Hemodynamic Monitoring

Client Management

-Read pressures at the end of expiration -Level transducer at phlebostatic axis -Remove all air from tubing and transducer -Use heparinized low flow flush solution to maintain patency and normal waveform -Calibrate the transducer (zero to atmospheric air) -Stabilize catheter with dressing to prevent kinking -Inflate balloon slowly, do not over inflate, when balloon inflated do not exceed 5-15 seconds -Do not aspirate air from inflated balloon; remove syringe and let balloon deflate passively -Keep balloon deflated except when obtaining readings -Monitor for complications for arrhythmias, infection, air emboli, pneumothorax and catheter clotting -If balloon does not move from the wedge position do not pull on the balloon, call the MD

Arterial Waveforms

A normal waveform consists of a rapid, sharp upstroke, a dicrotic notch, and a clear end-diastole; heart rate and rhythm may alter waveform configuration The baseline wave is the aortic end diastolic pressure (AEDP), indicating the minimum pressure reached in arteries during diastole The top of the wave is the peak systolic pressure (PSP) and indicates the maximum pressure reached in the arteries during systole; PSP is heard as the systolic B/P The dicrotic notch may be visible on the downstroke of the arterial waveform, indicating the closing of the aortic valve and beginning of diastole The remainder of the downstroke represents diastolic runoff of blood flow into the peripheral arterial vasculature https://www.youtube.com/watch?v=xEzCTJoN_lE

Arterial Pressure Monitoring

Arterial blood pressure is measured indirectly with a blood pressure cuff and stethoscope or automatic blood pressure device Direct intra-arterial pressure may be taken after insertion of a cannula into an artery and connecting the cannula to a pressure monitoring device -Used to get direct measurement of B/P in those clients with a major surgical or medical condition that compromises cardiac output, tissue perfusion and/or fluid volume status -More accurate, allows for continuous monitoring of systolic and diastolic blood pressure and mean arterial pressure -Allows for routine blood specimens to be obtained (including ABGs) to prevent multiple needle sticks The radial artery is the preferred site due to small size, superficiality, and good collateral circulation. The brachial and femoral arteries are less preferred sites as they are deep, have very limited to no collateral circulation and severely limit client movement. Catheter size determined by size of artery, Teflon catheters are preferred as they reduce the risk of thrombosis Systolic blood pressure (SBP) is the highest pressure in the arterial system and determines perfusion pressure on body tissues. It is an indirect indicator of stroke volume Diastolic blood pressure (DBP) is the lowest pressure and an indirect indicator of systemic vascular resistance Pulse pressure is the difference between systolic and diastolic B/P (normally 40-60 mmHg) and reflects the vascular resistance of the arterial system and stroke volume Mean arterial pressure (MAP) is the average pressure under which blood flows to the tissue during the cardiac cycle. (better indicator of perfusion to vital organs than systolic blood pressure (SBP) -A MAP of at least 60 mm Hg is needed to maintain autoregulation of the heart, brain, and kidneys. -A MAP of 70-90 Hg is ideal for cardiac clients to decrease left ventricular workload -After carotid endarterectomy or neurologic surgery a MAP of 90-110 mm Hg may be needed for cerebral perfusion The formula for calculation is MAP=SBP+(DBP x2) ÷ 3

Cardiac Output

Cardiac output is the amount of blood the heart pumps per minute and the product of heart rate multiplied by stroke volume -Provides valuable information about left ventricular function -Evaluates the adequacy of cardiac output to determine the extent of oxygen delivery to the cells Two methods the thermodilution bolus method and continuous monitoring -Thermodilution method 5-10 mL of iced or room temperature saline is injected into the proximal lumen of the catheter. The speed at which the solution moves is calculated by a cardiac output computer attached to the hub port of the PA catheter and based on this speed the cardiac output is determined. Requires three measurements and averaging the results -Continuous cardiac output monitoring using a PA catheter is much more frequently used in clinical practice. A thermal filament on the PA catheter emits a small energy signal into the blood stream that is detected by a sensor at the tip of catheter and this provides a continuous cardiac output reading. Normal cardiac output is 4-8 liters a minute

Central Venous Pressure Monitoring

Central venous pressure (CVP) is measured by a monometer connected to a central line or by a transducer connected to the proximal lumen of a pulmonary artery catheter. The insertion site of the catheter is generally the subclavian or internal jugular veins The catheter is located in the superior vena cava It is measured in millimeters of Mercury or centimeters of water. 1 mm Hg equals 1.36 cm of H2O Represents the the filling pressure or preload of the right ventricle or right ventricular end diastolic pressure Used to assess fluid volume status because the venous bed contains 60% of the blood volume Guides fluid volume administration Monitors effectiveness of diuretic therapy Unreliable indicator of left side heart pressure and function Normal reading is 4-10 cm of water or 3-7 mm Hg of Mercury Low CVP indicates hypovolemia High CVP indicates hypervolemia or poor myocardial contractility May also be used for drawing blood for lab and infusion of medication and fluids

Client Management

DO NOT insert any medication except heparin flush solution through arterial lines Level the transducer at the phlebostatic axis before obtaining readings Remove all air from tubing and transducer, air bubbles dampen or distort the waveform Use a heparinized solution (usually 1 unit heparin/1 milliliter flush) to maintain line patency and normal waveform (follow institution policy) Calibrate the transducer and compare arterial line pressures with cuff pressures at least once per shift A dampened wave form (indicated by loss of DN or flattened upstroke), indicates air, blood, or clots in the line Stabilize catheter with a dressing to prevent kinking Use luer-lock connectors to prevent breaks in the system Check collateral circulation by performing Allen's test before insertion https://www.youtube.com/watch?v=D1tJO0RW9UM Monitor for complications such as infection, hemorrhage, decreased or absent pulses distal to insertion site

Hemodynamic Monitoring

Hemodynamic monitoring is the invasive monitoring techniques used to measure pressures and values within the heart, lungs, and circulatory system Used for: Assessment of fluid status and guide replacement. Need for and titration of medication Assess treatment effectiveness Performed in emergency departments and critical care units. Considered a specialized nursing skill Each chamber of the heart and arterial system have normal pressures and to measure these pressures hemodynamic monitoring is required -A fluid filled catheter is inserted into an artery or one of the heart's chambers -The fluid filled catheter transmits pressure readings to a transducer which converts the pressure reading into an electrical signal represented by a wave form -The hemodynamic waveform is displayed on a bedside monitor and compared to normal values and client's baseline values

Equipment

Invasive catheter (different monitoring requires different types of catheters) and high pressure tubing to connect the client to the transducer Transducer receives the physiologic signal through catheter and tubing and coverts it into electrical energy that is then visualized on a monitor. Must be calibrated to atmospheric pressure, known as zeroing the transducer Transducer must be aligned to the tip of the invasive catheter. The phelebostatic axis is the reference point. -Found by drawing a theoretic line from the fourth intercostal space where it joins the sternum to the midaxillary line on the side of the chest. -This point approximates the level of the atria Flush system to maintain patency of the fluid filled system and catheter -Saline with Heparin (1 unit/mL) -Pressure infusion cuff inflated to 300 mm Hg -IV tubing -Three way stop cock -In line flow device for both continuous fluid infusion and manual flush -High pressure tubing to connect the invasive catheter to the transducer Bedside monitor contains the recorder which increases the volume of the electrical signal and displays it on an oscilloscope and on a digital scale https://www.youtube.com/watch?v=uv6t1raryjM

Trouble Shooting

Major complication is exsanguination if the luer lok connections are not tight or in-line stop cock is left open to air To prevent air emboli ensure all air bubbles are purged from a new line before attaching to an indwelling catheter Pressure alarms must always be on with high and low limits set. If low or high reading it is a nursing responsibility to determine if it is the client or the equipment A dampened waveform (flat) occurs when communication from the artery to the transducer is interrupted and produces false values. It is important to find the reason and correct it Ensure that the transducer is kept at the phlebosatic level. To maintain level some institutions have the transducer placed on the client's chest -Misplacement can occur if the client moves from bed to chair -Head of bed elevated -Bed is placed in Trendelenburg position At times catheter migrates against vessel wall, having client change position is helpful Calibrate system to atmospheric pressure every shift and as needed (zero to atmospheric pressure)

Pulmonary Artery Pressure Monitoring

Most invasive of critical care monitoring catheters; monitors direct intracardiac pressures Used for critically ill clients Also known as right heart catheter or swanz ganz catheter Used to measure pulmonary artery (PA) pressures The catheter has a balloon tip with two to seven lumens or ports; each lumen exits into the heart at a different point along the catheter length It is passed into the right atrium of the heart from the subclavian or internal jugular veins Once in the right atrium of the heart the balloon is inflated and the catheter advanced through the heart into the pulmonary artery. Once in the pulmonary artery the balloon is deflated and the catheter secured in place. The balloon is left deflated during monitoring When readings are taken the balloon is inflated and the catheter floats out to occlude a smaller branch of the pulmonary artery allowing for pressure in front of the balloon the be measured This pressure is called the pulmonary artery wedge pressure Provides information about vascular capacity, blood volume, pump effectiveness, and tissue perfusion Indirectly reflects left ventricular end-diastolic pressure which is an indication of left ventricular function The distal tip of the catheter measures PAP and PAWP The proximal port is used for continuous infusion of fluids or medication. It measures right atrial pressures when the distal tip is in the pulmonary artery Right atrial lumen is located in the right atrium -Used for IV infusion, -CVP measurements -Withdrawal of venous blood -Injection of fluid for cardiac output Pulmonary artery lumen is located at the distal tip of the PA catheter -Used to record PA pressure -Pulmonary artery pressure assesses the state of resistance in the pulmonary vasculature and ventricular function. -It is continuously monitored. -A normal reading indicates the catheter is located correctly as it can migrate forward or backward Balloon lumen opens into a balloon at the end of the catheter and can be inflated with 0.8-1.5 ml of air (dependant on size of catheter) -The balloon is inflated during insertion once the catheter enters the right atrium and to obtain pulmonary artery wedge pressures

PA Pressures

PA diastolic pressure is normally 4-13; it is normally 1-4 mm higher than PAWP -PA systolic pressure is normally 17-31mmHg -PA mean is 9-19 mmHg -Measured within the pulmonary artery PAWP (wedge) mean is 8-12mmHg -Waveform seen when the balloon wedges in a smaller branch of the pulmonary artery -Reflects left ventricular filling pressures. -Variations of PAWP are used to assess left ventricular function https://www.youtube.com/watch?v=uwcZ6qHHwE0 https://www.youtube.com/watch?v=y241HEaBkLA

PA Waveforms

The mechanical action of the heart is responsible for the characteristics of PA wave forms. The wave forms change as the catheter passes through the chambers of the heart -A right atrial waveform is visible when the balloon catheter is being inserted and floated through the right atrium -A right ventricular waveform is visible as the catheter passes through the right ventricle. It is pulsatile with a distinct systolic and diastolic pressure. Ventricular ectopy (irregular heart rhythm) may occur, have a defibrillator and crash cart available -Pulmonary artery wave forms occurs as the catheter enters the pulmonary artery. -Pulmonary Artery Wedge Pressure (PAWP or wedge) is obtained by inflating the balloon tip of the PA catheter and allowing blood flow within in the pulmonary artery to push the balloon into a branch of the pulmonary artery where it "wedges". Once the balloon is deflated it floats back into the pulmonary artery NEVER PULL ON THE BALLOON

CVP Waveform

The right atrial CVP waveform has three positive deflections called a, c, and v waves and two negative deflections known as x and y; it is a reflection of atrial heart functions The wave reflects atrial contraction and follows the P wave of the EKG The c wave reflects bulging of the closed tricuspid valve into the right atria during ventricular contraction. It is small and not always visible, corresponds to the QRS-T interval on the EKG The v wave represents atrial filling https://www.youtube.com/watch?v=8xpKr1t7YQE

Client Care

Use the phlebostatic axis for leveling of the transducer Observe for complications of infection and air emboli Keep luer lok connectors to help prevent air emboli Prevent infection with good handwashing, aseptic technique during medication administration, withdrawal of blood, dressing changes

Afterload

is the amount of pressure the ventricle has to generate during systole (emptying) to overcome the resistance within the arteries. (is the pressure the left ventricle must push against to empty) Systemic vascular resistance is the afterload of the left ventricle and normal is 800-1200 dynes/sec/cm-5 Pulmonary vascular resistance is the afterload of the right heart and normal PVR is 100 - 200 dynes/sec/cm-5

Preload

is the volume of blood in the ventricles at the end of diastole (filling) (is the amount of blood entering the ventricles that causes it to stretch before the next contraction)

Dynes

increases its velocity by one centimeter per second

Stoke volume

is amount of blood ejected by the ventricle with each heartbeat (normal 60-130 mL/min)

Cardiac Output

is the amount of blood the heart pumps in 1 minute and it is measured by multiplying the heart rate X stroke volume (4-6 L a min. in the resting adult)

Cardiac Index

represents cardiac output that has been adjusted for size. Cardiac index is derived by dividing cardiac output by the person's body surface area or BSA. (2.2-4.0 L a min. in a resting adult)