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
why does CO decrease during CO2 insufflation?
CO2 compresses vena cava
venous pooling in legs
decreased venous return to heart
(decreased preload)
what causes BP fluctuation during CO2 insufflation?
BP down:
- decr venous return
- decr CO
BP up:
- vasoconstriction (SVR incr) due to compensation for CO decrease
why can pts get shoulder pain with CO2 insufflation?
diaphragm and shoulder are innervated by the phrenic nerve
how can CO2 insufflation cause a partial pneumothorax?
if CO2 gets into the thoracic cavity
can partially collapse lung
CO2 gas embolism
accidental injection of CO2 into artery/vein
blockage of right ventricle or pulmonary artery
28% mortality rate
cause:
veres needle incorrectly place into vein or parenchymal organ
SubQ Emphysema
trapped air beneath the skin
Causes of SubQ emphysema (6)
multiple attempts at abdominal entry
improper cannula placement
incr intraabdominal pressure
long procedures (>3.5hrs)
gas flow rate
high total gas volume
SubQ CO2 insufflation safe range
0-20 mmHg
SubQ CO2 insufflation recommended range
12-14 mmHg
SubQ emphysema clinical significance
hypercarbia
acidosis
EtCO2 elevates at end of surgery
airway swelling
crepitus (crackling skin)
extubation likely contraindicated until symptoms resolved
gastric tube
orogastric tube: into mouth (OG)
nasal gastric tube: into nose (NG)
OG/NG tube purpose
- decompress stomach
- laproscopic surgery
- bowel obstruction
- drug overdose/poisoning
- feeding tube
OG tube indications
temporary
NG tube indications
more permanent
open abdominal
- vent intestinal gases to avoid ileus
- ask surgeon if they want OG or NG
ileus
temporary surgical induced gastroparesis
(bowel obstruction)
NG tube contraindications
facial fractures
OG/NG tube contraindications
pts w/prior gastric surgery
- risk of intestinal perforation
liver failure/cirrhosis
- esophageal varices can rupture
anaphylaxis
mast cells destabilize
release histamine
1. vasodilation
2. bronchoconstriction
- wheezing
- difficult ventilation
anaphylaxis diagnosis
low tidal volume
high circuit pressure
hives
anaphylaxis treatment
- epi pen (300mcg IM)
- Beta 2 agonist (bronchodilator)
- albuterol
- terbutaline (0.25mg) injection
- volatile agent (bronchodilator)
- sevo or iso
- antihistamine
- benadryl H1 blocker
- pepcid H2 blocker
- steroids (swelling reduction)
- solumedrol
- solucortef
compartment syndrome
decrease in BF/perfusion to body compartment due to increase in pressure inside compartment
can lead to permanent injury or amputation
causes of compartment syndrom
fracture
infiltrated IV
tight cast
compartment syndrome treatment
fasciotomy
incision into compartment to relieve pressure buildup/decompress vessels
vagal response
sudden onset of:
bradycardia
hypotension
mimics symptoms of vagal nerve stimulation
vagal response common causes
CO2 insufflation for lap surgery
eye surgery
abdominal/uterine surgery
steroids
enhance effectiveness of catecholamines
“stress dose” of steroids
given to pts if vasopressor therapy is not effective
likely needed for pts on chronic steroids
- more susceptible to hypotension
“stress dose” drugs
solu-medrol (methyprednisolone)
-most common
solu-cortef (hydrocortisone)
abdominal splinting
hypoventilation cause by pain of breathing
shallow breathing
abdominal splinting causes
abdomina/thoracic procedures
abdominal splinting prevention
adequate pain meds
nerve blocks (TAP, intercostal)
local anesthetic at surgical site
higher dose drug
fast onset
longer duration
lower dose drug
slower onset
shorter duration
fentanyl low vs high dosing
1mcg/kg bolus: 45 mins
5 mcg/kg bolus: hours
rocuronium low vs high dosing
100mg: fast onset/long lasting
20 mg: slow onset/short lasting
adverse opioid effects
- respiratory depression
- gastroparesis (full stomach)
- urinary retention
- itching
- constipation
- stiff chest syndrome (diaphragm)
- addiction
stiff chest syndrome treatments
succinycholine
best way to dose opioids
according to respiratory rate
- for SV pts only
dosing for mechanically ventilated pts
vital sings can indicate pain
tachycardia
hypertension
dosing of opioid based on procedure
some procedures are more painful
Ex lap/thoracotomy > cystoscopy
fentanyl dosing
2 mcg/kg per hour of surgical time
more painful surgeris
cardiothoracic
orthopedic
open abdominal
remifentanil uses
neuromonitoring cases when muscle relaxants and high doses of agent cannot be used (<0.5 MAC)
infusion allow profound analgesia w/minimal respiratory depression
toradol
IV NSAID
profound analgesia
minimal respiratory depression
toradol contraindications (10)
- allergies to NSAIDs
- bleeding risk (increases bleeding)
- renal disease
- geriatrics
-1/2 dose - Hx GI ulcers/bleedings
- Hx asthma
- lithium use
- neonates/labor pts
- gastric bypass pts
- bone surgery
torado renal impacts
decreases renal blood flow
increases renal vascular resistance
toradol infants impacts
promotes prematures closure of ductus arteriosus
toradol bone impacts
impair bone healing due to inhibition of prostaglandins
Ofirmev
IV acetominophen
analgesic
minimal respiratory depression
reduction of post-op shivering
Ofirmev onset
5-10 mins
peak effect: 1 hr
Ofimev contraindications
- pt w/liver disease
- alcoholics
- pts on vicodin or norco
- these contain acetominophen
precedex (dexmedetomidine)
analgesic
minimal respiratory depression
sedative
alpha 1 agonist
precedex common dosing
0.2-0.5 mcg/kg boluses at beginning and end of procedure
precedex side effects
decrease BP
decrease HR
induction agents onset/duration
onset: seconds
duration: 3-5 mins
what is the last sense to be suppressed by induction agents?
hearing
propofol advantages
minimal long term side effects
antiemetic propertiespro
propofol disadvantages
profound cardiac depressant
- high SV decrease
vasodilation
- profound BP decrease
profound respiratory depressant
Etomidate advantages
cardiovascularly stable
- minimal BP impacts
- hypertension after intubation
minimal respiratory depression
Etomidate disadvantages
PONV
adrenal suppression
hypertension post-intubation
Etomidate cauton
increased overall 30 day mortality when used
short term gain: stable induction
long term loss: adrenal suppression
Ketamine advantages
analgesic
bronchodilation
minimal respiratory depression
increase HR / BP
Ketamine disadvantages
increase airway secretions
increase PONV
hallucinations
low dose ketamine
25-50mg perioperatively reduces post-op pain, decrease opioid reqs
minimizes negative side effects
short sedation (MAC) with ketamine
mix 50mg ketamine into 20mL syringe of propofol
more analgesia
less respiratory depression
succinylcholine onset/druation
onset: 30-60 seconds
duration: 3-5 mins
succinylcholine indications
RSI for full stomach pts
succinylcholine contraindications
long operations
only used for intubation paralysis
MH
succinylcholine intubation dosing
0.3-0.5 mg/kg is adequate for intubation
drug card says: 1 mg/kg
non depolarizing muscle relaxants
roc
vec
cisatracurium
higher dose NDMR
speeds up onset
prolongs duration
avoid high dose for short cases
lower dose NDMR
slows onset
shortens duration
ideal for short cases
nondepolarizers “priming dose”
Roc - 0.5 mL
given prior to propofol
allows Roc to have faster onset when dosed for intubation
nondepolarizers “defasiculating dose”
0.5 mL Roc prior to succinylcholine
decreases Sux fasiculations
decreases post-op myalgia
metorpolol
beta 1 antagonist
decreases HR
esmolol
beta 1 antagonist
decreases HR
faster onset/shorter duration than metoprolol
labetalol
beta 1 antagonist
alpha 1 antagonist
decreases HR and BP
hydralazine
vasodilator (not beta blocker)
decreases BP
hydralazine indication
treat hypertension in pt with low or normal HR
hydralazine onset/duration
onset: 10 mins
duration: 2-4 hrs
lasix (furosemide) indications
give to fluid overloaded pts
lasix mechanism
blocks Na+ and H2O reabsorption in the loop of henle
diuresis
lasix contraindications
sulfa allergy
mannitol indications
renal protection
decreasing ICP (brain surgery)
mannitol mechanism
increasing osmolarity of blood
draws H2O out of blood
cells shrink
blood volume increases
mannitol effects
increase blood volume
increased renal perfusion
diuresis
mannitol contraindications
do not give if fluid overloaded
narcaon
reversal agent for narcotic overdose
flumazenil
reversal for versed overdose
LTA kit
numbs trachea prior to intubation
ETT less stimulating
- less coughing/bronchospasms
LTA kit indication
prevent coughing in shorter surgeries
non-paralyzed pts
LTA kit duration
20-30 mins
(1 hr maybe due to anesthetic pooling around inflated cuff)
