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CPFT practice questions

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Question 1Patient assessment and preparation

A patient uses albuterol as needed for relief of breathlessness. Before spirometry, the technologist should instruct the patient to withhold this medication for at least how long?

  1. 12 to 24 hours
  2. 48 hours
  3. 30 minutes
  4. 4 to 6 hours Correct answer.

Explanation

Short-acting beta-2 agonists are conventionally withheld for at least 4 to 6 hours before bronchodilator-responsive testing so that the airway is not already maximally dilated. Longer-acting agents require substantially longer washout periods. Adequate withholding preserves the ability to detect a bronchodilator response.

Question 2Patient assessment and preparation

Which instruction is most appropriate for a patient scheduled for diffusing capacity testing?

  1. Avoid smoking for 20 minutes before the test
  2. Smoke no more than one cigarette beforehand
  3. No change in smoking habits is needed
  4. Avoid smoking for at least 24 hours Correct answer.

Explanation

Smoking raises carboxyhemoglobin, which competes with carbon monoxide for hemoglobin binding sites and falsely lowers the measured diffusing capacity. A 24-hour abstinence period is therefore recommended before this test. Shorter intervals do not allow blood carbon monoxide levels to return to baseline.

Question 3Patient assessment and preparation

Spirometry is generally postponed for a patient who has had a myocardial infarction within which time frame?

  1. 2 years
  2. 1 month Correct answer.
  3. 6 months
  4. 1 week

Explanation

Maximal forced maneuvers transiently raise intrathoracic pressure and myocardial workload, so testing is deferred for about one month after an acute myocardial infarction. After that period, testing may proceed if the patient is clinically stable. Longer delays are not required for uncomplicated recovery.

Question 4Patient assessment and preparation

What should the technologist do first when a patient arrives at the pulmonary function laboratory?

  1. Verify that the spirometer has been calibrated that day
  2. Measure the patient's standing height and weight
  3. Confirm the patient's identity and date of birth Correct answer.
  4. Coach the patient through a practice blow

Explanation

Before any procedure or measurement, the technologist must confirm that the correct patient is present, typically by two identifiers such as name and date of birth. All technical steps, including calibration, anthropometry, and coaching, follow this verification. This safeguard prevents results from being attributed to the wrong record.

Question 5Patient assessment and preparation

Which body position is recommended for routine spirometry?

  1. Supine with the head elevated 30 degrees
  2. Standing with the neck extended
  3. Seated upright with the feet supported Correct answer.
  4. Seated with the trunk flexed forward

Explanation

An upright seated posture with feet supported optimizes diaphragm descent and chest wall expansion and reduces the risk of falling during a forced maneuver. This position also gives reproducible, comparable results across visits. Alternative positions either reduce lung volumes or add unnecessary risk.

Question 6Patient assessment and preparation

Which clothing instruction should be given before pulmonary function testing?

  1. Wear a rigid cervical collar for head support
  2. Wear a heavy coat to prevent chilling during the test
  3. Wear loose clothing that does not constrict the chest Correct answer.
  4. Wear a firm abdominal binder for support

Explanation

Garments that constrict the chest or abdomen limit chest wall excursion and diaphragm descent, lowering measured volumes and distorting results. Loose, comfortable clothing allows a full forced maneuver. Restrictive devices worn for other reasons should be loosened or removed if clinically safe.

Question 7Patient assessment and preparation

A patient wears full dentures that fit well. What guidance should the technologist give before spirometry?

  1. Remove them only if the patient becomes tired during testing
  2. Keep them in place during testing Correct answer.
  3. Remove them so the test can be performed edentulous
  4. Remove them, because they cause leaks around the mouthpiece

Explanation

Well-fitting dentures support the oral structures and help maintain a tight seal around the mouthpiece, so they should generally be left in place. Ill-fitting dentures that slip or cause air leaks may be removed if a better seal can be achieved without them. The decision is based on seal quality, not on routine removal.

Question 8Patient assessment and preparation

Before the patient's first spirometry effort, the technologist should:

  1. Withhold all explanation until three efforts have been recorded
  2. Demonstrate the maneuver and let the patient practice it Correct answer.
  3. Attach the nose clip only after the maneuver is complete
  4. Have the patient hyperventilate for one minute

Explanation

A clear demonstration followed by a practice attempt improves the chance that the first effort meets acceptability criteria. Instruction must precede the maneuver, since poor technique on early efforts is difficult to correct afterward. Practice also reduces anxiety and improves patient confidence.

Question 9Patient assessment and preparation

How should standing height be obtained for selecting reference values?

  1. With shoes on, rounded to the nearest inch
  2. Without shoes, standing erect with the head level Correct answer.
  3. Recumbent, using a tape measure along the bed
  4. From the height the patient reports at check-in

Explanation

Height should be measured directly with the patient standing erect, barefoot, with the head in a neutral position, because predicted values are indexed to measured height. Shoes and inaccurate self-report introduce systematic error that shifts predicted values in the wrong direction. Recumbent length is not interchangeable with standing height in adults.

Question 10Patient assessment and preparation

For which patient is arm span the most appropriate substitute for height?

  1. A patient with an acute upper respiratory infection
  2. A patient who has just finished a meal
  3. A patient who wears corrective glasses
  4. A patient with severe kyphosis who cannot stand erect Correct answer.

Explanation

When standing height cannot be measured reliably, as in severe kyphosis, inability to stand, or limb amputation, arm span provides a valid surrogate for predicting lung volumes. Arm span correlates closely with height in most adults. Other patient characteristics listed do not interfere with height measurement.

Question 11Patient assessment and preparation

A patient uses salmeterol twice daily. Before spirometry, this medication should be withheld for at least:

  1. 72 hours
  2. 4 hours
  3. 2 hours
  4. 12 hours Correct answer.

Explanation

Long-acting beta-2 agonists exert bronchodilation for roughly 12 hours, so a washout of at least 12 hours is required to avoid masking a bronchodilator response. Short-acting agents are withheld for only a few hours. Excessive withholding beyond the recommended interval is unnecessary and may worsen symptoms.

Question 12Patient assessment and preparation

Which practice best limits transmission of infection during pulmonary function testing?

  1. Wiping the mouthpiece with a dry tissue after each use
  2. Using a new in-line filter for each patient Correct answer.
  3. Testing patients who are coughing first, before other appointments
  4. Rinsing reusable mouthpieces under tap water between patients

Explanation

An in-line bacterial and viral filter placed between the patient and the equipment, combined with hand hygiene, is the main barrier against cross-contamination during forced exhalation and cough. Filters must be changed between patients. Simple rinsing or wiping does not remove or inactivate microorganisms.

Question 13Patient assessment and preparation

Testing should be postponed for a patient who presents with:

  1. New-onset fever and a productive cough Correct answer.
  2. Well-controlled asthma
  3. Stable angina relieved by nitroglycerin
  4. A history of seasonal allergic rhinitis

Explanation

An acute febrile respiratory illness both compromises the patient's ability to perform maximal efforts and creates a transmission risk in the laboratory. Testing is rescheduled once the acute illness resolves. Chronic, stable conditions such as controlled asthma or allergic rhinitis do not warrant postponement.

Question 14Patient assessment and preparation

Which condition is an absolute contraindication to spirometry?

  1. Treated hypertension
  2. Mild obesity
  3. Diet-controlled diabetes
  4. An untreated pneumothorax Correct answer.

Explanation

A forced expiratory maneuver raises intrathoracic pressure and could convert an untreated pneumothorax into a tension pneumothorax, so testing is absolutely contraindicated until it has resolved. The other listed conditions are common chronic diagnoses that do not prohibit testing. Relative contraindications are handled by deferral until the patient is cleared.

Question 15Patient assessment and preparation

A patient reports coughing up bright red blood earlier that morning. The technologist should:

  1. Proceed with testing but add a filter
  2. Encourage the patient to cough and then continue
  3. Postpone testing and notify the ordering provider Correct answer.
  4. Perform only the diffusing capacity measurement

Explanation

Hemoptysis of recent onset requires medical evaluation before any forced maneuver, which could aggravate bleeding. The technologist's role is to defer testing and communicate the finding to the ordering provider. Proceeding with any test that requires forceful breathing is unsafe.

Question 16Patient assessment and preparation

A patient underwent abdominal surgery 10 days ago and is scheduled for spirometry. The best action is to:

  1. Defer testing until the surgeon provides clearance Correct answer.
  2. Perform only forced expiratory maneuvers to limit strain
  3. Test with the patient lying flat to reduce discomfort
  4. Add extra trials so the best effort can be selected

Explanation

Forced maneuvers generate high intra-abdominal and intrathoracic pressures that can stress a recent surgical incision and increase the risk of dehiscence or pain-limited poor efforts. Testing is deferred until the surgical team confirms that forced breathing is safe. Reducing or repeating maneuvers does not remove the underlying risk.

Question 17Patient assessment and preparation

A patient becomes visibly anxious after entering a body plethysmograph. The technologist should:

  1. Reassure the patient and keep the door easy to open Correct answer.
  2. Sedate the patient before continuing the test
  3. Warn that testing will be cancelled if the patient moves
  4. Leave the patient alone to settle down

Explanation

Claustrophobia is common in the enclosed plethysmograph, and calm reassurance plus a clear understanding that the door can be opened at any time usually allows the test to continue. Anxiety increases respiratory rate and destabilizes the measurement. Sedation and threats are inappropriate responses.

Question 18Patient assessment and preparation

Which statement about spirometry during pregnancy is correct?

  1. It should be performed only with the patient supine
  2. It can be performed safely when clinically indicated Correct answer.
  3. It is absolutely contraindicated in all trimesters
  4. It requires stopping prenatal vitamins for one week beforehand

Explanation

Spirometry is not contraindicated by pregnancy and is often useful for managing asthma, which carries its own maternal and fetal risks when poorly controlled. The upright seated position should be maintained. Routine prenatal medications are not withheld for testing.

Question 19Patient assessment and preparation

A patient who uses continuous supplemental oxygen arrives for spirometry. The technologist should:

  1. Double the flow rate during the maneuver
  2. Discontinue oxygen abruptly for the whole visit
  3. Continue the prescribed oxygen and record the flow rate Correct answer.
  4. Postpone testing until oxygen has been stopped for 24 hours

Explanation

Prescribed oxygen is continued during spirometry so the patient is not made hypoxemic, and the flow rate is documented because oxygen therapy can influence some measurements. The technologist does not independently change a prescribed flow rate. There is no requirement to suspend oxygen for a day before testing.

Question 20Patient assessment and preparation

Which instruction applies to preparation for most pulmonary function tests?

  1. Avoid all fluids for 12 hours before the appointment
  2. Exercise vigorously for 20 minutes immediately beforehand
  3. Avoid vigorous exercise for about 30 minutes beforehand Correct answer.
  4. Take a sedative to relax before arriving

Explanation

Vigorous exercise transiently changes airway caliber and ventilation and can alter test results, so a short period of rest before testing is advised. Patients should be comfortable, hydrated, and alert. Sedation and dehydration are not part of standard preparation.

Question 21Patient assessment and preparation

Which finding on pre-test assessment is a relative contraindication to maximal forced maneuvers?

  1. A blood pressure of 118/76 mmHg
  2. A resting heart rate of 72 beats per minute
  3. A history of varicose veins in the legs
  4. A known thoracic aortic aneurysm Correct answer.

Explanation

A thoracic or abdominal aortic aneurysm may be a relative contraindication because the sharp pressure changes of a forced maneuver could theoretically stress the vessel wall; such patients are tested only after medical clearance. Normal vital signs and benign venous conditions do not pose this risk. Relative contraindications call for judgment rather than automatic refusal.

Question 22Patient assessment and preparation

A patient had cataract surgery 5 days ago. What is the main concern regarding pulmonary function testing?

  1. The nose clip cannot be worn after eye surgery
  2. An increased risk of ventilator-associated pneumonia
  3. Raised intraocular pressure from the forced effort Correct answer.
  4. The in-line filter may not seal on the mouthpiece

Explanation

Forced expiratory and inspiratory maneuvers raise intrathoracic and intraocular pressures, which could threaten a recently operated eye. Testing is therefore deferred until the ophthalmologic surgeon grants clearance. Filters and nose clips pose no specific problem after cataract surgery.

Question 23Patient assessment and preparation

A patient with mild cognitive impairment is unable to repeat the instructions for the forced maneuver. The best approach is to:

  1. Proceed with testing without further instruction
  2. Cancel testing permanently and document inability to cooperate
  3. Increase the number of required trials to ten
  4. Simplify instructions and confirm understanding with teach-back Correct answer.

Explanation

Short, simple instructions with demonstration and teach-back give the patient the best chance of producing interpretable efforts. Persistent inability to follow the maneuver after reasonable coaching is documented as a limitation, but permanent cancellation is premature. Adding trials does not substitute for understanding.

Question 24Patient assessment and preparation

During a forced expiratory maneuver, a patient reports chest pain and dizziness. The technologist should:

  1. Ask the patient to complete two additional efforts
  2. Increase verbal encouragement to achieve a plateau
  3. Continue the test but remove the nose clip
  4. Stop the test and assess the patient Correct answer.

Explanation

Chest pain or dizziness during testing may signal a cardiac or cerebrovascular event, and the priority is to stop the maneuver and evaluate the patient. Test quality is irrelevant when the patient is symptomatic. Escalation to the appropriate clinical staff follows the laboratory's emergency protocol.

Question 25Patient assessment and preparation

A patient known to carry a multidrug-resistant organism is scheduled for testing. Which approach is best?

  1. Test the patient first in the morning, before other appointments
  2. Schedule the patient last and follow contact precautions Correct answer.
  3. Skip hand hygiene because an in-line filter is in use
  4. Use the same filter for this patient and the next one

Explanation

Patients colonized with transmissible organisms are scheduled at the end of the day when possible, and standard plus contact precautions, including hand hygiene and appropriate barriers, are applied. Filters reduce but do not eliminate the need for other precautions. Reusing filters or omitting hand hygiene defeats the purpose of infection control.

Question 26Patient assessment and preparation

Before beginning any pulmonary function test, how should the technologist confirm the patient's identity?

  1. Confirm identity by checking the appointment time on the daily schedule
  2. Ask the patient to state the name of the ordering physician
  3. Compare the patient's full name and date of birth with the test request Correct answer.
  4. Ask the patient to describe the test that was ordered

Explanation

Two independent identifiers, typically full name plus date of birth (or a unique record number), must be matched against the request before testing. This prevents testing the wrong patient or attributing results to the wrong record.

Question 27Patient assessment and preparation

Which statement about eating before routine spirometry is correct?

  1. Food intake is irrelevant, so a large meal immediately before testing is encouraged
  2. Only clear liquids may be taken on the day of testing
  3. The patient must fast for at least 12 hours before testing
  4. A light meal is fine, but a large meal just before testing should be avoided Correct answer.

Explanation

Routine spirometry does not require fasting; a usual light meal is acceptable. A very large meal shortly before testing can cause abdominal discomfort and splint the diaphragm, interfering with maximal inspiratory and expiratory efforts.

Question 28Patient assessment and preparation

A patient arrives for spirometry directly after a vigorous 30-minute cycling session. What should the technologist do?

  1. Allow the patient to rest quietly before starting the test Correct answer.
  2. Refer the patient for exercise testing instead
  3. Cancel testing permanently and document inability to cooperate
  4. Begin the test at once, because exercise does not change spirometry results

Explanation

Vigorous exercise transiently alters breathing pattern, heart rate, and airway caliber, so the patient should rest quietly until settled before testing. A short rest preserves both safety and test validity without losing the appointment.

Question 29Patient assessment and preparation

When should the technologist explain the test procedure to the patient?

  1. Only if the patient asks questions about the test
  2. After the results have been printed
  3. Before testing, using plain language and confirming understanding Correct answer.
  4. Only after the first maneuver has been attempted

Explanation

Instruction must precede the effort so the patient knows what to expect and how to perform the maneuver. Plain language plus a check of understanding (for example, asking the patient to repeat the steps) is the standard approach.

Question 30Patient assessment and preparation

A patient scheduled for diffusing capacity testing reports smoking a cigarette about an hour ago. What is the most appropriate action?

  1. Cancel diffusing capacity testing permanently for this patient
  2. Proceed after asking the patient to take three slow deep breaths
  3. Proceed, because smoking affects only spirometry values, not diffusion
  4. Delay the test, because recent smoking lowers the measured diffusing capacity Correct answer.

Explanation

Cigarette smoke contains carbon monoxide, which raises carboxyhemoglobin and occupies hemoglobin binding sites, falsely lowering the measured diffusing capacity. Testing should be deferred until the effect has cleared, and the recent smoking should be documented.

Question 31Patient assessment and preparation

Which instruction should be given to a patient scheduled for a methacholine challenge?

  1. Avoid all fluids for 12 hours before the test
  2. Stop all inhaled corticosteroids 1 week before the test
  3. Avoid eating a light breakfast on the morning of the test
  4. Avoid coffee, tea, and cola on the day of the test Correct answer.

Explanation

Caffeine is a weak bronchodilator and can blunt the response to methacholine, so caffeinated beverages are withheld on the day of the challenge. Ordinary food and fluids are otherwise permitted, and inhaled corticosteroids are typically continued.

Question 32Patient assessment and preparation

Patients are asked to withhold H1-antihistamines before a methacholine challenge because these drugs can:

  1. Increase systemic absorption of inhaled methacholine
  2. Blunt airway responsiveness and produce a falsely negative result Correct answer.
  3. Cause acute bronchospasm during the challenge
  4. Damage the nebulizer tubing used for the challenge

Explanation

H1-antihistamines have bronchodilator and airway-protective effects that diminish the bronchoconstrictor response to methacholine. The result can look like a normal airway response when hyperresponsiveness is actually present.

Question 33Patient assessment and preparation

Which information about medications should be recorded during the pre-test interview?

  1. Only medications prescribed by the referring physician
  2. Only medications the patient received in the hospital
  3. All recent medications, with dose and time of the last dose Correct answer.
  4. Only inhaled medications

Explanation

Many drugs, including bronchodilators, antihistamines, and corticosteroids, alter pulmonary function results, so the full recent medication history with doses and timing must be documented. This allows the interpreting physician to judge whether results were affected.

Question 34Patient assessment and preparation

Which approach best prepares a 5-year-old child for spirometry?

  1. Tell the child the test will be painful so the child cooperates
  2. Require the child to perform the maneuver without coaching or encouragement
  3. Postpone spirometry for all children until age 12
  4. Use simple language, demonstration, and allow a parent to remain nearby Correct answer.

Explanation

Young children often perform acceptable spirometry when coached with brief, concrete language, visual feedback, and a demonstration. A calm caregiver nearby usually improves cooperation and reduces anxiety.

Question 35Patient assessment and preparation

A patient is breathing rapidly and feels light-headed after a difficult spirometry effort, and diffusing capacity is scheduled next. The best action is to:

  1. Ask the patient to run in place to warm up before the maneuver
  2. Skip the DLCO and record it as unobtainable
  3. Start the DLCO maneuver immediately to save time
  4. Let the patient rest and breathe normally, then perform the DLCO Correct answer.

Explanation

Hyperventilation and the associated changes in breathing pattern and blood gases can distort the single-breath diffusing capacity. The patient should be allowed to settle and breathe normally before the breath-hold maneuver.

Question 36Patient assessment and preparation

A patient referred for a methacholine challenge has a baseline FEV1 of 45% of predicted. The technologist should:

  1. Proceed with the challenge but use double the starting dose
  2. Proceed and report only the final dose administered
  3. Not perform the challenge and notify the ordering provider Correct answer.
  4. Perform the challenge only after the patient exercises

Explanation

A markedly reduced baseline FEV1 is a contraindication to bronchial challenge because of the risk of severe bronchospasm and because the response cannot be interpreted safely. The technologist should stop and contact the ordering provider rather than modify the protocol.

Question 37Patient assessment and preparation

Which pre-test finding is most important to document because it directly changes the interpretation of diffusing capacity?

  1. The time of the patient's last meal
  2. The patient's hemoglobin concentration Correct answer.
  3. The patient's usual blood pressure
  4. The patient's occupation

Explanation

Diffusing capacity depends on the amount of hemoglobin available to bind carbon monoxide, so the measured value is adjusted for hemoglobin. Anemia lowers and polycythemia raises the measured DLCO independently of lung disease.

Question 38Patient assessment and preparation

A patient had a viral upper respiratory infection 10 days ago and feels well now, and is scheduled for a methacholine challenge. The technologist should:

  1. Reschedule the test because recent viral infection alters airway responsiveness Correct answer.
  2. Cancel testing permanently and document that challenge testing is contraindicated
  3. Proceed but use half the usual maximum dose without informing the provider
  4. Proceed because a resolved infection has no effect on bronchial responsiveness

Explanation

Viral respiratory infections transiently increase bronchial responsiveness for several weeks, which can produce a false-positive challenge. The test is therefore deferred, typically until about four weeks after recovery, and the reason is documented.

Question 39Patient assessment and preparation

A patient scheduled for a methacholine challenge asks whether to take the usual morning dose of inhaled budesonide. The technologist should advise the patient to:

  1. Skip the dose for 1 week before the test
  2. Stop the medication permanently
  3. Take the medication as prescribed Correct answer.
  4. Take double the usual dose on the test day

Explanation

Inhaled corticosteroids are generally continued before bronchial challenge testing, and the technologist should not direct changes to prescribed therapy. Any question about altering a medication regimen is referred to the prescribing clinician.

Question 40Patient assessment and preparation

A patient reports smoking 1.5 packs per day for 20 years. The smoking history should be recorded as:

  1. 15 pack-years
  2. 30 pack-years Correct answer.
  3. 35 pack-years
  4. 20 pack-years

Explanation

Pack-years are calculated by multiplying packs smoked per day by the number of years smoked. In this case 1.5 packs per day times 20 years equals 30 pack-years.

Question 41Equipment setup, calibration, and quality control

Which device is used to perform the daily volume calibration check on a spirometer?

  1. A rotameter with a known flow
  2. A water-sealed manometer
  3. A 1-L volumetric flask
  4. A 3-L calibrated syringe Correct answer.

Explanation

Spirometer volume accuracy is verified daily by emptying a calibrated 3-L syringe into the device at a controlled flow and comparing the measured volume with the syringe volume. The syringe is a volume standard, so it is the correct tool; manometers, rotameters, and flasks do not deliver a known gas volume at a physiologic flow.

Question 42Equipment setup, calibration, and quality control

How often should the volume calibration of a spirometer be verified with a calibrated syringe?

  1. Before patient testing on each day of use Correct answer.
  2. Only after the device is repaired
  3. Once each month
  4. Once each week

Explanation

The calibration check is a daily quality control step performed before the first patient is tested on each day the laboratory operates. It is repeated after cleaning, relocation, or service and whenever results suggest a problem, but the routine interval is daily.

Question 43Equipment setup, calibration, and quality control

A biologic control (bioQC) program for spirometry is intended mainly to:

  1. Measure the resistance of the breathing filter
  2. Detect drift in equipment or technique Correct answer.
  3. Verify the accuracy of the calibration syringe
  4. Confirm the predicted values built into the software

Explanation

A healthy, nonsmoking control subject is tested repeatedly over time, and the results are charted against that individual's own established mean and control limits. Because the subject's lung function is stable, a shift in results signals a change in the equipment, the software, or the technologist's technique.

Question 44Equipment setup, calibration, and quality control

Before each day of DLCO testing, the CO and tracer gas analyzers are set using:

  1. A single span gas containing 0.3% CO
  2. A zero gas and a known span gas Correct answer.
  3. Room air drawn through the sample line
  4. The patient's own end-tidal gas sample

Explanation

Carbon monoxide and tracer analyzers require a two-point calibration before each testing day: a zero gas containing neither CO nor tracer gas, followed by a span gas of certified concentration. Both points are needed because the analyzer response is defined by a slope and an intercept.

Question 45Equipment setup, calibration, and quality control

Ambient temperature, barometric pressure, and humidity are recorded during testing because they are needed to:

  1. Set the CO analyzer to zero
  2. Adjust the filter dead space
  3. Convert measured gas volumes to BTPS Correct answer.
  4. Compute the patient's predicted FEV1

Explanation

Gas exhaled into a spirometer is at ambient temperature and humidity, whereas lung volumes are conventionally reported at body temperature, ambient pressure, saturated with water vapor (BTPS). The BTPS correction factor is calculated from the measured ambient temperature, barometric pressure, and water vapor pressure.

Question 46Equipment setup, calibration, and quality control

After a spirometer has been disinfected, moved to another room, or repaired, the technologist should first:

  1. Change the flow sensor filter
  2. Run a biologic control subject
  3. Recalculate predicted values
  4. Repeat the volume calibration check Correct answer.

Explanation

Disinfection, transport, and service can all alter the volume or flow signal, so the calibration check must be repeated before patient testing resumes. Biologic control testing follows the calibration check and is not a substitute for it.

Question 47Equipment setup, calibration, and quality control

Where is a disposable in-line filter placed in a spirometry circuit?

  1. On the exhalation port of the gas cylinder
  2. Between the mouthpiece and the spirometer Correct answer.
  3. Between the spirometer and the computer screen
  4. Inside the calibration syringe barrel

Explanation

The filter is positioned in the patient's expiratory path, between the mouthpiece and the flow sensor, so that exhaled droplets and particles are trapped before reaching the device. This protects the sensor and the next patient from cross-contamination.

Question 48Equipment setup, calibration, and quality control

The volume of a 3-L calibration syringe must itself be accurate to within approximately:

  1. ±0.5% of its stated volume Correct answer.
  2. ±2% of its stated volume
  3. ±10% of its stated volume
  4. ±5% of its stated volume

Explanation

The syringe is the reference standard for spirometer volume calibration, so its own volume must be accurate to about ±0.5% of a 3-L output, roughly 15 mL. A reference standard with a larger error could mask or exaggerate errors in the device being checked.

Question 49Equipment setup, calibration, and quality control

Injecting the 3-L calibration syringe at several different flows during the calibration check is done to verify:

  1. The resistance of the disposable filter
  2. The box pressure transducer gain
  3. Volume accuracy at different flow rates Correct answer.
  4. The accuracy of the CO analyzer

Explanation

Flow-sensing devices can lose accuracy when the injection is very slow or very fast, so the standard calls for emptying the syringe over a range of flows. Agreement at low, medium, and high flows demonstrates that the volume signal is accurate across the range encountered in patients.

Question 50Equipment setup, calibration, and quality control

The person selected as a biologic control for spirometry should be:

  1. A healthy nonsmoking adult Correct answer.
  2. A patient with a known restrictive defect
  3. Any technologist working in the laboratory
  4. A patient with stable asthma

Explanation

The control subject must have stable, normal lung function so that any change in serial results can be attributed to the equipment or the technologist. A healthy, nonsmoking adult without lung disease meets this requirement.