Hemodynamics Monitoring Fall 2024 - Student Notes PDF

HEMODYNAMIC MONITORING KRISTEN BOLTON – FALL 2024  Discuss indications for invasive hemodynamic monitoring Compare preload, afterload and contractility when determining cardiac function OBJECTIVES Explore hemodynamic values for P...

HEMODYNAMIC MONITORING KRISTEN BOLTON – FALL 2024  Discuss indications for invasive hemodynamic monitoring Compare preload, afterload and contractility when determining cardiac function OBJECTIVES Explore hemodynamic values for PA Cath, Art lines, CVP monitoring Hemodynamics: are the forces that circulate blood through the body Hemodynamic monitoring: refers to the measurement of pressure, flow and oxygenation of blood within the cardiovascular system Indications for Hemodynamic monitoring?? WHY DO WE HEMODYNAMICALLY MONITOR? 1. To allow for early detection, identification, treatment 2. To evaluate response to treatment 3. Evaluation cardiovascular function HEMODYNAMIC CONCEPTS Blood Pressure Flow Resistance CARDIAC CYCLE MEAN ARTERIAL PRESSURE (MAP) MAP is directly affected by factors such as: Amount of blood pumped out of the heart per minute (CO) Heart rate (beats per minute) Blood pressure Resistance to blood flow in the vessels (SVR) DETERMINANTS OF CARDIAC OUTPUT Heart Rate Preload Afterload Contractility PRELOAD PRELOAD Left ventricular end-diastolic VOLUME The VOLUME left in the ventricle when the mitral valve closes determines the amount of blood ejected into the systemic circulation The volume of blood EJECTED with each heartbeat refers to the Stroke Volume (SV)  WHAT INFLUENCES PRELOAD?  Can be measured as: Central Venous Pressure (CVP) = Measures preload in the Right side of PRELOAD the heart (2-8 mm/Hg) Pulmonary Artery Wedge Pressure PAOP/PAWP = Measures preload in the Left side of the heart (4-12 mm/Hg) PRELOAD Parameters related to preload Left - Pulmonary artery occlusion pressure (PAOP)/wedge pressure - Normal 5-12 mmHG Right - Central venous pressure/right atrial pressure CVP/RAP - Normal value 2-6 mmHg AFTERLOAD  Any resistance in which the ventricles must pump in order to eject its volume How hard the heart has to push to AFTERLOAD get the blood out “Resistance to flow” or how clamped the blood vessels are WHAT INFLUENCES AFTERLOAD?  SVR = Systemic Vascular Resistance AFTERLOAD PVR = Pulmonary Vascular Resistance CONTRACTILITY  Contractile force of the heart CONTRACTILITY Ability to shorten muscle fibres without altering length or muscle WHAT INFLUENCES CONTRACTILITY?  CONTRACTILITY Left ventricular stroke work index (LVSWI) Right ventricular stroke work index (RVSWI) = Amount of work the ventricle performs with each heartbeat PERFUSION PRELOAD AFTERLOAD CONTRACTILITY  Rubber Band = Heart muscle DON’T The less the rubber band is stretched FORGET the less it will propel in the air. The ABOUT further the rubber band is stretched FRANK the greater the force and it will propel STARLING in the air further. LAW Think about preload and how it relates…  HEMODYNAMIC MONITORING Continuous Non-invasive vs. vs. Invasive Intermittent  Invasive Hemodynamic Monitoring HEMODYNAMIC MONITORING INTRAARTERIAL BLOOD PRESSURE MONITORING (IABP)  Indications: Any major medical or surgical condition that has the potential to alter CO, tissue perfusion, or fluid balance INTRAARTERIAL BLOOD Continuous measurement of three blood PRESSURE pressure parameters; MONITORING Systole, Diastole & Mean arterial blood (IABP) = pressure (MAP) ART LINE MAP monitoring = continuous assessment of arterial perfusion to major organ systems of the body MEAN ARTERIAL PRESSURE (MAP) Can range from 70-110mmHg The average pressure of the arteries Clinical parameter used to assess perfusion MAP is directly affected by factors such as: Amount of blood pumped out of the heart per minute (cardiac output) Heart rate (beats per minute) Blood pressure Resistance to blood flow in the vessels INTRAARTERIAL BLOOD PRESSURE MONITORING (IABP)  Leveling – Phlebostatic axis Zeroing – The use of atmospheric pressure as a reference standard against which all HEMODYNAMIC other pressures are measured ACCURACY Square Wave/Flush test – Fast flushing the system for 1-2 seconds and note the waveform or the ‘square wave’ Rises sharp – plateaus – drops off sharply CENTRAL VENOUS PRESSURE MONITORING (CVP)  Indications: when a patient has significant alteration in fluid volume Central Venous Catheter (Subclavian and Internal Jugular) CENTRAL VENOUS CVP = Central Venous Pressure PRESSURE (Represents volume status in the body) MONITORING Normal value 2-5 mmHg or (0-7 mmHg) CVP WAVEFORM SPECIALIZED CENTRAL VENOUS CATHETER/ SWANS GANZ = PA CATH  PA CATH/ SWANS GANZ CATHETER Indications: Used for the most hemodynamically unstable patients for the diagnoses and evaluation of cardiogenic shock Can provide information: RAP/CVP PAOP/PAWP (Wedge Pressure) PCWP CO PHARMACOLOGY VASOPRESSORS: CLASS OF MEDICATIONS THAT INDUCE VASOCONSTRICTION & THEREFORE ELEVATE (MAP) INOTROPIC AGENT’S “INOTROPES”: ARE MEDICATIONS THAT ALTER CARDIAC CONTRACTILITY USE OF INOTROPES & VASOPRESSORS - To support the myocardium that is failing - To support the failing peripheral vascular system - To assist with hypotension  DOBUTAMINE Increases CO​ (Vasopressor. Inotrope) Mechanism of Action: Beta1 stimulation - increases contractility Some Beta 2 stimulation - mild vasodilation​ As effective as dopamine at increasing contractility, but doesn’t have as much vasodilatory effect so good for hypotensive patients 2.5-20 mcg/kg/min  NOREPINEPHRINE (LEVOPHED) Used to treat low blood pressure Powerful stimulator of alpha/beta receptors. Mechanism of Action: - Lower doses (< 2 mcg/min) - stimulate Beta1 receptors to increase contractility and CO - Higher doses (2-20 mcg/min) - stimulate Alpha receptors 0.5-30mcg/min  VASOPRESSIN (VASOPRESSOR) Also known as Antidiuretic hormone Mechanism of Action: Regulates body’s retention of water by increasing water retention in kidneys Vasoconstricts, increasing SVR and BP