PROCEDURE Arterial Pressure–Based Cardiac 60 Output Monitoring

Susan Scott PURPOSE: Arterial pressure–based cardiac output monitoring is a minimally invasive technology that can be used to obtain hemodynamic data on a continuous basis.

PREREQUISITE NURSING • The difference between the systolic and diastolic pressures KNOWLEDGE is called the pulse pressure, with a normal value of 40 mm Hg. • Arterial pressure is determined by the relationship between • Knowledge of the anatomy and physiology of the cardio- blood fl ow through the vessels (cardiac output), the com- vascular system is necessary. pliance of the aorta and larger vessels, and the resistance • Knowledge of the anatomy and physiology of the vascu- of the more peripheral vessel walls (systemic vascular lature and adjacent structures is needed. resistance). The arterial pressure is therefore affected by • Understanding of the pathophysiologic changes that occur any factors that change either cardiac output, compliance, in heart disease and affect fl ow dynamics is necessary. or systemic vascular resistance. • Understanding of aseptic technique is needed. • The average arterial pressure during a cardiac cycle is • Understanding of the hemodynamic effects of vasoactive called the mean arterial pressure (MAP). It is not the medications and fl uid resuscitation is needed. average of the systolic plus the diastolic pressures, because 1 • Understanding of the principles involved in hemodynamic at normal heart rates systole accounts for 3 of the cardiac 2 monitoring is necessary. cycle and diastole accounts for 3 of the cardiac cycle. • Knowledge of invasive cardiac output monitoring is needed. The MAP is calculated automatically by most patient • Knowledge of arterial waveform interpretation is needed. monitoring systems; however, it can be calculated manu- • Knowledge of defi nitions and norms for cardiac output, ally using the following formula: cardiac index, systemic vascular resistance, stroke volume, Systolic pressure +×()diastolic pressure 2 stroke index, preload, afterload, and contractility and stroke volume variation is necessary. 3 • Arterial pressure represents the forcible ejection of blood from the left ventricle into the aorta and out into the arte- • MAP represents the driving force (perfusion pressure) for rial system. During ventricular systole, blood is ejected blood fl ow through the cardiovascular system. MAP is at into the aorta, generating a pressure wave. Because of its highest point in the aorta. As blood travels through the the intermittent pumping action of the heart, this arterial circulatory system, systolic pressure increases and dia- pressure wave is generated in a pulsatile manner (see stolic pressure decreases, with an overall decline in the Fig. 59-1). The ascending limb of the aortic pressure wave MAP (see Fig. 59-2 ). (anacrotic limb) represents an increase in pressure because • Arterial pressure–based cardiac output (APCO) is obtained of left-ventricular ejection. The peak of this ejection is from an arterial catheter. 10–12 the peak systolic pressure, which is normally 100 to • APCO technology measures the rate of fl ow (cardiac out- 140 mm Hg in adults. After reaching this peak, the ven- put).10–12 tricular pressure declines to a level below aortic pressure • Stroke volume and heart rate are key determinants of cardiac and the aortic valve closes, marking the end of ventricular output. systole. The closure of the aortic valve produces a • Although systemic vascular resistance affects cardiac out- small rebound wave that creates a notch known as the put, the location of that effect is global and not limited dicrotic notch. The descending limb of the curve by location of that measurement because cardiac output is (diastolic down slope) represents diastole and is character- measured as fl ow per minute throughout the body. Man- ized by a long declining pressure wave, during which the ufacturers of the arterial pressure–based cardiac output aortic wall recoils and propels blood into the arterial systems have factored in variance for both radial artery network. The diastolic pressure is measured at the lowest catheters and femoral artery catheters.9 point of the diastolic down slope and is normally 60 to • Ultrasound guidance is recommended to place arterial 80 mm Hg. catheters if the technology is available.7

523 524 Unit II Cardiovascular System

EQUIPMENT PATIENT ASSESSMENT AND PREPARATION • Invasive arterial catheter and insertion kit • Specialized sterile transducer and sensor kit (manufac- Patient Assessment turer specifi c) • Obtain the patient ’ s medical history, including a history • Intravenous (IV) pole and transducer holder (manufac- of peripheral vascular disease, diabetes, and hypertension. turer specifi c) Rationale: These conditions increase the patient ’ s risk for • Pressure-transducer system, including fl ush solution rec- arterial or venous insuffi ciency. ommended according to institutional standards, a pressure • Obtain the patient ’ s medical history for peripheral vascu- bag or device, pressure tubing with transducer, and fl ush lar disease, vascular grafts, arteriovenous fi stulas or device shunts, arterial vasospasm, thrombosis, or embolism. In • Pressure module and cable for interface with the monitor addition, obtain the patient’ s history of coronary artery • Normal saline-fl ush solution bypass graft surgery in which radial arteries were removed • Monitoring system (central and bedside monitor) for use as conduits. Rationale: Extremities with any of • Special monitor to interface with the bedside monitor for these problems should be avoided as sites for cannulation trending and display of hemodynamic values (manufac- because of the potential for complications. turer specifi c) • Assess the neurovascular and peripheral vascular status of • Dual-channel recorder the extremity to be used for the arterial cannulation, • Indelible marker including color, temperature, presence and fullness of • Nonvented (noninjectable) caps pulses, capillary refi ll, presence of bruit, and motor and • Leveling device (low-intensity laser or carpenter level) sensory function (compared with the opposite extremity). • Sterile and nonsterile gloves Note: A modifi ed Allen’ s test may be performed before Additional equipment, to have available as needed, includes cannulation of the radial artery (see Fig. 81-3). Rationale: the following: This assessment may identify neurovascular or circulatory • Heparin if prescribed impairment, so potential complications related to radial • 3-mL syringe artery cannulation may be avoided. • Dressing supplies • Assess the patient ’ s vital signs and compliance factors • Tape (e.g., age, gender, height, weight). Rationale: This assess- • Sterile ultrasound probe cover ment provides baseline data. The compliance factors • Sterile ultrasound gel allow for the individual variables that ultimately dictate pulse pressure and its relevance (proportionality) to stroke PATIENT AND FAMILY EDUCATION volume.

• Explain the rationale for arterial line insertion, including Patient Preparation how the arterial pressure is displayed on the bedside • Verify that the patient is the correct patient using two monitor. Rationale: This explanation may decrease patient identifi ers. Rationale: Before performing a procedure, the and family anxiety and increase understanding. nurse should ensure the correct identifi cation of the patient • Explain the standard of care to the patient and family, for the intended intervention. including insertion procedure, alarms, dressings, and • Ensure that the patient and family understand preproce- length of time the catheter is expected to be in place. dural teaching. Answer questions as they arise, and rein- Rationale: This explanation encourages the patient and force information as needed. Rationale: Understanding family to ask questions and voice concerns about the of previously taught information is evaluated and procedure and may decrease patient and family anxiety. reinforced. • Explain the patient ’ s expected participation during the • Ensure that informed consent has been obtained. Ratio- procedure. Rationale: Patients will know how they can nale: Informed consent protects the rights of the patient help with the procedure. and makes a competent decision possible for the patient. • Explain the importance of keeping the affected extremity • Perform a preprocedure verifi cation and time out, if non- immobile. Rationale: This explanation encourages patient emergent. Rationale: Ensures patient safety. cooperation to prevent catheter dislodgment and ensures • Validate the patency of IV access. Rationale: Access may a more accurate waveform. be needed for administration of emergency medications • Instruct the patient to report any warmth, redness, pain, or fl uids. numbness, or wet feeling at the insertion site at any time, • Place the patient ’ s extremity in the appropriate position including after catheter removal. Rationale: These symp- with adequate lighting of the insertion site. Rationale: toms may indicate infection, bleeding, or disconnection of This placement prepares the site for cannulation and facil- the tubing or catheter. itates an accurate insertion. 60 Arterial Pressure–Based Cardiac Output Monitoring 525

Procedure for Arterial Pressure–Based Cardiac Output Monitoring Steps Rationale Special Considerations Initiating the Procedure 1 . HH 2 . PE 3. If the radial artery is to be used, The modifi ed Allen ’ s test has been The modifi ed Allen ’ s test does not perform the modifi ed Allen ’ s test recommended before a radial artery always ensure adequate fl ow before the puncture (see Fig. puncture to assess the patency of through the ulnar artery. 81-3 ). (Level C * ) the ulnar artery and an intact A Doppler ultrasound fl ow indicator superfi cial palmar arch.3,14 can also be used to further verify blood fl ow.1,2,4,7 4. Prepare the fl ush solution (see Heparinized fl ush solutions are Although heparin may prevent Procedure 75 ). commonly used to minimize thrombosis, 8,13,15 it has been A. Use an IV solution of normal thrombi and fi brin deposits on associated with thrombocytopenia saline. catheters that might lead to and other hematologic B. Follow institutional standards thrombosis or bacterial colonization complications.5 for adding heparin to the IV of the catheter. Other factors that promote patency of solution, if heparin is not the arterial line besides heparinized contraindicated. (Level B * ) saline solution include male gender, longer arterial catheters, larger vessels cannulated, patients receiving other anticoagulants or thrombolytics, and short-term use of the catheter.1 5. Gather the equipment needed for Prepares supplies. Refer to the specifi c manufacturer for obtaining an arterial pressure– additional required equipment for based cardiac output. setup and maintenance. Some technologies require additional calibration procedures and equipment.10 6. Obtain the patient ’ s baseline This information may be needed to Follow manufacturer guidelines. compliance factors (e.g., allow for the individual variables Some manufacturers require age, gender, height, weight). that ultimately dictate pulse calibration. (Level M * ) pressure and its relevance Manufacturers that do not require (proportionality) to stroke volume. calibration use age, gender, height, and weight to determine vascular compliance. An accurate height and weight refl ecting perfused tissue is important in the determination of body surface area (BSA) and cardiac index. Fluid weight gain often is discounted because it is not perfused tissue. Medications are generally based on perfused weight in the case of morbidly obese patients. Because adipose tissue is highly vascular, actual weight and height are necessary to determine BSA. BSA is needed for calculating indexed values. 7. Remove PE and discard used Reduces the transmission of supplies. microorganisms; Standard Precautions. 8 . HH

* Level B: Well-designed, controlled studies with results that consistently support a specifi c action, intervention, or treatment. * Level C: Qualitative studies, descriptive or correlational studies, integrative reviews, systematic reviews, or randomized controlled trials with inconsistent results. * Level M: Manufacturer ’ s recommendations only.

Procedure continues on following page 526 Unit II Cardiovascular System

Procedure for Arterial Pressure–Based Cardiac Output Monitoring—Continued Steps Rationale Special Considerations Setting Up the Arterial Pressure–Based Cardiac Output (APCO) System 1 . HH 2 . PE 3. Open the APCO sensor kit. Prepares equipment. Follow manufacturer recommendations. 4. Secure all connections. Tight connections ensure the integrity Vented caps are standard with of the system. transducer sets and kits, and allow for initial priming of the system. 5. Insert the APCO sensor into the Stabilizes the sensor. transducer holder that is secured on the IV pole next to the patient. 6. Level the vent port near the The reference point is the phlebostatic sensor to the phlebostatic axis. axis because it accurately refl ects central arterial pressure. 7. Prime or fl ush the entire APCO Removes air bubbles. Prime the system using gravity to system: minimize small bubbles. A. Activate the fl ush device to Removes air from the system. deliver the fl ush solution through the sensor and out through the vent port. B. Close the vent port by turning the stopcock to the neutral position. C. Place a sterile nonvented Maintains a closed sterile system. (noninjectable) cap on the top of the stopcock. D. Purge air from the remaining Prepares the monitoring system. part of the tubing. 8 . I n fl ate the pressure bag or device Infl ating the pressure bag to to 300 mm Hg. 300 mm Hg allows approximately 1–3 mL/hr of fl ush solution to be delivered through the catheter, thus maintaining catheter patency and minimizing clot formation. 9. Assist as needed with insertion of Provides needed assistance. the arterial catheter (See Procedures 58 & 59 ). 10. Connect the bedside monitor Information can then be transferred Follow manufacturer guidelines. cable to the APCO sensor from the sensor to the monitor. Some cables are color coded. ( Fig. 60-1 ). 11. Enter the patient ’ s gender, age, This information is needed to allow Follow manufacturer guidelines. height, and weight. (Level M * ) for the individual variables that Some manufacturers require ultimately dictate pulse pressure calibration. and its relevance (proportionality) to stroke volume. The result is stroke volume variability. 12. Set up the monitor. Prepares equipment. Follow the manufacturer ’ s guidelines as the setup may vary. 13. Observe the cardiac output (CO) Provides assessment data. The cardiac output value is updated display. regularly based on the manufacturer.

*Level M: Manufacturer’s recommendations only. 60 Arterial Pressure–Based Cardiac Output Monitoring 527

Figure 60-1 FloTrac sensor and Vigileo monitor. (Courtesy of Edwards Lifesciences, LLC, 2009.)

Procedure for Arterial Pressure–Based Cardiac Output Monitoring—Continued Steps Rationale Special Considerations 14. Set the alarm parameters Activates the bedside and central Follow manufacturer guidelines. according to the patient ’ s current alarm system. blood pressure. 15. Remove PE and discard used Reduces the transmission of Ensure sharps are safely disposed. supplies in appropriate microorganisms; Standard receptacles. Precautions. 16. HH

Expected Outcomes Unexpected Outcomes • Accurate measurement of cardic output (CO) • Poor-quality arterial pressure wave leading to the • Maintenance of catheter patency inability to obtain an accurate CO • Minimal discomfort from the arterial catheter • Infection • Maintenance of baseline hemoglobin and hematocrit • Impaired peripheral tissue perfusion (e.g., edema, levels coolness, pain, paleness, or slow capillary refi ll of the • Adequate circulation to the involved extremity fi ngers of the cannulated extremity) • Adequate sensory and motor function of the extremity • Perforated or lacerated artery • Maintenance of the catheter site without infection • Hematoma at the insertion site • Pain or discomfort from the arterial catheter insertion site • Decreased hemoglobin and hematocrit values • Catheter disconnection with signifi cant blood loss Procedure continues on following page 528 Unit II Cardiovascular System

Patient Monitoring and Care Steps Rationale Reportable Conditions These conditions should be reported if they persist despite nursing interventions. 1. Assess the neurovascular and Determines peripheral vascular and • Diminished or absent pulses peripheral vascular status of the neurovascular integrity. Changes in • Pale, mottled, or cyanotic cannulated extremity immediately sensation, motor function, pulses, appearance of the extremity after catheter insertion and every 4 color, temperature, or capillary refi ll • Extremity that is cool or cold to hours, or more often if needed. may indicate ischemia, arterial the touch Follow institutional standards. spasm, or neurovascular • Capillary refi ll time of more than 2 compromise. seconds (or longer than patient’ s baseline) • Diminished or absent sensation • Diminished or absent motor function 2. Assess the arterial catheter Identifi es the possibility of site • Redness at the site insertion site for signs and infection. • Purulent drainage symptoms of infection. • Tenderness or pain at the insertion site • Elevated temperature • Elevated white blood cell count 3. Continuously monitor heart rate, Provides assessment of patient status. • Abnormal vital signs blood pressure, and cardiac • Abnormal cardiac output indices. • Abnormal cardiac index 4. Follow institutional standards for Identifi es need for pain interventions. • Continued pain despite pain assessing pain. Administer interventions analgesia as prescribed. 5. Assess the patient ’ s response to The hemodynamic management of the • Abnormal cardiac output prescribed interventions. patient requires close monitoring • Abnormal cardiac index and interventions based on the • Abnormal vital signs parameters obtained from the APCO data. 6. Replace gauze dressings every 2 Decreases the risk for infection at the days and transparent dressings at catheter site. The Centers for least every 5–7 days and more Disease Control and Prevention frequently as needed.6,7,13,16 (CDC) 13 and the Infusion Nurses (Level D * ) Society 6,7 recommend replacing the dressing when the dressing becomes damp, loosened, or soiled, or when inspection of the site is necessary.

* Level D: Peer-reviewed professional and organizational standards with the support of clinical study recommendations.

Documentation Documentation should include the following: • Patient and family education • Type of fl ush used • Informed consent • Amount of fl ush solution on intake and output record • Preprocedure verifi cation and time out • Vital signs, cardiac output, cardiac index, and other • Patient tolerance of the procedure hemodynamic parameters • Peripheral vascular and neurovascular assessment • Positive fl ow by modifi ed Allen ’ s test if the radial before and after the procedure artery is used • Assessment of the insertion site • Site assessment • Patient response to the insertion procedure • Unexpected outcomes • Pain assessment, interventions, and effectiveness • Additional nursing interventions 60 Arterial Pressure–Based Cardiac Output Monitoring 529

References and Additional Readings For a complete list of references and additional readings for this procedure, scan this QR code with any freely available smartphone code reader app, or visit http://booksite.elsevier.com/9780323376624 .