Exam two part two: Acid Base Balance
The advantage that point-of-care testing has over traditional laboratory testing is that point-of-care testing
reduces turnaround time.
The transcutaneous blood gas electrode should not be placed on the
thigh.
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 with one hand, then plug the syringe.
Under ideal conditions, pulse oximeter readings patients usually fall in what range of those obtained with invasive hemoximetry?
3% to 5%
At the very beginning of exhalation, the PETCO2 normally should be at what level?
0 mm Hg
You are asked to calibrate an O2 analyzer. Which of the following gases would you use for this procedure? 1. 100% oxygen 2. 50% oxygen 3. 21% oxygen (room air)
1. 100% oxygen 3. 21% oxygen (room air)
Which of the following are true about a blood gas analyzer's waste fluids? 1. A strong disinfectant should be added to waste fluid containers. 2. Waste fluids should be handled as if they were blood samples. 3. Waste fluids should be treated as potentially infectious.
1. A strong disinfectant should be added to waste fluid containers. 2. Waste fluids should be handled as if they were blood samples. 3. Waste fluids should be treated as potentially infectious.
After obtaining an arterial blood sample, what should you do? 1. Apply pressure to the puncture site until bleeding stops. 2. Place the sample in a transport container with ice slush. 3. Check to see if the patient is getting anticoagulant therapy. 4. Mix the sample by rolling and inverting the syringe.
1. Apply pressure to the puncture site until bleeding stops. 2. Place the sample in a transport container with ice slush. 4. Mix the sample by rolling and inverting the syringe.
Precautions and/or possible complications of arterial puncture include which of the following? 1. Arteriospasm 2. Embolization 3. Infection 4. Hemorrhage
1. Arteriospasm 2. Embolization 3. Infection 4. Hemorrhage
To avoid thermal injury with transcutaneous blood gas monitor sensors, what should you do? 1. Carefully monitor the sensor temperature. 2. Apply hydrocortisone cream under the sensor. 3. Regularly rotate the sensor site.
1. Carefully monitor the sensor temperature. 3. Regularly rotate the sensor site.
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? 1. Check the function of the PCO2 electrode. 2. Rerun the control sample a second time. 3. Repair or replace any failed components. ,
1. Check the function of the PCO2 electrode 3. Repair or replace any failed components.
Which of the following changes would occur if an arterial blood sample of a patient breathing room air were exposed to a large air bubble? 1. Decreased PCO2 2. Decreased pH 3. Increased PO2
1. Decreased PCO2 3. Increased PO2
Which of the following can help avoid the problem of arterial blood sample contamination with air? 1. Discarding frothy samples 2. Fully expelling any bubbles 3. Mixing before expelling air 4. Capping syringe quickly
1. Discarding frothy samples 2. Fully expelling any bubbles 4. Capping syringe quickly
To avoid the dilution effects caused by too much sodium heparin during ABG sampling of an adult, what should you do? 1. Ensure a sample volume greater than 2 ml. 2. Use dry heparin instead. 3. Fill the needle dead space only. 4. Use saline if dry heparin is not available.
1. Ensure a sample volume greater than 2 ml. 2. Use dry heparin instead. 3. Fill the needle dead space only.
Which of the following are indications for capnography? 1. Evaluating the response to therapies affecting ventilation/perfusion ratio () relationships 2. Determining the position of an artificial airway (trachea vs. esophagus) 3. Assessing a patient's readiness for weaning from ventilatory support 4. Monitoring the integrity of the ventilatory circuit and artificial airway
1. Evaluating the response to therapies affecting ventilation/perfusion ratio () relationships 2. Determining the position of an artificial airway (trachea vs. esophagus) 4. Monitoring the integrity of the ventilatory circuit and artificial airway
Which of the following are reasons for finding an alternative site for arterial puncture? 1. Failed Allen test 2. History of peripheral vascular disease 3. Anticoagulation therapy 4. Presence of a surgical shunt
1. Failed Allen test 2. History of peripheral vascular disease 4. Presence of a surgical shunt
Which of the following sites are used for arterial blood sampling by percutaneous needle puncture? 1. Femoral 2. Radial 3. Brachial 4. Carotid
1. Femoral 2. Radial 3. Brachial
Which of the following Centers for Disease Control and Prevention (CDC) barrier precautions would you use when obtaining an arterial blood gas (ABG) through percutaneous puncture? 1. Gloves 2. Protective eyewear 3. Gown or apron
1. Gloves 2. Protective eyewear
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? 1. Inadequate warming of the capillary bed 2. Squeezing of the puncture site 3. Puncture of the infant's heel 4. Use of a lancet.
1. Inadequate warming of the capillary bed 2. Squeezing of the puncture site
Possible complications of capillary blood gas sampling include which of the following? 1. Infection 2. Hematoma 3. Hemorrhage 4. Hypotension
1. Infection 2. Hematoma 3. Hemorrhage
Which of the following are true about invasive versus noninvasive monitoring? 1. Invasive procedures require insertion of a device into the body. 2. Laboratory analysis of gas exchange is usually noninvasive in nature. 3. Physiologic monitoring can be either invasive or noninvasive. 4. Invasive procedures provide more accurate data but carry greater risks.
1. Invasive procedures require insertion of a device into the body.3. Physiologic monitoring can be either invasive or noninvasive. 4. Invasive procedures provide more accurate data but carry greater risks.
Why is the radial artery the preferred site for arterial blood sampling? 1. It is near the surface and easy to palpate and stabilize. 2. The ulnar artery normally provides good collateral circulation. 3. The radial artery is not near any large veins. 4. It is the largest artery located in the upper extremities.
1. It is near the surface and easy to palpate and stabilize. 2. The ulnar artery normally provides good collateral circulation. 3. The radial artery is not near any large veins.
Which of the following indicates venous admixture during arterial puncture? 1. Need to use syringe suction. 2. Dark-colored blood. 3. Small sample volumes.
1. Need to use syringe suction. 3. Small sample volumes.
A practitioner forgets to ice an ABG sample and leaves it at room temperature for 45 min. Which of the following parameters can you predict will increase in this sample during that period? 1. PCO2 2. pH 3. PO2
1. PCO2
What chart information should be checked before performing artery puncture? 1. Patient's primary diagnosis and history 2. Presence of bleeding disorders or blood-borne infections 3. Anticoagulant or thrombolytic drug prescriptions 4. Respiratory care orders (e.g., O2 therapy)
1. Patient's primary diagnosis and history 2. Presence of bleeding disorders or blood-borne infections 3. Anticoagulant or thrombolytic drug prescriptions 4. Respiratory care orders (e.g., O2 therapy)
A physician requests that you obtain and set up an arterial line system for invasive monitoring of blood pressure. Which of the following equipment would you gather? 1. Pressurized intravenous bag 2. Continuous flush device 3. Arterial catheter 4. Volume transducer
1. Pressurized intravenous bag 2. Continuous flush device 3. Arterial catheter
Most pre-analytical ABG errors can be avoided by ensuring that the sample is which of the following? 1. Properly anticoagulated. 2. Obtained anaerobically. 3. Analyzed within 15 to 30 min
1. Properly anticoagulated. 2. Obtained anaerobically. 3. Analyzed within 15 to 30 min.
Before attaching a transcutaneous blood gas monitor sensor to a patient, what should you do? 1. Provide a specified warm-up time and set the probe temperature. 2. Check the membrane and prepare a sensor with an adhesive ring and gel. 3. Prepare the monitoring site (remove excess hair and clean the skin).
1. Provide a specified warm-up time and set the probe temperature. 2. Check the membrane and prepare a sensor with an adhesive ring and gel. 3. Prepare the monitoring site (remove excess hair and clean the skin).
You return to a patient's room 20 min after drawing an ABG. Which of the following should you check at this time? 1. Puncture site for hematoma 2. Adequacy of distal circulation 3. Prothrombin or partial thromboplastin times
1. Puncture site for hematoma 2. Adequacy of distal circulation
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? 1. Random error 2. Bias 3. Imprecision 4. Systematic error
1. Random error 3. Imprecision
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)? 1. Repeat the analysis on a different analyzer. 2. Compare the control to an actual patient sample. 3. Rerun the control sample a second time.
1. Repeat the analysis on a different analyzer. 3. Rerun the control sample a second time.
A patient being monitored by capnography exhibits a sudden rise in end-tidal CO2 levels. Which of the following are possible causes? 1. Sudden release of a tourniquet 2. Massive pulmonary embolism 3. Sudden increase in cardiac output 4. Injection of NaHCO3
1. Sudden release of a tourniquet 3. Sudden increase in cardiac output 4. Injection of NaHCO3
Clinical indications for arterial blood analysis include which of the following? 1. Sudden, unexplained dyspnea 2. Cardiopulmonary resuscitation 3. Changes in ventilator settings 4. Chest pain
1. Sudden, unexplained dyspnea 2. Cardiopulmonary resuscitation 3. Changes in ventilator settings
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%. Which of the following is likely? 1. The pulmonary artery catheter balloon was not deflated. 2. The sample was drawn from the proximal, not distal port. 3. The blood sample was withdrawn too quickly.
1. The pulmonary artery catheter balloon was not deflated. 3. The blood sample was withdrawn too quickly.
Indications for pulse oximetry include which of the following? 1. To assess changes in HbO2 during certain procedures 2. To measure abnormal Hb 3. To comply with external regulations or recommendations 4. To monitor the adequacy of HbO2 saturation
1. To assess changes in HbO2 during certain procedures 3. To comply with external regulations or recommendations 4. To monitor the adequacy of HbO2 saturation
Transcutaneous blood gas monitoring is indicated when what need exists? 1. To continuously analyze gas exchange in infants or children 2. To quantify the real-time responses to bedside interventions 3. To continuously monitor for hyperoxia in newborn infants 4. To monitor CO levels following hyperbaric oxygen treatment
1. To continuously analyze gas exchange in infants or children 2. To quantify the real-time responses to bedside interventions 3. To continuously monitor for hyperoxia in newborn infants
Purposes of a needle-capping device include which of the following? 1. To isolate the sample from air exposure 2. To help prevent needlestick injuries 3. To hold the excess anticoagulant
1. To isolate the sample from air exposure 2. To help prevent needlestick injuries
Before a sample of capillary blood is taken, what should you do to the site? 1. Warmed to 42° C for 10 min. 2. Squeezed lightly until blanched. 3. Cleaned with an antiseptic solution.
1. Warmed to 42° C for 10 min. 3. Cleaned with an antiseptic solution.
Which of the following are true about capillary blood gas sampling? 1. capillary sampling can be used in lieu of direct arterial access in some infants and small children. 2. a capillary sample PO2 provides a fairly close estimate of actual arterial oxygenation. 3. clinicians should exercise caution when using capillary samples to guide decisions. 4. properly obtained capillary blood can provide estimates of arterial pH and PCO2 levels.
1. capillary sampling can be used in lieu of direct arterial access in some infants and small children. 3. clinicians should exercise caution when using capillary samples to guide decisions. 4. properly obtained capillary blood can provide estimates of arterial pH and PCO2 levels.
You obtain an SpO2 reading of 100% on a patient receiving O2 through a nonrebreathing mask. What range of PaO2 levels is possible in this patient?
100 to 600 mm Hg
What is a normal level for CaO2?
18 to 20 ml/100 ml
Statistically derived limits for internal quality control of blood gas samples are usually set at what appropriate level?
2 standard deviations from the mean
What is the appropriate interval for changing the site for a transcutaneous blood gas monitor sensor?
2 to 6 hr
Under ideal conditions, electrochemical oxygen (O2) analyzers have approximately what degree of accuracy?
2%
Capillary puncture should be performed at or through what location? 1. Edematous tissue 2. Earlobe 3. The heal of neonates 4. Toe
2. Earlobe 3. The heal of neonates 4. Toe
Warming a capillary bed to 42° C has which of the following effects? 1. It constricts the underlying blood vessels. 2. It increases blood flow well above tissue needs. 3. It "arterializes" the capillary blood.
2. It increases blood flow well above tissue needs. 3. It "arterializes" the capillary blood.
Which of the following guidelines should you adhere to when performing pulse oximetry? 1. Mix different sensors among different devices to ensure accuracy. 2. Make sure that the sensors are the correct size and are properly applied. 3. Avoid using pulse oximetry to monitor hyperoxia in neonates. 4. Whenever possible, validate the initial SpO2 against the actual SaO2.
2. Make sure that the sensors are the correct size and are properly applied. 3. Avoid using pulse oximetry to monitor hyperoxia in neonates. 4. Whenever possible, validate the initial SpO2 against the actual SaO2.
A blood gas analyzer measures which of the following? 1. HCO3- 2. PCO2 3. PO2 4. pH
2. PCO2 3. PO2 4. pH
Which of the following should be monitored during the sampling of arterial blood? 1. Blood pressure proximal to puncture site 2. Presence of pulsatile blood return 3. Presence of air bubbles or clots in sample 4. Appearance of puncture site
2. Presence of pulsatile blood return 3. Presence of air bubbles or clots in sample 4. Appearance of puncture site
Components of a laboratory blood gas analyzer include which of the following? 1. Two-electrode measuring chamber 2. Reagent containers 3. Calibrating gas tanks 4. Waste container
2. Reagent containers 3. Calibrating gas tanks 4. Waste container
After changing the FiO2 of a critically ill patient, how long should you wait to draw an ABG to monitor the patient's respiratory status?
20 to 30 min
How long should you wait before drawing an ABG on a chronic obstructive pulmonary disease (COPD) patient whose FiO2 has just been changed?
20 to 30 min
What size needle would you recommend to obtain an ABG sample through percutaneous puncture of an infant?
25 gauge
What is the normal gradient between PaCO2 and PETCO2?
3 to 5 mm Hg
What is a normal end-tidal PETCO2 range?
35 to 43 mm Hg
What is the normal range for end-tidal CO2 as measured by capnography?
5% to 6%
A PaO2 below what value would be considered moderate hypoxemia?
55 mm Hg
You obtain an SpO2 reading of 90% using an oximeter with an approximate accuracy of 5%. This could indicate a PO2 as low as what level?
55 mm Hg
Pulse oximeter readings are generally unreliable at saturations below what level?
80%
For continuous monitoring of adults and children, you should set a pulse oximeter's low alarm in what range?
88% to 92%
When is capillary blood gas sampling indicated?
ABG analysis is needed, but arterial access is not available.
Before connecting the sample syringe to an adult's arterial line stopcock, what would you do?
Aspirate 1 to 2 ml of fluid or blood using a waste syringe.
How often should blood gas calibration verification by control media take place?
At least two levels of control media should be analyzed every 8 hr.
The total instrument error (inaccuracy) of a blood gas analyzer equals which of the following?
Bias + imprecision
Which of the following patient parameters does not need to be assessed as part of arterial blood sampling?
Blood pressure
What is the measurement of CO2 in respiratory gases called?
Capnometry
Which of the following can cause false high readings when using a pulse oximeter?
Carboxyhemoglobin
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. Which of the following actions would be correct?
Change the sensor or electrode.
While monitoring an active infant through a transcutaneous blood gas system, you notice a rapid rise in PtcO2 from 63 to 145 mm Hg. At that 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 dislodgment.
To validate patient readings obtained from a transcutaneous blood gas monitor, what should you do?
Compare the monitor's readings to those obtained with a concurrent ABG sample.
How is the accuracy of a blood gas analyzer determined?
Comparing the analyzer's measurements to known values
Which of the following describes the correct procedure for an Allen test?
Compress both the radial and ulnar arteries, and then release the ulnar artery.
Which of the following factors contributing to imprecision (random) errors during blood gas analysis?
Contaminated buffers
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. Which of the following might help to confirm your suspicion?
Cross-check the sample with an SpO2 reading.
Which of the following would you expect to occur if too much heparin was used in gathering an ABG sample from a patient breathing room air?
Decrease in PCO2
You determine that a blood gas sample that requires analysis has been sitting in ice slush for 90 min. What should you do?
Discard the sample and notify the appropriate clinician.
Through which pulmonary artery catheter port would you obtain a mixed venous blood sample?
Distal (catheter tip) port
During a single-breath capnogram, what does the occurrence of a plateau indicate?
Exhalation of mainly alveolar gas
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. Which of the following analytic errors should you suspect?
Exposure of the blood sample to air
What is the greatest hazard of pulse oximetry?
False results leading to incorrect decisions
Which of the following is not a common tissue injury to be on guard for at the site of transcutaneous blood gas electrode placement?
Hematomas
If patient pain or anxiety occurs during arterial puncture, which of the following will probably occur?
Hyperventilation
While checking a polarographic (Clark) electrode, you determine that the device fails to read 100% when exposed to pure O2. Which of the following actions would be the proper first step?
Replace the analyzer's batteries.
What is the most common technique used to measure CO2 in respiratory gases?
Infrared absorption
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 respiratory gas
A patient suffering from traumatic brain injury in the ICU has a PtO2 (tissue oxygen) value of 10 to 15 mm Hg, what does this indicate?
Ischemic brain damage
Which of the following is false about the galvanic fuel cell O2 analyzer?
It requires an external power source (alternating current line or batteries).
How does the Clark polarographic O2 electrode function?
It uses O2 to produce a reduction-oxidation reaction.
What is the best site for capillary puncture in an infant?
Lateral aspect of the heel's plantar surface
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
In which of the following patients would transcutaneous blood gas monitoring most likely provide inaccurate or erroneous results?
Patient in hypovolemic shock
What is the most common source of error and false alarms with pulse oximetry?
Patient motion artifact
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 sec after pressure on the ulnar artery is released. What should you do?
Perform the Allen test on the right hand.
Before performing puncture or cannulation of the radial artery, what should you do?
Perform the Allen test to ensure collateral circulation.
What is the process of testing a new blood gas analyzer to confirm a manufacturer's claims?
Performance validation
What media are used to calibrate a blood gas analyzer's gas electrodes?
Precision mixtures of O2 and CO2
What is the quality control procedure of analysis and reporting on externally provided control media with unknown values?
Proficiency testing
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
To assess gas exchange at the tissues, you would obtain a blood sample from which of the following?
Pulmonary artery (balloon-inflated)
You must immediately begin monitoring the oxygenation status of an infant admitted to the emergency department in severe respiratory distress. Which of the following approaches would you select?
Pulse oximetry (SpO2)
The shape of the expired CO2 tracing of a patient is normal but instead of being zero, the baseline is elevated to approximately 12 mm Hg. Which of the following is the most likely problem?
Rebreathing
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 (<90%). Which of the following would be the best action to take in this situation?
Relocate the sensor to a more stable location.
Which of the following will result in falsely low HbO2 readings with a pulse oximeter?
Vascular dyes
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. Which of the following analytic errors should you suspect?
Sample admixture with venous blood
To measure PCO2, blood gas analyzers use what electrode?
Severinghaus
When performing a percutaneous needle puncture of the radial artery, you get only a small spurt of blood. Which of the following is the best action at this time?
Slowly withdraw the needle until a pulsatile flow fills the syringe.
Oximetry is the measurement of blood hemoglobin saturations using what technique?
Spectrophotometry
Which of the following factors does not contributing to bias (systematic) errors during blood gas analysis
Statistical probability
An alert outpatient awaiting bronchoscopy has an SpO2 reading of 81% breathing room air. The patient appears in no distress and exhibits no signs of hypoxemia. Which of the following would be the best initial action to take in this situation?
Switch sites or replace the sensor probe.
Which of the following is false about transcutaneous blood gas monitoring?
Transcutaneous blood gas monitoring is most accurate when used with older adults.
During capnography monitoring of a mechanically ventilated patient, you note that the PETCO2 has dropped to 0 mm Hg. Which of the following is the most likely problem?
Ventilator disconnection
An outpatient scheduled for an arterial blood sample enters the pulmonary lab 20 min late and out of breath, having run up four flights of stairs. What should you do?
Wait 5 min before taking the sample.
After obtaining an arterial blood sample from an arterial line, you would do which of the following? a. flush the line and stopcock with the heparinized intravenous solution. b. aspirate at least 5 ml of fluid or blood (dead space or waste). c. confirm stopcock port open to intravenous bag solution and catheter. d. confirm undamped pulse pressure waveform on monitor.
a. flush the line and stopcock with the heparinized intravenous solution. c. confirm stopcock port open to intravenous bag solution and catheter. d. confirm undamped pulse pressure waveform on monitor
Required equipment and supplies for percutaneous arterial blood sampling of an adult include all of the following except:
local anesthetic.
Which blood gas analyzer electrode uses a separate reference electrode?
pH
