Wk 5

Question 1

Calculation of SERUM anion gap

Answer 1

Na- (CL+HCO3)

Question 2

Elevated anion gap meaning

Answer 2

=metabolic acidosis
Implies it is the primary disorder and is not compensatory

Normal is 8-12

Question 3

Adjusted anion gap (albumin)

Answer 3

Calculated Gap+ 2.5(4-albumin)
If has hypoalbuminemia

Question 4

Base excess

Answer 4

Normal between -2 and +2

B.E. <-2 is metabolic acidosis (may be compensatory) =also called base deficit

B.E. >2 metabolic acidosis (may be compensatory)

Question 5

For metabolic disorders, what is a quick way to know if respiratory compensation is appropriate?

Answer 5

If PaCO2 is approximately similar to the second two digits after pH

7.27
PaCO2: 25
HCO3: 11

Question 6

Delta ratio

Answer 6

(Change in anion gap/change in bicarbonate)
ONLY in metabolic disorders

AGmeasured-AGnormal
HCO3normal-HCO3measured

Helps identify underlying cause of acidosis

Question 7

Delta gap

Answer 7

Alternative to delta ratio
Measured SAG- Normal SAG (12)

Less than -6= mixed high and normal anion gap acidosis

-6 to 6 = only high anion gap acidosis

Greater than 6 = mixed high anion gap acidosis and metabolic alkalosis

Question 8

Delta Delta

Answer 8

Is bicarbonate being conserved or excreted?
=Delta gap+measured bicarbonate

If <22 then patient is losing bicarbonate

If > 26 patient is retaining bicarbonate

Question 9

ABG on steroids (GAPGAP steps)

Answer 9

1. Delta gap= Measured SAG-12
2. Delta Delta= Delta gap + serum bicarb

<22= losing bicarb, if acidosis was not previously identified there is an additional concurrent non gap acidosis

> 26= retaining bicarb, and there is additional metabolic alkalosis

Question 10

Paramagnetic cell

Answer 10

Based on oxygen molecules unique attraction in magnetic fields (due to polarity)
-highly accurate
-compact
-durable

Displaces nitrogen dumbbell in magnetic field which is connected to a mirror- change in angle (amount of light beamed to photocell) indicates concentration of 02, greater the displacement the greater the concentration

Question 11

Galvanic Cell

Answer 11

In-line with inspiratory limb
More oxygen over cathode means greater flow of current through galvanic cell-
Based on flow of electrons liberated by an oxidative reaction

Question 12

Expired vs inspired oxygen

Answer 12

Expired is usually 3-5 % lower
So we inhale 21% from the atmosphere but exhale around 18%

Question 13

What types of gases does IR absorption analysis not detect?

Answer 13

Oxygen and nitrogen

Question 14

Simplified co2 absorpant equation

Answer 14

CO2 absorption ➡️ carbonates (CaCO3, K2CO3) + heat + water

Question 15

Indicator for CO2 absorbent ( name and pH)

Answer 15

Ethyl violet turns purple when pH < 10.3

Question 16

Which law governs pulse oximetry

Answer 16

Beer- lambert
-luminosity is based on distance traveled and characteristics of the medium it travels through

Detecting the ratio of light absorbed at 660 and 940nm

Question 17

Pa02 based on SpO2

Answer 17

SpO2 70. 80. 90. 93. 95. 96. 97.

PaO2. 40. 50. 60. 70. 80. 90. 100

Question 18

P50

Answer 18

Pa02 at which hemoglobin is 50% saturated (normally 26.7)

Question 19

Oxyhemoglobin right shift

Answer 19

Decreased hemoglobins affinity for oxygen

Low pH (Bohr effect)
Increased paCO2
Increased temp
Increased 2,3 DPG -glycolysis byproduct

Question 20

Left shift oxyhemoglobin

Answer 20

Increases hemoglobin affinity for oxygen

Increased pH
Low paCO2
Low temp
Low 2,3 DPG

P50 will go down

Question 21

Methemoglobin

Answer 21

Iron is in ferric state (3+) instead of 2+, typically less than <1% of normal hemoglobin, can be genetic but think drug exposure particularly nitrates (nitroprusside)

Methemoglobin impairs oxygen binding

It absorbs light equally at 660 and 940= inaccurate readings—- will read between btwn 80-85% no matter what

Question 22

Dyes and their impact on SpO2

Answer 22

Cause erroneously low SpO2
Methylene blue
Indigo carmine
Indocyanin green

Question 23

Henderson hasselbalch equation

Answer 23

Ph= pKa + log (products/reactants)

Question 24

Bohr effect

Answer 24

H+ as a product of carbonic acid dissociation (picked up co2 from tissue) displaces oxygen bound to hemoglobin and releases it to the tissue
Bicarbonate is also released into the tissue

Question 25

Oxidation and reduction reactions

Answer 25

Oil rig

Question 26

Na k pump

Answer 26

3NA OUT 2K IN ATPase- consumes one atp

Question 27

Mass spectrometry

Answer 27

Older technology Ionizes gas molecules and passes them through a magnetic field Molecules with the lowest mass to charge ratio are easily deflected by the magnetic field and collected by ion collector Identification is based on amount of deflection

Question 28

Piezoelectric gas analysis

Answer 28

the degree of frequency change in a crystal when a gas is dissolved in the surrounding liquid is proportional to the concentration- this gives us the partial pressure of the gas based on Henry’s law

Question 29

Infrared absorption analysis

Answer 29

A sample of gas is subjected to a range of infrared frequencies and the lost frequencies are measured. They can identify the gas based on what it absorbs

Question 30

Raman scattering analysis

Answer 30

The interaction of EMR with matter Laser beam the gas to create a vibration frequency of the excited particles, the scatter spectrum of a gas is unique

Question 31

Raman scattering analysis

Answer 31

The interaction of EMR with matter Laser beam the gas to create a vibration frequency of the excited particles, the scatter spectrum of a gas is unique

Question 32

What can IR absorption analysis NOT do?

Answer 32

Measure Oxygen and nitrogen

Question 33

Litholyme VS sodalime

Answer 33

Litholyme does not react with anesthetic gases so there’s no CO or compound A production!! Also does not regenerate indicator dye

Question 34

Beer-Lambert Law

Answer 34

The absorbance of light by a sample is directly proportional to the concentration

Question 35

Explain Pulse Oximetry

Answer 35

Reduced Hb absorbs light at 660 and Oxy-Hb absorbs at 940nm, pulse ox is the ratio Impacted by: Low hematocrit, pigmentation, light sources, motion, cautery, tourniquets, hypotension

Question 36

MRI Basics

Answer 36

Manipulation of hydrogen atoms in the body After placement in MRI H atoms are in alignment Radio frequency pulses deflect orientation of atoms As atoms relax back to resting state the energy emitted is used to produce the image

Question 37

Magnetic field in MRI

Answer 37

Strength in Tesla is 0.15-3.0 1T=10,000 Gauss Quality of the image depends on the strength of the field

Question 38

Ferromagnetic

Answer 38

Iron! Co, Ni, Gd Spontaneous groups of atoms are aligned in the material to create a very strong magnetic interaction -leads to complete alignment with magnetic fields=strong (quantum mechanics lol)

Question 39

Describe MRI VS x-ray in terms of ionizing radiation

Answer 39

X-ray is high on the EMR spectrum and is ionizing radiation (ie it has enough energy to remove an electron) MRI is non-ionizing