Chapter 08 - Perform Quality Control Procedures Flashcards Preview

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Flashcards in Chapter 08 - Perform Quality Control Procedures Deck (16)
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1

To periodically confirm the validity of blood gas analyzer or hemoximeter results, you would perform:

  1. internal statistical quality control
  2. instrument performance validation
  3. regular preventive maintenance
  4. control media calibration verification

4

To periodically confirm the validity of blood gas analyzer or hemoximeter results, you would perform calibration verification using control media. Calibration verification requires analysis of at least three materials with known values (controls) spanning the entire range of results expected for clinical samples. As a general recommendation, at least one control should be analyzed every 8-hour shift. A rotation system should assure that all three levels of the control media are analyzed at least once each 24 hours.

2

When conducting a manual leak test on a disposable ventilator circuit, you cannot reach the ventilator's pressure limit or hold the pressure during an inspiratory pause. Your first action should be to:

  1. discard the circuit and replace it with a new one
  2. decrease the volume delivered during the test
  3. recheck all circuit connections and repeat the test
  4. increase the inspiratory pause time during the test

3

When conducting a manual leak test on a disposable ventilator circuit, the resulting pressure should exceed the ventilator's pressure limit or hold at a static level (at zero flow during a pause). If you cannot reach the ventilator's pressure limit or hold the pressure during an inspiratory pause, the circuit has a leak. If the ventilator fails the automated or manual leak test, recheck all circuit connections and repeat the test. If a repeat leakage test also fails, replace the circuit.

3

To calibrate a portable bedside spirometer you need which of the following equipment?

  1. a U-tube water column manometer
  2. a mechanical (vane-type) respirometer
  3. a large volume (3 L) calibration syringe
  4. a precision calibrated flowmeter

3

Calibration of a portable bedside spirometer involves comparison of the device's volume and flow measurement to a standard. For volume calibration, you will need a large volume (3 liter) calibration syringe. Typically, you follow the prompts to push the syringe's calibrated volume through the spirometer's flow sensor over the recommended time interval, making sure that there are no leaks in the system.

4

Following prescribed daily quality control procedures in your blood gas lab, you run a control solution through the blood gas analyzer. You note that two successively PCO2 readings fall outside the acceptable range. Which of the following actions is appropriate at this time?

  1. Report results after compensating for the deviation
  2. Replace the PCO2 electrode and recalibrate the analyzer
  3. Analyze another control solution for comparison
  4. Perform a two-point calibration and rerun the control

4

When two successive readings fall outside the acceptable range, systematic error or bias is a possibility. Bias causes repetitive or trending-type measurement errors (as opposed to random errors). Common causes of bias measurement errors include (1) incorrect calibration (including use of incorrect gas concentrations), (2) contaminated buffer solutions, (3) incorrect procedures and (4) electrode failure. Before assuming electrode failure (which requires an expensive replacement), FIRST confirm that the instrument is properly calibrated and rerun the control.

5

During a ventilator test, you determine that the delivered volume is substantially less than the set volume. To determine if the ventilator volume setting is out of calibration, you would:

  1. measure the volume delivered at the ventilator outlet using a calibrated volumeter
  2. perform a manual circuit leak test using a low volume and inspiratory pause
  3. compare a variety of inspiratory time settings against a digital stop watch
  4. measure the volume delivered at the patient connector using a calibrated volumeter

1

Circuit leaks are among the most common problem causing loss of ventilator volume and pressure. However, ventilator malfunction can have the same effect. To distinguish a circuit leak from a ventilator malfunction, run a circuit leak test. If the circuit leak test is negative, then the ventilator may not be delivering the preset volume. To determine whether a ventilator is delivering the preset volume, you should compare the ventilator setting to that measured at the ventilator outlet using a calibrated volumeter.

6

According to ATS recommendations, diagnostic spirometers should be calibrated to within:

  1. ± 1% or 10 mL, whichever is greater
  2. ± 3% or 50 mL, whichever is greater
  3. ± 5% or 100 mL, whichever is greater
  4. ± 10% or 500 mL, whichever is greater

2

American Thoracic Society (ATS) recommendations for diagnostic spirometers are that calibration checks should be within ± 3% or 50 mL, whichever is larger.

7

Following prescribed daily quality control procedures in your blood gas lab, you run a control solution through the blood gas analyzer. You note that two successively PCO2 readings fall outside the acceptable range. Which of the following actions is appropriate at this time?

  1. report results after compensating for the deviation
  2. replace the PO2 electrode and recalibrate the analyzer
  3. analyze another control solution for comparison
  4. perform a two-point calibration and rerun the control

4

When two successive readings fall outside the acceptable range, systematic error or bias is a possibility. Bias causes repetitive or trending-type measurement errors (as opposed to random errors). Common causes of bias measurement errors include (1) incorrect calibration (including use of incorrect gas concentrations), (2) contaminated buffer solutions, (3) incorrect procedures and (4) electrode failure. Before assuming electrode failure (which requires an expensive replacement), FIRST confirm that the instrument is properly calibrated and rerun the control.

8

What is the minimum number of control media levels needed to periodically confirm the validity of blood gas analyzer results via calibration verification?

  1. one
  2. two
  3. three
  4. four

3

Calibration verification establishes and periodically confirms the validity of blood gas analyzer results. At least 3 levels of control media are needed and should span the entire range of results expected for clinical samples. As a general recommendation, at least one level should be analyzed every 8-hour shift, with all three levels analyzed least once each 24 hours.

9

When running an arterial blood gas on a point-of-care analyzer, you receive a calibration error message. You should:

  1. repeat the analysis using a fresh sample and the same cartridge
  2. repeat analysis using a fresh sample and new cartridge
  3. send the sample to the central laboratory for analysis
  4. repeat the analysis using the same sample and same cartridge

2

A calibration error on a point-of-care analyzer usually indicates a problem with the sample, calibrating solutions, sensors, or the function of the device's electrical or mechanical components. Normally this requires that you repeat the analysis using a fresh sample and new cartridge. If a message accompanies the error warning, you also should take the action recommended and report the error code to the point-of-care testing manager.

10

To calibrate a portable bedside spirometer you need which of the following equipment?

  1. a U-tube water column manometer
  2. a mechanical (vane-type) respirometer
  3. a large volume (1-3 L) calibration syringe
  4. a precision calibrated flowmeter

3

Calibration of a portable bedside spirometer involves comparison of the device's volume and flow measurement to a standard. For volume calibration, you will need a large volume (1 or 3 liter) calibration syringe. Typically, you follow the prompts to push the syringe's calibrated volume through the spirometer's flow sensor over the recommended time interval, making sure that there are no leaks in the system.

11

In assessing a patient’s FVC maneuver, you note on the volume vs. time graphic display of the spirometer a 'S' shaped pattern, similar to the oxyhemoglobin dissociation curve. How would you interpret this pattern?

  1. An obstructive pattern and acceptable test result
  2. The premature ending of expiration and an invalid test
  3. A restrictive pattern and acceptable test result
  4. Too slow a start to forced exhalation and an invalid test

4

An 'S' shaped pattern on a volume vs. time graph of an FVC maneuver indicates too slow a start to forced exhalation and an invalid test. A normal FVC trace would have the steepest slope (highest flow) early in the breath, then slowly decrease until the end-expiratory plateau is achieved. This test needs to be repeated, with the patient being coached to blow out as hard and fast as possible.

12

To manually validate the accuracy of a ventilator's volume delivery setting during its quality assurance test, you would:

  1. compare the volume setting of the ventilator to its expired volume display
  2. compare the volume setting to that measured by a calibrated external flowmeter
  3. compare the volume setting to that measured by a calibrated external volumeter
  4. compare the ventilator's expelled volume to that collected via the expiratory circuit

3

To manually validate the accuracy of a ventilator's volume delivery setting during its quality assurance test, you would compare the ventilator's volume setting to that measured by a calibrated external volumeter. All measurements should be within ±5% of the settings (and displays, if so equipped).

13

When calibrating a Clark electrode O2 analyzer, you cannot get the unit to read higher than 80% when the sensor is exposed to 100% O2. Your first action should be to:

  1. reset the alarms
  2. replace the batteries
  3. replace the membrane
  4. replace the electrode

2

When a Clark electrode O2 analyzer fails to accurately read 100% O2, the first step should be to check/replace the batteries. If fresh batteries do not solve the problem, likely the electrode needs replacement.

14

To verify the operation of a pulse oximeter, you would:

  1. Expose the oximeter sensor to a calibrated high and low O2 gas source
  2. Measure the SpO2 on two patients with different ABG saturation values
  3. Confirm measurements with high/low HbO2 saturation control media
  4. Confirm an SpO2 o≥ 97% and an accurate pulse reading on a normal person

4

Pulse oximeters measures relative light intensities, as opposed to absolute values. For this reason, they do not require "true value" or control media calibration, as do blood gas analyzers. Instead, to verify the operation of a pulse oximeter, connect the device to a normal person, compare the pulse reading with the actual pulse measured manually, check and confirm an SpO2 reading of at least 97% and confirm loss of signal detection by removing the device.

15

When calibrating a bedside capnograph, you expose the sensor to a precision gas mixture of 5% CO2. Approximately what PCO2 should the device read if properly calibrated at ATPD?

  1. 32 mm Hg
  2. 38 mm Hg
  3. 44 mm Hg
  4. 50 mm Hg

2

Since most capnographs automatically ‘zero’ on room air samples, 2-point calibration requires only that you measure a known CO2%, usually 5%. Under ATPD conditions this is equivalent to 0.05 x 760 mm Hg = 38 mm Hg. The most often cited accuracy standard for capnograph calibration is ±0.3%, or a range of 4.7–5.3% (36–40 mm Hg).

Record and monitor QC data using accepted statistical methods 1

16

Which of the following actions would you consider appropriate if a single blood gas calibration control media reading falls outside the pre-established ± 2 standard deviation (SD) range?

1. repeat analysis on a different analyzer
2. repair/replace failed components
3. rerun the control

  1. 1 only
  2. 2 only
  3. 1 and 3
  4. 1, 2 and 3

3

A single control media reading falling outside the pre-established ± 2SD range is a random error. Typically, random errors in blood gas statistical QC are due to either probability (a chance occurrence), sample contamination or sample mishandling. When you encounter what appears to be a random error you should either rerun the control or repeat the analysis on a different instrument.