egans ch 19
The transcutaneous blood gas electrode should not be placed on the:
thigh.
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, 2, and 4 only
The advantage that point-of-care testing has over traditional laboratory testing is that point-of-care testing:
reduces turnaround time.
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 and 2 only
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 and 2 only
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 The blood sample was withdrawn too quickly.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 and 3 only
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 and 3 only
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 and 3 only
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 and 3 only
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 and 3 only
You are asked to calibrate an O2 analyzer. Which of the following gases would you use for this procedure?1. 100% oxygen2. 50% oxygen3. 21% oxygen (room air)
1 and 3 only
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. PCO22. pH3. PO2 Correct!
1 only
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, 2, and 3 only
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, 2, and 3 only
Transcutaneous blood gas monitoring is indicated when what need exists?1. To continuously analyze gas exchange in infants or children2. To quantify the real-time responses to bedside interventions3. To continuously monitor for hyperoxia in newborn infants4. To monitor CO levels following hyperbaric oxygen treatment
1, 2, and 3 only
Which of the following sites are used for arterial blood sampling by percutaneous needle puncture? 1. Femoral 2. Radial 3. Brachial 4. Carotid
1, 2, and 3 only
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, 2, and 3 only
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, 2, and 4 only
Which of the following are indications for capnography?1. Evaluating the response to therapies affecting ventilation/perfusion ratio relationships2. Determining the position of an artificial airway (trachea vs. esophagus)3. Assessing a patient's readiness for weaning from ventilatory support4. Monitoring the integrity of the ventilatory circuit and artificial airway
1, 2, and 4 only
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, 2, and 4 only
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.
At the very beginning of exhalation, the PETCO2 normally should be at what level?
0 mm Hg
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. Gloves2. Protective eyewear3. Gown or apron
1 and 2 only
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 bag2. Continuous flush device3. Arterial catheter4. Volume transducer
1, 2, and 3 only
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
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 and 3 only
What is the appropriate interval for changing the site for a transcutaneous blood gas monitor sensor?
2 to 6 hr
Components of a laboratory blood gas analyzer include which of the following?1. Two-electrode measuring chamber2. Reagent containers3. Calibrating gas tanks4. Waste container
2, 3, and 4 only
Which of the following should be monitored during the sampling of arterial blood?1. Blood pressure proximal to puncture site2. Presence of pulsatile blood return3. Presence of air bubbles or clots in sample4. Appearance of puncture site
2, 3, and 4 only
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 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
A PaO2 below what value would be considered moderate hypoxemia?
55 mm Hg
Pulse oximeter readings are generally unreliable at saturations below what level?
80%
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.
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
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.
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
If patient pain or anxiety occurs during arterial puncture, which of the following will probably occur?
Hyperventilation
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
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 media are used to calibrate a blood gas analyzer's gas electrodes?
Precision mixtures of O2 and CO2
To assess gas exchange at the tissues, you would obtain a blood sample from which of the following?
Pulmonary artery (balloon-inflated)
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.
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
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
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.
All of the following are true about capillary blood gas sampling except:
a capillary sample PO2 provides a fairly close estimate of actual arterial oxygenation.
After obtaining an arterial blood sample from an arterial line, you would do all of the following except:
aspirate at least 5 ml of fluid or blood (dead space or waste).
Required equipment and supplies for percutaneous arterial blood sampling of an adult include all of the following except:
local anesthetic.
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).
All of the above
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.
All of the above
Precautions and/or possible complications of arterial puncture include which of the following?1. Arteriospasm2. Embolization3. Infection4. Hemorrhage
All of the above
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)
All of the above
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.
All of the above
Which of the following patient parameters does not need to be assessed as part of arterial blood sampling?
Blood pressure
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.
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.
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
