5. OR Concepts Flashcards
baroreceptros
pressure sensors
detect pressure of blood flowing through arteries
baroreceptor locations
carotid sinuses
aortic arch
baroreceptor reflex
helps mx normal cardiac output with high or low BP
baroreceptor reflex process
- sense change in BP
- send signal to brain to correct BP
- Low BP: ANS increase HR (CO)
- High BP: ANS decrease HR (CO)
reflex bradycardia
vasoconstriction (high BP) causes HR to decrease
reflex bradycardia commonly caused by what drug
phenylephrine
reflex tachycardia
vasodilation (low BP) causes HR to increase
drugs that can trigger reflex tachycardia
propofol or hydralazine
carotid body
chemoreceptors that sense hypoxia
stimulate respirations (hypoxic drive)
also sense: temp, pH, CO2
carotid sinus
baroreceptors adjust HR to mx normal CO/BP
cerebral vascular accident (CVA)
stroke
sudden brain cell death cause by inadequate blood flow
causes of stroke
blood clot
intracranial hemorrhage
prolonged hypotension
hypertension
Ischemic stroke
Blood clot
intracranial hemorrhage
hemorrhagic stroke
prolonged hypothension can be caused by
inadequate brain perfusion
hypertension can lead to
stress on walls of blood vessels
intracranial hemorrhage
DVT
blood clot in vein (usually in leg)
more likely to develop if blood from is static
Pts at risk for blood clots
bedridden pts
heart arrythmias that decrease BF through heart
- afib
pulmonary embolism
DVT dislodged from legs that moves to heart and lungs
life threatening emergency
DVT prevention
walking/movement
blood thinners
sequential compression stockings during surgery
intracellular fluid
(ICF)
inside cells
65%
extracellular fluid
(ECF)
outside cells
35%
2 divisions of ECF
interstitial fluid
intravascular fluid
edema
swelling
excess fluid in interstitial space
pulmonary edema
excess fluid in alveoli
commonly caused by some degree of heart failure
interstitial fluid
any fluid not inside cells or inside intravascular space (arteries/veins)
transmural pressure
difference in pressure between 2 sides of a wall
pulmonary edema causes
pressure in lungs is drastically reduced
pressure in capillaries is relatively higher
Plungs<Pcapillaries
blood moves from capillaries into lungs
common causes of negative pressure pulmonary edema
biting on ETT
laryngospasm
kinked tube
obstructed airway
how to treat negative pressure pulmonary edema caused by biting on ETT
pull tube
or
relax bite w/propofol/sux
prevent pt from biting on ETT
place bite block prior to emergence
treat pt biting on LMA
deflate cuff
air can now move around the cuff into trachea
preload
volume of blood returning to RV
blood available to be pumped on next contraction
venous return
afterload
resistance the LV pumps against
preload is proportional to
pts volume status
- hypovolemia = low preload
- hypervolemia = high preload
pts position
- head up = high preload
- head down = low preload
how is preload measured
central venous pressure (CVP)
only measured w/central line
CVP
blood pressure within the superior vena cava
normal: 5-12 mmHgce
central lines are placed in
internal jugular
subclavian
(large central vein)
low CVP indicates
low preload
(hypovolemia)
high CVP indicates
fluid overload
high CVP is common in what pts
heart failure
renal failure
afterload is proportional to
level of vasoconstriction
- vasoconstriction = high afterload
- vasodilation = low afterload
blood pressure
- high BP = high afterload
- low BP = low afterload
when can you have high afterload and low blood pressure?
if pt is bleeding to death (exsanguinating)
low BP due to hypovolemia
vasoconstriction to try to keep blood pressure high would cause high afterload
systemic vascular resistance (SVR)
AKA afterload
AKA peripheral vascular resistance
arterial vasoconstriction = high SVR
arterial vasodilation = low SVR
pulmonary vascular resistance
(PVR)
resistance that the right ventricle must pump against
afffected by vascular tone of pulmonary arteries
pulmoary artery vasoconstriction = high PVR
pulmonary artery vasodialtion = low PVR
positive intrathoracic pressure
**decrease BP
compresses heart/veins
incr resistance to BF
decr preload/venous return
decr SV
decr CO
decr BP
types of positive intrathoracic pressure
PPV
PEEP
valsalva maneuver
drops BP
negative intrathoracic pressure
reduces pressure to heart/veins
decr resistance to BF
incr preload/venous return
decr SV
types of negative intrathoracic pressure
spontaneous ventilation
cautery
cautery pen = bovie
cuts tissue
burns/coags blood vessels
requires grounding pad
cautery electrical loop
required for current to flow
- machine
- bovie
- patient
- grounding
- machine
if you do not have grounding pad, current cannot flow
grounding pad
return electrode to the eletrocautery unit
required for current to flow
large surface area
place over well perfused muscle to dissipate heat (thigh)
unipolar bovie
superior coagulation
requires grounding pad
more current flow
bipolar bovie advantages
2 cautery tips
- less current flows between tips
- more controlled == delicate areas
(nerves)
no grounding required
bipolar bovie disadvantage
cauterizes small areas
not good for controlling large bleeding
cautery safety
minimal electrocution risk
high current freq (>200,000Hz)
pts with interior metal are burn risk
- remove jewelry
- place pad away from internal metal
implications of Pnemoperitoneum (CO2 insufflation) (8)
- intubation required
- atelectasis more likely
- hypercarbia more likely
- vagal response
- CO decreases
- BP fluctuation
- referred pain in shoulder
- partial pneymothorax
why can CO2 insufflation cause atelectatsis?
diaphragm compression
resistance to lung expansion
decrease FRC
why is hypercarbia more likely w/CO2 insufflation?
CO2 diffuses to arteries
what are the impacts of a vagal response during CO2 insuflation?
bradycardia
hypotension
during insufflation