HEMODYNAMICS Flashcards
what is stroke volume dependent on?
preload, afterload, contractility
what is normal CO and CI?
4-8L/min; 2.5-4.0L/min/m2
what is preload?
volume/pressure in the ventricle at the end of diastole after the AV valves close, just prior to ejection. The RA pressure or CVP reflects the right ventricular preload. PAOP reflects the LV preload;
As preload increases, what happens to SV and CO?
SV and CO increase up to a point. too high preload may lead to heart failure
what is afterload?
pressure (resistance) against which the ventricle must pump to open the valve (pulmonic/aortic); clinically measured by pulmonary vascular resistance (PVR) for the right ventricle or systemic vascular resistance (SVR) for the LV
what happens to SV and CO as afterload increases?
SV and CO decrease
what is contractility?
contractile force of the myofibrils independent of preload and afterload
what happens to SV and CO as contractility increases?
SV and CO increase
what is normal SV and SI?
50-100ml/beat; 25-45ml/beat/m2
what is normal right atrial pressure?
2-6mmHg 3-8cm H20
what is normal pulmonary artery pressure (PAP) and pulmonary artery occlusive pressure (PAOP)?
20/8-30/15mmHg; mean: <20mmHg; 8-12mmHg (although varies depending on LV function)
what is normal systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR)?
800-1200 dynes/s/cm^-5; 50-250 dynes/s/cm^-5
what is normal coronary artery perfusion pressure (CAPP)?
60-80mmHg
what is normal mixed venous oxygen saturation (SvO2), central venous oxygen saturation (ScvO2), and arterial oxygen saturation (SaO2)?
60-75%, >70%, 95-99% on RA
what is normal arterial oxygen content (CaO2), oxygen delivery (DO2), and oxygen consumption (VO2)?
12-16mL/dl; 900-1100mL/min; 250-350mL/min
what increases preload?
- volume expanders (crystalloids, colloids)
- pressors
what decreases preload?
- diuretics
- dilators: nitrates, nitroprusside, nesiritide
- morphine
what increases after load?
- norepi
- phenylephrine
- high dose dopamine
- epi drip
what decreases after load?
- nitroprusside
- ACEI
- hydralazine
- CCBs
- IABP
- nitro high dose
what increases contractility?
- positive inotropes: dobutamine, dopamine 5-10mcg/kg/min, primacor, epi drip
what decreases contractility?
- negative inotopes: BBs, CCBs
- metabolic problems (metabolic acidosis, endotoxins of sepsis)
what is the most sensitive indicator of cellular oxygenation?
mixed venous oxygen saturation (SvO2)
normal: 60-75%
what is used to monitor therapy for septic shock?
central venous oxygen saturation (ScvO2)
normal: >70%
what will cause a decrease in oxygen delivery (DO2)?
pump problems
oxygen consumption (VO2) is low with what?
septic shock
oxygen extraction increases with a drop in what?
CO
normal: ~50% of O2 delivery
what increases SvO2?
- septic shock
- hypothermia
- paralysis
what should you assess for if SvO2 is increased?
- severe sepsis, septic shock
- hypothermia
what decreases SvO2?
- low CO
- decreased PaO2
- increased O2 demand (fever, shivering, sz, increased WOB)
what should you assess for if SvO2 is deceased?
- hypoxemia, increased WOB
- hypoTN
- hypovolemia
- hemoglobin drop
- fever
- arrhythmias
how does the PAOP waveform change when mitral valve insufficiency (regurgitation) is present?
giant V waves
what is the dynamic response test/square wave test?
assess the accuracy or the hemodynamic monitoring system
what is an over damped wave response?
- results in a falsely decreased systolic pressure and false high diastolic pressure as well as poorly defined components of the pressure tracing such as diminished or absent dicrotic notch
- may be due to air or blood clot in system, loose connections, loss of air in the pressure bag, or kinking of the catheter/tubing system
what is an underdamped wave response?
- results in false high systolic pressures (overshoot), possibly false low diastolic pressures, and “ringing” artifacts on the waveform
- may be due to pinpoint air bubbles in the system, add-on tubing, or defective transducer
