High-Acuity Nursing, 6th Edition

Introduction to Hemodynamic Monitoring Objectives: 1. Describe cardiac output as the major parameter of interest in monitoring a patient’s hemodynamic status. 2. Discuss noninvasive and minimally invasive hemodynamic monitoring technologies, including impedance cardiography and Doppler ultrasound, central venous pressure, direct arterial blood pressure measurement, and arterial pulse contour analysis technology. 3. Explain pulmonary artery catheters, including their purpose, required competencies, interpretation of data, functional components, and care of the catheter. 4. Apply knowledge of PA catheter insertion and management and measurements obtained using the PA catheter. 5. Describe right atrial and right ventricular pressures, including the purposes, measurement, waveform analysis, clinical findings, and treatment of abnormal pressures. 6. Discuss pulmonary artery pressure and pulmonary artery wedge pressure (a measure of left ventricular end diastolic pressure [LVEDP]), including the purposes, measurement, waveform analysis, clinical findings, and related interventions for treating abnormal pressures. 7. Describe vascular resistance (systemic and pulmonary) and its measurements, including treatments for abnormal levels. I. Introduction to Hemodynamic parameters A. Hemodynamics 1. Physiologic term that refers to the forces involved in the flow of blood as it circulates through the cardiovascular system. 2. Hemodynamics can be measured by obtaining the blood pressure (using a blood pressure cuff and sphygmomanometer), heart rate by auscultating or palpating, and urine output, all basic assessments that are easily acquired. B. Cardiac output and cardiac index 1. Cardiac output is the amount of blood pumped by the heart each minute: CO+HRxSV a) Normal range of CO is 4 to 8 L/min. 2. Cardiac index a) Individualizes patients’ CO by taking body size into account. b) CI provides meaning to CO and determines what is normal for each patient. c) Important parameter in guiding clinical decisions. C. Heart rate 1. Heart rate is the first determinant of cardiac output and is an easily measured parameter. 2. The heart rate is dictated by the heart’s pacemaker sites, with influence from the sympathetic and parasympathetic nervous systems. D. Stroke volume—is the amount of blood ejected by each heartbeat, and it is not readily measurable using simple hemodynamic technologies. 1. Preload a) The pressure or stretch exerted on the walls of the ventricle by the volume of blood filling the ventricle at the end of diastole (ventricular filling). 2. Afterload a) The resistance to ventricular contraction. b) The pressure the ventricle must overcome to open the aortic or pulmonic valve and eject blood out of the ventricle into the systemic or pulmonary circulation, respectively. 3. Contractility a) Is a property of myocardial muscle fibers that slows them to shorten PowerPoint Slides 1. Hemodynamics Flow of blood as it circulates through the cardiovascular system Measured by obtaining the blood pressure heart rate and urine output 2. Cardiac Output and Cardiac Index Individualizes patients’ CO CI provides meaning to CO Important parameter in guiding clinical decisions 3. Heart Rate First determinant of cardiac output; fluid temperature is cooler than blood temperature Dictated by the heart’s pacemaker sites 4. Stroke Volume Reload Afterload Contractility II. Noninvasive and Minimally Invasive Hemodynamic Technologies 1. New, less invasive technologies are emerging for hemodynamic assessment to avoid complications associated with the PA catheter. 2. Ideal cardiac output monitor would be: a) Noninvasive b) Valid c) Reliable under various hemodynamic situations d) Easy to use e) Continuous f) Cost-effective A. Noninvasive technologies 1. Impedance cardiography a) Uses high frequency, low-amplitude current to measure the resistance to electrical current flow. b) Directly measures volume of electrically participating tissue. c) Indirectly measures stroke volume, cardiac output, and contractility indicators. 2. Doppler ultrasound measures blood flow velocity in the vessel. a) Helps to determine: (1) Cardiac output (2) Preload (3) Afterload (4) Contractility status b) Has specific algorithms that determine vessel or valve cross-sectional area. c) Probe is placed on specified area. d) Stroke volume calculated based on blood flow velocity and vessel or valve area. B. Minimally invasive hemodynamic technologies 1. Central venous accesses and measurement a) An indicator of central blood volume and is influenced by a variety of factors, including cardiac output, systemic venous return to the heart, total blood volume an other factors. 2. Arterial access and measurements a) Arterial access line (1) Facilitates monitoring the patient’s blood pressure on a continuous basis, which allows the nurse to monitor the patient’s response to interventions without having to disturb the patient to take a manual blood pressure reading. b) Insertion of the arterial access line (1) The nurse typically is responsible for setting up the equipment for catheter insertion, calibrating the equipment to ensure accurate readings, and assisting the physician with the procedure. c) Arterial waveform (1) Characteristic morphology is related to the cardiac cycle (Fig. 7-4). d) Arterial pulse contour analysis (1) The use of the pulse contour analysis is based on the principle that the SV may be measured by assessing the beat-to-beat changes in the amplitude of the pulse pressure as displayed on the waveform. e) Mean arterial pressure (MAP) (1) MAP represents the average pressure in the systemic circulation throughout the cardiac cycle. (2) MAP represents the average pressure in the systemic circulation throughout the cardiac cycle. (3) Normal range is 70–90 mmHg. (4) Provided by arterial line or automatic blood pressure equipment. (5) Arterial line is most accurate: measured, not calculated. PowerPoint Slides 1. New Hemodynamic Monitoring Technologies New, less invasive technologies are emerging for hemodynamic assessment to avoid complications associated with the PA catheter. 2. Impedance Cardiography Assesses cardiac function by measuring resistance to high-frequency, low-amplitude electrical current Directly measures volume of electrically participating tissue Indirectly measures stroke volume, cardiac output, and contractility indicators 3. Doppler Ultrasound Measures blood flow velocity in the vessel Helps to determine: Cardiac output Preload Afterload Contractility status 4. Minimally Invasive Hemodynamic Technologies Central venous access and measurement Arterial access and measurements Arterial access line Insertion of the arterial access line Arterial waveform Arterial pulse contour analysis Mean arterial pressure (MAP). III. Introduction to Pulmonary Artery Catheters A. Purpose of PA catheters 1. The pulmonary artery (PA) catheter is an invasive diagnostic tool used for the following purposes: a) Determining the pressures within the right heart and PA b) Indirectly measuring left heart pressures c) Determining cardiac output d) Sampling mixed venous blood from the PA e) Infusing fluids B. Required provider competencies 1. Three essential steps required for hemodynamic assessment with the PA catheter: a) Obtain accurate data. (Nurses must ensure proper calibration of hemodynamic monitoring equipment.) b) Perform waveform analysis. c) Integrate data with other assessment parameters. C. Interpretation of data 1. Careful clinical assessment, integrated with the data collected from PA catheter, provides a basis for nursing interventions and the manipulation of potent vasoactive medications or fluids. D. Standard PA catheter construction and components 1. Proximal injectate lumen and hub a) Terminates in the proximal heart chamber, the right atrium. b) Proximal is usually imprinted on the hub or tubing close to it—check for it. c) Tubing is usually blue. e) Monitors and samples RAP when connected to a transducer. f) Injectate used to determine cardiac output placed in this lumen. g) Can also be used to infuse IV fluids. 2. P proximal Infusion Lumen and Hub (Optional) a) Terminates in the right atrium b) White tubing for quick identification c) Used as the “central line” for IV fluid infusions d) Can be used to obtain cardiac output if the proximal injectate is blocked 3. Distal lumen and hub a) Terminates in the PA. b) Distal is usually imprinted on the hub or tubing close to it—check for it. c) Yellow tubing for quick identification. d) Always connected to transducer for continuous monitoring of the PA pressure (PAP) and waveform. e) Used to obtain PAWP by balloon inflation. f) Used to obtain venous blood oxygen saturation. g) Not used to infuse medications and IV solutions. 4. Thermistor a) A wire that terminates near the catheter tip b) Exposed to blood flowing from the PA c) Detects changes in blood temperature d) Monitors core body temperature e) Proximal end connects to the cardiac output–monitoring device 5. Balloon inflation lumen and valve a) Located near the small balloon at the distal end of the catheter. b) Can be opened or closed with “gate valve” mechanism. c) Balloon inflates to monitor PA waveform. d) Maximum recommended inflation volume should not be exceeded. e) Deflation is always passive—should not be done manually. f) Should not be left in the passive position. E. Hemodynamic monitoring equipment 1. Transducer translates mechanical energy sensed by the catheter into electrical energy, displayed on the monitor screen as a waveform. a) Leveling the Transducer corrects for hydrostatic pressure changes in vessels above and below the heart. b) Zeroing the Transducer corrects for any drift or deviation from baseline that may occur. 2. Pressure bag is used to overcome the pressure within the pulmonary artery and prevent blood from backing up into the pressure tubing. F. Special pulmonary artery catheters. These have the standard design properties of all PA catheters plus additional properties that meet special therapeutic or measurement needs. 1. Pacing port 2. Continuous cardiac output (CCO) 3. Oximetry 4. Volumetrics G. Care of central venous catheters 1. Catheter site dressing regimens 2. Needleless intravascular catheter systems 3. Recommendations for central venous catheters 4. Skin preparation 5. Maximal sterile barrier precautions 6. Replacing administration sets 7. Replacement of peripheral and midline catheters 8. Catheter securement devices PowerPoint Slides 1. Introduction to Pulmonary Artery Catheters Purpose of PA catheters Required provider competencies Interpretation of data Standard PA catheter construction and components 2. Standard PA Catheter Construction and Components Proximal injectate lumen and hub Proximal infusion lumen and hub (optional) Distal lumen and hub Thermistor Balloon inflation lumen and valve 3. Transducer translates mechanical energy Leveling Zeroing 4. Special Pulmonary Artery Catheters General care focuses on optimizing preload by restoring volume Pacing port Oximetry Continuous cardiac output (CCO) Volumetric 5. Care of Central Venous Catheters Catheter site dressing regimens Needleless intravascular catheter systems Recommendations for central venous catheters Skin preparation Maximal sterile barrier precautions Replacing administration sets Replacement of peripheral and midline catheters Catheter securement devices IV. Pulmonary Artery Catheter Insertion and Measurements A. Catheter insertion and management 1. Preprocedure patients and family education a) The patient may be awake when the catheter is inserted, and it can be a frightening experience if he or she does not know what to expect; patient and family education should include information about the procedure. 2. Insertion of the PA catheter a) The ibsertuib if a PA catheter is performed in critical care uits, cardiac catheterization laboratories and operating rooms. b) The insertion of a PA catheter is always a sterile procedure involving maximal bararier precautions. 3. Post-procedure management a) The nurse assumes responsibility for patient safety and comfort and system maintenance. 4. Obtaining accurate hemodynamic measurements a) Repositioning the patient is an important consideration in continuous hemodynamic monitoring. b) Measuring waveforms—evidence suggests that obtaining accurate measurements require reading pressure waveforms at end-expiration, when pleural pressure is at its lowest level. B. PA catheter measurements 1. Measuring cardiac output a) Intermittent Fluid Bolus Thermo dilution Method—the traditional method of thermodilution CO requires the use of injectate, a 10-ml bolus of IV normal saline that is injected through the proximal injectate port of the PA catheter into the right atrium. b) Continuous CO Thermal Filament Thermo dilution Method—uses a thermal (heating) filament about 11 cm in length that is a part of the PA catheter wall. 2. Measuring preload—preload is reflected in two PA catheter measurements, the right atrial pressure (RAP) and the pulmonary artery wedge pressure (PAWP). 3. Measuring afterload a) Systemic vascular resistance (SVR) b) Pulmonary vascular resistance 4. Measuring contractility a) Ventricular stroke work index (VSWI) PowerPoint Slides 1. Catheter Insertion and Management Preprocedure patient and family education Insertion of the PA catheter Postprocedure management Obtaining accurate hemodynamic measurements 2. Measuring Cardiac Output Intermittent Fluid Bolus Thermo Dilution Method Continuous CO Thermal Filament Thermo Dilution Method 3. Measuring Preload Pulmonary artery wedge pressure (PAWP) Right arterial pressure (RAP) 4. Measuring Afterload Systemic vascular resistance (SVR) Pulmonary vascular resistance 5. Measuring Contractility Ventricular stroke work index (VSWI) V. Right Atrial and Ventricular Pressures A. Right atrial pressure 1. An estimate of right ventricular preload (volume status of the right heart) 2. An estimate of right ventricular end-diastolic pressure (RVEDP) 3. Obtaining Measurements a) Normal right atrial waveform b) Undulating pattern of three positive and two negative excursions c) Positive excursions: a, c, and v waves d) Negative excursions: x and y deflections 4. Waveform analysis 5. Conditions leading to alterations in RAP a) Causes of increased RAP and associated clinical findings b) Causes of decreased RAP and associated clinical findings 6. Interventions for treating abnormal RAP a) Treating increased RAP (1) General care focuses on optimizing preload by reducing volume. (2) Restricting fluid and sodium. (3) Administering diuretics or vasodilation medications. (4) Assessing patient’s response to interventions. (5) Dietary consults—sodium and fluid restrictions. (6) Patient education about medications. b) Treating decreased RAP (1) General care focuses on optimizing preload by restoring volume. (2) Oral replacement of fluids or careful IV hydration. (3) Surgical correction of hemorrhage and volume replacement with IV fluids and blood products. (4) Hypovolemia and low preload related to sepsis. (5) Regular assessment of patient’s response to interventions. B. Right ventricular pressure is not continuously monitored with a traditional PA catheter but is observed and documented during insertion of the catheter. 1. Waveform recognition consists of a steep upstroke and a sharp downstroke. 2. Clinical implications. PowerPoint Slides 1. Right Atrial Pressure An estimate of right ventricular preload An estimate of right ventricular end-diastolic pressure (RVEDP) Obtaining measurements 2. Positive a, c, and v waves A wave produced by the rise in atrial pressure caused by left atrial contraction. C wave (when it appears) produced by closure of the mitral valve at the initiation of ventricular systole. V wave forms as the left atrium fills during ventricular systole. 3. Negative x and y descents X descent reflects decreased volume in the left atrium after atrial systole. Y descent results from the pressure drop in the left atrium when the mitral valve opens prior to atrial contraction, permitting passive emptying of the left atrium. 4. Conditions Leading to Alterations in RAP Causes of increased RAP and associated clinical findings Causes of decreased RAP and associated clinical findings 5. Interventions for Treating Abnormal RAP Treating increased RAP Treating decreased RAP 6. Right Ventricular Pressure Waveform recognition Clinical implications VI. Pulmonary Artery and Pulmonary Artery Wedge Pressures A. Pulmonary artery pressure normally reflects both right and left heart pressures and is read as a systoic and diastolic pressure. 1. Waveform analysis—the PA waveform pattern a) Steep upstroke and down stroke with a dicrotic notch formed by the closure of the pulmonic valve. b) The dicrotic notch is lost when the catheter tip retreats into the right ventricle. c) Knowing the waveform positions helps nurses identify correct catheter position. 2. Elevated pulmonary artery pressure a) Elevated PAS can result from any condition that increases the afterload of the right ventricle, such as pulmonary hypertension. (1) Right heart failure—distended neck veins, peripheral edema, tender liver, and ascites. (2) Right ventricular lift. (3) S3 and S4 heart sounds. (4) Chronic lung disease patients have chronically elevated PAS pressure. (5) Pulmonary embolus. (6) Can present as a medical emergency—dyspnea, chest pain, hemoptysis, and hemodynamic instability. b) Elevated PAD-associated with conditions of the left heart (1) Angina (2) Myocardial infarction (3) Fluid overload (4) Mitral stenosis (5) Left-to-right intracardiac shunts c) Treatment of elevated PAP (1) General care approach is reducing preload. (2) Administering diuretics. (3) Restricting fluid and sodium intake. (4) Novel therapies aimed at pulmonary vascular vasodilation can also treat pulmonary hypertension. (5) Cardiac contractility—improved by use of inotropic medications, such as digoxin and dopamine. (6) Intra-aortic balloon pump (7) Careful administration of potent medications (8) Intake and output measurements (9) Daily weights 3. Low pulmonary artery diastolic pressure a) Low preload state related to inadequate venous return to the left heart B. Pulmonary artery wedge pressure 1. Measurements are obtained through the distal port of the PA catheter. 2. PAWP Waveform Analysis—the normal range is 4 to 12 mm Hg. 3. Key Points for obtaining PAWP a) Observe the waveform constantly b) Use the smallest inflation volume possible c) Maintain inflation d) Obtain the PAWP at end expiration e) Allow balloon to deflate passively f) Stop if resistance is felt during balloon inflation 4. Elevated PAWP a) Clinical findings vary according to the degree of elevation. b) Interventions are directed toward optimizing preload by administering diuretics and vasodilators and restricting sodium and fluid. 5. Low PAWP is related to inadequate circulating blood volume. PowerPoint Slides 1. Pulmonary Artery Pressure (PAP) Normally reflects both right and left heart pressures and is read as a systoic and diastolic pressure. PA waveform is monitored continuously. 2. PA Waveform Pattern A steep upstroke and downstroke with a dicrotic notch. The dicrotic notch lost when catheter tip retreats into the right ventricle. Knowing waveform positions helps nurses identify correct catheter position. 3. Elevated pulmonary artery systolic (PAS) pressure Results from an increase in the afterload of the right ventricle 4. Elevated PAS Pressure—Clinical Findings Right heart failure Right ventricular lift S3 and S4 heart sounds Chronic lung disease patients have chronically elevated PAS pressure Pulmonary embolus 5. Elevated Pulmonary Artery Diastolic (PAD) Pressure Associated with conditions of the left heart Angina Myocardial infarction Fluid overload Mitral stenosis Left-to-right intracardiac shunts 6. Elevated PAD Pressure—Clinical Findings Left heart failure can cause the following signs and symptoms: Dyspnea Tachycardia S3 or S4 Bilateral crackles in the lungs 7a. Elevated PAS or PAD pressure Nursing interventions. General care approach is reducing preload. Administering diuretics. Restricting fluid and sodium intake. Novel therapies aimed at pulmonary vascular vasodilation. Cardiac contractility. Intra-aortic balloon pump. 7b. Elevated PAS or PAD pressure (continued) Nursing care Careful administration of potent medications Intake and output measurements Daily weights Planning physical activities followed by rest periods 8. Low Pulmonary Artery Diastolic (PAD) Pressure Low preload state related to inadequate venous return to the left heart 9. Low PAD Pressure—Clinical Findings Tachycardia Flat neck veins Clear lungs Dry oral mucosa Poor skin turgor Hypotension Decreased urine output Severe cases—signs of advanced shock 10. Low PAD Pressure—Nursing Interventions Focus is on improving left ventricle (LV) preload through volume replacement Nursing care Managing fluid replacement 11. Key Points for Obtaining PAWP Observe the waveform constantly Use the smallest inflation volume possible Maintain inflation Obtain the PAWP at end expiration Allow balloon to deflate passively 12. Elevated PAWP Nursing Interventions Treatment is directed toward optimizing preload. Diuretics and vasodilators. Sodium and fluid restrictions. Intravenous and oral nitrates. Control of dysrhythmias. 13. Low PAWP Clinical Findings Flat neck veins Clear lungs Low pulse pressure Decreased urine output Hypotension Tachycardia Thirst 14. Low PAWP Nursing Interventions Treatment Careful replacement of fluids or blood products correlated with patient’s response to treatment Nursing care Hourly urine output Intake and output records Daily weights VII. Vascular Resistance and Stroke Work 1. Measurements of systemic and pulmonary vascular resistance are the major means of evaluation afterload; stroke volume and ventricular stroke work index are indirect measures of contractility. A. Systemic vascular resistance is an estimate of left ventricular afterload. 1. Elevated SVR or SVRI may be the result of hypothermia, hypovolemia or cardiac failure. a) Collaborative management. 2. Low SVR or SVRI is caused by widespread vasodilation. B. Pulmonary vascular resistance is an estimate of right ventricular afterload. 1. High PVR or PVRI is elevated with hypoxemia, acute lung injury, acute respiratory distress syndrome, pulmonary hypertension and pulmonary congestion. C. Stroke volume 1. Determining the SV can provide valuable information about contractility, particularly if preload and afterload statuses are already known. D. Ventricular stroke work 1. Left Ventricular Stroke Work Index represents work that is influenced by the pressure the heart beats and the volume the ventricle must pump forward. 2. Right Ventricular Stroke Work Index is the amount of work involved in moving blood in the right ventricle with each beat. PowerPoint Slides 1. Systemic Vascular Resistance Elevated SVR or SVRI may be the result of hypothermia, hypovolemia, or cardiac failure. Low SVR or SVRI is caused by widespread vasodilation. 2. High Pulmonary Vascular Resistance Hypoxemia Acute lung injury Acute respiratory Distress syndrome Pulmonary hypertension Pulmonary congestion 3. C. Stroke Volume Can provide valuable information about contractility 4. Ventricular Stroke Work Left Ventricular Stroke Work Index Right Ventricular Stroke Work Index VIII. Chapter Summary IX. Clinical Reasoning Checkpoint X. Post-Test XI. References Suggestions for Classroom Activities Review Figure 13-5—a right atrial waveform with the a and v wave components identified. Discuss how the waveforms are produced, and compare normal and abnormal waveforms. Discuss ways to prevent the catheter tip from moving into the RV. Suggestions for Clinical Activities Discuss nursing protocols for responding to a catheter tip in the RV with the clinical educator of the acute care nursing unit. Discuss how nurses can develop the bedside critical-thinking skills that improve patient outcomes for elevated PAWP and other pulmonary conditions. Wagner et al., Instructor’s Resource Manual for High-Acuity Nursing, 6th Edition ©2014 by Education, Inc.