inhaled 2 part II Flashcards
___ % of patients should not move at 1.2 MAC
95
___ % of patients should not move at 1.3 MAC
99
MAC-awake
defined as the minimum alveolar concentration at which 50% of subjects will respond to the command “open your eyes”
loss of recall is at
1/3 MAC
MAC-BAR represents
the MAC necessary to block adrenergic response to skin incision
MAC-BAR is usually ___ than MAC
higher.. around 1.5
MAC intubation
similar to MAC-BAR in that its values exceed the anesthetic requirements for surgical skin incision
Different stimuli are evaluated with different ____
end-tidal concentrations
mac of des
6.6
mac of iso
1.2
mac of sevo
2.2
if you have 4L of flow and want 50% nitrous, you would have how much O2 and how much nitrous
2L of each
you want 1 MAC using nitrous and sevo. you’re running 4L of flow. and Nitrous Is at 70%. how much sevo?
3L of nitrous, and 1L of O2, and sevo to .66 (2.2 x 30%)
so this gives a total of 1MAC. 70% of it coming from nitrous and 30% coming from sevo.
uptake means
absorption from alveoli into the systemic circulation
what is used as an index of anesthetic depth, a reflection of the rate of induction and recovery from anesthesia
PA
PA is determined by
input minus uptake
uptake is determined by
solubility (blood:gas), CO, alveolar to venous partial pressure difference
transfer of inhaled anesthetic from arterial blood to brain is dependent on
brain-blood partition coefficient, cerebral blood flow, arterial venous partial pressure difference
concentration effect accelerates the rate of
induction
second gas effect
the ability of the large-volume uptake of one gas (first gas) to accelerate the rate of increased PA of a concurrently administered companion gas(second gas)
increased alveolar ventilation promotes input of inhaled anesthetics to offset ___
uptake by the blood (maintain high alveolar concentration)
if blood gas partition is 10 what does that mean?
the concentration of the inhaled anesthetic is 10 in the blood and 1 in the alveolar gas when the partial pressure of the anesthetic in these two phases is identical
high blood solubility means
a large amt of agent must be dissolved(undergo uptake) in the blood before equilibrium with the gas phase is reached.
high CO results in ___ uptake and ___ induction
fast , slow
low CO results in ___ uptake and ___ induction
slow, fast
a right to left intracardiac or intrapulmonary shunt ___ the rate of induction
slows (because the shunted blood dilutes the blood coming from ventilated alveoli)
complete equilbration of any tissue, including the brain, with the Pa requires at least __ time constraints
3
alveolar to venous partial pressure differences (PA-PV) reflects
tissue uptake of inhaled anesthetics
highly perfused organs account for less than __ % of body mass but receive __ % of cardiac output
10, 75
highly perfused tissues equilibrate __ with the PA
rapidly
after 3 time constraints, __% o the returning venous blood flow is at the same partial pressure as the PA
75
as alveolar pressure decreases, anesthetic is transferred from the ___ into the ___
tissues to alveoli (emergence)
hypoventilation or use of fresh gas flows low enough to permit rebreathing of anesthetic will have what effect on emergence
prolonged
which anesthetics have the fastest offset ?
nitrous des. because they are less soluble in the fat/blood
diffusion hypoxia
when N20 is abruptly discontinued, the N20 still in the body rapidly diffuses across capillary/alveoli membrane diluting the O2 concentration to a point where it can cause the PAO2 to drop and hypoxia develops
how do you offset diffusion hypoxia
100 O2 at the conclusion of nitrous oxide administration
other factors that influence emergence
duration, temp (if cold, longer wake up), physical condition, obesity.
concentration effect occurs only in ___
induction. not emergence!
context sensitive half time depends on what two things
length of administration (context),and solubility (blood& tissues)
increased CO –> increased uptake —> ___ FA, ___ induction
decreased, slower
Decreased CO —> decreased uptake —> __ FA, ___ induction
increased, faster
something that is associated with higher incidence of awareness means ___ MAC
increased. (takes more agent to get them under)
