alpha & beta receptors Flashcards
where are alpha 1 receptors? presynaptic or postsynpatic
postsynaptic
where are alpha 1 receptors located throughout the body
smooth muscle throughout the body
what is the most important cardiovascular effect of alpha 1 stimulation
vasoconstriction
increase PVR, after load and BP
what is the negative effect of alpha 1 stimulation
bronchoconstriction
are alpha 2 receptors presynaptic postsynaptic
presynaptic
what does stimulation of alpha 2 receptors in the CNS cause
sedation and reduces sympathetic outflow, leading to peripheral vasodilation and lower bp
are beta 1 presynaptic or post synpatic
postsynaptic
what is the result of simulating beta 1 receptros
positive chronotropic
positive dromotropic
positive inotropic
are beta 2 pre or post
postsynaptic
beta 2 stimulation creates what effect?
relaxes smooth muscle, bronchodilator, vasodilation and relaxation of the uterus.
what does beta 2 do to electrolytes
activates Na/K pump, which drives potassium intracellularly which can induce hypokalemia and dysrhythmias
what is the effect of volatile anesthetics on BP
dose dependent decreases in Systemic BP
what does nitrous oxide (not volatile) do to BP
direct mild myocardial depression BUT also causes sympathetic activation
what do volatile anesthetics do at the cellular levels to produce their cardiac effects
influencing L-Type Calcium channels
how do halothane and enflurane predominantly effect blood pressure
myocardial contractile function
iso sevo and des predominantly effect blood pressure
decreases SVR
what is the order that volatile anesthetics lower the arrhythmogenic threshold for EPI
halothane >enflurance>sevo>iso>Des
how does thiopental affect hemodynamics
decreases contractility- from reduced availability of calcium to the myofibrils and decreased venous return
why does thiopental increase HR
baroreceptor mediated sympathetic reflex stimulation
why is thiopental used during CPB
cerebral protection
which anthesthic drug changes hemodynamic variables the least
etomidate
what is the dose for adrenal corticosuppression
no one knows
what is the most common and successful approaches to blocking ketamine induced hypertension and tachycardia
prior administration of benzodiazepines
what two situations make ketamine the safest and most efficacious drug
decreased blood volume or cardiac tamponade
ketamine increases?
HR, CI, SVR, PAP, and systemic artery pressure
with the exception of meperidine what do all opioids produce
bradycardia
the major advantage of fentanyl and its analogs for patients undergoing cardiac surgery
lack of cardiovascular depression(smooth CV induction)
what is the most common mediastinal diagnostic procedure
cervical mediastinoscopy
how is the mediastinoscope inserted
toward the carina via blunt dissection
what does the innominate artery supply
right arm and right common carotid artery
patients who do not have good cerebral collateral circulation are at risk for what
cerebrovascular ischemia
preoperative evaluation for mediastinoscopy includes
assessing the patients ability to lie supine or the presence of a cough or dyspnea
where do we place the cuff and aline and pulse of a patient getting amediastinoscopy
NIBP left
aline-right
pulse ox right
d/t innominate artery
what is the most severe complication of mediastinoscopy
hemorrhage- may require emergent thoracotomy be prepared
if an a line is not necessary in all vases what do we need on the right arm
pulse ox
what must you do if you suspect recurrent laryngeal nerve damage
vocal cords should be visualized whilthe patient is spontaneously breathing
what is an abolsute contraindication to mediastinoscopy
prior mediastinoscopy
what are the relative contraindications to mediastinoscopy
superior vena cava obstruction, tracheal deviation, thoracic aortic aneurysm, cerebrovascular disease
