OR Concepts Flashcards
pressure receptors that detect pressure of blood flowing through the arteries
baroreceptors
where are baroreceptors located?
- ) carotid sinuses
2. ) aortic arch
how does the brain try to correct for a low blood pressure?
the brain stimulated the ANS to increase the heart rate (increases cardiac output)
vasoconstriction causes the heart rate to decrease
reflex bradycardia
vasodilation causes the heart rate to increase
reflex tachycardia
contains baroreceptors that adjust heart rate to maintain normal cardiac output/blood pressure?
carotid sinus
cluster of cells that primarily sense hypoxia and stimulate faster respirations
carotid body
refers to sudden brain cell death caused by inadequate blood flow
cerebral vascular accident; stroke
possible causes of stroke (4)
- ) blood clot
- ) intracranial hemorrhage
- ) prolonged hypotension
- ) hypertension
refers to blood clot in a vein (usually in the legs)
deep vein thrombosis
Examples of pts at risk for developing blood clots:
- ) bedridden pts that cant ambulate
2. ) heart arrhythmias that decrease the blood flow through heart
when a DVT becomes dislodged from the legs it can move to the heart and lungs causing ____.
pulmonary embolism
How to prevent DVT? (3)
- walking/movement/ ambulation
- blood thinners ( medication)
- sequential compression stockings during surgery (squeeze the legs and promote blood flow)
excess fluid in the interstitial space
edema (“swelling”
excess fluid in the alveoli; caused by some degree of heart failure ( which causes some blood to back up into the lungs)
pulmonary edema
refers to “venous return” or VOLUME of blood that is returning to the right ventricle and available for the heart to pump on the next contraction
preload
refers to the RESISTANCE the left ventricle has to pump against
afterload
True/False: pt with a low blood volume (bleeding pt) will have a decreased venous return or low preload
true
how does a pt’s position in Trendelenburg affect preload?
it will INCREASE preload
how can you measure preload?
central venous pressure (CVP)
what is central venous pressure?
blood pressure within the superior vena cava (5-12 mm Hg)
If pt is supine…a low CVP indicates ___ ____
low preload
if pt is supine a high CVP indicates ____ ____
fluid overload (usually in heart failure and renal failure pts)
vasoconstriction = ___ afterload
high afterload
vasodilation = ___ afterload
low afterload
example of patient with high afterload yet low blood pressure
exsanguinating patients (bleeding to death)
refers to the difference in pressure between two sides of a wall or equivalent separator
transmural pressure
clinical example of transmural pressure is ___ ___
pulmonary edema
explain how pulmonary edema affects transmural pressure
pressure in the lungs on one side of the membrane becomes drastically reduced; means pressure on the other side of the membrane is relatively much higher which can lead to blood entering the lungs from the pulmonary capillaries
occurs when a patient tries to breathe while their airway is obstructed
negative pressure pulmonary edema
2 examples of negative pressure pulmonary edema
- the pt bites down on their ETT tube during emergence
2. the patient experiences a laryngospasm
Explain what happens when pts bite down on their ETT tube and experience larygospasm and how that contributes to pulmonary edema
intrathoracic pressure becomes more and more negative as the patient breathes (b/c air from the atmospher cannot enter the lungs); the negative pressure inside the lungs will “suck” blood into the alveoli from the pulmonary capillaries causing pulmonary edema
refers to resistance that the left ventricle must pump against and it is affected by peripheral arterial vascular tone
systemic vascular resistance
arterial vasoconstriction= ____ SVR
high SVR
arterial vasodilation = ___ SVR
low SVR
refers to the resistance that the right ventricle must pump against, and is affected by the vascular tone in the pulmonary arteries
peripheral vascular resistance (PVR)
pulmonary artery vasoconstriction = ___ PVR ; while pulmonary artery vasodilation= ___ PVR
high PVR; low PVR
True/False: PVR is usually much higher than SVR.
FALSE; lower than SVR
what must be placed in order for a bovie to work?
grounding pad
where is ground pad usually placed to dissipate heat?
thigh
advantages of bipolar cautery (2)
- less current flow through the body
2. the surgeon can control cautery in delicate areas
Why doesnt a patient get electrocute with a cautery?
because the cautery is set on a ultra high current frequency (> 200,000 Hz) which allows the current to pass through the body w/o electrocution
8 implications of pneumoperitoneum (CO2 insufflation)
- ) intubation is required
- ) atelectasis is more likely
- ) hypercarbia is more likely
- ) a vagal response is somewhat common
- ) cardiac output decreases
- ) blood pressure can go up or down
- ) pts can get referred pain in the shoulder
- ) partial pneumothorax (collapsed lung)
When would you use a larger diameter ETT tube?
obese pt in trendelenburg with abdomen insufflated with CO2
how does a larger diameter ETT help with an obese pt in trendelenburg with/ abdomen insufflated with CO2?
decreases the resistance of ventilation and lower the peak inspiratory pressure required to effectively move the patient’s diaphragm
can occur with accidental infusion of CO2 into an injured vein or artery and results in blockage of the right ventricle
CO2 gas embolism
refers to trapped air underneath the skin and can occur during laparoscopic sx as CO2 diffuses into the subcutaneous space
subcutaneous emphysema
factors that can cause subQ emphysema (6)
- multiple attempts of abdominal entry
- improper cannula placement
- increased intra-abdominal pressure
- procedures lasting >3.5 hours
- gas flow rate
- high total gas volume
“safe” range for pneumoperitoneum
0-20 mmHg; RECOMMENDED: 12-14 mm HG
When is extubation contraindicated during subQ emphysema? (3)
- ETCO2 is elevated
- airway swelling
- crepitus (crackling, crinkly, or grating feeling or sound under the skin)
purpose of OG/NG tubes (4)
- can decompress the stomach
- can vent gases if pt has a bowel obstruction
- can deliver tube feedings directly to the stomach
- can empty the stomach of poison or drug overdose
indications using a OG tube
intubated pts w/ full stomach or undergoing laparoscopic surgery
indications for NG tube
most open abdominal procedures, b/c abdominal sx increases the risk of a pt developing postoperative ileus
defined as gastroparesis and can lead to abdominal distention
ileus
When do NG usually stay in ?
postoperatively
when should you avoid using an OG/NG tube? (2)
- ) for pts who have had prior gastric surgery; if it needs to be done need to use radiology
- ) pts with liver failure (cirrhosis ) b/c they can develop esophageal varices which can rupture with an OG/NG tube
caused by excess histamine release
anaphylaxis
2 main problems associated with anaphylaxis
- vasodilation (hTN)
2. bronchoconstriction (wheezing)
tx for anaphylaxis (4)
- subcutaneous epinephrine
- bronchodilators (beta 2 agonists)
- histamine blockers
- steroid (100 mg hydrocortisone)
refers to decrease in blood flow to a bodily compartment due to an increase of pressure inside the compartment and which compressed blood vessels
compartment syndrome
tx for compartment syndrome
surgical fasciotomy
causes of compartment syndrome (3)
- fracture
- infiltrated IV
- tight cast
sudden onset of bradycardia and/or hypotension
vagal response
when are vagal response commonly seen?
- CO2 insufflation for laparoscopic sx
- eye surgery
- abdominal or uterine surgery
if vasopressor therapy is not as effect what should you consider?
stress dose of steroids
what steroids are used for “Stress dose”
solu-medrol or solu-cortef
hypoventilation that is caused by the pain of breathing
abdominal splinting
how to prevent splinting? (3)
- dosing pain med
- supplementing anesthetic w/ nerve blocks
- local anesthetic injection at the surgical site
