OR Concepts Flashcards
baroreceptors
pressure receptors in aortic arch and carotid sinuses
baroreceptor reflex
if it senses low BP then increases cardiac output (and opposite)
reflex bradycardia
when vasoconstriction causes the heart rate to decrease (phenylephrine)
relex tachycardia
vasodilation causes heart rate to increase (propofol)
carotid sinus
contains baroreceptors
carotid body
primarily sense hypoxia
Cerebral vascular accident
stroke
brain cell death due to loss of blood flow
What are the possible causes of stroke?
1- blood clot
2- intracranial hemorrhage
3- prolonged hypotension
4- hypertension
Deep venous thrombosis (DVT)
blood clot in a vein
What patients are at risk for developing DVT?
bedridden patients
heart arrhythmias that decrease blood flow through the heart
pulmonary embolism
DVT moves into the lungs
How do you decrease the risk of developing a DVT during surgery?
compression stockings
edema
excess fluid in the interstitial space
pulmonary edema
excess fluid in the alveolar spaces (usually caused by heart failure)
preload
volume that is returned to the right ventricle
afterload
resistance the left ventricle has to pump against
Will a patient with hypovolemia have a high or low preload?
low
will a patient in REVERSE trendeleburg have a high or low preload?
low
How do you monitor preload?
central venous pressure
what is the blood pressure in the superior vena cava normally?
5-12mmHg
If a patient is hypertensive then will the afterload be high or low?
high
If someone was bleeding to death and had low blood pressure would the afterload be high or low?
high
transmural pressure
the difference in pressure between two sides of a wall or equivalent separator
negative pressure pulmonary edema
trying to inhale while airway is obstructed
- bite on ETT
- laryngospasm
systemic vascular resistance (SVR)
resistance that the left ventricle must pump against
pulmonary vascular resistance (PVR)
resistance that the right ventricle must pump against
Is SVR or PVR normally lower?
PVR
cautery/bovie
cut and burn at the same time
grounding pad
used in cautery in order to make a full circuit
list the electrical loop for cautery
machine bovie patient grounding pad machine
should the grounding pad be placed on muscular or non muscular area?
muscular area so that it is well perfused to dissipate heat
difference between unipolar cautery and bipolar cautery
unipolar must have a grounding pad and more current flows through the body
advantages of bipolar cautery
less current flow through body
control cautery in delicate areas
disadvantage of bipolar cautery
cauterizes small areas not good for controlling large amounts of bleeding
why is it not likely to be electrocuted by cautery?
ultra high current frequencies (>200,000 Hz)
Can a patient get burned if they have a piercing?
yes the current could pass through metal and cause burn
what could you do if the patient could not take the piercing out?
place the grounding pad away from the metal
pneumoperitoneum
abnormal presence of air or other gas in the peritoneal cavity
implications of laparoscopic surgery (8 things)
1-intubation required 2- atelectasis more likely 3- hypercarbia 4-vagal response common 5- decrease CO 6- BP up or down 7-pain in the shoulder (phrenic nerve) 8- possible pneumothorax
When to use a 8.0 ETT?
laparoscopic surgery in the Trendelenburg position
it decreases the resistance of ventilation, lowers PIP
CO2 gas embolism
infusion of CO2 into a vein or artery and results in blockage
what is CO2 injected into the abdominal cavity with?
veres needle
what causes a CO2 gas embolism?
misplacement of veres needle
subcutaneous emphysema (SubQ)
trapped air under the skin
occurs as CO2 diffuses into the subQ space
What would happen if you increase the pressure in the abdomen with CO2 above 20mmHg?
too high and increase the likelihood of tissue dissection and subQ
What is the safe range of pneumoperitoneum pressure?
0-20
12-14 recommended
What is the clinical significance of subQ?
hypercarbia
acidosis
Would you extubate a patient that had SubQ?
no
What are the four purposes of an OG/NG tube
1- decompress stomach
2-can vent gases (bowel obstruction)
3- tube feedings
4-empty stomach of poison or drug OD
should you use a OG tube during laparoscopic surgeries? Why or why not?
yes, decreases the chance of injury upon trocar insertion and improves surgical view
ileus
gastroparesis as a side effect of surgery
T/F NG tubes are indicated for most open abdominal surgeries
true, patient is at risk of post op ileus
Do OG tubes usually stay in post op? What about NG tubes?
OG tubes are temporary and usually come out
NG tubes usually stay in post op
What is a contraindication for NG tube?
blood thinners
facial fracture
What is a dangerous thing that can happen from incorrect placement of an NG tube
NG tube in brain if you don’t angle it correctly
Do you place OG/NG tubes in patients with prior gastric surgery?
no
if you must radiology must aid
T/F OG/NG tubes are safe to place in patients with liver failure.
false, they could have esophageal varices and could rupture
cirrhosis
liver failure
anaphylaxis
excess histamine release
what are the two main problems with anaphylaxis?
1- vasodilation (leak into interstitial space and cause localized edema (hives))
2-bronchoconstriction
anaphylaxis treatments
1- subcutaneous epinephrine
2-bronchodilator
3-histamine blocker
4- steroid
what is the epi dose for adults and peds for anaphylaxis?
adult 100-500mcg
peds 10mcg/kg
benadryl
histamine blocker
25-50mg
compartment syndrome
decrease in the blood flow to a body compartment due to increased pressure inside the compartment
what is the treatment for compartment syndrome?
surgical fasciotomy
what are possible causes of compartment syndrome?
fracture
infiltrated iv
tight cast
vagal response
bradycardia
hypotension
when can you commonly see the vagal response?
laparoscopic surgery
eye surgery
abdominal/uterine surgery
stress dose of steroids
steroids “enhance” the effectiveness of catecholamines
catecholamines
hormones released by adrenal glands
-dopamine, NE and Epi
what does chronic steroid use do to the catecholamines?
decreases their effectiveness if steroids are not taken that day, may decrease the effectiveness of vasopressors
What steroids are in our pyxis that can be used for a stress dose?
solu-medrol (most common)
solu-cortef
abdominal splinting
hypoventilation cause from the pain of breathing
how do you counteract abdominal splinting?
narcotic
nerve blocks
local anesthetic
