Basic (from TL) Flashcards
Spinal cord anatomy adults and kids
In newborns, the dural sac typically ends at S3 and the conus medullaris at L3. In adults, the dural sac typically ends at S1-S2 and the conus medullaris at L1-L2.
Enzyme/receptor polymorphisms: CYP2C19 CYP2C9 2D6 MC1R OPRM CYP3A4 - and what inhibits it
2C19: PPIs, antidepressants
2C9: phenytoin, warfarin, ibuprofen
2D6: codeine, beta-blockers, tramadol, diltiazem, some anti-arrhythmics
MC1R: red hair, increased response to morphine
OPRM: less response to morphine
CYP3A4: metabolism of most anesthetics, lidocaine, dexamethasone; inhibited by midaz
How is ETCO2 measured? What is it proportional to?
End-tidal CO2 (ETCO2) is measured by infrared spectrophotometry where a wavelength of infrared light is passed through a gas sample and the amount of energy detected is INVERSELY proportional to the gas partial pressure.
driving force to raise the bellows?
exhaled gases from the patient
what is the time constant in anesthesia circuit?
The time constant is the volume or capacity of the circuit (Vc) divided by the fresh gas flow (FGF).
how many time constants to reach equilibrium? what is time constant for iso? sevo? des? n2o?
Time constants also apply to the tissue-blood partition coefficients, meaning the amount of inhaled anesthetic that can be dissolved in the tissues divided by tissue blood flow. The time constant for isoflurane is about 3-4 minutes. Complete equilibrium of isoflurane with any tissue, including the brain, would take 3 time constants (10-15 minutes). For nitrous oxide, desflurane, and sevoflurane, the time constant is about 2 minutes. Brain equilibrium then would take about 6 minutes.
normal serum osmolality
The normal reference range of serum osmolality is 275 to 295 mosm/kg (mmol/kg).
formula plasma osmolality
Plasma osmolality (Posm) = 2 x [Na] + [glucose]/18 + blood urea nitrogen/2.8
composition of commonly used IVF
Composition of several commonly used intravenous fluids:
——————–NS…….LR…….Alb…….Plasmalyte
Na (mEq/L)………154……130……130-160……140
Cl (mEq/L)……….154……109……130-160……98
K (mEq/L)………….0…………4………0………………5
Osmolarity (mOsm/L) 308-310 275 310 294
Lactate (mEq/L) 0…….28………0……………0
alveolar gas equation
PAO2 = (Patm - PH2O) FiO2 - PaCO2/RQ
Patm is the atmospheric pressure (at sea level 760 mm Hg), PH2O is partial pressure of water (approximately 45 mm Hg). FiO2 is the fraction of inspired oxygen. PaCO2 is partial pressure of carbon dioxide in alveoli (in normal physiological conditions around 40 to 45 mmHg). RQ is the respiratory quotient. The value of the RQ can vary depending upon the type of diet and metabolic state. RQ is different for carbohydrates, fats, and proteins (average value is around 0.82 for the human diet).
Decreased MA value on TEG
Maximum amplitude (MA), measures the strength of the fully formed clot. It is the maximal width of the TEG. This reflects clot strength as determined by platelet number and function (primarily) as well as fibrin cross-linking. Normal is 50-60 mm.
Decreased MA values primarily suggest quantitative and/or qualitative platelet dysfunction or, to a lesser extent, inadequate fibrinogen. The best treatment is administration of platelets.
TEG prolonged K value
Coagulation time (K) measures speed of clot formation and strengthening. It is equal to the time from amplitude of 2 mm to 20 mm and relies on fibrinogen. Note that some TEG images show varying lengths for K, but it is always measured to 20 mm amplitude.
Prolonged K values suggest deficiencies of thrombin formation or generation of fibrin from fibrinogen/inadequate fibrinogen. Treatment Cryo
A decrease of the alpha angle has similar implication to a prolongation of K. Measures of clot lysis consistent w/ dramatically narrowing amplitudes and short, tapering rates of fibrinolysis (teardrop configuration) suggest abnormal fibrinolysis. Treatment is with antifibrinolytics.
decrease alpha angle TEG
Alpha-angle is the speed of clot formation, and is represented by the angle between baseline and a line tangential to the TEG at 2 mm amplitude. Like the K value, this relies on fibrinogen. Normal alpha angle is 45-55 degrees.
Prolonged K values suggest deficiencies of thrombin formation or generation of fibrin from fibrinogen/inadequate fibrinogen. A decrease of the alpha angle has similar implication to a prolongation of K. Measures of clot lysis consistent w/ dramatically narrowing amplitudes and short, tapering rates of fibrinolysis (teardrop configuration) suggest abnormal fibrinolysis. Treatment is with antifibrinolytics.
TEG R values
Reaction time (R) is from time zero to initial clot formation, defined as a width (amplitude) of 2 mm. Normal range is 1-3 minutes.
Short R values result from aggressive factor replacement or hypercoagulable state.
Prolonged R values result from coagulation factor abnormalities, factor deficiencies or heparin administration. Treatment consists of giving fresh frozen plasma (FFP).
Pressure of N2O tanks
A full tank of N2O contains 1590 L at a pressure of ~745 psig. Pressure within a tank of N2O will remain at ~745 psig until all liquefied gas is used up.
What is in cryo?
Cryoprecipitate contains factor VIII:C, factor VIII:vWF, fibrinogen, factor XIII, and fibronectin.
hemophilia B
Hemophilia B is an X-linked recessive disorder that results in the deficiency of factor IX, thus factor VIII concentrate would not be an appropriate treatment. Recombinant factor IX is the treatment of choice for hemophilia B.
hemophilia A
Factor VIII concentrate is the mainstay of therapy for hemophilia A and 30% of levels are needed for hemostasis.
hemophilia C
Hemophilia C is a disease that results from deficiency of factor XI, thus factor VIII would not be an appropriate treatment. Prediction on bleeding risk is not possible from factor XI levels alone and replacement with factor XI concentrates can be dangerous due to the increased risk of thrombotic events in certain patient populations.
Line Isolation System
Line isolation systems (isolation transformer + line isolation monitor) protect persons from electrocution by turning a normal “grounded system” (that exists outside the operating room) which only needs a single fault to cause electrocution into a “protected” system in which two faults are needed to deliver a shock. The line isolation monitor determines the degree of isolation between the two power wires and the ground and predicts how much current could flow if a second short-circuit were to develop. An alarm goes off if an unacceptable amount of current to the ground is possible (e.g. the “isolated” system is no longer isolated, but rather is grounded, thus only one additional fault could result in a shock).
First step: unplug the last thing that was plugged in (unless it’s vital obviously)
Boyle’s law
water Boyle’s at a constant temperature and Prince Charles is under constant pressure to be king
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Charles’ law
water Boyle’s at a constant temperature and Prince Charles is under constant pressure to be king
Note that Charles’ law is similar to Gay-Lussac’s law: Charles’ law states that the volume of a given mass of gas is directly proportional to its temperature when at a constant pressure: V1/T1 = V2/T2 or V ∝ T.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Gay-Lussac’s law
Note that Charles’ law is similar to Gay-Lussac’s law: Charles’ law states that the volume of a given mass of gas is directly proportional to its temperature when at a constant pressure: V1/T1 = V2/T2 or V ∝ T.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn
Henry’s law
Henry’s law indicates that at a constant temperature, the concentration of a gas dissolved in a solution is directly proportional to the partial pressure of that gas: C = kP (where k is a solubility constant) or C ∝ P. As the volume percentage of a volatile anesthetic is increased, the alveolar partial pressure increases. An increased alveolar partial pressure, therefore, leads to an increased concentration of the volatile anesthetic in the blood which increases the speed of induction and depth of anesthesia.
Boyle’s law: P1V1 = P2V2 or P ∝ 1/V (at constant temperature and mass of gas)
Charles’ law: V1/T1 = V2/T2 or V ∝ T (at constant pressure and mass of gas)
Gay-Lussac’s law: P1/T1 = P2/T2 or P ∝ T (at constant volume and mass of gas)
Henry’s law: C = kP or C ∝ P (at constant temperature)
Dalton’s law: PTotal = P1 + P2 + P3 + …+ Pn