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Hemodynamics Review Packet2014Hemodynamics Review 2013-2014Cardiac CyclePressures equalize between RV & PA, as well as LA & Aorta at peak systolePressures equalize between atria & ventricles at end diastoleContractilityPreloadAfterloadWatch video on :Hemodynamic Monitoring Concepts by SuCollegeThe Hemodynamic ProfileCardiac Output = the amount of blood ejected from the heart each minute. Cardiac Index is CO/BSA.Stroke Volume = the volume of blood ejected from the ventricle at each beat of the heart.CO = HR X SVHeart RateChanges in HR may alter cardiac outputSlight increases in HR with a constant SV will result in an increased cardiac outputRapid HR will result in decreased filling time & will decrease cardiac outputBradycardia usually results in a decreased cardiac outputSV has three components: Preload, Afterload & Contractility.Preload = the pressure in the heart at end-diastole (just before contraction). Preload is an indicator of:Volume of blood in the ventricles at end-diastoleDegree of myocardial fiber stretch just before contraction (Starling’s Law)Compliance of ventricles (stiffness or thickness of cardiac muscle)Measured using the CVP (RAP), PAD, PAWPLow Preload: Hypovolemia, vasodilatationHigh Preload: Hypervolemia, vasoconstriction, right CHF, pulmonary hypertension, pulmonary edemaInterventions: Fluid Resuscitation, diureticsAfterload = the amount of resistance the ventricles must overcome to eject blood. Factors affecting afterload:Pulmonary artery pressuresViscosity of bloodOutflow valvesPeripheral vasculature Measured using SVR & PVR which are calculated measurementsFactors Affecting Afterload: Ventricular outflow obstruction, arterial vasoconstriction, sympathetic nervous system, temperatureInterventions: Vasodilators, vasoconstrictors, ACE InhibitorsContractility = the force with which the ventricles contractMeasured with Stroke Index (Stroke Volume/BSA)Factors Affecting Contractility: Scarred myocardial tissue, oxygenation, acidosis, electrolyte imbalance, cardiac ischemia, chemical or pharmacological effects, pathologic conditionsInterventions: Inotropes, beta blockersNormal Parameters & ValuesParameters ValuesSystolic & Diastolic Blood Pressure100-130/60-90 mmHgMean Arterial Pressure70-105 mmHgRight Atrial Pressure (CVP)2-6 mmHgRight Ventricular Pressure25-30/0-8 mmHgPulmonary Artery Pressure (PA)15-30/6-12 mmHgPulmonary Artery Occlusive Pressure (PAOP) aka Pulmonary Artery Wedge Pressure (PAWP)4-12 mmHgCardiac Output/Cardiac Index4-8 L/min/2.5-4.2 L/min/m2Systemic Vascular Resistance770-1500 dyne/sec/cm-5Pulmonary Vascular Resistance20-120 dyne/sec/cm-5Stroke IndexRVSWI 7-12g/m2/beat; LVSWI 35-85g/m2/beatHemodynamic MonitoringThe pulmonary artery catheter (Swan-Ganz) with its different waveforms as it travels through the heart.Fluid-filled monitoring systems consist of a catheter connected to a transducer via a system of stopcocks & tubing. A pressure transducer is a device that changes varying physiologic pressures into an electrical signal displayed on the monitor. The air-fluid interface aka the zeroing stopcock must be leveled to the patient’s phlebostatic axis (4th intercostal space, mid-axillary line). If the stopcock is above the axis, an artificially low reading will be displayed; if it is below the axis, an artificially high number will be displayed. To zero the lines, the air-fluid interface stopcock must be opened to air (off to the patient), and then the zero button on the monitor is pressed. (Be sure any unvented stopcocks have been removed). When the second beep occurs, there should be a (0) reading on the monitor. Then turn the stopcock off to the air, and a pressure reading should now show on the monitor. Potential Complications: Vessel Rupture, ventricular arrhythmias, pneumothorax, emboli, catheter migration, pulmonary infarct, ventricular arrhythmias, infection, balloon rupturePulmonary Artery Wedge PressureMeasurement reflecting the left side of the heart indirectly--end diastolic left ventricular pressureInflate the balloon with only enough air to wedge the catheter -- NEVER more than 1.5 mls of air Do not leave balloon inflated for more than 15 secondsPerform reading at end-exhalationAllow passive deflation of the balloonSome physicians do not use the wedge as pulmonary problems can affect the wedge reading The wedge pressure can give us an indication of fluid volume status Increased PAWP: Left sided heart failure, mitral stenosis or insufficiency, tamponade, overwedging (too much air in balloon), high PEEPDecreased PAWP: Hypovolemia Cardiac output Measured by thermodilution--a thermistor at the end of the catheter measures temperature changes when injectate passes over the thermistor and displays this temperature change as a curve on the monitor 5 mLs of Normal Saline should be injected over 4 seconds through the distal port of the catheter (CVP or blue port) at end-expiration At least 3 measurements should be taken and averaged to ensure accuracyFactors that may affect CO: Irregular heart rhythms & varying rates, septal defects, sensor malfunction, tricuspid regurgitationFICK Formula—may be used if CO is invalid.(SaO2-SvO2) X 1.36 X Hgb=x Ex: Hgb: 11.5, SaO2 98%, SvO2 62%.125/x= y (98-62) X 1.36 X 11.5 = 563.04y X 10= CI 125/563.04 = .222 .222 X 10 = 2.22TroubleshootingDampened Waveform: Air bubble or clot in system, kink or knot in system, small leak in system, decreased fluid or pressure in pressure bagNo waveform: transducer not open to catheter, clotted catheter tip, large leak in system (loose connections)Right Ventricular Waveform: Catheter migration. Assess for ectopy. May need to pull back catheter until RA waveform is seenContinuous PAWP waveform: Catheter is wedged. Deflate balloon, open to air, reposition patient. If doesn’t work, pull back catheter 1-2mm to achieve resumption of PA waveformSwan Ganz CatheterWaveform AnalysisPulmonary Artery Pressure (PAP)Central Venous Pressure (CVP aka Right Atrial Pressure RAP)Pulmonary Artery Wedge Pressure (PAWP) aka Occlusive Pressure (PAOP)Cardiac OutputDrip Chart & the Effects on Afterload, Heart Rate & Contractility Key: small arrow indicates minimal effect; double arrows indicate strong effect; blank = no effectDrugSVRHRCardiac OutputMilrinone (primacor)Levophed (norepinephrine)EpinephrineDobutrex (dobutamine)Cardene (nicardipine)DopaminePhenylephrine (neosynephrine)VasopressinNipride (nitroprusside)NitroglycerinCommon Hemodynamic DripsVasopressors act by stimulating alpha or beta receptors or both. Physiology:Alpha 1 Receptors: Arteries, arterioles, veinsAlpha 2 Receptors: GI tractBeta 1 Receptors: HeartBeta 2 Receptors: Skeletal muscle, blood vessels, coronary arteries, bronchial smooth muscleContractility EnhancementDobutamine (Dobutrex)Stimulates alpha 1, beta 1, beta 2Mix: Premixed 250 mg/250 mls D5W & 500mg/250mlsDosing: Start 2-5 mcg/kg/min. May titrate if ordered by physician. Max 20 mcg/kg/min.Milrinone (Primacor)Increases contractility, vasodilatesMix: PremixedDosing: 0.375 mcg/kg/min-0.75 mcg/kg/minIncrease AfterloadDopamineStimulates alpha 1, beta 1Mix: Premixed 400 mg/250 mls Dosing: Dosed in mcg/kg/min. Titrate to prescribed parameters (Max: 20 mcg/kg/min)EpinephrineStimulates alpha 1, alpha 2, beta 1, beta 2Mix: 4 mg/250 ml NS or D5Dosing: Dosed in mcg/kg/min. Titrate to prescribed parameters.Norepinephrine (Levophed)Stimulates alpha 1 & 2, beta 1Mix: 4 mg/250 ml D5W (NOT NS) Dosed in mcg/min or mcg/kg/min. Titrate to prescribed parameters (Max: 3 mcg/kg/min) Phenylephrine (Neosynephrine)Stimulates alpa 1, alpha 2 (good choice if tachycardic)Mix: 10 mg/250 ml NSDosing: Dosed as mcg/min. Titrate to prescribed parameters (Max: 8 mcg/kg/min)VasopressinStimulates vasopressin receptors found in arterial smooth muscle and renal tubulesMix: 20 mg/100 ml NSDosing: 0.01 to 0.04 units/minute. Titrate to prescribed parameters. Decrease Afterload & PreloadNitroglycerinDilates arteries & veinsMix: 40 mg/250 mls Dosing: Dosed in mcg/min or mcg/kg/min. Titrate to prescribed parameters.Nitroprusside (Nipride)Peripheral vasodilatation Mix: 50 mg/250 mls D5Dosing: Dosed as mcg/kg/min. Titrate to prescribed parameters. Max 10 mcg/kg/minMonitor for cyanide toxicity. Protect from light Nicardipine (Cardene)Arterial Vasodilatation Mix: Premix 50 mg/250 mls D5W Dosing: Initial 5 mg/hour. Titrate up by 2.5 mg/hour every 5-15 minutes until desired effect is achieved. Max 15 mg/hour Decrease PreloadFurosemide (Lasix)Dosing: 20-80 mg IVP. May be given as continuous infusionMonitor urine output & serum potassium (K)Bumetadine (Bumex)Dosing: 0.5-1 mg IVP. May be given as continuous infusionMonitor urine output & serum potassium (K) ................
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