IA Up/Dist Flashcards
Uptake =
Solubility (upside down y) x Q (CO) X (A-v)
A-v= diff in partial p of alveolar and venous blood
If solubility, CO, or partial pressure difference is 0
Uptake will be 0
Equilibrium refers to
State of equal partial pressures (not concentration)
Blood/gas coefficients:
Des
N2O
- 42
0. 47
Blood/gas coefficients:
Sevo
ISO
- 69
1. 4
Blood/gas coefficients:
Enflurane
Halothane
Diethyl ether
1.8
2.4
12
Order of low to high solubility
Do not say i eat heavy dopamine
How hct alters blood gas coefficients
Lower hct= lower solubility coefficient. If anemic, alveolar buildup of gas is faster b/c fewer binding sites
FA reaching FI determines what
When equal= faster uptake into brain and induction
FA represents what
Partial p of anesthetic going into brain. No gradient between alveoli and brain bc large perfusion
How we control FI
Vaporizer setting, inspired %
Alveolar partial pressure used to estimate
Anesthetic depth, recovery, and MAC
PA is determined by what
PI (inhaled partial p), alveolar ventilation, breathing circuit, and FRC
Alveolar ventilation =
In one minute. Normal minute vent (VE) 6l - 2L (anatomical dead space)
Change in alveolar concentration faster when anesthetist does what
Hyperventilates (faster rate lower volume)
FA/FI curves First knee- Second knee- Continues \_\_\_ \_\_ after \_\_ \_\_ for agents
Initial rapid rise
Less rapid rise
More slowly
Same shape for all agents
___ soluble agents have fastedt rate of alveolar gas/inspired conc over time
Least
First knee __ __ group
Second knee __ group
Vessel rich
Muscle
If uptake removes 1/2 anesthetic in lung, FA would be __ of FI
1/2
If uptake removes 2/3 of anesthetic in lung, FA would be __ of FI
1/3
Overpressure
Use of high delivered concentrations to compensate for slowness
Impact of solubility on emergence
Lower the b/g solubility coefficient, shorter time emergence will take
Emergence ___ induction with respect to solubility
Parallels. High solubility= takes longer to induce and emerge (more left in reservoir)
How cardiac output affects induction
Dec CO- inc speed. Inc CO- dec induction speed. If CO 0= uptake = 0
How CO effects FA/FI curve
Increase CO: ratio decreases, takes longer to rise
Decrease CO: inc ratio, straight up faster
Effect of CO change greatest on FA/FI curve when what
Agent is more soluble (less effect on n20)
Tissue uptake of anesthetic =
Same factors as lung. = tissue/blood coefficient x flow x (a-t)
Coefficients for brain vs fat
Brain: 1-2
Fat: n20 (2.3) rest are higher 27-67
Vessel rich group: components, equilibrium when
Brain, heart, liver, kidney. 5-15 min equilibrium w FI
Muscle group: parts and what
Muscle, skin, highest % of body mass
Vessel poor group
Bone, ligaments, tendons, 0% CO
% Body mass VRG MG FG VPG
% body mass VRG- 9% MG- 50% FG- 19% VPG- 22%
% of cardiac output VRG MG FG VPG
% CO VRG- 75% MG- 18% FG- 7% VPG- 0%
What happens in FA/FI curve:
Initial steep rise
First knee
Initial: a-v diff= 0, no agent in alveoli, no uptake
1st: uptake by VRG balances input
What happens in FA/FI curves
2nd rise
2nd knee
Rise: dec uptake by VRG, muscle group uptake
Knee: 4-8 min, uptake by MRG slows
PA (alveoli P) of volatile determined by what
PI, alveolar vent, breathing circuit, and FRC
Impact of ventilation on induction and emergence
Increased: both more rapid
Decreased: slower (both)
Effect of increased ventilation on FA/FI curve
Increases it for a highly soluble agent. Wont inc for N20 (low solubility)
How FRC/alveolar ventilation affects induction
Greater alveolar vent/FRC= faster induction. Dec FRC and inc alveolar vent= faster induction
What happens when inc CO and ventilation
FA/FI increases slightly.
V/Q abn have what effect on FA/FI
Rise in FA until ventil high, rise in arterial blood depressed (undervent lung not offset by inc vent lung). Dilutional effect= slower induction with LESS soluble agents
Concentration effect is what
Large vol of gas abs: residual gas in lung is conc as vol decreases, ins vent increases which adds anesthetic and negative p created by uptake draws more gas into lung
Washout
Which agents washout 1st
What happens as anes duration lengthens
Least soluble
Washout prolonged- more anesthetic in reservoirs
Impact of solubility on emergence
Higher b/g solubility= longer emergence will take
Slower inc in FA toward FA with ___ solubility
Washout more rapid with __ solubility
High
Low
