Egan's Ch. 18 & Wilkens Ch. 8

17. After obtaining an arterial blood sample through percutaneous puncture using a syringe that does not have a capping safety device, what should you do?

"Scoop" the needle cap up the one hand, then plug the syringe

116. At the very beginning of exhalation, the PETCO2 normally should be at what level?

0 mmHg

119. What is the normal gradient between PaCO2 and PETCO2?

1-5 mmHg

29. You are asked to calibrate an O2 analyzer. What gases would you use for this procedure?

100% O2, 21% O2

109. You obtain a SpO2 reading of 100% on a patient receiving O2 through a nonrebreathing mask. What range of PaO2 levels is possible in this patient?

100-600 mmHg

48. What is a normal level for CaO2?

16-22ml

74. Statistically derived limits for internal quality control of blood gas samples are usually set at what appropriate level?

2 standard deviations from the mean

2. Under ideal conditions, electrochemical oxygen (O2) analyzers have approximately what degree of accuracy?

2%

90. What is the appropriate interval for changing the site for a transcutaneous blood gas monitor sensor?

2-6 hours

127. After changing the FIO2 of a patient with emphysema, how long should you wait to draw an ABG to monitor the patient's respiratory status?

20-30 min

24. How long should you wait before drawing an ABG on a chronic obstructive pulmonary disease (COPD) patient whose FIO2 has just been changed?

20-30 minutes

19. What size needle would you recommend to obtain an ABG sample through percutaneous puncture of an infant?

25 gauge

100. Under ideal conditions, pulse oximeter readings patients usually fall in what range of those obtained with invasive hemoximetry?

3-5%

64. Components of a laboratory blood gas analyzer include what?

3-electrode measuring chamber, reagent containers, calibrating gas tanks, waste container

118. What is a normal end-tidal PETCO2 range?

35-43 mmHg

120. What is the normal range for end-tidal CO2 as measured by capnography?

5-6% (35-46 mmHg)

108. You obtain a SpO2 reading of 90% using an oximeter with an approximate accuracy of 5%. This could indicate a PO2 as low as what level?

55 mmHg or less

99. Pulse oximeter readings are generally unreliable at saturations below what level?

80%

103. For continuous monitoring of adults and children, you should set a pulse oximeter's low alarm in what range?

88-92%

47. A PaO2 below what value would be considered moderate hypoxemia?

< 60mmHg

68. What is known about blood gas analyzer's waste fluids?

A strong disinfectant should be added to waste fluid containers, waste fluids should be handled as if they were blood samples, & waste fluids should be treated as potentially infectious.

67. When conducting ABG analysis in the laboratory, what are the obvious signs of pre-analytical error?

Air in sample, unmixed sample, excess liquid heparin, metabolic effect

101. Before taking a spot reading with a pulse oximeter, what should you do?

Allow sufficient response time, set the low alarm to 88% instead of 90%, confirm adequacy of pulse signal

20. Required equipment and supplies for percutaneous arterial blood sampling of an adult include what?

Antiseptic (alcohol), 20-22 gauge needle, pt / sample label

23. After obtaining an arterial blood sample, what should you do?

Apply pressure to stop bleeding (3-5 min), mix the sample by rolling and investing the syringe, ice slush if needed

12. Precautions and/or possible complications of arterial puncture include what?

Arteriospasm, infection, embolization, hemorrhage

50. Before connecting the sample syringe to an adult's arterial line stopcock, what would you do?

Aspirate at least 2ml of fluid or blood using a waste syringe

73. How often should blood gas calibration verification by control media take place?

At least 2 levels of control media should be analyzed every 8 hours

76. The total instrument error (inaccuracy) of a blood gas analyzer equals what?

Bias & imprecision

111. What is the measurement of CO2 in respiratory gases called?

Capnometry

104. What can cause false high readings when using a pulse oximeter?

Carboxyhemoglobin or CO poisoning

92. To avoid thermal injury with transcutaneous blood gas monitor sensors, what should you do?

Carefully monitor the sensor temperature, & regularly rotate the sensor site

8. What sites are used for arterial blood sampling by percutaneous needle puncture except:

Carotid

6. During calibration of a Clark polarographic O2 analyzer, you cannot get the sensor to read 100% when exposed to 100% O2, even after adjusting its calibration control. The unit has new batteries. What action(s) would be correct?

Change the sensor or electrode

80. While analyzing a blood gas control sample, you notice a trending of several PCO2 values above the 2 SD range over the last six control samples run. What corrective action would you consider at this time?

Check the function of the PACO2 electrode, & repair/replace any failed components.

93. While monitoring an active infant through a transcutaneous blood gas system, you notice a rapid rise in PtcO2 from 63 to 145 mm Hg. During the same time, the (PtcCO2) drops from 35 to 7 mm Hg. What is the most appropriate action in this case?

Check the sensor for air leaks or dislodgement

88. To validate patient readings obtained from a transcutaneous blood gas monitor, what should you do?

Compare the monitor reading to those obtained with a concurrent ABG sample

70. How is the accuracy of a blood gas analyzer determined?

Comparing the analyzer's measurements to known values

22. What describes the correct procedure for an Allen test?

Compress both radial and ulnar arteries while pt flexes hand until blanching occurs, then release ulnar artery

77. Factors contributing to imprecision (random) errors during blood gas analysis include what?

Contaminated buffers

79. Factors contributing to bias (systematic) errors during blood gas analysis include what?

Contaminated buffers, incorrect gas concentration, incorrect procedures, component failure

60. Possible complications of capillary blood gas sampling include what?

Contamination & infection, Inadvertent puncture, tibial artery laceration, burns, hematoma, bone calcification, nerve damage, scarring, pain or bleeding, bruising

43. Because of an extremely low PO2, you suspect that an arterial blood sample taken from a patient's brachial artery might have been contaminated with venous blood. What might help to confirm your suspicion?

Cross-check the sample with an SPO2 reading

105. What will tend to cause false low readings when using a pulse oximeter except:

Dark nail polish

36. What would you expect to occur if too much heparin was used in gathering an ABG sample from a patient breathing room air?

Decreased PCO2

40. What changes would occur if an arterial blood sample of a patient breathing room air were exposed to a large air bubble?

Decreased PCO2, Increased PO2

56. Warming a capillary bed to 42° C has what effects?

Dilation of vessels, increasing capillary flow well above tissue needs (arteriolizing)

44. You determine that a blood gas sample that requires analysis has been sitting in ice slush for 90 minutes. What should you do?

Discard the sample and notify the appropriate clinician

53. Through which pulmonary artery catheter port would you obtain a mixed venous blood sample?

Distal (catheter tip) port

3. How does the Clark polarographic O2 electrode function?

Electrodes are immersed in an electrolyte cell. An O2 permeable membrane covers one surface of the cell; when a polarizing voltage is applied to the cathode, electrons combine with O2 molecules and reduce them to hydroxide ions.

37. To avoid the dilution effects caused by too much sodium heparin during ABG sampling of an adult, what should you do?

Ensure a sample volume greater than 2ml, use dry heparin instead, fill the needle dead space only

98. Continuous SpO2 monitoring (versus a spot check) is indicated in what types of situations?

Exercise therapy, Bronchoscopy, Sleep Studies

117. During a single-breath capnogram, what does the occurrence of a plateau indicate?

Exhalation of mainly alveolar gas

39. When analyzing an ABG sample from a patient with acute respiratory distress syndrome and refractory hypoxemia, you notice a PaO2 of 141 mm Hg and a PaCO2 of 14 mm Hg. What errors should you suspect?

Exposure of the blood sample to the air

97. What is the greatest hazard of pulse oximetry?

False results leading to incorrect decisions

51. After obtaining an arterial blood sample from an arterial line, you would do what?

Flush the line and stopcock with heparin; confirm stopcock port open to intravenous, confirm under dipping pulse pressure waveform on monitor

4. What is known about the galvanic fuel cell O2 analyzer?

Galvanic fuel cell analyzers uses a gold cathode and a lead anode

18. What Centers for Disease Control and Prevention (CDC) barrier precautions would you use when obtaining an arterial blood gas (ABG) through percutaneous puncture?

Gloves, protective eye wear

55. What are the characteristics about capillary blood gas sampling?

Good capillary sample can accurately reflect Ph & PCO2, used for infants, PaO2 reading unreliable

86. Tissue injuries to be on guard for at the site of transcutaneous blood gas electrode placement include what?

Hematomas

34. If patient pain or anxiety occurs during arterial puncture, What will probably occur?

Hyperventilation

128. You are monitoring a nurse acquiring a capillary blood sample from an infant. The nurse immediately punctures the infant's heel with a lancet and then squeezes the puncture site to increase the flow of blood. What mistakes has the nurse made while obtaining the capillary blood sample?

Inadequate warming of the capillary bed, she didn't disinfect the puncture site, & squeezing of the puncture site

123. A mechanically ventilated patient exhibits a sudden decrease in end-tidal CO2 levels. What are possible causes of this change except:

Increased CO2 production

59. Capillary puncture should NOT be performed at or through what location?

Inflamed or edematous tissue, localized area of infection, previous puncture sites

121. During a single-breath capnogram, the sharp downstroke and return to baseline that normally occurs after the end-tidal point indicates what?

Inspiration of fresh breath

130. A patient suffering from traumatic brain injury in the ICU has a PtO2 (tissue oxygen) value of 10-15 mmHg, what does this indicate?

Ischemic brain damage

9. Why is the radial artery the preferred site for arterial blood sampling?

It's near the surface and easy palpation. Ulnar good backup, but radial is not near any long veins

1. What is false about invasive versus noninvasive monitoring?

Laboratory analysis of gas exchange is usually noninvasive in nature

61. The equipment necessary for capillary blood sampling includes what?

Lancet, preheparinized capillary tubes, small metal stirrer bar (metal flea), a magnet; clay, or wax sealant (or caps), gauze / cotton balls, bandages, ice, gloves, skin antiseptic, warming pads, sharps container, and labeling materials.

58. What is the best site for capillary puncture in an infant?

Lateral aspect of the heels plantar surface

63. A blood gas analyzer measures what?

MEASURES Ph, PCO2, PO2; CALCULATES Bicarb, base excess, hemoglobin, plasma

112. What is the most common technique used to measure CO2 in respiratory gases?

Mainstream or sidestream location

115. What are the uses of capnometry?

Measure CO2 concentration in expired gases

41. What can help avoid the problem of arterial blood sample contamination with air except:

Mixing before expelling air

13. Treatment parameters that should be assessed as part of arterial blood sampling include what?

Mode of ventilatory support and setting, FIO2 (analyzed) or prescribed flow, proper application of the O2 device

10. Indications for arterial blood sampling by percutaneous needle puncture include the need to:

Monitor disease progress, assess response to therapy, acid base, and O2 saturation + ventilation

96. What are the indications for pulse oximetry?

Monitor the adequacy of arterial oxyhemoglobin saturation, quantify the response of arterial oxyhemoglobin saturation to therapeutic intervention or while doing a bronchoscopy to check saturations

102. What guidelines should you adhere to when performing pulse oximetry?

Never mix different sensors among different devices, & make sure sensors are correct size & properly applied

57. When is capillary blood gas sampling indicated?

No arterial access is available, noninvasive monitor readings are abnormal; assessment of initiation, administration, or change in therapy is indicated, monitoring the severity and progression of disease, &/or Hx change / physical assessment

114. What are the advantages of mainstream capnometry except:

No bulky sensor and short delay

124. During capnography monitoring of a mechanically ventilated patient, you note that the PETCO2 has dropped to 0 mm Hg. What are the possible causes of this finding?

No cardiac output, system leak, ETT displacement, Esophageal fistula, cuff deflation

83. What is the procedure for setting up transcutaneous blood gas monitoring?

Once electrodes are properly placed, compare monitor readings with a concurrent ABG result. Consistent numbers between the two validates monitor performance under current conditions Repeat validation any time patient status undergoes significant change. Electrode site and arterial sampling site should be on the same 'side' of shunt.

38. A practitioner forgets to ice an ABG sample and leaves it at room temperature for 45 minutes. What parameters can you predict will increase in this sample during that period?

PCO2

46. What must be charted after obtaining an ABG sample through the brachial artery?

PT temp, position, and activity level, & inspired O2 concentration or ventilator settings

72. To ensure that the output of a blood gas analyzer is both accurate and linear across the range of measured values, a calibration procedure must measure what?

Parameters with known input values at two points

84. In what patient types would transcutaneous blood gas monitoring most likely provide inaccurate or erroneous results?

Patient in hypovolemic shock

106. What is the most common source of error and false alarms with pulse oximetry?

Patient motion artifact or shock

27. When performing an Allen test on the left hand of a patient, you notice that the palm, fingers, and thumb remain blanched for more than 15 seconds after pressure on the ulnar artery is released. What should you do?

Perform the Allen test on the right hand

25. Before performing puncture or cannulation of the radial artery, what should you do?

Perform the Allen's Test to ensure collateral circulation, clean puncture site with alcohol swab

65. Which blood gas analyzer electrode uses a separate reference electrode?

Ph

71. What media are used to calibrate a blood gas analyzer's gas electrodes?

Precision mixtures of O2 & CO2

14. What should be monitored during the sampling of arterial blood?

Presence of pulsatile blood return, presence of air bubbles or clots in sample, appearance of puncture site

11. What grounds for finding an alternative site for arterial puncture except:

Presence of surgical shunt

52. A physician requests that you obtain and set up an arterial line system for invasive monitoring of blood pressure. What equipment would you gather?

Pressurized intravenous bag, continuous flush device, arterial catheter IV, pressure transducer, amplifier or monitor

28. What conditions make interpreting the results of a modified Allen test difficult?

Prior radial artery cannulation, severe circulatory insufficiency, wrist/hand burns, or jaundice

81. What is the quality control procedure of analysis and reporting on externally provided control media with unknown values?

Proficiency testing

35. Most preanalytical ABG errors can be avoided by ensuring that the sample is what?

Properly anticoagulated, obtained anaerobically, analyzed within 15 min

89. Before attaching a transcutaneous blood gas monitor sensor to a patient, what should you do?

Provide a specified warm-up time and set the probe temp, check the membrane & prepare a sensor with an adhesive ring/gel, & prepare the monitoring site (i.e. remove hair)

7. You are asked to provide continuous monitoring of the FIO2 provided by a humidified O2 delivery system using a galvanic cell analyzer. Where would you install the analyzer's sensor?

Proximal to the heated humidifier

21. What chart information should be checked before performing artery puncture?

Pt diagnosis & history, presence of bleeding disorder or blood-borne infection, anticoagulant drug, respiratory care orders

126. You are asked to perform an ABG on a patient that comes into the ER feeling light-headed with a blood pressure of 90/60. What may you need to do to obtain an adequate blood sample on this patient?

Pull gently on the syringe barrel to apply suction

49. To assess gas exchange at the tissues, you would obtain a blood sample from what?

Pulmonary artery

26. You return to a patient's room 20 minutes after drawing an ABG. What should you check at this time?

Puncture site for hematoma or bleeding, adequacy of distal circulation

91. You must immediately begin monitoring the oxygenation status of an infant admitted to the emergency department in severe respiratory distress. What approach(es) would you select?

Put them on a pulse ox

75. When inspecting an internal quality-control plot for a blood gas analyzer, you notice several data points sporadically appearing outside the 2 standard deviation (SD) range. This represents what type of analytic error?

Random error, systematic error

129. Potential benefits of continuous, intraarterial (In Vivo) blood gas analysis include:

Real time monitoring, less blood loss, lower infection risk, eliminates need for specimen transport

125. The shape of the expired CO2 tracing of a patient is normal but instead of being zero, the baseline is elevated to about 12 mm Hg. What is the most likely problem?

Rebreathing (mechanical deadspace)

69. What is the process of testing a new blood gas analyzer to confirm a manufacturer's claims?

Record keeping, performance validation, preventative maintenance & function check, automated calibration, internal statistical quality, external quality control, remedial action

82. The advantage that point-of-care testing has over traditional laboratory testing is that point-of-care testing:

Reduces turnaround time

107. During continuous monitoring of an active 5-year-old patient with a finger pulse oximetry probe, you obtain frequent and repeated false low HbO2 alarms (less than 90%). What would be the best action to take in this situation?

Relocate the sensor to a more stable location

78. When analyzing a blood gas control sample, you notice that the result falls outside the 2 SD range. How could you verify that this was a random error (error of imprecision)?

Repeat the analysis on a different analyzer, rerun the control sample a 2nd time

5. While checking a polarographic (Clark) electrode, you determine that the device fails to read 100% when exposed to pure O2. What actions would be the proper first step?

Replace the batteries

42. Analysis of an arterial blood sample taken from a healthy athlete reveals a pH of 7.36, a PCO2 of 45 mm Hg, and a PO2 of 43 mm Hg. What analytic errors should you suspect?

Sample admixture with venous blood

66. To measure PCO2, blood gas analyzers use what electrode?

Severinghaus

95. What can result in falsely high HbO2 readings with a laboratory hemoximeter?

Sickle cell anemia

32. When performing a percutaneous needle puncture of the radial artery, you get only a small spurt of blood. What is the best action at this time?

Slowly withdraw the needle until a pulsatile flow fill the syringe

33. What indicates venous admixture during arterial puncture?

Smaller sample size, filling pressure would be slower and blood drawn would be darker

94. Oximetry is the measurement of blood hemoglobin saturations using what technique?

Spectrophotometry

122. A patient being monitored by capnography exhibits a sudden rise in end-tidal CO2 levels. What are the possible causes of this change?

Sudden release of a tourniquet, sudden increase in cardiac output, and/or injection of NaHCO3

110. An alert outpatient awaiting bronchoscopy has a SpO2 reading of 81% breathing room air. The patient appears in no distress and exhibits no signs of hypoxemia. What be the best initial action to take in this situation?

Switch sites or replace the sensor probe

15. Patient parameters that should be assessed as part of arterial blood sampling include what?

Temperature, Position, Activity level, Clinical appearance

30. What factors determine the volume needed for an arterial blood sample?

The anticoagulant used, requirements of specific analyzer used, & whether other tests will be performed on the sample

54. A mixed venous blood sample obtained from a pulmonary artery catheter sample has a PO2 of 85 mm Hg and a hemoglobin saturation of 95%. What is likely?

The pulmonary artery catheter balloon was not deflated, the blood sample was withdrawn too quickly

87. What are common sites for transcutaneous blood gas electrode placement except the:

Thigh

85. Transcutaneous blood gas monitoring is indicated when what need exists?

To continuously analyze gas exchange in infants or children, quantify the real time responses to bedside interventions, & continuously monitor for hyperoxia in newborn infants

16. Purposes of a needle-capping device include what?

To isolate the sample from air exposure, and help prevent needlestick injuries

113. What are the indications for capnography?

Undergoing general anesthesia, mechanical ventilation, post intubation airway check

31. To avoid transmission of blood-borne diseases when handling a used needle, what should you do?

Use counter or bed to place cap onto needle, and dispose of the needle into a sharps container

45. An outpatient scheduled for an arterial blood sample enters the pulmonary lab 20 minutes late and out of breath, having run up four flights of stairs. What should you do?

Wait ~5 minutes before taking the sample

62. Before a sample of capillary blood is taken, what should you do to the site?

Warmed to 42 degrees Celsius for 10 min, area cleaned with antiseptic solution