Bedside Pulmonary Artery Catheterization

Published on 22/03/2015 by admin

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W5 Bedside Pulmonary Artery Catheterization

Jean-Louis Vincent

image Before Procedure

Indications

• Need for continuous monitoring of pulmonary artery and right atrial (RA) pressures, cardiac output, and mixed venous oxygen saturation (SvO2) providing that:

• The data collected will help in the management of the patient
• The same measurements cannot be obtained by a less invasive method

Contraindications

• Absolute contraindications:

• Tricuspid or pulmonary valve endocarditis

• Relative contraindications:

• Tricuspid or pulmonary valve mechanical prosthesis
• Right heart mass (thrombus and/or tumor)
• Complete left bundle branch block
• Severe clotting abnormalities

Equipment

• Sterile gowns, gloves, and masks
• 8F to 9F gauge introducer
• Sterile saline solution for flushing
• Volume-limited syringe for pulmonary artery catheter (PAC) balloon
• Pressure monitor transduction system and connector tubing

image Anatomy

The inflated balloon of the PAC facilitates the catheter progression through a branch of the pulmonary artery. The distal lumen of the PAC measures the pressure downstream. It is assumed that there is a continuous column of blood between the distal lumen and the left ventricle (LV), and therefore the balloon-occluded pressure (PAOP) is equal to left ventricular end-diastolic pressure (LVEDP). PAOP reflects the pressure where the nonflowing blood (in the obstructed vessel) joins the blood flowing from the nonoccluded branches of the pulmonary artery. PAOP is actually intermediate between pulmonary capillary pressure and left atrial (LA) pressure. There are conditions, however, in which this theoretical continuous column of blood is interrupted, and in these circumstances PAOP no longer reflects LVEDP.

image Procedure

• Check the patient’s electrocardiogram (ECG), coagulation profile, and serum electrolytes panel. One should consider correcting major clotting disorders. If the patient already has a pacemaker, it may be better to place the catheter under radiographic guidance to avoid dislodging it.
• Inflate the catheter balloon as a test prior to catheter insertion.
• Connect the distal lumen to the pressure-monitoring system, and flush all lumens with sterile saline solution.
• Zero-reference the pressure transducer to the mid-chest position.
• Slide the protective sleeve onto the catheter to maintain sterility for further manipulations.
• Place sterile field.
• Provide local anesthesia.
• Insert introducer into a central vein, preferably the internal jugular or subclavian, using the Seldinger technique.
• Pass the catheter through the hemostatic valve of the introducer.
• Inflate the balloon once the catheter tip has passed about 15 cm.
• Advance the catheter for another 15 cm. It should pass into the right ventricle (RV) and give an RV pressure waveform.
• Advance the catheter further to pass into the PA, and finally to obtain a PAOP (PAWP) waveform.
• Once a PAOP waveform has been obtained, deflate the balloon to return to the PA waveform.
• Once the catheter is in place, check the position with a chest radiograph. In the vast majority of cases, the tip is in the right lung. The tip should be within 2 cm of the cardiac shadow.
• All pressures should be measured at end expiration, when alveolar pressure should be closest to atmospheric pressure.

Procedural Precautions

• Always have the PA trace displayed on the monitor.
• Never withdraw the catheter without first deflating the balloon.
• Do not insert large lengths of catheter without observing a pressure change, because this maneuver may lead to looping and knotting of the catheter.
• There may be difficulties in reaching the RV or PA owing to RA or RV dilatation, tricuspid regurgitation, or abnormalities of the central veins. An option may be to advance the catheter with the balloon partially deflated during inspiration, repositioning the patient in a head-up or right lateral position, or flushing the catheter with iced saline to make it more rigid.
• If the PAOP trace is obtained when the balloon is inflated with less than 1 mL of air, or if there is a progressive elevation of pressure when the balloon is inflated (“overwedging”), the catheter tip is too advanced and should be withdrawn by a few centimeters to decrease the risk of PA rupture/infarction.

image After Procedure

Postprocedure Care

• The PAC can be kept in situ for several days but should be removed as soon as it is no longer required for patient care.
• Balloon rupture can be identified by failure to wedge and failure of the syringe plunger to spontaneously deflate the balloon.

Interpretation Of Measured Pressures

• The pulmonary artery waveform has a systolic and diastolic pressure with a dicrotic notch corresponding to closure of the pulmonary valve.
• The PAOP, like the central venous pressure (CVP), has a venous waveform with a, c, and v waves corresponding to LA contraction, closure of the mitral valve, and passive LA filling, respectively.
• The a wave coincides with the point of maximal filling of the LV and is therefore the value that should be used for measurement of LVEDP. A large-amplitude a wave with an increase in measured PAOP suggests LV ischemia and decreased ventricular compliance.
• A large v wave on the PAOP trace represents mitral regurgitation or an acute volume load to the LA, as occurs with septal rupture. The PAOP level should be measured without consideration for this v wave.
• The RA pressure waveform can look like an RV waveform if there is significant tricuspid regurgitation.
• In cardiac tamponade, RA pressure and PAOP are high and similar as they equilibrate with pericardial pressures.
• A “dip-and-plateau” waveform may be seen in the RV pressure tracing in constrictive pericarditis, restrictive cardiomyopathy, RV infarction, and massive pulmonary embolism. This pattern is due to impaired ventricular filling during diastole.

Measurement Of Cardiac Output With The Pac

• Thermodilution is the standard method for the measurement of cardiac output.
• Measurement is based on the indicator dilution principle: when an indicator substance is added to a stream of flowing blood, the flow rate is inversely proportional to the mean concentration of the indicator at a downstream site. In the case of thermodilution, the indicator used is temperature, using either a bolus of cold injectate (cold thermodilution) or a thermal filament to generate heat (warm thermodilution).

• The old technique included a 10-mL bolus of room temperature 5% dextrose solution or saline injected over 4 seconds through the proximal port of the PAC. The thermistor proximal to the balloon then recorded the temperature change in the pulmonary artery, and a temperature time curve was displayed. The average of at least three curves was then obtained.
• Modern catheters provide a semicontinuous method in which a thermal filament is mounted on the PAC 14 to 25 cm from the tip. The filament intermittently generates pulses of heat, and the temperature change is recorded by the thermistor in the pulmonary artery. These pulses of heat are pseudorandom to minimize the influence of other sources of temperature change such as infusions or respiratory fluctuations. The cardiac output is updated every 30 to 60 seconds and is time-averaged over the previous 3 to 6 minutes.

Complications

Complications that are unique to the PAC and not just due to insertion of a central venous catheter can be divided into those caused by placement and the longer-term complications due to its presence:

• Placement:

• Common:

• Arrhythmias, most commonly premature atrial or ventricular contractions that are self-limiting and can occur on insertion or withdrawal of the catheter

• Rare:

• Knotting of the catheter; a knot generally can be removed by placing a guidewire through the PAC to undo the loop or by pulling the loop tight against the introducer sheath and removing the whole unit.
• Tricuspid pulmonary regurgitation or chordae tendineae rupture can occur if the catheter is withdrawn with the balloon inflated.

• Presence of the catheter:

• Common:

• Arrhythmias, most commonly premature atrial or ventricular contractions that are self-limiting and can occur on insertion or withdrawal of the catheter
• Catheter-related infections

• Rare:

• Pulmonary infarction due to catheter-related thromboembolism, obstruction of the pulmonary blood flow by the catheter tip, or prolonged inflation of the balloon. Usually without consequences.
• Endocarditis
• Pulmonary artery rupture occurs in less than 0.1% of cases, associated with a mortality of greater than 30%. Warning signs include hemoptysis, with shadowing on the chest radiograph. Diagnosis is confirmed by pulmonary angiography. Treatment consists of embolization or thoracotomy. Factors increasing the risk of rupture include pulmonary hypertension, advanced age, hypothermia, coagulation disorders, and distal positioning of the catheter.

image Outcomes and Evidence

• Benefits of bedside pulmonary artery catheterization remain controversial, and insertion of a PAC cannot, per se, improve patient survival.
• Pulmonary artery catheters should not be inserted routinely but only in patients in whom the data collected will help in the patient’s management, and the same measurements cannot be obtained by a less invasive method.
• To be beneficial, data from the PAC must be collected, interpreted, and applied correctly.

Suggested Reading

Swan H, Ganz W, Forrester J, et al. Catheterisation of the heart in man with use of a flow-directed balloon tipped catheter. N Engl J Med. 1970;283:447-451.

Harvey S, Harrison DA, Singer M, et al. Assessment of the clinical effectiveness of pulmonary artery catheters in management of patients in intensive care (PAC-Man): a randomised controlled trial. Lancet. 2005;366:472-477.

Shah MR, Hasselblad V, Stevenson LW, et al. Impact of the pulmonary artery catheter in critically ill patients: meta-analysis of randomized clinical trials. JAMA. 2005;294:1664-1670.

Vincent JL, Pinsky MR, Sprung CL, et al. The pulmonary artery catheter: in medio virtus. Crit Care Med. 2008;36:3093-3096.

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W5 Bedside Pulmonary Artery Catheterization

Jean-Louis Vincent

image Before Procedure

Indications

• Need for continuous monitoring of pulmonary artery and right atrial (RA) pressures, cardiac output, and mixed venous oxygen saturation (SvO2) providing that:

• The data collected will help in the management of the patient
• The same measurements cannot be obtained by a less invasive method

Contraindications

• Absolute contraindications:

• Tricuspid or pulmonary valve endocarditis

• Relative contraindications:

• Tricuspid or pulmonary valve mechanical prosthesis
• Right heart mass (thrombus and/or tumor)
• Complete left bundle branch block
• Severe clotting abnormalities

Equipment

• Sterile gowns, gloves, and masks
• 8F to 9F gauge introducer
• Sterile saline solution for flushing
• Volume-limited syringe for pulmonary artery catheter (PAC) balloon
• Pressure monitor transduction system and connector tubing

image Anatomy

The inflated balloon of the PAC facilitates the catheter progression through a branch of the pulmonary artery. The distal lumen of the PAC measures the pressure downstream. It is assumed that there is a continuous column of blood between the distal lumen and the left ventricle (LV), and therefore the balloon-occluded pressure (PAOP) is equal to left ventricular end-diastolic pressure (LVEDP). PAOP reflects the pressure where the nonflowing blood (in the obstructed vessel) joins the blood flowing from the nonoccluded branches of the pulmonary artery. PAOP is actually intermediate between pulmonary capillary pressure and left atrial (LA) pressure. There are conditions, however, in which this theoretical continuous column of blood is interrupted, and in these circumstances PAOP no longer reflects LVEDP.

image Procedure

• Check the patient’s electrocardiogram (ECG), coagulation profile, and serum electrolytes panel. One should consider correcting major clotting disorders. If the patient already has a pacemaker, it may be better to place the catheter under radiographic guidance to avoid dislodging it.
• Inflate the catheter balloon as a test prior to catheter insertion.
• Connect the distal lumen to the pressure-monitoring system, and flush all lumens with sterile saline solution.
• Zero-reference the pressure transducer to the mid-chest position.
• Slide the protective sleeve onto the catheter to maintain sterility for further manipulations.
• Place sterile field.
• Provide local anesthesia.
• Insert introducer into a central vein, preferably the internal jugular or subclavian, using the Seldinger technique.
• Pass the catheter through the hemostatic valve of the introducer.
• Inflate the balloon once the catheter tip has passed about 15 cm.
• Advance the catheter for another 15 cm. It should pass into the right ventricle (RV) and give an RV pressure waveform.
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