Perfusion Flashcards
perfusion
the process of nutrient delivery of arterial blood to a capillary bed
(supplying an organ or tissue with oxygen and nutrients)
noninvasive assessment of perfusion
LOC
skin
urine output
color, BP, HR
capillary refill time
perfusion scanning methods
CT perfusion
MRI perfusion
nuclear medicine perfusion
cardiac output
the amount of volume/blood ejected/pumped from the heart in one minute
CO=HR*SV
normal CO
4-8L/min
normal cardiac index
2.4-4 L/min
stroke volume
volume of blood pumped with each heartbeat
normal SV
60-70mL with each ventricular contraction
impact of HR on CO
severe increase in HR decreases SV due to decreased filling time, and therefore decreased CO
four determinants of CO
heart rate
contractility
preload
afterload
preload
amount of blood in ventricle at end of diastole
the degree of stretch in myocardial fibers at the end of diastole
the end diastolic ventricular volume
a function of volume and ventricular compliance
factors affecting preload
volume: venous return, total blood volume, atrial kick
compliance: stiffness and thickness of ventricular wall
manifestations of decreased preload
tachycardia
decreased urine output
increased specific gravity
dry mucous membranes
tented skin
sunken eyes
orthostatic hypotension
increased preload
JVD
pedal edema
S3, S4
crackles
dyspnea
pink frothy sputum
ascities, hepatic engorgement
medications affecting preload
fluids
diuretics
venodilators: nitrates, morphine, ACE inhibitors
frank starling law of heart
increasing venous return, increases filling pressure of the ventricle will lead to increased force of contraction and stroke volume
afterload
ventricular pressure at the end of systole, the resistance against which the heart pumps blood
factors affecting afterload
aortic impedance
blood viscosity
blood volume
vascular tone
systemic vascular resistance
resistance to ejection from left side of heart
normal 800-1200
pulmonary vascular resistance
resistance to ejection from right side of heart
normal 50-250
increased afterload
pale, cool, clammy skin
HTN
non-healing wounds
thick, brittle nails
slow cap refill
decreased urine output
decreased afterload
warm, flushed skin
increased CO
decreased BP
contractility
the ability of a muscle to shorten when stimulated
the force of myocardial contraction
independent of preload & afterload
SNS and PNS innervation
measured as EF
decreased contracility
hypotension
fatigue
SOB
dizziness
low urine output
increased contractility
increased blood pressure
indications for hemodynamic monitoring
alterations in cardiac output
alterations in fluid volume
alterations in tissue perfusion
central venous pressure
volume/pressure on the right side of the heart
reflects filling pressures in the right ventricle
guides overall fluid balance
noninvasive hemodynamic technologies
impedance cardiography
doppler ultrasound
minimally hemodynamic technologies
CVP
arterial access line
MAP
arterial line indications
monitoring blood pressure
frequent ABGs
pulmonary artery catheter advantages
real-time data
measure a variety of hemodynamic parameters
able to rapidly assess pts response to interventions
PA catheters disadvantages
infection
insertion complications
air emboli, exsanguination
balloon rupture
pulmonary artery rupture
pulmonary artery wedge pressure
4-12mmHg
reflects left side preload
pulmonary artery pressure
20-30/10s mmHg
blood pressure
central venous pressure
2-6mmHg
reflects right sided preload
pulmonary vascular resistance
50-250 dynes/sec/cm-5
reflects right sided afterload
systemic vascular resistance
800-1200 dynes/sec/cm-5
pulmonic valve stenosis/calcification
insidious process that happens over time
increased afterload on right ventricle
pulmonary hypertension
increased afterload on right ventricle, which impacts right ventricular emptying
interventions for elevated PA pressures
find cause/root of problem
reduction in preload (circulating volume)
decrease venous return to the right side
increase/improve contractility
meds: vasodilators, diuretics, Na and fluid restriction, valve replacement/repair
