Hemodynamics CCRN Questions and Answers well Explained Latest 2024/2025 Update 100% Correct.

Tx to decrease preload - -Diuretics -Dilators (nitrates, nitroprusside, morphine) Define preload - -Preload is the volume/pressure in the ventricle at the end of DIASTOLE after the AV valves close, just prior to ejection -As preload increases, SV and CO will increase up to a point -Too high of a preload may lead to heart failure -Preload will seldom be elevate if the heart is without disease and there are no metabolic abnormalities Cardiac output equation - CO = HR x SV Components of stroke volume - Preload Afterload Contractility Preload components - CVP (right ventricular) - central venous pressure PAOP (left ventricular) - pulmonary artery occlusive pressure Afterload components - PVR (right ventricular) - pulmonary vascular resistance SVR (left ventricular) - systemic vascular resistance Normal cardiac output - 4-8L/min CI - -Cardiac index -take into account body surface area and is a more meaningful value than CONormal cardiac index (CI) - 2.5-4.0L/min/m2 CO and HR - -As heart rate increases -Cardiac output increases up to a point -Extreme bradycardia results in low CO and hypotension -Increase in HR >> first sign of compensation for a low CO Definition of stroke volume - -How many mL pr beat the left ventricle ejects Stroke Volume and CO - -As stroke volume increases, cardiac output increases Normal SV (stroke volume) - 50-100 mL per beat What pressures reflect the right ventricle preload? - -Right atrial (RA) -Central venous pressure (CVP) What pressure reflects the left ventricle preload? - -Pulmonary artery wedge pressure (PAOP) Define afterload - -Afterload is the pressure (resistance) against which the ventricle must pump to open the valve (pulmonic and aortic) How is afterload measured for the right ventricle? - -Pulmonary Vascular Resistance (PVR) How is afterload measured for the left ventricle? - -Systemic Vascular Resistance (SVR) Afterload and CO - -As afterload increases, SV and CO decreaseDefine contractility - -Is the contractile force of the myofibrils independent of preload and afterload -As contractility increases, SV and CO increase Stroke Index - 25-45 ml/beat/m2 Right Atrial pressure (RAP) - 2-6 mmHg 3-8 cm H20 Pulmonary Artery Pressure (PAP) - 20/8-30/15 Mean: <20 Pulmonary Artery Wedge Pressure (PAOP) - 8-12 mmHg Systemic Vascular Resistance (SVR) - 800-1200 dynes/s/cm Pulmonary Vascular Resistance (PVR) - 50-250 dynes/s/cm Coronary Artery Perfusion Pressure (CAPP) - 60-80 mmHg Mixed Venous Oxygen Saturation (SvO2) - 60-75% *Direct measurement from pulmonary artery Central Venous Oxygen Saturation (ScvO2) - >70% *Direct measurement from superior vena cava Arterial Oxygen Saturation (SaO2) - 95-99%Arterial Oxygen Content (CaO2) - 12-16 mL/dl Oxygen Delivery (DO2) - 900-1100 Oxygen Consumption - 250-350 mL/min Tx to increase preload - -Volume expanders (crystalloids/colloids) -Pressors Tx to decrease afterload - -Nitroprusside -ACE inhibitors -Hydralazine -Calcium channel blockers -IABP -Nitroglycerin Tx to increase contractility - -Dobutamine -Dopmaine 5-10 mcg/kg/min -Primacor -Epi drip Tx to decrease contractility - -Beta blockers -Calicum channel blockers -Metabolic problems (met acidosis, endotoxins of sepsis) Most sensitive indicator of cellular oxygenation - Mixed venous Oxygen Saturation (SvO2) 60-75%Oxygen parameter used to measure therapy for septic shock - -ScvO2 >70% What will decrease Do2 (Oxygen delivery) - -Pump problems (heart) Oxygen consumption is (low or high) in septic shock - LOW Increased SvO2 - >75% Septic shock** Hypothermia** Paralysis Decreased SvO2 - <60% Low cardiac output Decreased PaO2 Increased O2 demand (fever, shivering, seizures, increased WOB)