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Pulmonary Artery Catheterization

Norm of Pulmonary Artery Catheterization

Adult Pressures
Right atrial (RA) pressure 3–11 mm Hg
Central venous pressure (CVP) 2–6 mm Hg (2.7–12 cm H2O)
Right ventricular systolic pressure (RVSP) 20–30 mm Hg
Right ventricular end-diastolic pressure (RVEDP) <5 mm Hg
Pulmonary artery systolic (PAS) pressure 20–30 mm Hg
Pulmonary artery end-diastolic pressure (PAEDP) 8–15 mm Hg
Pulmonary artery mean (PAM) pressure <20 mm Hg
Pulmonary artery wedge pressure (PAWP) or pulmonary capillary wedge pressure (PCWP) 4–12 mm Hg
Cardiac output (CO) 5–8 L/minute

Cardiac index

2.5–3.5 L/minute/m2

Pulmonary vascular resistance

80–240 dyne/second/cm-5

Systemic vascular resistance

800–1300 dyne/second/cm-5

 

Usage of Pulmonary Artery Catheterization

Assessment, diagnosis, and evaluation of the effects of therapy on right and left ventricular function; measurement of cardiac output and cardiac and pulmonary pressures; access to central venous blood and mixed venous blood samples; monitoring of mixed venous oxygen saturation (Svo2); temporary atrial, ventricular, or atrioventricular sequential pacing by means of a thermodilution pulmonary arterial pacing catheter; and preoperative, intraoperative, and postoperative uses, including monitoring of high-risk clients (those with a history of angina, cardiopulmonary disease, or potential fluid shifts during surgery), elderly clients, and high or low cardiac output states, and in situations when hypotensive anesthesia is used. Indications for pulmonary artery catheterization include acute myocardial infarction, angina (severe), burns (severe), cardiomyopathy, congestive heart failure, cardiac tamponade, intraoperative cardiac collapse, failure to respond to appropriate resuscitative measures, fluid-related hypotension and hypovolemia, intravascular control problems, noncardiogenic pulmonary edema, pulmonary congestive states, pulmonary edema, pulmonary failure, pulmonary hypertension, renal disease, right and left ventricular failure, shock states (cardiogenic, hypovolemic, septic, traumatic with concomitant heart failure), tissue perfusion (altered), and titration of chronotropic, inotropic, or vasoactive pharmacologic agents.

 

Description of Pulmonary Artery Catheterization

Pulmonary artery (PA) catheterization is an invasive procedure using a radiopaque polyvinyl chloride, flow-directed, balloon-tipped catheter containing fluid-filled proximal, distal, and thermistor lumens and a balloon inflation lumen with a valve. Proper placement of the catheter in the PA, in the lower one third of the lung (zone 3), where venous pressures are greater than alveolar pressure, allows for measurement of CVP, PAS, PAEDP, PAM, and PAWP pressures. Intermittent occlusion of the PA branch by inflation of the balloon tip with air or carbon dioxide (never fluid) temporarily impedes blood flow from the right side of the heart to the lungs. The mitral valve opens during diastole, permitting the distal part of the catheter to record pressure that is reflected backward through the left atrium and pulmonary capillary bed. Identical pressures in the left ventricle, left atrium, and pulmonary vasculature momentarily occur during diastole and are captured as the PAWP when the balloon is inflated.

 

Professional Considerations of Pulmonary Artery Catheterization

Consent form MAY be required.

Risks
Air embolism, arterial occlusion, dysrhythmias, hemothorax, infection, perforation of the pulmonary vasculature or myocardium, pneumothorax, pulmonary embolus or thrombus, ventricular tachycardia, cardiac valvular damage, complete heart block in clients with preexisting left bundle branch block.
Contraindications
History of latex allergy (for catheters containing latex or latex balloons).

 

Preparation

1. Cardiac assessment for history of complete left bundle branch block is indicated before insertion of a PA catheter because there is slight risk for developing a right bundle branch block during catheter insertion, resulting in complete heart block. Standby external transcutaneous pacemaker, insertion of temporary pacemaker, or use of a pacing thermodilution PA catheter can be used for those at risk for this complication.

2. Assemble and prepare monitoring equipment according to institutional protocol. This includes the following:

a. Program the monitor for PA pressure display.

b. Prepare a transducer with high-pressure tubing for hemodynamic monitoring and a pressure bag of normal saline or heparin flush solution according to institutional protocol.

c. Balance the transducer at the phlebostatic axis (the level of the client's right atrium, the fourth intercostal space at the midaxillary line).

3. Have an emergency cart on standby. Have lidocaine (100 mg) for intravenous use at the bedside in the event of sustained ventricular tachycardia caused by catheter irritation of the right ventricle.

4. Obtain povidone-iodine solution, sterile drapes, 1%–2% lidocaine (Xylocaine), introducer (sheath, Cordis) trays, a pulmonary artery catheter tray, and 0.9% saline or heparin flush solution.

5. The physician(s) performing the procedure should wear the following: a sterile gown, a sterile mask, a cap, and sterile gloves.

6. The procedure may be performed at the bedside or under fluoroscopy.

 

Procedure

1. The PA catheter may be inserted percutaneously into the external or internal jugular veins, femoral or subclavian veins, and the antecubital fossa veins by venous cutdown.

2. The client is placed in the supine position. For subclavian or internal jugular insertions, the head of the bed is lowered slightly into a shallow Trendelenburg position. The flat supine position is preferred; however, if not tolerated by the client, a low semi-Fowler's position is acceptable, provided that the same position is maintained throughout the procedure.

3. Electrocardiographic monitoring is performed throughout the procedure.

4. After the site is cleansed with povidone-iodine solution and allowed to dry, it is covered with sterile drapes.

5. A protective sleeve is placed over the PA catheter, and the catheter is flushed with sterile 0.9% saline or heparin flush solution (heparin 100 U/mL of 0.9% saline). The balloon at the distal end of the PA catheter is tested for proper inflation and integrity by injection of 1–1.5 cc of air into the PA distal injection port.

6. The PA distal port is connected to the transducer tubing and a paper printout of the PA tracing is started and run continuously throughout the catheter insertion.

7. The site is anesthetized with 1%–2% lidocaine. For subclavian or internal jugular (IJ) insertions, the Seldinger technique is used as follows: The vessel is cannulated with a 22- or 25-gauge needle (IJ insertions only; subclavian insertions omit this step). A large-bore needle is inserted over the small needle, and the small needle is removed. A guidewire is inserted through the large-bore needle, and that needle is removed. The introducer is then inserted over the guidewire, and the guidewire is removed. The introducer is then secured into place.

8. The PA catheter is inserted through the introducer and directed into the right atrium and through the tricuspid valve into the right ventricle. As the catheter traverses the right ventricle, the balloon at the distal portion of the catheter is inflated to permit normal cardiac blood flow to carry (float) the catheter through the pulmonic valve into the PA. Inflation of the balloon and flow-direction minimize the potential of catheter-induced ventricular dysrhythmias and irritability. However, the risk for ventricular tachycardia is greatest while the PA catheter tip is passing through the right ventricle. If ventricular tachycardia occurs, the catheter should be either advanced through the pulmonary valve or withdrawn into the right atrium. Lidocaine and emergency measures are seldom needed because the removal of the catheter as a ventricular irritant is usually sufficient to stop the tachycardia.

9. As the catheter is slowly inserted, placement and progress are assessed by observation of the monitor for the waveform and pressure changes characteristic of the different chambers and vessels of the cardiac and pulmonary anatomy. When the waveform changes from a PA waveform to a PAWP waveform, the balloon is allowed to deflate, and the catheter is secured into this position. The syringes of flush solution are removed, and the ports are either connected to a continuous flush solution or capped, according to the policy of the institution.

 

Postprocedure Care

1. Apply an occlusive sterile dressing to the PA catheter insertion site.

2. Obtain a chest radiograph for verification of the catheter placement if fluoroscopy has not been used.

3. PA pressures should be monitored continuously. The waveform should be frequently observed for progression of the catheter tip into a wedge position.

 

Client and Family Teaching

1. If the access is subclavian or jugular, the head will be covered with a sterile drape during the procedure.

2. Activity may be limited during the time a PA catheter is in place.

 

Factors That Affect Results

  1. The mechanical factors that invalidate pressure measurements include the following:
    • a. Air bubbles in pressure tubing system or transducer cause dampening of the waveform.
    • b. Kinking of pressure tubing causes dampening of the waveform.
    • c. Improper tubing length: Tubing should not exceed 48 inches in length from the client to the transducer.
    • d. Loose connections interfere with the high-pressure pathway along the tubing and may cause waveform artifact and false readings.
    • e. Stopcocks between the transducer and the PA distal port distort PA pressures slightly, but effects increase with an increased number of stopcocks. For this reason, use no more than one stopcock for ports through which pressures are monitored.
    • f. Blood return in the transducer tubing. The continual flush–counteracting pressure should be maintained at 300 mm Hg.
    • g. Catheter artifact (catheter whip, catheter fling) results from excessive catheter movement during cardiac contraction when the distal tip of the catheter is too close to the pulmonary valve.
    • h. Catheter displacement may result from backward recoil into the right ventricle as evidenced by large RV waveforms. It may also result from forward migration into a wedged position.
    • Migration of the catheter against the vessel wall may cause a dampened waveform and affect pressure readings. Repositioning the client or asking the client to cough may help to return the tip to a floating position. The catheter should never be flushed if a spontaneous wedge position is suspected.
    • j. Flush solution rate affects pressure readings. Clot formation near the distal port as a result of too slow a flush rate dampens the waveform and causes falsely low readings. Falsely high readings may result from a flush rate >3–6 mL/hour.
    • k. Incorrect transducer position below the phlebostatic axis causes falsely low pressure readings. A transducer higher than the phlebostatic axis causes falsely high pressure readings. Each 1-cm difference alters the reading by 1 mm Hg.
    • l. Malfunction of equipment, which may include the amplifier, the oscilloscope, the recording devices, or the transducer.
    • m. Positive-pressure mechanical ventilation (PEEP) elevates pressures slightly. Formulas are available to compensate for this effect. PEEP should never be discontinued to obtain pressure readings because the discontinuation has been shown to be deleterious to the client's condition.
    • n. Overinflation of the balloon results in inflation larger than what is necessary for the vessel size, recognized by a drifting up or down of the PAWP waveform. Overinflation may cause rupture of the pulmonary capillary. Air should be injected into the balloon very slowly while one continuously watches for a waveform change to a wedge position. Proper placement of the PA catheter is indicated when a PAWP waveform is obtained with 0.8–1.2 cc of air. At no time should more than 1.5 cc of air be injected into the balloon. Assessment or adjustment of PA catheter placement by a physician is indicated if a PAWP waveform cannot be obtained with ≥1.5 cc of air.
    • o. A ruptured balloon is indicated when one feels no resistance to air injection into the balloon port, along with an absence of a PAWP waveform, or by the presence of blood in the PA distal (balloon) port. Balloon rupture may result from a manufacturing defect or from balloon weakening after many inflations. Manual deflation may accelerate balloon weakening. If a ruptured balloon is suspected, no more air should be injected, and a physician should immediately assess the client.
    • p. Respiratory variation as a result of inspiration and expiration cannot be accounted for by digital averaging. The most accurate readings of pressures are calculated manually from paper recordings of the waveforms at end expiration.
    • q. Retrograde injection during cardiac output measurement is indicated when a backflow of blood or fluid is detected in the introducer or protective sleeve of the catheter. This is an indication that the catheter injectate opening is located within the lumen of the introducer, rather than in the right atrium. Retrograde injection results in inadequate thermodilution and falsely high cardiac output values.
  2. Physiologic conditions that alter pressure measurements of the different chambers and vessels include the following:
    • a. RA/CVP: Cardiac tamponade, fluid overload, pulmonary disease, pulmonary hypertension, right heart failure, tricuspid regurgitation, and tricuspid stenosis.
    • b. RV: Chronic congestive heart failure, constrictive pericarditis, pericardial effusion, pulmonary hypertension, pulmonary valvular stenosis, right ventricular failure, and ventricular septal defects.
    • c. PAS/PAD: Chronic obstructive pulmonary disease, increased pulmonary blood flow, left-to-right shunts secondary to atrial or ventricular septal defects, mitral stenosis, pulmonary edema, pulmonary embolus, and pulmonary hypertension.
    • d. PAWP/PCWP: Cardiac insufficiency, cardiac tamponade, left ventricular failure, mitral regurgitation, and mitral stenosis.

 

Other Data

  1. Transducers should be balanced every 2–4 hours with position and ventilator changes and before each measurement of PA catheter parameters.
  2. PA catheter balloons should never be manually deflated. The air should be allowed to flow back into the syringe spontaneously.
  3. The flexible PA catheter includes two-lumen, three-lumen, four-lumen thermo dilutional, and five-lumen catheters of varying lengths. Sizes include 5, 6, 7, and 7.5 Fr, with markings at 10-cm increments along the outer surface.
  4. Although the information obtained from the pulmonary artery catheter can help diagnose certain conditions, a meta-analysis routine perioperative use in vascular surgery and a study of use of continuous SvO2 monitoring during cardiac surgery have not been consistently shown to reduce morbidity and mortality.
  5. Later generations of catheter development include the capability for atrial, ventricular, or AV sequential pacing; continuous mixed venous oxygen saturation (SvO2); continuous cardiac output; using fiberoptic oximetry; and additional lumens or ports for fluid infusions.