Chapters 1-5 Flashcards
What is the MOA of halothane effect on CV system?
Halothane interferes with Na-Ca exchange resulting in direct myocardial depression and decrease in MAP through a decrease in CO but it DOES NOT decrease SVR. It also blunts baroreceptor reflex.
How does isoflurane effect CV system?
Coronary artery vasodilation, decrease SVR, increase heart rate (baroreceptor activation from the decrease SVR). CO is maintained by increase in HR
What can cause compound A release?
Halothane or sevo
What are risk factors for compound A?
long duration, low fresh gas flow, higher absorbant temperatures and dessication
How does desflurane effect CV system?
No coronary artery vasodilation (this is ONLY iso), decreased MAP, decreased SVR, increase HR. Near normal CO from increase rise in HR.
how long do you have to wait to use nitrous oxide on a patient that had eye surgery and use air bubble?
5 days
how long do you have to wait to use nitrous oxide on a patient that had eye surgery and used sulfur hexafluroide bubble?
10 days
What is the pathway for SSEP monitoring?
electrical stimulation to posterior tib, median nerve or ulnar nerve.
Electrical stimulation –> posterior column –> medial lemniscus pathway –> scalp
How is desflurane treated to improve specificity of its vaporizer output?
Desflurane vapor pressure is 660 mmHg which is close to sea level (760 mm Hg) so small changes in pressure or temperature can have a huge impact on amount the vaporizer releases.
Desflurane is heated to 39 degrees celcius and partial pressure of des is 1500 mmHg at that point which allows for accurate administration of des
If you are at higher altitude with desflurane what do you need to do to give appropriate depth of anesthesia?
because You are higher your patient must be higher too! because there is a decrease in the partial pressure of the anesthetic gas delivered.
What is the key factor for delivering inhalational anesthesia? Percentage or partial pressure
partial pressure!
What what percent does MAC change per decade?
6%
What is 1 MAC of nitrous oxide?
105%
By what percent are all of the gases metabolized? Des/Sevo/Iso/Halothane
Des-
What can metabolism of enflurane cause?
high concentration of fluoride ions leading to high output renal failure.
Full tank of O2 pressure and volume in L?
2000 psi and 625 L
Full tank of nitrous oxide pressure and volume in L?
750 psi and 1600 L
Once you see the pressure in the nitrous oxide tank falling, what is the approximate volume in liters remaining?
200-400 or 25%
What enzymes does nitrous oxide effect and what are the effects?e
it irreversibily oxizes the cobalt atom in vitamin B12.
Enzymes/Use
Thymidylate synthetase/ DNA synthesis
methionine synthetase/ myelin
What type of metabolism does halothane undergo?
oxidative- trifluoacetic acid
reductive- fluoride ions
Which volitile prolongs NMB the longest?
desflurane
What is ischemic preconditioning? When it is effective for volitiles?
Ischemic preconditioning describes short episodes of ischemia prior to a larger insult will confer protection to the tissues and delay necrosis.
Effective 1-2 hours and then again 24-3days
What is the MOA of ischemic preconditioning of volatile anesthetics?
ATP-sensitive potassium channels are activated
What is critical temperature?
The temperature of a substance at an dabove which vapor of the substance cannot be liquefied no matter how much pressure is applied.
In the setting of a shunt (endobronchial intubation) how will it affect induction with inhaled anesthetics?
Slows induction with insoluble agent > soluble agent because the soluble agent will have uptake that will partially compensate for the dilutional effect
What effects do you see with a left to right shunt on speed of inhalation induction?
minimal
What effect do you see if you change CO on speed of inhalation induction?
Decrease CO = increase speed of induction
Increase CO = decrease speed of induction
***greater effect on soluble agents
What is the MOA of change in HR and BP seen with rapid changes of desflurane?
release of catecholamine
What is the second gas effect?
uptake of one gas enhances rate of rise of alveolar partial pressure of another gas that is administered at the same time.
What is the concentrating effect?
absorption of 1 gas into the blood results in concentrating a second gas into the alveoli because the loss of the first gas causes an overall decrease in alveolar volume
What is the concentration effect?
inspired partial pressure of anesthetic gas is so high that is causes the alveolar concentration of the gas to rise quickly
What are the vapor pressures of the commonly used volatile anesthestics?
DHIESM
D- 670 H- 244 I- 240 E- 172 S- 160 M- 23
What is the affinity differences between O2 and CO for hemoglobin?
230 x stronger CO than O2 for hemoglobin
What are the important pulse oximeter wave lengths and what do they absorb?
940 nm- deoxyHgb
660 nm-COHgb and oxyHgb
What does isoflurane do that no other volatiles do in terms of neuro positive effects?
increase CSF absorption
Which volatile is the worst for MH?
Halothane
What is the usual volume of FRC for adults?
35 mL/kg
What is hysteresis?
compliance of lung is greater during deflation than during inflation. More than expected pressure to inflate a lung and less than expected recoil pressure. Due to surfactant.
What is LaPlaces Law and when do we consider it clinically?
Pressure= 2(wall tension)/ radius
Alveoli and cardiac oxygen demands
What is Poiseuille’s Law and when do we consider it clinically?
describes the flow rate of a liquid in a straight circular tube. Resistance = 8viscositylength/ pi*radius^4
consider it for flow rates for IV, airway pressures
What is the alveolar gas equation?
PaO2 = FiO2 x [Barometric pressure ((760)) - water pressure ((47))] -(PaCO2/R)
What is the Bohr Effect?
change in hemoglobins affinity for oxygent with changes in PCo2 and pH. Affinity increases with decrease in PCo2 and increase in pH.
When you shift the Oxygentation curve to the right what happens to the P50?
p50 increases
What happens to pH in chronic respiratory acidosis?
increase 0.03 U
In the medulla the dorsal respiratory group is responsible for what?
pacemaker of the respiratory system. Effects the CO2
In the medulla, the ventral respiratory group is responsible for what?
coordinates expiration
What can you use to calculate dead space to tidal volume ratio and what is the equation
Bohr equation
Vd/Vt= (PaCO2 - PeCO2)/ PaCO2
When can you have hypoxia without having a change in the A-a gradient?
hypoventalation from either obesity hypoventilation syndome OR opiate induction hypoventalation OR elevated altitude