Exam 1 Flashcards by Sarah King

What type of specimen is used Gas analysis?

-Whole blood (Unclouded, unseparated)
-arterial most common
-Venous is fine for acid-base

How well did you know this?

Not at all

Perfectly

”capillary” can be considered as “arterialized” if limb is warmed to _____ Degrees Celsius (Increases blood flow) prior to collection

How well did you know this?

Not at all

Perfectly

What are four pre-analytical considerations for blood gas analysis?

-specimen container
-Anticoagulants
-Technique of collection
-Storage and transport

How well did you know this?

Not at all

Perfectly

What specimen containers can be used?

-glass (best for pO2), Well Stoppared-gas tight for 2 hours
-plastic syringes (Permeable to gas)
-Capillary tubes*

How well did you know this?

Not at all

Perfectly

If plastic container is used for pO2, The sample must be analyzed within ____ Minutes of being drawn

15*

How well did you know this?

Not at all

Perfectly

Plastic is permeable to gas (ok for pH, pCO2, HCO3-, ___________ and ___________).

Base excess, electrolytes

How well did you know this?

Not at all

Perfectly

What anticoagulant is used for blood gas analysis?

Heparin

How well did you know this?

Not at all

Perfectly

do you want to use the minimum amount of anticoagulant necessary. Otherwise how would the results be altered?

Decreased pH, [HCO3-], base excess, Ca2+

How well did you know this?

Not at all

Perfectly

What are the two forms of heparin?

-dry
-Solution

How well did you know this?

Not at all

Perfectly

Form of heparin that has the advantage of little dilution of specimen, disadvantage- takes time for heparin to dissolve and mix

Dry heparin

How well did you know this?

Not at all

Perfectly

Form of heparin that is fast mixing but requires dilution of sample

Solution heparin

How well did you know this?

Not at all

Perfectly

Form of heparin that…
-decreased electrolytes, HCO3-, Hb
-Increased pO2, Because 02 in heparin solution is equalliberated with atmospheric air

Solution heparin

How well did you know this?

Not at all

Perfectly

Venous occlusion by tourniquet should be less than _____ Minutes

How well did you know this?

Not at all

Perfectly

Where are the important factors for Specimen collection?

-patient should have calm, steady ventilation for 15 minutes, 30 minutes for patients receiving artificial air or CO2
-Pain and anxiety should be minimized
-Sample should be drawn anaerobically in presence of anticoagulants
-Samples with air bubble should be discarded
-Keep Hemolysis to a minimum

How well did you know this?

Not at all

Perfectly

How should glass specimens be stored?

-Should be placed on ice/water slurry immediately (Slow down enzymatic activity)
-stable for about two hours

How well did you know this?

Not at all

Perfectly

How should a plastic specimen be stored?

-should be analyzed immediately
-Stable for 15 minutes

How well did you know this?

Not at all

Perfectly

Prolonged storage of specimen may decrease _____ and increase ______ (Recommended that samples be analyzed within one hour)

Ca2+, K+

How well did you know this?

Not at all

Perfectly

What are the analytical methods for determining acid base balances and blood gas analysis?

• pH electrode
•pCO2 electrode
•pO2 electrode

How well did you know this?

Not at all

Perfectly

Calibrators, buffers and electrodes must be at the same ________.

Temperature

How well did you know this?

Not at all

Perfectly

How is pH electrode calibrated?

Calibrated with buffer solutions that bracket pH of sample (Normal 7.35-7.45)

How well did you know this?

Not at all

Perfectly

pCO2 electrode is a __________ pH Electrode.

Modified

How well did you know this?

Not at all

Perfectly

How does pCO2 electrode determine pH?

Takes a vantage that pH has a linear relationship to log pCO2 Over the range of 10-90 mmHg (normal pCO2 is about 35 to 45 mmHg)

How well did you know this?

Not at all

Perfectly

What is normal pCO2 range?

35-45 mmHg

How well did you know this?

Not at all

Perfectly

what are the two types of pCO2 electrode?

-invasive: Requires blood to be drawn
-Noninvasive: Transcutaneous pCO2 (tcpCO2)

How well did you know this?

Not at all

Perfectly

How is invasive pCO2 electrode calibrated?

Zero gas and a slope gas (40 mmHg) - Usually bubbled through a humidifier to include contribution of water vapor pressure

Non-invasive transcutaneous pCO2, has the same detection principle Except detection occurs on skin (Require scan to be warmed to _______ Degrees Celsius) -Electrode for CO2 accumulation during analysis -calibration is to gas mixture‘s (same s other)

42-43

What is normal pO2?

80-110 mmHg

pO2 Electrode is also known as _____________ electrode. -Invasive, requires blood to be drawn

Clark Polargraph

-Specificity of electrode is dependent on membrane permeability -O2 is consumed, current is proportional to [O2]

pO2 Electrode

How is p02 electrode calibrated?

Two gases (Zero and another with O2)

Noninvasive, transcutaneous pO2 (tcpO2) Same detection except occurs on the skin and requires a skin to be __________.

Warmed -calibration is atmospheric O2

How is sample OD measured?

Dilutant O.D. (Your measurement) X stock concentration / Stock O.D. (Given)

OD and Concentration have a __________ Relationship.

Linear

How is anion gap calculated?

(Na + K) - (Cl- HCO3) = 15 mmol/L (10-20) (Na) + ( Cl - HCO3) = 12 mmol/L (7-16)

What are possible sources of error when measuring electrolytes?

-Lipemic blood -Hemolysis (special attention to potassium) -Storage temperature -Timing of plasma separation

Glass membrane electrodes are used for….

Sodium*

Valinomycin coated polyvinyl chloride electrodes are used for…

Potassium*

What type of spectroscopy is used for detecting sodium and potassium?

Flame atomic emission spectroscopy Or ion selective electrode is used

What is most commonly used for chemistry testing, Serum or plasma?

Serum If plasma is used, do not use EDTA Anticoagulant

Is capillary blood is used what temperature does it need to be to cause vasodilation?

40 degrees Celsius

For electrolyte testing, what temperature is needed for specimen storage?

4°C 37°C, oxygen Use is increased (Enzymes) That can result in hypoxic tissues and Can cause cell death/hemolysis

Why is timing of plasma separation important?

Living cells release metabolites that alter levels or cause Hemolysis

ion selective electrodes: Is direct or indirect effected by hyperlipidemia?

Indirect (Diluted)*

How does ion selective electrode work?

Two different electrodes, one is exposed to liquid of known pH (Reference electrode) The other is exposed to the sampleMeasures the change between the two electrodes

What method for detecting sodium and potassium is highly sensitive and accurate and used as the reference method?

Flame atomic emission spectroscopy

flame atomic emission spectrum Spectroscopy isn’t a popular method for Sodium and potassium measurement but is very important for what?

Measuring calcium and magnesium levels!*******

Flame atomic emission spectroscopy: Difference in voltage change is proportional to…..

Concentration of the sample

What is the disadvantage of flame atomic emission spectroscopy?

Protein will interfere with the test -Pseudohyponatremia and pseudohypochloremia -Potassium is less effected (Too low to matter)

Flame atomic emission spectroscopy: Na- ______nm

589

Flame atomic emission spectroscopy: K ______nm

766 nm

Flame atomic emission spectroscopy: Cs- ______nm

852

Flame atomic emission spectroscopy: Li ______nm

671

Flame atomic emission spectroscopy: Intensity of emitted light is proportional to…

Sample

Flame atomic emission spectroscopy is an __________ a method that requires dilution

Indirect

________ should be used for potassium detection (Potassium is released during clotting or Hemolysis)

Plasma

What should not be used for sodium and potassium?

Na heparin or NH4-heparin (Increases hydrogen and pH which can cause Hemolysis, leakage, and increased potassium)

How long are sodium and potassium samples good for?

-whole blood must be analyzed within three hours -Plasma, serum, and urine are stable For one week at room temperature or 4°C -Stable for one year at -20°C

Chloride interferes with other….

Halides

What are the four methods for detecting chloride?

-coulometric titration -Mercuric Thiocyanate Spectroscopy -ISE -Schales and Schales Titration

Which method for detecting chloride is the preferred method That is very accurate?

coulometric titration

Method of detecting chloride that Detects excess silver to signal the endpoint

coulometric titration * The more chloride there is, the longer till silver is detected

What method is good for detecting chloride that is in normal range (80-125 mM)?

Mercuric Thiocyanate Spectroscopy

Why can’t Mercuric Thiocyanate Spectroscopy be used for detecting low chloride levels?

There is signal noise at lower chloride levels

Method for detecting chloride: • Ferric-Isothlocyanate (Colorimeticaly) Color • Extremely temperature sensitive Interfering factor: Bilirubin, Hb, & llpemia

Mercuric Thiocyanate Spectroscopy

Method for detecting chloride that is the most common method?

ISE -Direct -Indirect

Method for detecting chloride that uses Ag-AgCl or Ag-S sensing elements

ISE -has the same limitations as sodium and potassium

-Chloride ions in serum or complex with mercury nitrite**** to form soluble HgCl2* -serum proteins are precipitated with tungstic acid -soluble fraction is titrated with mercuric nitrate in the presence of s-diphenylcarbazone as indicator

Schales and Schales Titration

In Schales and Schales Titration, when does the indicator turn violet-blue?

With first excess of mercuric ion -value is calculated by how much Mercuric nitrate is left in the dropper

What may secure the endpoint in Schales and Schales Titration?

Bilirubin or hemoglobin

What causes the violet color in Schales and Schales Titration?

Hg2 + diphenylcarbazone —-> violet color

What kind of sample is used for cystic fibrosis screening in newborns?

Sweat chloride****

What specimens are used to measure sweat chloride?

Serum, heparinized plasma, urine, sweat, and other body fluids

Why should all fluids be rapidly separated from cells When testing for chloride?

To avoid pH changes (Associated with bicarbonate and chloride) and shift in ionic equilibrium due to cellular metabolism

ISE Measurements of whole blood should be performed within _____ hours

Choroid and serum, plasma, urine and other fluids are stable for _______ at room temperature, and at both 2 and -20°C

1 week

What causes cystic fibrosis? What are three things that it can effect?

Defect in CFTR protein***** -electrical balance -COPD disease -Pancreatic instability

What is the normal range for sweat chloride? What is the range for cystic fibrosis?

0-40 mmol/L Less than 60 mmol/L

What induces sweating in the sweat chloride test?

Pilocarpine****

How is the sweat chloride test performed?

-Metal electrode is used to drive medicine into the skin (pilocarpine) -Sample is collected in gauze for measurement ***

What are the percentages of the three different carbon sources? *need to know*

CO2- 3% Carbamino derivatives of plasma proteins- 33% HCO3- 64%

What is the normal values for bicarbonate?

22-30 mmol/L (method dependent) ***

what are the three lab methods for detecting HCO3 (total CO2)?

-Manometric (gas pressure) -Spectrophotometric (color change) -pCO2 electrode (Measures pressure gradient) Monitored by glass pH electrode * Are they all acidify the sample to convert all CO2 forms to CO2 gas

What is the most common method to measure all CO2 forms?

Enzymatic- Spectrophotometric***

Enzymatic- Spectrophotometric: All CO2 forms are converted to bicarbonate by addition of __________. NADH consumption measured as decrease in _______ nm absorption.

Alkali serum*** 340 (NEED TO KNOW THIS!!!)***

Enzymatic- Spectrophotometric measures production of ________ or consumption of _________.

NDH, NADH

What kind of specimen is used for total CO2 measurement?

Serum, HEPARINIZED plasma, • CANNOT use other anticoagulant (disturb erythrocyte and plasma CO) Whole blood cannot be used due to heme-bound CO and carbamino- bound CO2

What is the major source of error associated with total CO2 measurements?

Handling of sample -Exposure to air should be minimal and centrifugation at 37°C tightly stop right before analysis

How long is serum or plasma total CO2 stable for?

For several days at 4°C

Color change from orange to yellow

540 nm

Color change from yellow to green

560 nm

Color change from green to blue

490

Color change from blue to violet

430

Color change from violet to red

400-700??

Color change from red to orange

630