Course 108 Unit 4.2 Operating ABG and Co Ox analyzers

Question 1

What is a sanz electrode?

Answer 1

• measures pH
• measurements are made by comparisons
• comparison between a solution of known pH (reference electrode) and a solution of unknown pH (blood)
• two solutions are separated by pH sensitive glass membrane
• electrical potential across membrane read as pH
• requires buffer for calibration (2 standards are required and must be in physiologic range)

Question 2

What is ABG analysis?

Answer 2

Functional operation of blood gas electrodes

Question 3

What is an anode?

Answer 3

positive pole (Ag/ AgCl)

Question 4

What is a Cathode?

Answer 4

negative pole (Platinum)

Question 5

What is oxidation?

Answer 5

a loss of an electron by a particle

Question 6

What is reduction?

Answer 6

a gain of electrons by a particle

Question 7

What is Severinghaus electrode?

Answer 7

• measures PCO2
• based on Henry’s Law (states the amount of gas diffusing across the membrane is directly proportional to the pressure gradient
• as blood passes through the semi permeable membrane CO2 diffuses across and reacts chemically with the aqueous bicarbonate solution on the other side
• -hydrogen ion concentration developed is directly proportional to the PCO2 in contact with the membrane

Question 8

What is a Clark electrode?

Answer 8

• measures PO2
• made of silver anode immersed in a KCl electrolyte solution (oxidation occurs between the anode and KCl creating free electrons (e-)
• an adjacent platinum cathode will react with O2 and H2O utilizing the electrons (reduction)
• results in a flow of current between the anode and the cathode
• an increase in O2 concentration will the current
• measuring the change in current (electron flow) between the anode and cathode, the amount of O2 in the electrode solution can be determined

Question 9

What are the procedures for ABG analysis?

Answer 9

1. Obtain sample: wear protective gloves any time you are dealing with blood or bodily fluids * in case of an accidental needle stick or any other possible type of contamination notify your NCOIC and or shift leader immediately
2. Ensure all air bubbles have been removed from the syringe
3. Mix sample thoroughly: roll between hands, especially if sample has been stored for more than a few minutes
4. Introduce sample into analyzer
5. Watch for air bubbles and clots as sample run through analyzer
6. Print/ record and report results IOW local policy
7. Check results for errors: if results seem inaccurate run sample through another analyzer and compare results; if another analyzer isn’t available place sample on ice then run control through analyzer to check for accuracy (do results appear how they should for blood and oxygenation level

Question 10

Can temperature be corrected for ABG analysis?

Answer 10

yes, results can be corrected if patient temp is other than 37 degrees C or 96.6 degrees F

Question 11

What makes a spectrophotometric oximeter operate?

Answer 11

Spectrophotometry:

• Spectro: spectrum
• Photo: light
• Metry: measurement
• light is transmitted at specific wavelengths, passes through the substance being analyzed (blood) by a photo detector on the opposite side: Light transmission will either be:
• absorbed (optical density)
• pass through (inverse to light absorbed)
• be reflected (backscatter oximetry)

Question 12

What is the light absorption principle?

Answer 12

Lambert-Beer Law: determines hemoglobin saturation/ concentration (each Hb has its own unique absorption/transmission spectrum)

Question 13

How many wavelengths does co-oximetry use?

Answer 13

uses eight light wavelengths to differentiate hemogloblin species

• 1. HbO2 (oxygenated Hb)
     
     2. Hb (deoxygenated
     3. MetHb (Met-hemoglobin Fe 3+)
     4. HbOC (carboxyhemoglobin)

Question 14

What is an isobestic point?

Answer 14

where 2 Hb species absorb light equally at a given wavelength (also known as common points)

Question 15

What are the different co-oximetry measurements?

Answer 15

1. total Hb: tHb (g/dl)
2. oxyhemoglobin saturation (SpO2= functional SaO2)
   - oximetry via 2 wavelength spectrophotometers
   - HbCO and MetHb are excluded= non functional Hb (deoxygenated Hb)
3. oxihemoglobin sat (SaO2 (fractional SaO2= disfunctional Hb)
   - carboxyhemoglobin HbCO (smoke inhalation): normal range; 1.5 to 9.0 percent of tHb
   - met-hemoglobin met-Hb (INO and Hurricane tropical anesthetic and others): normal is 1 percent or less
   - sulfhemoglobin HbS (sickle cell anemia)

Question 16

What is functional SpO2?

Answer 16

• compares functional HbO2 to Hbtot
• SpO2 is integrated in the functional light wavelength of SaO2
• Not reliable if there are abnormal forms of Hb

Question 17

What is fractional SaO2?

Answer 17

Compares HbO2 to all forms of Hb

Question 18

What are co-oximeters used for?

Answer 18

Calculate oxygen content

Question 19

What is the procedure for the performing a routine blood co-oximetry analysis?

Answer 19

Same procedure as analyzing ABG’s

Question 20

What are the interpretations for co-oximetry results?

Answer 20

Total Hemoglobin- tHb:

• newborn 14.0 to 24.0 g/dL
• adult male 13.5 to 18.0 g/dL
• adult female 12.0 to 16.0 g/dL

Question 21

What is the definition of point care testing?

Answer 21

Laboratory testing performed “outside of the central laboratory” generally at the patient bedside
*moderately complex according to CLIA

Question 22

What are the benefits of point of care testing?

Answer 22

• shortened turnaround time
• more timely intervention
• correlation with patient status at bedside
• reduced errors related to handling, labeling and reporting
• small sample size: 2 to 3 drops of blood

Question 23

What is the equipment needed for a point of care testing?

Answer 23

Handheld analyzer:

• cartridge port
• numerical keypad
• storage of results
• 50 patient samples
• IR transmitting results
• battery powered
• 37 degree symbol and it meanir

Cartridges:

• CG8+
• PT (tells how quick the blood is clotting or thinning)
• G
• ACT

Portable printer:

• temporary copy (thermal paper which has to be kept cool otherwise turns black)
• use every eight hours for blood gas testing

Question 24

How do you operate the i-STAT system?

Answer 24

-obtain a blood specimen (fresh whole blood)
-collect in a syringe
(if using capillary tubes test within 3 minutes; if using syringe or an anticoagulant test within 5 minutes)
-gently mix sample in syringes or collection tubes before use
-other sample handling precautions IAW organization policies

Question 25

What is done to analyze a specimen using point of care testing?

Answer 25

• fill cartridge via sample well using slow and steady pressures
• close cartridge using snap closure: press on tab

Question 26

What is the i-STAT test cycle?

Answer 26

Initiated by insertion of cartridge:

• electrical contact made with cartridge
• cartridge type identified
• calibration fluid released to sensors
• barometric pressure measured
• sensors heated to 37 degrees C
• electrical signals generated at sensors are measured
• calibration solution displaced by sample
• operator and patient ID numbers accepted
• blood gas and patient parameters accepted
• results are calculated and displayed (no membranes to perform measurements)
• results are stored
• report results