure?
RVEF
What does the Thermal Filament on the Swan-Ganz measure?
CCO
Distance to the RA via the Right Internal Jugular Vein?
15 cm
Distance to the RV via the Right Internal Jugular Vein?
25 cm
Distance to the PA via the Right Internal Jugular Vein?
40 cm
Distance to the PAWP via the Right Internal Jugular Vein?
45 cm
Double-lumen PA catheter
# 1 lumen = PA pressure measurement #2 lumen = Balloon inflation
Quad-lumen PA catheter
1 Distal PA port = PA & PAWP measurement
#2 Balloon port = Inflation / deflation
#3 Proximal RA port = 30 cm from the PAC tip. Lies in the RA, Used to measure the following.
a.) Right Atrial pressures
b.) Administer fluids and/or electrolytes
c.) Injection of solution for CO measurements
#4 Thermistor port = Temperature sensitive wire 4-6 cm
proximal to the catheter tip. Allows CO calculation
using thermodilution technique.
Volume infusion port (VIP) thermodilution PAC.
Has an additional right atrial port for fluid, electrolyte, and or drug administration.
Quad-lumen “Position Monitoring” thermodilution PAC
Termination of the proximal lumen is located 10 cm from the catheter tip, RV pressures are now recorded rather than RA pressures. We would see a change from RV to PA waveforms indicating distal migration of the catheter.
Fiberoptic thermodilution PAC
Has an additional lumen which has 2 fiberoptic bundles exposed near the catheter tip.
Continuous monitoring of SVO2 in addition to thermodilution features.
Pacemaker thermodilution PAC
Used for the following
- ) Atrial,Ventricular, and AV sequential pacing.
- ) Recording of Intra-cardiac rhythm strips
Thermodilution ejection fraction PAC
Measurement of the following:
- ) RVEF
- ) RV end-systolic volumes
- ) RV end-diastolic volumes
Thermodilution PAC for CCO measurements
Continuous thermodilution CO measurements are possible with 8Fr catheter with a built in thermal filament. Powered and controlled by its own companion cardiac output computer.
Patient preparation procedures for PAC insertion.
- ) Explain procedure / obtain consent
- ) Local sedative / analgestic drugs
- ) If -ETT pt, place a surgical mask and hair cap on pt.
- ) Apply Pulse oximeter. Check BP Q5 min
- ) Label IV tubing for emergency drug administration.
- ) Turn off NG feedings / connect NG tube to suction.
- ) Trendelenburg if cannulating central veins.
After the balloon is inflated with 1.5 ml of air, does it cover the sensing tip?
No, the balloon protrudes over and cushions it, but does not completely cover it.
Step #1 in preparation for PAC insertion.
- )Inflate balloon with 1.5 ml of air, check for symmetrical inflation.
- ) Submerge under sterile water to check for leaks.
- ) Check for sensing tip exposure
Step #2 in preparation for PAC insertion.
- ) Attach stopcocks to Proximal and Distal Ports.
- ) Flush with saline solution
- ) Close stopcocks to keep flush solution within the PAC
Step #3 in preparation for PAC insertion.
Wipe PAC with a wet gauze pad and pass through sterility shield.
Step #4 in preparation for PAC insertion.
- ) Attach Distal Port to CO computer.
2. ) Attach Distal Port to tubing which is attached to a leveled and zeroed transducer/monitor.
Step #5 preparation for PAC insertion.
Have a Defribillator and lidocane (Xylocaine) at bedside ready to cardiovert.
Risks of Balloon Under-inflation during flotation?
Endovascular or endocardial injury by the exposed PAC sensing tip.
Risks of Balloon Over-inflation during flotation?
Balloon rupture or wedging in a proximal pulmonary artery segment.
When is CO2 recommended during PAC insertion?
If right-to-left intracardiac shunts are suspected, the use of CO2 eliminates the risk of systemic or cerebral embolization.
While floating a PAC what should you monitor for?
Monitor the oscilloscope for arrhythmias
PAC measurements seem bizarre or incongruent with the HX and clinical picture. What do you do?
- ) Apirate and then flush the distal catheter lumen
- ) Re-calibrate
- ) re-zero the monitoring system.
Normally passage of the PAC from the RA to PWP takes about 10-20 seconds. With what patients should I expect a difficult and prolonged passage? What other equipment would these circumstance require?
- ) Dilated RV
- ) Low Cardiac Output
- ) Tricuspid regurgitation
- ) Pulmonary HTN
This would require the use of fluoroscopy to visually direct the catheter to the PA position.
Normal RA pressures?
0-8 mmHg
Normal RV pressures?
15-25
_____ mmHg
0 - 8
Normal PA pressures?
15-25
_____
8 - 15 mmHg
Pressures sensed within the Pulmonary Veins with the PAC correlate with what?
- ) Left Atrial pressure /waveforms
2. )LVED pressure.
Normal LA pressures?
4 - 12 mmHG
Normal LV pressures?
110 -130
_______ mmHG
4 - 12
How long should the balloon remain in the wedge position?
15 seconds
or
2-3 respiratory cycles
3 Prolonged Wedging Risks?
- ) Pulmonary Vascular Injury
- ) Rupture
- ) Ischemia of lung segment distal to PAC
Prolonged wedging or hyperinflation may result in a false elevation of PWP measurement know as OVERWEDGING. What are the waveform characteristics of over-wedging? meaningless values
- ) “a” and “v” waves are not displayed.
- ) Waveform rises slowly and progressively
- ) Waveform abruptly falls
- ) Waveform again rises slowly and progressively
PA diastolic pressure is usually what, in reference to LA PWP ?
PA diastolic pressure = 1 - 4 mmHg > LA pressures.
The LA pressure = 4-12 mmHg
This means that when PA is wedged, we can indirectly measure the LA pressures. If we retract from the LA > Pulmonary veins > lung > PA.
What conditions can cause an increase in PVR?
- ) Hypoxemia
- ) Acidemia
- ) Massive PE
- ) Pulmonary Vascular Disease
PA systolic/diastolic pressures increase but PWP does NOT.
What causes the continuously rising pressure associated with overwedging?
It is due to the build-up of intra-catheter pressure form the high-pressure flush system.
Normal PWP ?
4 - 12 mmHg
PA diastolic pressure > 4 - 5 mmHg higher than the PWP indicates what?
Increased PVR
Increased PVR would be noted if ?
PA diastolic pressure = 4 - 5 mmHg higher than the PWP
The greater the increase in PVR, the greater the difference between what ?
PA diastolic pressure and PWP
What are the following 3 criteria to follow any time a wedge pressure is in question?
1.) Balloon deflation = PA waveform appears
2.) Balloon Inflation = PA pressure trace flattens to a
characteristic LA pressure trace
with “a” and “v” waves.
3.) Mean PWP < Mean PA pressure or diastolic pressure.
PWP > PA diastolic pressure = artifact induced except
in pts with MITRAL REGURGITATION with
giant “v” waves.
Normal PA pressure?
15 - 25
______ mmHg (9-18 mmHg) mean
8 - 15
DISTAL Catheter tip location may result in what 4 things ?
- ) wrong CO
- ) Damage to PA
- ) Spontaneous Wedging
- ) Contamination of mixed venous specimen with arterialized blood.
PROXIMAL Catheter tip location may result in what 2 things ?
- ) catheter slippage into RV
2. ) Catheter whip artifact
Wedging balloon volume < 1 ml indicates what ?
Spontaneous distal migration
If there is a good correlation between PA diastolic pressure with PWP and the patient is stable, the PA diastolic pressure may be used to do what?
Track LA pressures
If factors know to increase PVR are present; (hypoxemia, PE, acidosis) how would you assess the LA pressure?
PWP
How will you obtain a mixed venous blood sample?
- ) Balloon deflated
- )Withdraw 2 - 5 ml slowly (1 ml /20 sec) from the stopcock attached to PA distal port and DISCARD.
- Withdraw a second 2 ml specimen very slowly, label PA aspirate, ice and send it to the lab.
Rapid aspiration of a mixed venous blood sample from the distal PA port would cause what?
Contamination of the specimen with fully oxygenated blood from the pulmonary capillaries.
patient forcibly exhales against a closed nose and mouth while bearing down, as if having a bowel movement, specific changes occur in blood pressure and the rate and volume of blood returning to the heart.
The Valsalva maneuver
7 steps in the removal of PAC ?
- ) Rule out catheter entrapment
- ) Explain Valsalva maneuver
- ) Remove dressings and sutures
- ) Pt in supine position
- ) Close stopcocks
- ) Ask pt to repeat Valsalva maneuver
- ) Apply gentle traction, if no resistance gently withdraw PAC.
LA & LVEDP may not exist in the following 3 pts.
- ) Acute, Severe MR
- ) LV dysfunction
- ) Mitral stenosis, LA myxoma
In pts. with MR or LV dysfunction how would you estimate LVEDP via PWP waveform?
By measuring the pressure at the:
Crest of the “a” wave if the patient is in sinus rhythm.
Area just prior to “v” wave if pt. is in A-fib.
In pts. with Mitral Stenosis or left atrial myxoma there is an obstruction of blood flow between the LA and the LV. PWP bears not relationship to the LVEDP, but does however correlate with LA pressure.
- ) Acute rises in the chronically elevated PWP indicate what?
- ) Decrease in PWP indicate what ?
- ) Risk of acute Pulmonary edema
2. ) Hypovolemia despite normal ranging pressures.
During quiet spontaneous breathing, Inspiration requires a slight ___ __ ____ _____?
decrease in intrathoracic pressure
During quiet spontaneous breathing, exhalation requires a slight ____ __ ____ _____?
increase in intrathoracic pressure
During spontaneous or labored breathing, evaluate PWP measurements at ?
End-expiration brief plateau on the downstroke following peak expiratory pressure.
&
Include 3 respiratory cycles.
When available display the following:
- ) PA pressures
- ) Airway pressures
- ) end-tidal CO2, volume may be used to identify end-expiration.
Pulmonary blood volume, Itravascular pressures, and capillary patency are GREATEST in the gravity-dependent lung areas. Where are they?
- ) Lung bases on an UPRIGHT patient
2. ) Lung areas adjacent to the back in a SUPINE patient.
Pulmonary blood volume, Itravascular pressures, and capillary patency are the LEAST in what areas of the lung?
- ) The (Apices) in an UPRIGHTt patient
2. ) Directly under the anterior chest wall in a SUPINE pt.
Zone 1 of the lung ?
Uppermost portion, capillaries are consistently compressed by Alveoli and there is no blood flow. A PAC in zone 1 would record only ALVEOLAR Pressures. PA pressures and PWP would be invalid
Zone 2 of the lung ?
Upper 1/3 of the lung. In this portion of the lung capillaries are:
Open in systole and compressed by alveoli in diastole. PAC in zone 2 would generate rue PA systolic pressure but PA diastolic pressure and PWP would be invalid.
Zone 3 of the lung ?
Lower 2/3s of the lung. Pulmonary capillaries are consistently patent. PA systolic, diastolic, & PWPs are valid.
Invalid or inconsistent PA pressure and PWP may be the result of:
- ) Inadvertent re-wedging in zone 1 or 2.
2. )Increases in the size of zone 1 or 2 due to hypovolemia, addition of PEEP or CPAP.
A dampened PWP tracing with patent catheter and tubing suggests what ?
PAC in Zone 1 or 2
Mechanical Ventilation poses 3 problems on PA pressures, what are they?
- ) Waveform baseline follows the pressure fluctuations related to the ventilator mode.
- ) Cardiac Output decreases as mean airway pressure increases.
- ) PEEP, CPAD, or alveolar air trapping may increase Zone 1 and 2 lung areas, specially if hypovolemic.
Waveform baseline follows the pressure fluctuations related to the ventilator mode. How can you avoid this?
Record PA pressures at end-expiration
Cardiac Output decreases as mean airway pressure increases. How would you solve this ?
- ) Gradually add PEEP while maintaining hemodynamic stability.
- ) IV volume to support ventricular filling, while guarding against pulmonary edema. Maintain PWP < 18-20 mmHg.
- )Consider inotropic agent
What is the optimum level of PEEP for any patient?
PaO2 > 60 mmHg
SaO2 > 90 mmHg
w/o compromising Cardiac Output.
5 cm H2O of PEEP increases PWP by ?
1 mmHg
Ability to aspirate blood through the Balloon inflation port suggests what?
Balloon rupture
Ventricular Function Curve
Illustrates the relationship between PRELOAD and VENTRICULAR PERFORMANCE
Right Ventricular Pre-Load may be expressed as ?
end-diastolic volume
Using thermodilution PAC Right and Left ventricular pre-load may be expressed as what ?
Ventricular filling pressure (RA pressure for the RV and PWP for the LV).
Causes of increased SVR ?
Anything that causes systemic vasoconstriction.
Hypovolemia
Hypothermia
Low CO syndromes
Excessive catecholamine secretion or administration
Causes of decreased SVR ?
Anything that causes systemic vasodilation. Hyperdynamic sepsis cirrhosis Compensated AR Anemia Neurogenic & Anaphylactic shock
Normal SVR ?
770 - 1500 dynes/sec/cm^-5
Normal PVR?
20 - 120 dynes/sec/cm^-5
Causes of Increased PVR ?
Any factors that cause pulmonary vasoconstriction. Pulmonary Edema Sepsis Acidemia Hypoxemia PHTN Congenital and Valvular Heart diseases Obstruction of Pulmonary circulation Massive PE Pulmonary micro-emboli
Causes of Decreased PVR ?
Any factor that causes pulmonary vasodilation.
Vasodilation therapy
correction of academia or hypoxemia
Vasodilator =
Afterload reducing
Vasopressor =
Afterload increasing
The hydrostatic pressure within the pulmonary capillaries as estimated by PWP is the principal determinant of what ?
Rate and volume of fluid movement from the pulmonary capillaries into the lungs.
If plasma concentrations are normal and pulmonary capillaries are intact ?
Fluid content of the lungs remains normal as long as the PWP is < 18 - 20 mmHg.
PWP at levels of 20 - 30 mmHg indicate what ?
Increase of water in the lungs which will develop into: Tachypnea Dyspnea Cough Crackles and wheezes upon auscultation.
PWP at levels of 30 - 35 mmHg indicate what ?
Florid Pulmonary Edema, incompatible with survival beyond a few hours, unless treated.
Pulmonary Shunt Fraction =
% of RV blood that does not exchange gases with the alveolar air. Normal shunt fraction is about 3 - 5 %
> 10 % = Common with CP disease
> 20% = Obvious on Chest X-Ray
> 25% = Significant lung disease and indication for +ETT with PEEP
Cause of increase in Pulmonary Shunt Fraction =
Atelactisis, Alveolar Edema, or Consolidation from Pneumonia increases intrapulmonary shunting proportional to the severity of the underlying lung disease.
As pulmonary shunt fraction increases, PaO2 ____?
Decreases
Pulmonary Shunt Formula?
Pulmonary capillary O2 content - Arterial O2 content
__________________________________________
Pulmonary capillary O2 content - Mixed Venous O2 cont
