Egan's Chapter 14 and 19
Factors contributing to bias (systematic) errors during blood gas analysis include all of the following except: a. incorrect procedures b. statistical probability c. contaminated buffers d. component failure
b. statistical probability
Treatment parameters that should be assessed as part of arterial blood sampling include all of the following except: a. mode of ventilatory support and settings b. time of last incentive breathing exercise c. FIO2 (analyzed) or prescribed flow d. proper application of the O2 device
b. time of last incentive breathing exercise
What media are used to calibrate a blood gas analyzer's gas electrodes? a. standard pH buffer solutions b. blood-like control media c. precision mixtures of O2 and CO2 d. tonometered human blood samples
c. precision mixtures of O2 and CO2
What is the quality control procedure of analysis and reporting on externally provided control media with unknown values? a. automated calibration b. performance validation c. proficiency testing d. preventive maintenance
c. proficiency testing
What size needle would you recommend to obtain an ABG sample through percutaneous puncture of an infant? a. 18 gauge b. 20 gauge c. 22 gauge d. 25 gauge
d. 25 gauge
All of the following are common sites for transcutaneous blood gas electrode placement except the: a. chest b. abdomen c. lower back d. thigh
d. thigh
Compensation for metabolic acidosis occurs through which of the following?
decrease in blood CO2- levels
If the blood PCO2 is high, the kidneys will do which of the following?
excrete more H+ and reabsorb more HCO3-
What explains the lack of an increased anion gap seen in metabolic acidosis caused by HCO3- loss?
for each HCO3- ion lost, a Cl- ion is reabsorbed by the kidney
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.38, PCO2 = 21 mm Hg, HCO3- = 11.7 mEq/L
fully compensated metabolic acidosis
A patient who has fully compensated respiratory acidosis becomes severely hypoxic. If her lungs are not too severely compromised, what might her gases now appear to be?
fully compensated metabolic alkalosis
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.35, PCO2 = 68 mm Hg, HCO3- = 34.3 mEq/L
fully compensated respiratory acidosis
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.43, PCO2 = 20 mm Hg, HCO3- = 12.6 mEq/L
fully compensated respiratory alkalosis
Primary metabolic alkalosis is associated with which of the following?
gain of buffer base
What would be an example of an iatrogenic cause of metabolic alkalosis?
gastric suction
Of the non-bicarbonate buffer systems, which one is the most important?
hemoglobin
What is the main compensatory mechanism for metabolic acidosis?
hyperventilation
What compensates for a metabolic alkalosis?
hypoventilation
What is the most common cause of respiratory alkalosis?
hypoxemia
In regard to acid excretion by the body, which of the following statements are true?
if one system fails the other help compensate, the kidneys can only remove fixed acids, and the lungs can quickly remove acid
What is the primary chemical event in respiratory acidosis?
increase in blood CO2 levels
Compensation for respiratory acidosis occurs through which of the following?
increase in blood HCO3- levels
What is the primary chemical event in metabolic alkalosis?
increase in blood HCO3- levels
What is the limiting factor for H+ excretion in the renal tubules?
insufficient buffers
What are the major mechanisms responsible for maintaining a stable pH despite massive CO2 production?
isohydric buffering and pulmonary ventilation
Of what use is the Henderson-Hasselbach equation for a clinician?
it allows validation of the reported values on a blood gas report
What effect does hyperventilation have on the closed buffer systems?
it causes them to release more H+
What is the role of carbonic anhydrase in the kidneys?
it drives the recovery of HCO3 and excretion of H+
Fixed acids are produced primarily from the catabolism of which of the following?
proteins
Which organ system maintains the normal level of HCO3- at 24 mEq/L?
renal
The numerator of the Henderson-Hasselbach (H-H) equation (HCO3-) related to which of the following?
renal buffering and excretion of fixed acids
Compensation for respiratory alkalosis occurs through which of the following?
renal excretion of HCO3-
An increase in the H+ ion concentration [H+] of the blood due only to an increase in the arterial PCO2 (hypercapnia) best describes which of the following?
respiratory acidosis
A decrease in the H+ ion concentration (H+) of the blood caused by a low PaCO2 best describes which of the following?
respiratory alkalosis
An ABG result shows the pH to be 7.56 and the HCO3- to be 23 mEq/L. Which of the following is the most likely disorder?
respiratory alkalosis
Normally which of the following occur when the kidneys eliminate H+?
sodium ions (and water) are reabsorbed, HCO3- is reabsorbed in proportion to the H+ excreted, and bicarbonate buffer capacity is restored
What is the kidney's most important function?
sodium maintenance
In order to eliminate the influence of PCO2 changes on plasma HCO3- concentrations, what additional measures of the metabolic component of acid-base balance can be used?
standard bicarbonate
Which of the following statements about the equilibrium constant of an acid is true?
the equilibrium constant of a weak acid is small
A patient has an anion gap of 21 mEq/L. Based on this information, what can you conclude?
the patient probably has metabolic acidosis because there is an abnormal excess of unmeasured anions in his plasma
The majority of the acid the body produces in a day is excreted through the lungs as CO2. What happens to the H+ ions?
they bind to an OH-forming H2O
Using the Henderson-Hasselbalch equation, determine the accuracy of the gas below. To be considered accurate, it must be within 0.03 pH unit. pH = 7.22, PCO2 = 49 mm Hg, HCO3- = 20 mEq/L
this gas is accurate as the calculated pH is 7.23
Using the Henderson-Hasselbach equation, determine the accuracy of the gas below. To be considered accurate, it must be within 0.03 pH unit.pH = 7.35, PCO2 = 77 mm Hg, HCO3- = 41 mEq/L
this gas is completely accurate
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.08, PCO2 = 39 mm Hg, HCO3- = 11.8 mEq/L
uncompensated metabolic acidosis
Based on the following ABG results, what is the most likely acid-base diagnosis? pH=7.62, PCO2=41 mmHg, HCO3=40.9 mEq/L
uncompensated metabolic alkalosis
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 7.28, PCO2 = 53 mm Hg, HCO3- = 25.8 mEq/L
uncompensated respiratory acidosis
What drives the bicarbonate buffer system enormous ability to buffer acids?
ventilation continually removing CO2 from system
When a strong acid is added to the bicarbonate buffer system, what is the result?
weak acid and neutral salt
Approximately how much CO2 is removed daily by the lungs?
~24,000 mmol/L of CO2
What is the normal range for BE?
±2 mEq/L
In acute respiratory acidosis, what would you expect the BE range to be?
+2 to -2 mEq/L
Which of the following are potential causes of respiratory alkalosis?
- anxiety - hypoxemia - pain
Which of the following are signs and symptoms of acute respiratory alkalosis?
- convulsions - dizziness - paresthesia
In the face of uncompensated respiratory acidosis, which of the following blood gas abnormalities would you expect to encounter?
- decreased pH - increased PCO2
Which of the following is/are causes of metabolic alkalosis?
- diuretics - hypochloremia - vomiting
Which of the following clinical findings would you expect in a fully compensated respiratory acidosis?
- elevated HCO3- - pH between 7.35-7.39
Which of the following is/are true about the relationship between chloride (Cl-) and bicarbonate HCO3- in acid-base balance?
- for each Cl- ion excreted into the urine, the blood gas gains an HCO3- ion - blood Cl- and HCO3- ion levels are reciprocally related - people with chronically high CO2 tend to have low blood Cl-levels
Which of the following are components of the body's non-bicarbonate buffer system?
- hemoglobin - plasma proteins - organic phosphates - inorganic phosphates
Which of the following is/are causes of hyperchloremic metabolic acidosis?
- hyperalimentation - NH4Cl administration
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 - didn't disinfect area
In a patient with partially compensated respiratory alkalosis, which of the following blood gas abnormalities would you expect to encounter?
- increased pH - decreased PCO2 - decreased HCO3-
What are some causes of metabolic acidosis with an increased anion gap?
- ketoacidosis - lactic acidosis - renal failure
Causes of respiratory acidosis in patients with normal lungs include which of the following?
- neuromuscular disorders - spinal cord trauma - anesthesia
Which of the following mechanisms helps to eliminate excess H+ via the kidneys?
- reabsorption of HC03- - phosphate buffering - ammonia buffering
Correction of metabolic alkalosis may involve which of the following?
- restoring normal fluid volume - administering acidifying agents - restoring normal K+ and Cl- levels
A 21 year old woman in the emergency room is displaying rapid and deep, labored breathing. Her room ABG reveals a pH of 7.25, PaCO2 of 28, HCO3- of 14 mEq/L, and a base excess of -14 mEQ/L. How would the respiratory therapist assess her acid-base condition?
- severe hyperventilation - partially compensated and metabolic acidosis - compensatory response to the metabolic acidosis
When does a state of alkalemia exist?
- the HCO3-/CO2 ratio exceeds 20:1 - the blood pH exceeds 7.45
According to the Henderson-Hassebach equation, the blood pH will rise (alkalemia) under which of the following conditions?
- the buffer capacity increases - the volatile acid (CO2) decreases
A patient has a PCO2 of 80 mm Hg. What is the concentration of dissolved CO2 (in mmol/L) in the blood?
2.4 mmol/L
According to the Henderson-Hasselbach equation, the pH of the blood will be normal as long as the ratio of HC03- to dissolved CO2 in which of the following?
20:1
What is the normal arterial blood pH range?
7.35-7.45
A patient has a bicarbonate concentration of 36 mEq and a PCO2 of 60 mm Hg. What is the approximate pH?
7.4
What is a normal anion gap range?
9 to 14 mEq/L
What is the normal range for end-tidal CO2 as measured by capnography? a. 0% to 5% b. 5% to 6% c. 6% to 8% d. 35% to 45%
b. 5% to 6%
A patient with a measured plasma HCO3- concentration of 24 mmol/L has an episode of acute hypoventilation, with the PCO2 rising from 40 to 70 mm Hg. What do you predict will happen acutely to the plasma HC03- concentration?
HC03- will rise to approximately 27 to 28 mmol/L
What is the primary buffer system for fixed acids?
HCO3-
Which of the following systems is primarily responsible for the buffering of fixed acids?
HCO3-
[H+] can be determined by the use of which factors?
HCO3- and H2C03
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
What is the treatment for severe metabolic acidosis?
NaHCO3- infusion
A PaO2 below what value would be considered moderate hypoxemia? a. 60 mm Hg b. 50 mm Hg c. 40 mm Hg d. depends on the FIO2
b. 50 mm Hg
What is the best site for capillary puncture in an infant? a. lateral aspect of the heel's plantar surface b. anterior curvature of the heel c. medial aspect of the heel's plantar surface d. posterior curvature of the heel
a. lateral aspect of the heel's plantar surface
At the very beginning of exhalation, the PETCO2 normally should be at what level? a. 0 mm Hg b. 15 mm Hg c. 25 mm Hg d. 40 mm Hg
a. 0 mm Hg
A practitioner forgets to ice an ABG sample and leaves it at room temperature for 45 minutes. Which of the following parameters can you predict will increase in this sample during that period? 1. PCO2 2. pH 3. PO2 a. 1 b. 1 and 2 c. 2 and 3 d. 1, 2, and 3
a. 1
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 a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
a. 1 and 2
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 a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
a. 1 and 2
You return to a patient's room 20 minutes 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 a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
a. 1 and 2
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 a. 1 and 3 b. 2 and 4 c. 1, 2, and 4 d. 1, 2, 3, and 4
a. 1 and 3
What is the normal gradient between PaCO2 and PETCO2? a. 3 to 5 mm Hg b. 5 to 10 mm Hg c. 10 to 15 mm Hg d. 15 to 20 mm Hg
a. 3 to 5 mm Hg
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? a. 55 mm Hg b. 60 mm Hg c. 65 mm Hg d. 70 mm Hg
a. 55 mm Hg
A blood gas analyzer measures all of the following except: a. HCO3 b. PCO2 c. PO2 d. pH
a. HCO3
To measure PCO2, blood gas analyzers use what electrode? a. Severinghaus b. Clark c. Sahn d. White
a. 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? a. Slowly withdraw the needle until a pulsatile flow fills the syringe. b. Pull out entirely, use a different angle and then reinsert it. c. Slowly advance the needle until a pulsatile flow fills the syringe. d. Repeat the procedure with a fresh blood gas kit.
a. Slowly withdraw the needle until a pulsatile flow fills the syringe.
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. Which of the following would be the best initial action to take in this situation? a. Switch sites or replace the sensor probe. b. Immediately start O2 therapy. c. Obtain an ABG. d. Cancel the bronchoscopy procedure.
a. Switch sites or replace the sensor probe.
The total instrument error (inaccuracy) of a blood gas analyzer equals which of the following? a. bias + imprecision b. imprecision + random error c. bias + systematic error d. trend error + bias
a. bias + imprecision
What is the greatest hazard of pulse oximetry? a. false results leading to incorrect decisions b. pressure sores at the measuring site c. skin burns due to using incompatible probes d. electrical shock at the measuring site
a. false results leading to incorrect decisions
What is the most common technique used to measure CO2 in respiratory gases? a. infrared absorption b. mass spectroscopy c. photoacoustics d. Raman scattering
a. infrared absorption
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? a. proximal to the heated humidifier b. on the expiratory side of the circuit c. distal to the heated humidifier d. as close to the patient as possible
a. proximal to the heated humidifier
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? a. pulse oximetry (SpO2) b. transcutaneous monitoring (PtcO2) c. arterial puncture (PaO2) d. intraarterial optode monitoring
a. pulse oximetry (SpO2)
The advantage that point-of-care testing has over traditional laboratory testing is that point-of-care testing: a. reduces turnaround time b. utilizes equipment that is less expensive c. does not require trained personnel to run the tests d. is more accurate than traditional laboratory testing
a. reduces turnaround time
All of the following can result in falsely high HbO2 readings with a laboratory hemoximeter except: a. sickle cell anemia b. high levels of fetal Hb c. elevated bilirubin levels d. dirty cuvet chamber
a. sickle cell anemia
A patient has a pH of 7.49. How would you describe this?
alkalemia
Why is a buffer system such as phosphate considered a closed system?
all the components remain in the system
Metabolic acidosis may be caused by:
an increase in fixed (nonvolatile) acids and excessive loss of bicarbonate (HCO3-)
After obtaining an arterial blood sample through percutaneous puncture using a syringe that does not have a capping safety device, what should you do? a. Remove the needle with a Kelly clamp, then plug the syringe. b. "Scoop" the needle cap up with one hand, then plug the syringe. c. Force the needle into a rubber cork or plastic stopper. d. Manually remove and bend the needle, then plug the syringe.
b. "Scoop" the needle cap up with one hand, then plug the syringe.
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
Pulse oximeter readings are generally unreliable at saturations below what level? a. 70% b. 80% c. 90% d. 95%
b. 80%
Before a sample of capillary blood is taken, what should you do to the site? 1. warmed to 42° C for 10 minutes 2. squeezed lightly until blanched 3. cleaned with an antiseptic solution a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
What is a normal end-tidal PETCO2 range? a. 30 to 38 mm Hg b. 35 to 43 mm Hg c. 38 to 46 mm Hg d. 42 to 50 mm Hg
b. 35 to 43 mm Hg
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
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 a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
Which of the following indicates venous admixture during arterial puncture? 1. need to use syringe suction 2. dark-colored blood 3. small sample volumes a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
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). a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
b. 1 and 3
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. a. 1 and 2 b. 1, 2, and 4 c. 3 and 4 d. 1, 2, 3, and 4
b. 1, 2, and 4
Statistically derived limits for internal quality control of blood gas samples are usually set at what appropriate level? a. 1 standard deviation from the mean b. 2 standard deviations from the mean c. 3 standard deviations from the mean d. 5 standard deviations from the mean
b. 2 standard deviations from the mean
What is the appropriate interval for changing the site for a transcutaneous blood gas monitor sensor? a. 1 to 2 hours b. 2 to 6 hours c. 6 to 8 hours d. 8 to 12 hours
b. 2 to 6 hours
Under ideal conditions, electrochemical oxygen (O2) analyzers have approximately what degree of accuracy? a. 1% b. 2% c. 3% d. 4%
b. 2%
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 a. 1, 2, and 3 b. 2, 3, and 4 c. 1, 2, 3, and 4 d. 2 and 3
b. 2, 3, and 4
All of the following are TRUE about capillary blood gas sampling except: a. Capillary sampling can be used in lieu of direct arterial access in some infants and small children. b. A capillary sample PO2 provides a fairly close estimate of actual arterial oxygenation. c. Clinicians should exercise caution when using capillary samples to guide decisions. d. Properly obtained capillary blood can provide estimates of arterial pH and PCO2 levels.
b. 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: 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.
b. Aspirate at least 5 ml of fluid or blood (dead space or waste).
Before connecting the sample syringe to an adult's arterial line stopcock, what would you do? a. Flush the line and stopcock with the heparinized intravenous solution. b. Aspirate at least 5 ml of fluid or blood using a waste syringe. c. Align the stopcock off to the patient and on to the flush solution. d. Increase the flush-solution bag pressure by 20 to 30 mm Hg.
b. Aspirate at least 5 ml of fluid or blood using a waste syringe.
Which of the following describes the correct procedure for an Allen test? a. Compress both the radial and ulnar arteries, then release the radial artery. b. Compress both the radial and ulnar arteries, then release the ulnar artery. c. Compress both the radial and ulnar arteries, then release both arteries at once. d. Compress the brachial artery only and observe circulation to the hand.
b. Compress both the radial and ulnar arteries, then release the ulnar artery.
Which of the following is FALSE about the galvanic fuel cell O2 analyzer? a. It actually measures the PO2 and not the O2 concentration. b. It requires an external power source (alternating current line or batteries). c. It has a slower response time than the Clark electrode. d. Its fuel cells deplete and must be periodically replaced.
b. It requires an external power source (alternating current line or batteries).
Which of the following is false about invasive versus noninvasive monitoring? a. Invasive procedures require insertion of a device into the body. b. Laboratory analysis of gas exchange is usually noninvasive in nature. c. Physiologic monitoring can be either invasive or noninvasive. d. Invasive procedures provide more accurate data but carry greater risks.
b. Laboratory analysis of gas exchange is usually noninvasive in nature.
Before performing puncture or cannulation of the radial artery, what should you do? a. Fix and tighten a tourniquet above the antecubital fossa. b. Perform the Allen test to ensure collateral circulation. c. Inject heparin into the adjoining subcutaneous tissues. d. Apply firm pressure to the arterial site for 5 minutes.
b. Perform the Allen test to ensure collateral circulation.
Which of the following is FALSE about transcutaneous blood gas monitoring? a. Transcutaneous blood gas monitoring provides a reasonable estimate of PaO2 and PaCO2. b. Transcutaneous blood gas monitoring is most accurate when used with older adults. c. Accurate estimates of transcutaneous blood gases are difficult in patients with shock. d. Transcutaneous blood gas monitors use heated skin electrodes to arterialize the blood.
b. Transcutaneous blood gas monitoring is most accurate when used with older adults.
Indications for arterial blood sampling by percutaneous needle puncture include all of the following except the need to: a. monitor the severity of a disease process b. assess the adequacy of tissue oxygenation c. evaluate ventilation and acid-base status d. evaluate a patient's response to therapy
b. assess the adequacy of tissue oxygenation
What is the measurement of CO2 in respiratory gases called? a. oximetry b. capnometry c. optometry d. barometryb. capnometry
b. capnometry
How is the accuracy of a blood gas analyzer determined? a. examining the repeatability of the analyzer's results b. comparing the analyzer's measurements to known values c. adjusting the offset (or balance) of the instrument d. adjusting the gain (or slope) of the instrument
b. comparing the analyzer's measurements to known values
Factors contributing to imprecision (random) errors during blood gas analysis include all of the following except: a. sample contamination b. contaminated buffers c. statistical probability d. sample mishandling
b. contaminated buffers
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? a. increase in HCO3- b. decrease in PCO2 c. decrease in pH d. decrease in PO2
b. decrease in PCO2
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? a. excessive time since sample collection b. exposure of the blood sample to air c. excessive heparin in the sample d. sample admixture with venous blood
b. exposure of the blood sample to air
Indications for pulse oximetry include all of the following except the need a. to assess changes in HbO2 during certain procedures b. for measurements of abnormal Hb c. to comply with external regulations or recommendations d. to monitor the adequacy of HbO2 saturation
b. for measurements of abnormal Hb
Tissue injuries to be on guard for at the site of transcutaneous blood gas electrode placement include all of the following except which one? a. erythema b. hematomas c. burns or blisters d. skin tears
b. hematomas
If patient pain or anxiety occurs during arterial puncture, which of the following will probably occur? a. hypoventilation b. hyperventilation c. respiratory acidosis d. hypoxemia
b. hyperventilation
During a single-breath capnogram, the sharp downstroke and return to baseline that normally occurs after the end-tidal point indicates what? a. exhalation of mainly dead space gas b. inspiration of fresh respiratory gas c. exhalation of mixed alveolar and dead space gas d. exhalation of mainly alveolar gas
b. inspiration of fresh respiratory gas
A patient being monitored by capnography exhibits a sudden rise in end-tidal CO2 levels. All of the following are possible causes of this change except: a. sudden release of a tourniquet b. massive pulmonary embolism c. sudden increase in cardiac output d. injection of NaHCO3
b. massive pulmonary embolism
Which blood gas analyzer electrode uses a separate reference electrode? a. O2 b. pH c. Clark d. HCO3
b. pH
What is the most common source of error and false alarms with pulse oximetry? a. presence of HbCO b. patient motion artifact c. presence of vascular dyes d. ambient light detection
b. patient motion artifact
What is the process of testing a new blood gas analyzer to confirm a manufacturer's claims? a. automated calibration b. performance validation c. proficiency testing d. preventive maintenance
b. performance validation
Which buffer system has the greatest capacity?
bicarbonate
Which of the following acts as the "first-line" or immediate defense against the accumulation of H+ ions?
blood buffer system
An ABG result shows pH of 7.35, PaCO2 of 30 mmHg, and HCO3- of 18 mEq/L. What compensatory measures has the body taken to at least partially compensate for the acid-base disorder?
blown off CO2
What is the sum of all blood buffers in 1 L of blood?
buffer base
A solution that resists large changes in pH upon addition of an acid or a base best describes which of the following?
buffer solution
How is acute respiratory acidosis accomplished?
by increasing alveolar ventilation
What is a normal level for CaO2? a. 12 to 15 ml/100 ml b. 14 to 16 ml/100 ml c. 18 to 20 ml/100 ml d. 16 to 22 ml/100 ml
c. 18 to 20 ml/100 ml
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
c. 2 and 3
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? a. 5-10 minutes b. 10-20 minutes c. 20-30 minutes d. 30-40 minutes
c. 20-30 minutes
Under ideal conditions, pulse oximeter readings patients usually fall in what range of those obtained with invasive hemoximetry? a. 1% to 2% b. 2% to 3% c. 3% to 5% d. 5% to 7%
c. 3% to 5%
For continuous monitoring of adults and children, you should set a pulse oximeter's low alarm in what range? a. 80% to 85% b. 85% to 88% c. 88% to 92% d. 93% to 97%
c. 88% to 92%
When is capillary blood gas sampling indicated? a. There is a need for direct analysis of blood oxygenation. b. Normal noninvasive monitor readings need to be checked. c. ABG analysis is needed, but arterial access is not available. d. Continuous data on patient ventilation status are needed.
c. ABG analysis is needed, but arterial access is not available.
How often should blood gas calibration verification by control media take place? a. At least one level of control media should be analyzed every 8 hours. b. At least two levels of control media should be analyzed every day. c. At least two levels of control media should be analyzed every 8 hours. d. At least two levels of control media should be analyzed every hour.
c. At least two levels of control media should be analyzed every 8 hours.
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? a. Perform a quick assessment of the infant's airway. b. Stabilize the infant and call for emergency assistance. c. Check the sensor for air leaks or dislodgment. d. Remove the sensor and recalibrate the instrument.
c. Check the sensor for air leaks or dislodgment.
To validate patient readings obtained from a transcutaneous blood gas monitor, what should you do? a. Measure and compare the PtcO2 and PtcCO2 at three or more different sites. b. Compare the monitor's readings to a concurrent pulse oximetry reading. c. Compare the monitor's readings to those obtained with a concurrent ABG sample. d. Compare the patient reading to those obtained when calibrating the sensor.
c. Compare the monitor's readings to those obtained with a concurrent ABG sample.
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? a. Call the lab to get the latest chemistry report. b. Inspect the sample for color and consistency. c. Cross-check the sample with a SpO2 reading. d. Measure the sample's actual hemoglobin saturation.
c. Cross-check the sample with a SpO2 reading.
How does the Clark polarographic O2 electrode function? a. It measures the magnetic properties of O2 versus N2. b. It measures the electrical potential across a Wheatstone bridge. c. It uses O2 to produce a reduction-oxidation reaction. d. It measures the comparative cooling effect on a heated wire.
c. It uses O2 to produce a reduction-oxidation reaction.
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? a. Check the silica crystals. b. Send the device out for repair. c. Replace the analyzer's batteries. d. Change the analyzer's fuel cell.
c. Replace the analyzer's batteries.
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? a. Postpone the blood sample until tomorrow. b. Scold the patient for being so late. c. Wait 5 minutes before taking the sample. d. Scold the patient for using the stairs.
c. Wait 5 minutes before taking the sample.
All of the following are grounds for finding an alternative site for arterial puncture except: a. failed Allen test b. history of peripheral vascular disease c. anticoagulation therapy d. presence of a surgical shunt
c. anticoagulation therapy
All of the following are indications for capnography except: a. evaluating the response to therapies affecting ventilation/perfusion ratio relationships b. determining the position of an artificial airway (trachea versus esophagus) c. assessing a patient's readiness for weaning from ventilatory support d. monitoring the integrity of the ventilatory circuit and artificial airway
c. assessing a patient's readiness for weaning from ventilatory support
Which of the following can cause false high readings when using a pulse oximeter? a. fetal hemoglobin b. intravascular dyes c. carboxyhemoglobin d. presence of metHb
c. carboxyhemoglobin
Through which pulmonary artery catheter port would you obtain a mixed venous blood sample? a. proximal (right atrium) port b. catheter thermistor connector c. distal (catheter tip) port d. balloon inflation port
c. distal (catheter tip) port
During capnography monitoring of a mechanically ventilated patient, you note that the PETCO2 has dropped to 0 mm Hg. All of the following are possible causes of this finding except: a. ventilator disconnection b. esophageal intubation c. increased cardiac output d. cardiac arrest
c. increased cardiac output
All of the following can help avoid the problem of arterial blood sample contamination with air except: a. discarding frothy samples b. fully expelling any bubbles c. mixing before expelling air d. capping syringe quickly
c. mixing before expelling air
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. Which of the following is the most likely problem? a. patient disconnected from the system b. obstruction of the sampling tube c. rebreathing d. presence of N2O
c. rebreathing
A metabolic acidosis caused by HCO3- loss:
can be a result of ammonium chloride ingestion, may be referred to as hyperchloremic acidosis, accompanied by Cl- gain
Which of the following is a volatile acid of physiologic significance?
carbonic
Based on the following ABG results, what is most likely acid-base diagnosis? pH = 7.62, PCO2 = 32 mm Hg, HCO3- = 29 mEq/L
combined metabolic and respiratory alkalosis
Based on the following ABG results, what is the most likely acid-base diagnosis?pH = 7.01, PCO2 = 71 mm Hg, HCO3- = 16.3 mEq/L
combined respiratory and metabolic acidosis
What is a normal response of the body to a failure in one component of the acid-base regulatory mechanism?
compensation
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. pressure transducer 5. amplifier or monitor a. 1, 3, and 4 b. 2, 3, 4, and 5 c. 3, 4, and 5 d. 1, 2, 3, 4, and 5
d. 1, 2, 3, 4, and 5
Capillary puncture should NOT be performed at or through what location? 1. inflamed or edematous tissue 2. localized areas of infection 3. the fingers of neonates 4. previous puncture sites 5. ring or great finger a. 2 and 3 b. 2 and 4 c. 1, 2, 4, and 5 d. 1, 2, 3, and 4
d. 1, 2, 3, and 4
Components of a laboratory blood gas analyzer include which of the following? 1. three-electrode measuring chamber 2. reagent containers 3. calibrating gas tanks 4. waste container a. 1, 2, and 4 b. 2 and 3 c. 2 and 4 d. 1, 2, 3, and 4
d. 1, 2, 3, and 4
Precautions and/or possible complications of arterial puncture include which of the following? 1. arteriospasm 2. embolization 3. infection 4. hemorrhage a. 1, 2, and 3 b. 2 and 3 c. 2 and 4 d. 1, 2, 3, and 4
d. 1, 2, 3, and 4
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) a. 1, 2, and 3 b. 2 and 3 c. 2, 3, and 4 d. 1, 2, 3, and 4
d. 1, 2, 3, and 4
Which of the following guidelines should you adhere to when performing pulse oximetry? 1. Never mix different sensors among different devices. 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. 1 and 3 b. 1, 2, and 3 c. 3 and 4 d. 1, 2, 3, and 4
d. 1, 2, 3, and 4
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). a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
Most preanalytical 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 minutes a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
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 a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
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. a. 1 and 2 b. 1 and 3 c. 2 and 3 d. 1, 2, and 3
d. 1, 2, and 3
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? a. 60 to 90 mm Hg b. 90 to 100 mm Hg c. 100 to 200 mm Hg d. 100 to 600 mm Hg
d. 100 to 600 mm Hg
How long should you wait before drawing an ABG on a chronic obstructive pulmonary disease (COPD) patient whose FIO2 has just been changed? a. 5 to 10 minutes b. 10 to 15 minutes c. 15 to 20 minutes d. 20 to 30 minutes
d. 20 to 30 minutes
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. Which of the following actions would be correct? a. Use it only with low Fio2 values. b. Send the device out for repair. c. Replace the unit's batteries. d. Change the sensor or electrode.
d. Change the sensor or electrode.
You determine that a blood gas sample that requires analysis has been sitting in ice slush for 90 minutes. What should you do? a. Go ahead and analyze the sample (because it was on ice). b. Warm the sample to room temperature before analysis. c. Readjust the blood gas analyzer temperature to 0 C. d. Discard the sample and notify the appropriate clinician.
d. Discard the sample and notify the appropriate clinician.
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? a. Use the brachial site for sampling. b. Sample from the contralateral radial artery. c. Use the femoral site for sampling. d. Perform the Allen test on the right hand.
d. Perform the Allen test on the right hand.
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%). Which of the following would be the best action to take in this situation? a. Sedate the patient and restrain the arms. b. Reset the low alarm limit to the 80% to 85% range. c. Use a spot check instead of continuous monitoring. d. Relocate the sensor to a more stable location.
d. Relocate the sensor to a more stable location.
All of the following sites are used for arterial blood sampling by percutaneous needle puncture except: a. femoral b. radial c. brachial d. carotid
d. carotid
During a single-breath capnogram, what does the occurrence of a plateau indicate? a. exhalation of mainly dead space gas b. inspiration of fresh respiratory gas c. exhalation of mixed alveolar and dead space gas d. exhalation of mainly alveolar gas
d. exhalation of mainly alveolar gas
Possible complications of capillary blood gas sampling include all of the following except: a. infection b. hematoma c. hemorrhage d. hypotension
d. hypotension
Required equipment and supplies for percutaneous arterial blood sampling of an adult include all of the following except: a. antiseptic (alcohol or Betadine) b. patient or sample label c. 20- to 22-gauge needle d. local anesthetic
d. local anesthetic
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? a. two different parameters at the same time b. parameters with known input values at one point c. two different parameters at different times d. parameters with known input values at two points
d. 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? a. newborn infant with respiratory distress syndrome (RDS) b. patient with hypoxemia c. patient with a hyperpyrexia d. patient in hypovolemic shock
d. patient in hypovolemic shock
To assess gas exchange at the tissues, you would obtain a blood sample from which of the following? a. pulmonary artery (balloon-deflated) b. peripheral artery (radial, brachial) c. central vein (superior or inferior vena cava) d. pulmonary artery (balloon-inflated)
d. pulmonary artery (balloon-inflated)
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? a. excessive time since sample collection b. exposure of the blood sample to air c. excessive heparin in the sample d. sample admixture with venous blood
d. sample admixture with venous blood
Oximetry is the measurement of blood hemoglobin saturations using what technique? a. electrochemical dissociation b. photoplethysmography c. photochemical reactions d. spectrophotometry
d. spectrophotometry
A patient has a blood gas result of: pH 7.29, PaCO2 of 60 mmHg, and a HCO3- of 18 mEq/L. What is the blood gas indicating?
it is indicating a combined acidosis, patient has a primary respiratory and a primary metabolic disorder, and compensation is not possible
Why is the bicarbonate buffer system considered an open buffer system?
its acid (carbonic acid) is converted to CO2 and removed
Which organ system actually excreted H+ from the body?
kidneys
Which of the following organ systems assist in acid excretion?
kidneys and lungs
Which of the following accurately describes compensation for acid-base disorders?
kidneys take hours to days to compensate for respiratory disorders
What effect does hyperventilation have on HCO3- recovery in the kidneys?
less H+ excretion, greater HCO3- loss
By comparison, how much fixed acids is produced in any given period compared to the volatile acid CO2?
less fixed than volatile
What factor would limit the ability of the H2CO3/HCO3- buffer system to perform efficiently?
lungs failing to excrete adequate levels of CO2
What condition or treatment could cause iatrogenic respiratory alkalosis?
mechanical hyperventilation
An ABG result shows pH of 7.35, PaCO2 of 30 mm Hg, and HCO3- of 18 mEq/L. Which of the following is the patient's most likely primary disorder?
metabolic acidosis
In a patient with Kussmaul's respirations, what acid-base disturbance would you expect to see?
metabolic acidosis
A 31-year-old man suffering from food poisoning is having severe vomiting for the last 2 days. His blood gas and serum electrolyte analyses revealed the following: pH of 7.60, PaCO2 of 49 mm Hg, an HCO3- of 47 mEq/L, a base excess (BE) of +20 mEq/L, a serum K+ of 2.5 mEq/L, and a serum of Cl- of 92 mEq/L. How would the respiratory therapist assess his acid-base condition?
metabolic alkalosis and minimal hypoventilation
Based on the following ABG results, what is the most likely acid-base diagnosis? pH=7.43, PCO2=39mmHg, HCO3-=25.1 mEq/L
normal acid base
The primary goal of acid-base homeostasis is to maintain which of the following?
normal pH
Based on the following ABG results, what is the most likely acid-base diagnosis? pH = 6.89, PCO2 = 24 mm Hg, HCO3- = 4.7 mEq/L
partially compensated metabolic acidosis
