Unit II (a) Methods of Heamodynamic Management - Copy.pptx

Methods of hemodynamic monitoring

1. Unit II (a) Methods of Hemodynamic Management

2. OBJECTIVES At the end learners will develop an understanding of different tool that are used in critical care setting for patients care monitoring. D i s c u s s v ar i ou s me t hod s ava i labl e to m on i t o r different variables of hemodynamic Intra-arterial pressure monitoring CVP care Pulmonary arterial pressure monitoring Left arterial pressure monitoring Cardiac output monitoring

3. Introduction H em ody nam i c mon i t o r i n g i n c ri t i c a l common care unit . Studies relationships among several variables: Heart rate Blood flow Oxygen delivery Tissue perfusion The goal of hemodynamic monitoring is to accurately assess the patient and provide therapies to optimize oxygen delivery and tissue perfusion 4

4. Introduction • The purposes of hemodynamic monitoring are to aid the diagnosis of various cardiovascular disorders, guide therapies to minimize cardiovascular dysfunction or To treat disorders, and evaluate response to therapy Basic equipment necessary to measure hemodynamic pressures includes; Noncompliant pressure tubing A transducer An amplifier A means of recording or displaying the information collected •

5. A&P Cardiovascular System 6 Figure 8-1. Diagram of the cardiovascular system. (From McCance KL, Huether S, eds. Pathophysiology: the Biologic Basis for Disease in Adults and Children , 6th ed. St. Louis: Mosby; 2015.) Copyright © 2017 Elsevier Inc. All rights reserved.

6. A&P Cardiovascular System (Cont.) • Pumps oxygenated blood via arteries to systemic circulation Receives deoxygenated blood via venous vasculature 7 Figure 8-5. Normal blood flow through the heart and intrachamber pressures; arrows indicate the normal direction of blood flow. This schematic representation of the heart shows all four chambers and valves visible in the anterior view to facilitate conceptualization of blood flow. (Modified from Darovic, G. Hemodynamic Monitoring: Invasive and Noninvasive Clinical Application . Philadelphia: Saunders; 2002 .)

7. A&P Cardiovascular System (Cont.) Pressure = flow × resistance Pressure—force exerted on the liquid mm Hg Flow: amount of fluid moved over time L/min or mL/min Resistance: opposition to flow Copyright © 2017 Elsevier Inc. All rights reserved. 8

8. Cardiac Output Cardiac output—volume of blood ejected from heart/min CO = HR × Stroke volume (volume of blood ejected with each beat) 4 to 8 L/min Ejection fraction—fraction of blood ejected with each beat Normal 60% to 70% Copyright © 2017 Elsevier Inc. All rights reserved. 9

9. Give it a Reading Pre Load After Load Systemic Vascular Resistance

10. D e t e rm i n a n t s O f C a r d i a c P e r f o r m anc e Preload After load Contractility

11. Factors Influencing Cardiac Output 1 2 Figure 8-6. Factors regulating blood flow. (Modified from McCance KL, Huether S, eds. Pathophysiology: the Biologic Basis for Disease in Adults and Children , 6th ed. St. Louis: Mosby; 2009.) Copyright © 2017 Elsevier Inc. All rights reserved.

12. Cardiac Output Versus Index Index is a better assessment; based on body size CI = CO/body surface area Calculated on the computer after entering patient’s height and weight Cardiac index provides a measure of cardiac output specific to patient body size , providing a better assessment. Cardiac output is a calculated value and is the product of cardiac output divided by the patient’s body surface area. Copyright © 2017 Elsevier Inc. All rights reserved. 1 3

13. Hem o d y n a m i c s Hemodynamics term is used to describe the intravascular pressure and flow that occurs when the heart contract and pumps blood throughout the body.

14. D e f i n iti o n “ Hemodynamic monitoring refers to m easurement of pressure , flow and oxygenation of blood within the cardiovascular system”

15. P u r p os e Early detection identification and treatment of life threatening conditions such as heart failure and Cardiac Temponade. Evaluate the patients immediate response to treatment such as drugs and mechanical support. Evaluate the effectiveness of ca r diova s cu l a r f unc t i o n su c h a s c ard i ac output and cardiac index.

16. Common Indications for Hemodynamic Monitoring Assesses cardiac function and evaluates effectiveness of therapy Cardiogenic Shock Severe Heart Failure Sepsis Or Septic Shock Multiple Organ System Dysfunction Syndrome(MODS) Acute Respiratory Distress Syndrome (ARDS) Cardiac Surgery

17. Types of Hemodynamic Monitoring Noninvasive modalities Noninvasive blood pressure Assessment of jugular venous pressure Pulse , HR, Capillary Refill Assessment of serum lactate levels: Serum lactate levels can provide information regarding end- organ perfusion. Copyright © 2017 Elsevier Inc. All rights reserved. 1 8 Invasive modalities Arterial pressure monitoring Pulmonary artery pressure monitoring Right atria l pressure monitoring

18. NORMAL VALUES CVP 8-12 mmHg Right Ventricular Pressure systolic 20-30mmHg Pulmonary artery systolic pressure 18 - 25 mmHg Pulmonary artery occlusion pressure 8-12 mmHg Cardic output 4-8L/min Cardic Index 2.5-4L/min/m2 Ventricular end diastolic volume 120-130 ml Ventricular end systolic pressure 50-60 ml Stroke volume 70 ml B.P 120/80 mmHg

19. Equipments needed for invasive monitoring An Invasive catheter: CV C , pulmonary artery catheter, arterial catheter. A flush system composed of intravenous solution tubing 3-way stop cocks and a flush device which provides continuous and manual flushing of system. A pressure bag placed around the flush solution that is maintained at 300mmHg pressure ; the pressurized flush system delivers 3-5ml of solution per hour through the catheter to prevent clotting and backflow of blood into the pressure monitoring system.

20. A transducer : convert the pressure coming from the artery or heart chamber into an electrical signal (waveform) A n a m p l i f i e r o r monitor Which increases the size of electrical signals

21. Steps for hemodynamic monitoring Obtain barrier kit (Gloves, gown, mask etc), sterile gloves and correct swan catheter. Also needed extra IV pole, transducer holder, and cables. Check to make sure signed consent is in chart, and that patient and or family understand procedure. Everyone in the room should be wearing a mask. Position patient supine and flat if tolerable. Assist physician in sterile draping and sterile setup for swan insertion.

22. Setup pressure lines and transducer. Level pressure flush monitoring system and transducers to the phlebostatic axis. Connect tubing to the patient when patient is ready to flush the swan. While floating the swan observe for ventriculator ectopy on the monitor. A ft e r s w a n i s i n p l a c e d a s s i st wi th the c l ean u p an d let patient know the procedure is complete. Obtain all the values. Perform hem calculations. Document finding in ICU flow sheet .

23. Zeroing and Leveling The zero reference point ( phlebostatic axis ) is established at the intersection of the Mid–anterior-posterior line Fourth intercostal space The transducer should be zeroed with any change in the bed or patient’s position, elevation of the head of the bed, and patient transport. It also should be zeroed every 8 hours

24. Zeroing and Leveling Place the patient in the supine position The head of the bed may be elevated as much as 40 degrees Measurements should not be obtained in the side- lying position If the air–fluid interface is raised above the phlebostatic axis, the values displayed will be erroneously low, and I f the interface is lowered below the phlebostatic axis, the values displayed will be erroneously high.

25. Pressure Monitoring System Indwelling arterial catheter. attached by pressure tubing to a transducer. The transducer is connected to an amplifier/monitor that visually displays a waveform and systolic, diastolic, and mean pressure values. The system is composed of; A flush solution under pressure, A continuous flush device, and A series of stopcocks. closest to the insertion site is used to draw blood samples from the artery, Located near the transducer is used for zeroing

26. Pressure Monitoring System The flush solution may be; – Normal saline or D5W and is usually heparinized. The solution is placed in a pressure bag that is inflated to 300 mmHg to maintain a constant pressure through the transducer and flush device A continuous flow of approximately 3 mL/hour prevents backflow of blood through the catheter and tubing The system can be flushed manually by activation of a fast flush device

27. Accuracy in Hemodynamic Monitoring Levelling, Zeroing , - Phlebostatic Axis Dynamic response testing (Square wave test): The square-wave test is used to determine the system’s ability to accurately measure pressures Copyright © 2017 Elsevier Inc. All rights reserved. 3

28. Square-Wave Test Whether the hemodynamic system is optimized Fast flush device for 1 or 2 seconds The pressure waveform on the oscilloscope is replaced by a square wave An optimized system, the square wave has; Straight vertical upstroke from base line Straight horizontal component Straight vertical down-stroke back to the baseline with two of three sharp oscillations Causes of non-optimized systems; air bubbles, blood, loose connections, cracks, leaks, or soft IV tubing in the system

29. OPTIMAL USE OF THE MONITORING SYSTEM T e c h n i c a l o r mechani c al factors may cause inaccuracies of the hemodynamic waveforms and values air bubbles or blood in the tubing or transducer system distorts pressure readings continuous pressure of 300 mmHg on the flush solution bag The use of soft, distensible tubing distorts and reduces the amplitude of the pressure waveforms

30. 3 4 T ro u blesh o o t i ng Damped Waveforms Pressure bag inflated to 300 mmHg Reposition extremity or patient Verify appropriate scale Flush or aspirate line Check or replace module or cable

31. 3 5 Troubleshooting Inability to obtain/zero waveform Connections between cable & monitor Position of stopcocks Retry zeroing after above adjustments

32. Invasive Hemodynamic Monitoring Pressure Monitoring System Arterial Pressure Monitoring Central Venous Pressure Monitoring Pulmonary Artery Pressure Monitoring Determination of Cardiac Output Evaluation of Oxygen Delivery and Demand Balance

33. M e th o d s o f h e m o d y n a m i c mo ni t o r i n g Arterial blood pressure Non invasive Oscillometry Ausculatory Intra-arterial Pressure Monitoring Central venous pressure monitoring Pulmonary artery pressure monitoring

34. Non-Invasive BP Monitoring Lower edge of cuff approximately 2.5 cm above the antecubital space

35. O scillo m e t r i c m ea s u r e m e n t devices Auscultatory Measurement Devices The auscultatory method (also known as the Riva Rocci Korotkoff or manual method for blood pressure measurement) is the LISTENING of Korotkoff sounds in the brachial artery . Oscillometric measurement devices use an electronic pressure sensor with a numerical readout of blood pressure

36. Jugular Venous Pressure Monitoring

37. Jugular Venous Pressure 4 2 Place the patient in a supine position with the head of bed elevated 30 to 45 degrees. Position yourself at the patient’s right side. Have the patient turn head slightly to the left. If you cannot readily identify the jugular vein, place light pressure with your fingertips across the sternocleidomastoid muscle just superior and parallel to the clavicle. This pressure obstructs the external jugular vein and allows it to fill. Shine a pen light tangentially across the neck to accentuate the pulsations .

38. Assess for jugular venous distension at end exhalation. Any fullness in the vein extending >3 cm above the sternal angle or angle of Louis is considered elevated jugular venous pressure. The higher the degree of elevation, the higher the central venous pressure. Observe the highest point of pulsation in the internal jugular vein at the end exhalation. Measure the vertical distance between this pulsation and the angle of Louis in centimeters

39. Intra-arterial Pressure Monitoring

40. Intra-arterial Pres s ure Monitoring Arterial pressure monitoring allows continuous monitoring of the systemic arterial blood pressure and provides vascular access for obtaining blood samples. In addition, when therapeutic decision depend on obtaining accurate blood pressure values, arterial monitoring is gold standard.

41. I nd i c a ti o n s F o r A r t e ria l P r e s s u r e Mo n i t or i n g Vasoactive IV Infusions. Cardiovascular Instability. Fluctuating Unstable Blood Pressures. Frequent Blood Draws.

42. Equipment and Setup When selecting the artery for cannulation T h e a r ter y s hou l d b e l arg e e n oug h t o accommodate the catheter without occluding or significantly impeding flow. T h e site s h ou l d b e eas il y a c c e ss i b l e a n d f r e e fro m c o n t am i na t i o n b y b o d y secretions. There should be adequate collateral blood flow in the event that the cannulated artery becomes occluded

43. Si t e s f o r c a t h e t e r i z a ti o n Radial Artery Allen’s test prior to insertion to verify collateral circulation in the extremity Femoral Artery Brachial Artery

44. Complications External H emorrhage Massive Ec c hymosis Air embolism Blood loss Pain Arteriospasm Accidental blood loss Secure and tighten connections. Immobilize extremity . Infection Observe a sterile technique. Maintain a closed system. Impaired circulation or Local destruction with distal i schemia Assess color, sensation, temperature, and movement of extremity.

45. Nursing Intervention Before insertion of a catheter, the site is prepared by shaving if necessary and by cleaning with an antiseptic solution. A local anesthetic may be used. Once the arterial catheter is inserted, it is secured and dry, sterile dressing is applied. The site is inspected daily for the signs of infection. The dressing and pressure monitoring system or water manometer is changed according to the hospital policy. Although the arterial monitoring system provides vascular access for obtaining blood samples, no IV solution or medication should be administered through the arterial pressure monitoring system at any time.

46. In general dressing is to be kept dry and air occlusive. Dressing changes are performed with the use of sterile dressing. To measure the arterial pressure the transducer or the zero mark on the manometer must be placed at a standard reference point called the phlebostatic axis.

47. Arterial BP Waveform The normal arterial pressure waveform c onsists of a rapid upstroke (produced by the rapid ejection of blood from the left ventricle into the aorta), a clear dicrotic notch (which signals closure of the aortic valve and the beginning of diastole), and a definite end point (which reflects the end of diastole). Loss of the dicrotic notch is a sign of overdamping.

48. Arterial BP Waveform

49. Data Interpretation Value at peak of wavefrom is systolic pressure Value at lowest point of wavefrom is Diastolic pressure. Difference between systolic and diastolic pressure is Pulse Pressure. Mean Arterial Pressure (MAP)= Evaluates perfusion of vital organs. Formula for MAP:- Systolic Pressure+(Diastolic Pressure*2) 3

50. In normotensive patients, blood pressure measurements obtained through arterial pressure monitoring are very similar to those obtained with a cuff ( the intra - arterial systolic pressure is 5 to 10 mm Hg higher ) .

51. Central Venous Pressure Monitoring

52. Central Venous Pressure/RAP Monitoring Reflects the pressure of blood in the right atrium or vena cava Provides information about; Intravascular blood volume, Right ventricular end-diastolic pressure Right ventricular function . Indirectly reflects left ventricular end diastolic volume and function. Alterations in volume status or ventricular function usually are associated with abnormally high or low CVP measurements Normal values 8 to 12 mm Hg

53. 5 9 Central Venous Pressure (CVP) Central line or pulmonary artery catheter Low CVP = hypovolemia or ↓ venous return High CVP = over hydration, ↑ venous return, or right-sided heart failure

54. Insertion Sites Central venous pressure (CVP) is typically measured in the superior vena cava near the right atrium via a PICC line or a central line catheter placed in: External jugular veins – this site is chosen frequently as there is a high rate of successful insertion and a low incidence of complications such as pneumothorax .

55. Internal jugular veins are short, straight and relatively large allowing easy access, however, catheter occlusion may occur as a result of head movement and may cause irritation in conscious patients . Subclavian veins –Because this site is positioned beneath the clavicle there is a risk of pneumothorax.

56. Femoral veins – this site provides rapid central access during an emergency such as a cardiac arrest. As the CVC is placed in a vein near the groin there is an increased risk of associated infection. In addition, femoral CVCs are reported to be uncomfortable and may discourage the conscious patient from moving .

57. I ns e r ti o n O f A C V P

58. Indications for CV Line Volume resuscitation. Emergency venous access. Nutritional support. Administration of caustic medications (eg, vasopressors) Central venous pressure monitoring. Trans venous pacing wire introduction. Hemodialysis

59. P r o c e d u r e B e f or e in s er t i o n o f a C V P c a t he t e r t h e s i te i s prepared by shaving if necessary and by cleansing with an antiseptic solution. A lo c a l ane s t he t i c m a y b e used . T h e phy s i c ian threads a single lumen o r multilumen catheter through the external jugular, anticubital. Or femoral vein into the vena cava just above or within the right atrium.

60. CVC SET

61. Complications of Central Venous Catheters • Infection Assess the site. Observe a sterile technique with any catheter manipulation. Thrombosis Monitor waveform, ability to flush, blood return. Pn e umoth o r ax Heamothorax CXR post-insertion Air embolism Ensure tight c o n ne c t i o n s . 10 to 20 mL- symptomati O2 for management • • • • • • • • •

62. Carotid puncture Heart perforation Dysrhythmias Extravasation CVC occlusion Heparin lock

63. Causes of Alterations in (CVP) Measurements Low CVP Measurements Hypovolemic state Diuretic therapy Vasodilation (eg, sepsis, vasodilating medications) High CVP Measurements Right ventricular failure Pulmonary embolism Pulmonary hypertension Left ventricular failure Mechanical ventilation Hypervolemic state

64. A CVP value alone is meaningless, but when used in conjunction with other clinical data (eg, breath sounds, heart and respiratory rate, neck vein distention, urine output, electrocardiographic data), it is a valuable aid in managing and predicting the patient’s clinical course

65. Figure 1

66. Find the three-way tap that leads from the fluid bag to the CVC. Catheters differ between manufacturers, however, the white or proximal lumen is suitable for measuring CVP. Turn the tap off to the patient and open to the air by removing the cap from the three-way port opening the system to the atmosphere. Press the zero button on the monitor and wait while calibration occurs. When ‘zeroed’ is displayed on the monitor, replace the cap on the three-way tap and turn the tap on to the patient.

67. 4. Observe the CVP trace on the monitor. The waveform undulates as the right atrium contracts and relaxes , emptying and filling with blood. 5. Document the measurement and report any changes or abnormalities .

68. C o n t… • A wave: Rise in pressure due to atrial contraction C wave: Rise in pressure due to ventricular contraction (V=atrial filling, X=atrial relaxing, Y=ventricular filling) • • •

69. Nursing interventions: Once the CVP is inserted it is secured and a dry sterile dressing is applied. Catheter placement is confirmed by a chest X-ray and the site is inspected daily for the signs of infection. The dressing and pressure monitoring system or water manometer are changed according to the hospital policy. In general dressing is to be kept dry and air occlusive. Dressing changes are performed with the use of sterile dressing . ▪

70. CVP can be used for infusing intravenous fluids. Administering intravenous medications, and drawing blood specimens in addition to m onitoring pressure. To measure the CVP the transducer or the zero mark on the manometer must be placed at standard reference point called the phlebostatic axis. Patient position – Head of bed between 0 and 60 degrees Correlate values with assessment Monitor for complications

71. Change tubing and fluid bag q 96hrs No vaso pressors through CVP port Antibiotics, NS boluses, blood, & IV pushes are allowed through the CVP line .

72. Pulmonary Artery P r e s s u r e Mo n i t o r i n g

73. Pulmonary Artery Pressure Monitoring • • 7 9 Pulmonary artery catheter (PAC) Introduced in 1970 Drs. Swan and Ganz Swan-Ganz is a brand Reflects left ventricular function Figure 8-10. Example of a pulmonary artery catheter with capability of monitoring mixed venous

74. Pulmonary Artery Monitoring • P r e ss u r e In Pulmonary artery pressure (PAP) monitoring a c a t het e r is p l a c ed thr o ugh t h e ri g ht s id e o f t h e he a rt i n to t h e pulmonary artery. By measuring pressures in the right atrium, right ventricle, and pulmonary artery, it is possible to assess right ventricular function , pulmonary vascular status, and, indirectly, left ventricular function. The pulmonary artery catheter (PAC) also allows evaluation of cardiac output.

75. Pulmonary Artery Pres s ure Monitoring Pulmonary artery pressure monitoring is an important tool used in critical care for assessing left ventricular function diagnosing the etiology of shock and evaluating the patients response to medical interventions ( e.g fluid administration, vasoactive medications). Pulmonary artery pressure monitoring is achieved by using a pulmonary catheter and pressure monitoring

76. Pulmonary Artery Pressure Monitoring Assess right ventricular function, pulmonary vascular status, and, indirectly, left ventricular function. By using a PA catheter Cardiac output, right atrial, right ventricular, and PA pressures, PA wedge pressure (PAWP) are measured Facilitate diagnosis of cardiovascular and cardiopulmonary dysfunction, determine the therapy needed, & evaluate the effectiveness of the interventions

77. Several types of PACs are available. The type of catheter used is determined by the parameters to be monitored. All PACs have multiple external lumens. A typical PAC has four lumens: Distal hub and lumen … attached to a transducer and a continuous flush system Used for the withdrawal of mixed venous blood gases Not used for fluid or medication administration PA Catheter

78. P A C a t h e t e r Proximal hub and lumen , or right atrial lumen may be used for infusion of fluids or medications, RAP and CO monitoring , attached to transducer Balloon inflation valve & lumen … with a small volume of air (1.5ml) to measure the PA occlusion pressure, known as the PAWP.. Fluid is never infused Thermis tor connector and lumen … connected to the bedside monitor measurement of the patient’s temperature in the PA (core temperature) Some PACs may have additional lumens

79. PULMONARY ARTERY CATHETER

80. Pulmonary Artery Catheter Flow-directed catheter Inserted via subclavian, internal jugular, or femoral vein Balloon tipped Multiple lumens Variations Continuous cardiac output (CCO) Copyright © 2017 Elsevier Inc. All rights reserved. 8 7

81. P r o c e d u r e This procedure can be performed in the operating room or cardiac catheterization laboratory or at the bedside in the critical care unit. Catheters vary in their number of lumens and their types of measurement (eg, cardiac output, oxygen saturation) or pacing capabilities. ▪ All types require that a balloon-tipped, flow directed catheter be inserted into a large vein (usually the subclavian, jugular, or femoral vein); the catheter is then passed into the vena cava and right atrium.

82. Proper position of patient – Trendelenburg common In the right atrium, the balloon tip is inflated, and the catheter is carried rapidly by the flow of blood through the tricuspid valve, into the right ventricle, through the pulmonic valve, and into a branch of the pulmonary artery. During insertion of the pulmonary artery catheter, the bedside monitor is observed for waveform and ECG changes as the catheter is moved through the heart chambers on the right side and into the pulmonary Artery.

83. ▪ When the catheter reaches a small pulmonary artery, the balloon is deflated and the catheter is secured with sutures. Fluoroscopy may be used during insertion to visualize the progression of the catheter through the heart chambers to the pulmonary artery. ▪ Af t e r t h e c a t he t e r i s co r re c t l y p os i t i o n e d , t he following pressures can be measured

84. ▪ CVP Or Right Atrial Pressure. ▪ Pulmonary Artery Systolic, Diastolic Pressures ▪ Mean Pulmonary Artery Pressure ▪ Pulmonary Artery Wedge Pressure

85. Co m p l ic a t i o n s Infection. Pulmonary Artery Rupture and perforation- monitor wave form and inflate balloon with 1.25-1.5 ml Pulmonary Thromboembolism. Pulmonary Infarction- Monitor wave form Catheter Kinking. Dysrhythmias (Ventricular dysrhythmias). If the PAC is not properly secured, it may become dislodged and the tip may “fall back” into the right ventricle. The patient may experience dysrhythmias (as a result of endocardial irritation by the catheter tip), Air Embolism .

86. Data Interpretation • The mechanical activity of the heart (ie, systole and diastole) follows the electrical activity of the heart. Therefore, mechanical activity must be correlated to electrical activity by interpreting the hemodynamic waveforms alongside an electrocardiographic Measurement of all pressures is most accurate when obtained at the end of expiration In mechanically ventilated patients, the waveform used for measurement is the last clear wave occurring just before the inspiratory rise • •

87. Data Interpretation Right atrial pressure 2 to 6 mm Hg Measures pressure in the right ventricle during diastole (right ventricular end-diastolic pressure ), equals CVP A wave: Rise in pressure due to atrial contraction C wave: Rise in pressure due to ventricular contraction (V=atrial filling, X=atrial relaxing, Y=ventricular filling)

88. Data Interpretation

89. Data Interpretation Right ventricular pressure 20 to 30 mm Hg –Equals the pulmonary artery systolic pressure

90. Data Interpretation

91. Data Interpretation (cont.) Pulmonary artery pressure Systolic pressure equals right ventricular systolic function 20 to 30 mm Hg. Diastolic pressure equals the left ventricular end-diastolic pressure (LVEDP) 8 to 15 mm Hg.

92. Data Interpretation (cont.)

93. Data Interpretation (cont.) Pulmonary artery wedge pressure 8 to 12 mm Hg – More accurate measure of LVEDP

94. Nursing Interventions Whereas the physician is responsible for insertion of the catheter, the nurse is responsible for monitoring the patient and monitoring and recording values during catheter insertion. Catheter site care is essentially the same as for a CVP catheter. As in measuring CVP, the transducer must be positioned at the phlebostatic axis to ensure accurate readings . The nurse who obtains the wedge reading ensures that the catheter has returned to its normal position in the pulmonary artery by evaluating the pulmonary artery pressure waveform.

95. At end-diastole, when the mitral valve is open, the wedge pressure is the same as the pressure in the left atrium and the left ventricle, unless the patient has mitral valve disease or pulmonary hypertension.

96. Critically ill patients usually require higher left v e n t r i c ula r f illi n g p r e s su r e s t o o p t i m i ze ca r diac output. These patients may need to have their wedge pressure maintained as high as 18 mm Hg • • • Monitor waveform. Observe for dysrhythmias. Maintain sterile dressing. *Central catheter placement must be confirmed by CXR before accessing the device.

97. Cardiac Output Monitoring

98. Cardiac Output Cardiac output (CO)—the amount of blood ejected from the heart per minute 4 to 8L/minute at rest Stroke volume (SV)—the milliliters of blood ejected from the ventricle with each contraction HR x SV=CO Cardiac index (CI)—relates cardiac output to body size; normal is 2.5 to 4L/min/m 2 .

99. Stroke Volume Preload Amount of stretch on the myocardial muscle fibers at end diastole Afterload The resistance to ejection of blood from the ventricles Contractility Ability of the heart to contract independent of preload and afterload

100. Methods of Evaluating Cardiac Output Thermodilution Arterial pressure and waveform-based methods Electrical bioimpedance cardiography Esophageal Doppler monitoring

101. Thermodilution The thermodilution technique uses a special thermistor-tipped catheter (Swan-Ganz catheter) that is inserted from a peripheral vein into the pulmonary artery.

102. Thermodilution Technique Gold standard for evaluating cardiac output Intermittent Measures change in blood temperature following injection of indicator solution Continuous Specialized PACs with thermal filaments

103. P r i nc i p l e P h a s e s O f T h e rm o d i l u ti o n Injection A cold saline solution of known temperature and volume is injected into the right atrium from a proximal catheter port Mixing And Dilution The injectate mixes with the blood as it passes through the ventricle and into the pulmonary artery, thus cooling the blood.

104. Detection The blood temperature is measured by a thermistor at the catheter tip, which lies within the pulmonary artery Calculation A computer is used to acquire the thermo dilution profile; that is, the computer quantifies the change in blood temperature as it flows over the thermistor surface.

105. Thermodilution Cardiac Output (TdCO) Method Inject solution within 4 seconds (5 to 10 mL) 0.9% normal saline Wait approximately 1 minute between injections to allow the catheter thermistor to return to baseline Increased accuracy at end expiration Check waveform Repeat at least three measurements Average values within 10% of each other Calculate CO and CI (computer does this) Copyright © 2017 Elsevier Inc. All rights reserved. 1 1 4

106. Thermodilution Technique (cont.)

107. Co n ti nu o u s C a r d ia c O u t p u t M oni t o r i n g • • T h e r m a l f ila m e n t i s us ed f or the continuous monitoring of cardiac output Thermal Filament increases the t e m pe r a t u r e o f b l o o d t i h n e r i g h t a t rium through radiation the warmer blood travels in the pulmonary artery. Thermistor de t e c t s t h e a l t e r at i on i n w h e r e blood temperature.

108. C o n ti n u o u s Ca r d i ac Outpu t ( C C O) Method • Continuous monitoring via specialized PAC Copper filament at distal catheter en d • Copyright © 2017 Elsevier Inc. All rights reserved. 1 1 7 Figure 8-22. A sample monitor interface displaying hemodynamic parameters and trends, including continuous cardiac output (CCO) and mixed venous oxygen saturation (SvO 2 ). (Courtesy Edwards Lifesciences, Irvine, CA.)

109. Arterial Pressure and Waveform- Based Method Proportional relationship between pulse pressure and stroke volume Inverse relationship between pulse pressure and aortic compliance Measures using an arterial line, special sensor, and a monitor that uses an algorithm for SV and CO

110. Cardiac Output Curves

111. Impedance Cardiography Electrodes placed on the base of the neck and lower thorax Measures impedance over time and is mathematically converted into SV and CO values using an algorithm

112. Esophageal Doppler Monitoring Doppler transducer in nasogastric tube Placed in esophagus and monitors blood flow velocity through the descending aorta Continuous CO and SV are calculated using an algorithm.

113. Evaluation of Oxygen Delivery and Demand Balance Oxygen delivery (DaO 2 ) Amount of oxygen transported to tissues Depends on cardiac output, hemoglobin levels, and arterial oxygen saturation

114. Oxygen Consumption: The amount oxygen used by the cells of the body Primary determinants: Oxygen demand—the cells requirement for oxygen Oxygen delivery—need adequate supply of oxygen to deliver to the cells Oxygen extraction—the amount of oxygen removed from Hgb to be used by the cells

115. Evaluation of Global Tissue Oxygenation Status Metabolic indicators Lactate levels, serum pH, and base excess/base deficit Venous oxygen saturation Evaluates oxygen supply versus oxygen demand Mixed venous oxygen saturation SvO 2 Venous oxygen saturation ScvO 2

116. Factors Affecting Oxygen Supply Versus Demand • • • • • Surgery Infection Pain H ypot h er m i a Sedation • • • • • Sepsis A ne s t he s i a Suctioning Pharmacological paralysis Anxiety

117. Evaluation of Regional Tissue Gastric tonometry – Specialized pr essure of carbon dioxide (PCO 2 ) Sublingual capnometry – Measures PCO 2 under the tongue