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NIOSH SSS practice questions

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Question 1Indications for spirometry and contraindications to testing

According to NIOSH spirometry practice, which finding is a standard indication for performing spirometry?

  1. Evaluating a worker with a chronic cough and suspected occupational lung disease Correct answer.
  2. Routine testing of every employee regardless of exposure or symptoms
  3. Screening a worker who has no respiratory symptoms and no exposure history
  4. Documenting a baseline for a worker whose only risk is occasional office dust

Explanation

Spirometry is indicated to evaluate respiratory symptoms such as chronic cough, dyspnea, or wheeze, and to assess workers with suspected occupational lung disease. Testing is also used for surveillance of workers exposed to respiratory hazards. Testing people with no symptoms and no exposure is not a recognized indication.

Question 2Indications for spirometry and contraindications to testing

A worker is being considered for spirometry. Which condition is a recognized absolute contraindication to forced expiratory maneuvers?

  1. Well-controlled seasonal allergies
  2. Mild intermittent asthma
  3. Recent myocardial infarction Correct answer.
  4. Corrected refractive error

Explanation

A recent myocardial infarction is an absolute contraindication because the forced effort increases intrathoracic and cardiac stress. Other absolute contraindications include recent pneumothorax, unstable angina, and active hemoptysis of unknown origin. Conditions such as controlled allergies or mild asthma do not preclude testing.

Question 3Indications for spirometry and contraindications to testing

Which finding is a relative contraindication that requires the spirometry technician to weigh risk before proceeding?

  1. Wearing corrective eyeglasses
  2. Recent uncomplicated viral rhinitis
  3. Resting tachycardia or a recent respiratory infection Correct answer.
  4. Use of a walking cane

Explanation

Relative contraindications such as tachycardia, recent respiratory infection, or elevated blood pressure call for clinical judgment before testing. The technician should consult the supervising clinician and document the decision. The other listed items have no meaningful effect on the safety of forced expiration.

Question 4Indications for spirometry and contraindications to testing

Why is a recent pneumothorax considered a contraindication to spirometry?

  1. Pneumothorax history invalidates the reference equations used for interpretation
  2. The spirometer cannot accurately measure flow in patients with prior lung injury
  3. The forced maneuver may raise intrathoracic pressure and risk recurrence or extension of the pneumothorax Correct answer.
  4. The maneuver causes irreversible airway collapse in these patients

Explanation

Forced expiration generates high intrathoracic pressure, which can worsen or recur a recent pneumothorax. Spirometry is therefore deferred until the pneumothorax has resolved and the clinician clears the patient. Measurement accuracy and reference equations are not the reason for the restriction.

Question 5Indications for spirometry and contraindications to testing

Which patient instruction best reflects the purpose of spirometry when it is ordered for preoperative assessment?

  1. The test confirms a diagnosis of pneumonia
  2. The test replaces a chest radiograph before surgery
  3. The test estimates functional lung capacity to help predict surgical risk Correct answer.
  4. The test measures gas diffusion to predict anesthesia risk

Explanation

Preoperative spirometry is used to estimate lung function and help predict pulmonary risk for surgery, particularly thoracic or upper abdominal procedures. It does not measure diffusion capacity, replace imaging, or diagnose pneumonia. The result informs perioperative planning rather than serving as a stand-alone diagnostic test.

Question 6Indications for spirometry and contraindications to testing

A worker reports chest pain that is currently unstable. What is the most appropriate action regarding spirometry?

  1. Proceed because chest pain is only a relative contraindication
  2. Defer testing until the unstable condition is evaluated by a clinician Correct answer.
  3. Perform the test with a shorter forced expiratory time
  4. Perform only the slow vital capacity maneuver

Explanation

Unstable chest pain, such as suspected unstable angina, is an absolute contraindication until the patient is medically evaluated. Forced maneuvers could provoke cardiac stress. Modifying the maneuver does not remove the underlying risk, so testing should be deferred.

Question 7Indications for spirometry and contraindications to testing

A worker with known asthma is scheduled for spirometry. How should the technician proceed?

  1. Require a chest radiograph before any forced maneuver
  2. Perform the test only if the worker has no symptoms that day
  3. Proceed, since asthma is a common indication, while monitoring for bronchospasm Correct answer.
  4. Cancel testing permanently because asthma is a contraindication

Explanation

Asthma is a frequent indication for spirometry, which helps confirm and monitor airflow obstruction. The technician should follow bronchodilator withholding instructions and watch for cough or bronchospasm during testing. Asthma is not a contraindication, and routine imaging is not a prerequisite.

Question 8Indications for spirometry and contraindications to testing

Which combination best describes the general indications for spirometry in an occupational health setting?

  1. Evaluating respiratory symptoms, assessing exposure-related impairment, and monitoring lung function over time Correct answer.
  2. Diagnosing sleep apnea and measuring oxygen saturation
  3. Determining blood gas values and acid-base status
  4. Screening for hearing loss and vision deficits

Explanation

Occupational spirometry is indicated to evaluate symptoms, assess impairment related to workplace exposures, and track lung function over time through surveillance. It does not measure oxygen saturation, blood gases, or sensory function. Those require different testing modalities.

Question 9Indications for spirometry and contraindications to testing

A worker had abdominal surgery two weeks ago and is scheduled for spirometry. What is the most appropriate consideration?

  1. Defer or consult the clinician because recent abdominal surgery is a relative contraindication Correct answer.
  2. Perform only the forced expiratory volume in one second
  3. Increase the number of trials to compensate for discomfort
  4. Proceed without modification because abdominal surgery is unrelated

Explanation

Recent abdominal or thoracic surgery is a relative contraindication because forced expiration increases intra-abdominal pressure and can cause pain or strain. The supervising clinician should decide whether to defer testing. Proceeding without modification or altering only part of the maneuver does not address the risk.

Question 10Indications for spirometry and contraindications to testing

Which patient history most strongly supports ordering spirometry for suspected occupational lung disease?

  1. Occasional use of a multivitamin
  2. A family history of diabetes
  3. Ten years of exposure to respirable crystalline silica with progressive dyspnea Correct answer.
  4. A single episode of sunburn last summer

Explanation

Long-term exposure to respirable crystalline silica with progressive dyspnea is a classic indication for spirometry to detect and monitor restrictive or obstructive impairment. The other items have no respiratory relevance. Exposure history combined with symptoms is the key trigger for testing.

Question 11Indications for spirometry and contraindications to testing

A worker is coughing up blood of unknown origin. How does this affect the decision to perform spirometry?

  1. It requires only that the technician wear gloves
  2. It is acceptable if the worker feels well otherwise
  3. It is a reason to use a smaller mouthpiece
  4. It is an absolute contraindication until the cause is evaluated Correct answer.

Explanation

Hemoptysis of unknown origin is an absolute contraindication because forced maneuvers could worsen bleeding or obscure the clinical picture. The patient should be evaluated before any testing. Equipment adjustments or glove use do not address the underlying risk.

Question 12Indications for spirometry and contraindications to testing

When spirometry is ordered as part of a respirator medical evaluation, what is the primary purpose?

  1. To determine whether the worker can safely use a respirator given lung function Correct answer.
  2. To measure the respirator's filtration efficiency
  3. To replace the employer's hazard assessment
  4. To certify that the worker will never develop lung disease

Explanation

Spirometry in respirator medical evaluation helps determine whether a worker's lung function permits safe respirator use. It supports, but does not replace, the employer's hazard assessment. It cannot guarantee freedom from future disease and does not test the respirator itself.

Question 13Indications for spirometry and contraindications to testing

Which instruction about withholding bronchodilators before spirometry is most consistent with NIOSH guidance?

  1. Bronchodilators never affect spirometry results
  2. Short-acting bronchodilators are typically withheld for several hours per protocol Correct answer.
  3. Only inhaled steroids need to be withheld
  4. All bronchodilators should be stopped for two weeks before testing

Explanation

Short-acting bronchodilators are usually withheld for a few hours before testing so results reflect baseline function, following the supervising clinician's protocol. Long-acting agents may require longer withholding. Bronchodilators clearly affect airflow measurements, and inhaled steroids are not the primary concern for timing.

Question 14Indications for spirometry and contraindications to testing

A worker with a resting heart rate of 130 beats per minute arrives for spirometry. What is the best course of action?

  1. Notify the supervising clinician and defer testing pending evaluation Correct answer.
  2. Double the number of trials to average the results
  3. Perform the test but omit the forced expiratory maneuver
  4. Proceed immediately because heart rate is irrelevant

Explanation

Significant tachycardia is a relative contraindication that warrants clinician review before testing. The technician should document the finding and defer until the patient is cleared. Heart rate is relevant to safety, and omitting forced maneuvers or adding trials does not resolve the concern.

Question 15Indications for spirometry and contraindications to testing

Which scenario best illustrates appropriate use of spirometry for monitoring rather than diagnosis?

  1. Testing to measure arterial oxygen tension
  2. Testing a new worker with acute breathlessness to identify the cause
  3. Serial annual testing of a worker exposed to isocyanates to detect decline Correct answer.
  4. Testing a patient once to confirm a pneumonia diagnosis

Explanation

Serial spirometry in workers exposed to respiratory sensitizers such as isocyanates supports early detection of decline across time. This is a monitoring use, distinct from diagnostic evaluation of acute symptoms. Spirometry does not diagnose pneumonia or measure arterial oxygen tension.

Question 16Indications for spirometry and contraindications to testing

A worker with a known aortic aneurysm is scheduled for spirometry. Why does this condition warrant caution?

  1. Forced expiration raises intrathoracic pressure and may stress the aneurysm Correct answer.
  2. Aneurysms interfere with the spirometer's flow sensor
  3. Aneurysms cause falsely low forced vital capacity
  4. The condition requires a different reference equation

Explanation

A known thoracic or abdominal aortic aneurysm is a relative contraindication because forced maneuvers raise intrathoracic and intra-abdominal pressure. The clinician should weigh the risk before testing. Aneurysms do not affect sensor function or reference equations.

Question 17Indications for spirometry and contraindications to testing

A technician must decide whether to test a worker who reports an acute respiratory infection with fever. What is the most defensible reasoning?

  1. Cancel spirometry permanently for this worker
  2. Proceed because infection affects only the lower airways
  3. Proceed but record the temperature in the report
  4. Defer because acute infection is a relative contraindication and may affect results and safety Correct answer.

Explanation

Acute respiratory infection is a relative contraindication because it can worsen symptoms during forced effort and distort results. Testing is typically deferred until recovery. Permanent cancellation is inappropriate, and simply recording temperature does not address the risk or validity concerns.

Question 18Indications for spirometry and contraindications to testing

Which reasoning best explains why spirometry should not be performed during an acute exacerbation of asthma?

  1. Spirometers are inaccurate at high altitudes only
  2. Asthma is an absolute contraindication at all times
  3. Exacerbations make the worker ineligible for respirator use permanently
  4. The forced maneuver may provoke further bronchospasm and the results will not reflect baseline function Correct answer.

Explanation

During an acute exacerbation, forced effort can aggravate bronchospasm and the resulting values do not represent the patient's stable baseline. Testing is therefore postponed until the exacerbation resolves. Asthma is not a permanent contraindication, and altitude is not the relevant issue here.

Question 19Indications for spirometry and contraindications to testing

A worker with a documented history of a collapsed lung five years ago now has fully resolved imaging and clinician clearance. How should the technician interpret the pneumothorax history?

  1. It remains an absolute contraindication indefinitely
  2. It requires measurement of diffusion capacity instead
  3. It is no longer an active contraindication once resolved and cleared Correct answer.
  4. It mandates that only slow vital capacity be recorded

Explanation

The contraindication applies to a recent or unresolved pneumothorax; once it has resolved and the clinician provides clearance, spirometry may proceed. The history does not permanently bar testing. Diffusion capacity and slow vital capacity are not substitutes dictated by this history.

Question 20Indications for spirometry and contraindications to testing

A worker scheduled for spirometry reports recent eye surgery. What is the most appropriate response?

  1. Proceed because eye surgery is unrelated to breathing
  2. Consult the clinician because recent eye surgery is a relative contraindication due to pressure effects Correct answer.
  3. Refuse testing permanently
  4. Perform only the slow maneuver without clinician input

Explanation

Recent eye surgery is a relative contraindication because forced expiration raises intraocular and intrathoracic pressure. The supervising clinician should decide whether testing can proceed safely. Permanent refusal is inappropriate, and technician-initiated maneuver changes do not substitute for clinical judgment.

Question 21Spirometer performance, calibration verification, and quality control

A 3-L syringe is used to perform a calibration check on a spirometer. Which delivered volume should the spirometer register for the check to pass?

  1. 3.00 L ±5% (2.85–3.15 L)
  2. 3.00 L ±3% (2.91–3.09 L) Correct answer.
  3. 3.00 L ±10% (2.70–3.30 L)
  4. 3.00 L ±1% (2.97–3.03 L)

Explanation

Spirometer calibration verification uses a 3-L syringe, and the measured volume must fall within ±3% of the delivered volume, i.e., between 2.91 L and 3.09 L. This tolerance comes from the standardized calibration-check protocol and is tighter than the older ±5% convention sometimes quoted.

Question 22Spirometer performance, calibration verification, and quality control

During a daily spirometer check, the technologist notes the room temperature is 24 °C. Which statement describes the correct handling of this reading?

  1. Record it only if the spirometer uses a heated pneumotachograph
  2. Ignore it, because temperature has no effect on spirometry results
  3. Record it, because temperature affects BTPS correction and must be documented Correct answer.
  4. Record it only when the patient's temperature exceeds 37 °C

Explanation

Ambient temperature is part of the required quality-control record because expired air is corrected from ATPS to BTPS, and the correction factor depends on the temperature at which the volume was measured. Documenting it allows later verification that conditions were within the device's validated range.

Question 23Spirometer performance, calibration verification, and quality control

Which action is required when a spirometer fails its daily calibration verification with a 3-L syringe?

  1. Continue testing patients and repeat the check at the end of the day
  2. Report only the passing checks and discard failed results
  3. Repeat the check after correcting the problem and document the resolution before testing patients Correct answer.
  4. Recalibrate the device once every six months instead

Explanation

A failed calibration check means the device cannot be trusted for clinical results until the cause is corrected and the check is repeated successfully. The failure, the corrective action, and the repeat result must all be documented so the record shows when the device returned to service.

Question 24Spirometer performance, calibration verification, and quality control

Which measure best describes the linearity requirement assessed during spirometer calibration verification?

  1. Agreement of the flow sensor with a heated reference thermometer
  2. Agreement of the displayed time with a stopwatch
  3. Agreement of two technologists' coaching styles
  4. Agreement of measured volume with delivered volume across a range of flows and volumes Correct answer.

Explanation

Linearity testing confirms that the spirometer reports accurate volumes across the range of flows and volumes it will encounter clinically, not just at a single syringe delivery. A device can pass at one flow and still be inaccurate at high or low flows if linearity is poor.

Question 25Spirometer performance, calibration verification, and quality control

How often must biologic quality control (a healthy nonsmoking staff member) generally be performed on a spirometer?

  1. Monthly, only after a sensor replacement
  2. Weekly, only if the calibration check fails
  3. Annually, as part of the equipment inventory
  4. Daily, at the same time the calibration verification is done Correct answer.

Explanation

Biologic QC is performed daily so that trends in a known healthy subject's results can reveal drift, leaks, or sensor problems that a syringe check may not detect. The same person should be tested at approximately the same time of day to keep the comparison meaningful.

Question 26Spirometer performance, calibration verification, and quality control

Which value is used to judge whether the biologic control subject's FEV1 on a given day is acceptable?

  1. The manufacturer's specified FEV1 for the device
  2. The subject's own established mean and the control chart limits derived from prior values Correct answer.
  3. The FEV1 of the most recent patient tested
  4. The predicted FEV1 from the reference equation for that subject

Explanation

Biologic QC compares today's result with the subject's own historical mean and control limits, because the purpose is to detect device change rather than to assess the subject's lung health. Predicted values are irrelevant to this comparison.

Question 27Spirometer performance, calibration verification, and quality control

A spirometer's volume accuracy check is performed with the syringe emptied slowly over about 6 seconds and then rapidly over about 1 second. Why are both maneuvers required?

  1. To confirm the syringe's own calibration
  2. To measure the device's maximum sampling rate
  3. To test the printer output
  4. To verify accuracy across the range of flows generated by patients Correct answer.

Explanation

Patients generate widely different expiratory flows, so the calibration check must confirm accuracy at both low and high flow. A device accurate only at one flow could misreport volumes for patients with obstructive or restrictive physiology.

Question 28Spirometer performance, calibration verification, and quality control

Which of the following is a required element of a spirometer calibration verification log entry?

  1. Date, time, measured volume, and the initials of the person performing the check Correct answer.
  2. Referring physician's signature
  3. Insurance authorization number
  4. Patient name and medical record number

Explanation

The calibration log documents the device's performance over time, so each entry needs the date, time, measured value, and identity of the tester, along with any corrective action. Patient identifiers and billing data do not belong in an equipment log.

Question 29Spirometer performance, calibration verification, and quality control

A 3-L syringe check yields 2.80 L on three consecutive attempts. What is the most appropriate interpretation?

  1. The syringe must be replaced because it delivered too little volume
  2. The device is outside the ±3% tolerance and must be corrected before clinical use Correct answer.
  3. The device is acceptable because 2.80 L is within ±10%
  4. The device is acceptable because the result is consistent across attempts

Explanation

2.80 L is 6.7% below the delivered 3.00 L, which exceeds the ±3% acceptance limit, so the device fails regardless of consistency. Consistency across attempts shows a systematic error, not random variation, and the device must be serviced before use.

Question 30Spirometer performance, calibration verification, and quality control

A spirometer passes the 3-L syringe check but the biologic control subject's FEV1 falls below the lower control limit for two consecutive days. What is the best next step?

  1. Discard the control subject's results and select a new subject
  2. Investigate the device and testing setup, such as leaks, sensor drift, or software changes, before resuming patient testing Correct answer.
  3. Recalibrate the syringe and continue testing
  4. Conclude that the control subject has developed lung disease

Explanation

Biologic QC detects problems, such as leaks, sensor drift, or software changes, that a single-volume syringe check may miss, so a sustained out-of-limit trend requires investigation of the device and testing setup. The control subject's health is not the object of the test, and changing subjects would hide the problem.

Question 31Spirometer performance, calibration verification, and quality control

Which condition most likely explains a spirometer that reads consistently low on the syringe check at low flow but is accurate at high flow?

  1. A small leak in the tubing or connections Correct answer.
  2. A room that is too warm
  3. A printer that is out of paper
  4. A clock that runs fast

Explanation

A leak disproportionately affects low-flow deliveries, because more time is available for volume to escape before it is sensed, while a rapid delivery may lose proportionally less. Flow-dependent error of this pattern should prompt a leak check of tubing, connections, and the syringe seal.

Question 32Spirometer performance, calibration verification, and quality control

Before performing a calibration verification, the technologist should confirm which condition regarding the syringe?

  1. The syringe is at or near room temperature and free of leaks Correct answer.
  2. The syringe is filled with humidified gas
  3. The syringe has been stored below freezing
  4. The syringe has been warmed to 37 °C

Explanation

The syringe should be equilibrated to room temperature and checked for leaks so that the delivered volume is known and the BTPS correction is appropriate. A syringe at an extreme temperature would deliver a volume that differs from its nominal value.

Question 33Spirometer performance, calibration verification, and quality control

Which statement correctly describes the relationship between calibration and calibration verification?

  1. Calibration is performed only by the manufacturer and never in the laboratory
  2. Calibration verification permanently adjusts the device, while calibration only documents performance
  3. Calibration verification confirms performance against a reference, while calibration adjusts the device to a reference Correct answer.
  4. Both terms describe the same procedure and are interchangeable

Explanation

Calibration verification is a check that the device still measures accurately against a known standard, whereas calibration is the process of adjusting the device so that it does. Many modern spirometers are not user-calibrated, but all require regular verification.

Question 34Spirometer performance, calibration verification, and quality control

A spirometer uses a flow sensor that is sensitive to condensation. Which quality-control practice best addresses this risk?

  1. Increasing the number of syringe checks to hourly
  2. Following the manufacturer's cleaning and drying schedule and inspecting the sensor for moisture before checks Correct answer.
  3. Disabling BTPS correction
  4. Removing the sensor and storing it between patients

Explanation

Sensor-specific maintenance requirements, such as cleaning and drying intervals, are set by the manufacturer to prevent condensation-related drift. Inspecting for moisture before verification helps catch a compromised sensor before it affects patient results.

Question 35Spirometer performance, calibration verification, and quality control

Which result indicates that a spirometer's timing accuracy is acceptable when checked with a 3-L syringe delivered at a constant flow over 6 seconds?

  1. A measured expiratory time of 12 seconds
  2. A measured expiratory time close to 6 seconds, within the manufacturer's stated tolerance Correct answer.
  3. Any value, because timing is not part of spirometer verification
  4. A measured expiratory time of exactly 3 seconds

Explanation

Timing accuracy is verified by comparing the device's reported maneuver time with the known delivery time, within the tolerance specified by the manufacturer or protocol. A large discrepancy would distort derived values such as FEV1/FVC ratio and back-extrapolated volume.

Question 36Spirometer performance, calibration verification, and quality control

A laboratory's spirometer passes daily syringe checks, but the biologic control subject's FVC varies by more than the established coefficient of variation over a week. Which factor should be evaluated first?

  1. The syringe's certification date
  2. The printer's toner level
  3. The office's billing software
  4. Technologist technique and subject effort, including coaching and posture Correct answer.

Explanation

When the device passes syringe checks but a known subject's values become more variable, the most likely causes are changes in coaching, effort, posture, or the tester. Reviewing technique and retraining as needed is the appropriate first step before assuming device failure.

Question 37Spirometer performance, calibration verification, and quality control

Which of the following best describes the purpose of the ATS/ERS acceptability and repeatability criteria in the context of spirometry quality control?

  1. They specify the purchase price of spirometers
  2. They replace the need for calibration verification
  3. They determine the patient's insurance coverage
  4. They define standards for maneuver performance and for the technical quality of the resulting curves Correct answer.

Explanation

The ATS/ERS standards specify how maneuvers should be performed and which technical features the resulting curves must show to be acceptable and repeatable. These criteria guide technologist coaching and interpretation, but they do not substitute for device quality control.

Question 38Spirometer performance, calibration verification, and quality control

A spirometer's displayed volume is 3.10 L when a 3-L syringe is delivered. What is the percent error, and does it meet the ±3% criterion?

  1. About 10% error, which exceeds the criterion
  2. About 3.3% error, which exceeds the criterion Correct answer.
  3. About 1.0% error, which meets the criterion
  4. About 0.3% error, which meets the criterion

Explanation

Percent error is (measured − delivered) ÷ delivered × 100, so (3.10 − 3.00) ÷ 3.00 × 100 ≈ 3.3%. Because 3.3% exceeds the ±3% limit of 3.09 L, the check fails and the device requires correction.

Question 39Spirometer performance, calibration verification, and quality control

Which practice best ensures that a spirometer's calibration verification is traceable and defensible?

  1. Performing checks only when a problem is suspected
  2. Storing logs in an unsecured drawer
  3. Relying on the technologist's memory of past results
  4. Using a syringe with documented calibration and recording the device and syringe identifiers with each check Correct answer.

Explanation

Traceability requires that the reference standard itself be calibrated and that the check record link the specific device and syringe to the result. This allows an auditor or reviewer to reconstruct the conditions under which the device was verified.

Question 40Spirometer performance, calibration verification, and quality control

A spirometer check shows the measured volume varies by ±0.15 L across five syringe deliveries. Which conclusion is most defensible?

  1. The variation is irrelevant because only the mean matters
  2. The variation proves the syringe is defective
  3. Precision is poor even if the mean is near 3.00 L, so the device should be evaluated Correct answer.
  4. The device is acceptable because the mean is close to 3.00 L

Explanation

Both accuracy (agreement with the reference) and precision (reproducibility across attempts) matter, and a scatter of ±0.15 L indicates instability that could affect clinical results. The device should be investigated even if the average is close to the delivered volume.

Question 41Spirometer performance, calibration verification, and quality control

Which of the following is the most appropriate action when a spirometer's software is updated?

  1. Delay verification until the next annual service
  2. Assume the update does not affect measurements
  3. Repeat calibration verification and biologic QC before resuming patient testing Correct answer.
  4. Test only one patient to confirm the update

Explanation

Software updates can alter volume integration, BTPS correction, or reporting, so the device must be re-verified with the syringe and biologic QC before clinical use. Documenting the update and the verification results maintains a complete quality record.

Question 42Spirometer performance, calibration verification, and quality control

A laboratory uses a spirometer with a manufacturer-specified accuracy of ±2.5% and performs a 3-L syringe check that yields 3.07 L. How should this result be judged?

  1. It cannot be judged without knowing the patient's age
  2. It fails because it exceeds the manufacturer's ±2.5% specification
  3. It fails because it exceeds the ±3% protocol limit
  4. It meets both the ±3% protocol limit and the manufacturer's tighter specification Correct answer.

Explanation

3.07 L is 2.3% above the delivered 3.00 L, which is within both the ±3% protocol limit (up to 3.09 L) and the tighter ±2.5% manufacturer specification (up to 3.075 L). Both criteria must be satisfied, and this result satisfies them.

Question 43Spirometer performance, calibration verification, and quality control

A technologist observes that the biologic control subject's FEV1 has drifted downward gradually over three months while remaining within control limits. What is the most appropriate response?

  1. Stop performing biologic QC for this subject
  2. Immediately replace the spirometer
  3. Take no action because all values remain within limits
  4. Review the control chart for a trend and investigate possible causes such as sensor aging or technique drift Correct answer.

Explanation

A gradual trend, even within limits, can signal developing problems such as sensor aging, changing technique, or environmental shifts, and control-chart review is designed to detect such patterns. Early investigation prevents the drift from becoming a frank failure.

Question 44Spirometer performance, calibration verification, and quality control

A spirometer passes syringe checks at room temperature but a heated pneumotachograph reports low volumes when the laboratory is cold. Which explanation is most consistent with these findings?

  1. A syringe that delivers less volume when cold
  2. Temperature-dependent sensor behavior that is not captured by a room-temperature syringe check Correct answer.
  3. A leak that only occurs at low temperature
  4. A software error that affects all checks equally

Explanation

Some flow sensors are temperature-sensitive, and a check performed at one ambient temperature may not reveal error at another, which is why ambient conditions are documented and the device is used within its validated range. The pattern of passing at room temperature but failing in a cold room points to temperature-dependent sensor behavior.

Question 45Spirometer performance, calibration verification, and quality control

A laboratory's quality plan requires both daily calibration verification and daily biologic QC. Which statement best justifies requiring both?

  1. The syringe check tests volume accuracy against a known standard, while biologic QC detects changes in the total testing system, including technique and sensors Correct answer.
  2. The syringe check evaluates patient effort
  3. Biologic QC replaces the need for a reference standard
  4. The two checks are redundant and either alone is sufficient

Explanation

The syringe check verifies that the device measures a known volume accurately, while biologic QC exercises the entire testing system with a real maneuver, capturing sensor drift, leaks, and technique changes that a single-volume check may miss. Together they provide complementary assurance of result validity.

Question 46Spirometer performance, calibration verification, and quality control

During a calibration verification, a 3-L syringe is delivered into a spirometer and the displayed volume is 3.12 L. Using the standard formula, what is the percent error, and does it fall within the ATS/ERS tolerance for volume accuracy?

  1. +4.0%, which exceeds the ±3.5% tolerance Correct answer.
  2. +1.2%, which is within the ±3.5% tolerance
  3. +4.0%, which is within the ±3.5% tolerance
  4. −4.0%, which exceeds the ±3.5% tolerance

Explanation

Percent error is calculated as (measured − syringe volume) ÷ syringe volume × 100, giving (3.12 − 3.00) ÷ 3.00 × 100 = +4.0%. The ATS/ERS standard for volume accuracy is ±3.5% (roughly ±0.105 L on a 3-L syringe), so a 4.0% error fails the check and requires investigation before testing continues.

Question 47Spirometer performance, calibration verification, and quality control

Which practice best preserves the metrologic traceability of a spirometer's calibration verification over time?

  1. Recording the syringe's serial number and calibration due date alongside each check result Correct answer.
  2. Storing syringe check printouts in the subject's medical record
  3. Having each technologist use a personal syringe kept at the workstation
  4. Recalibrating the spirometer monthly regardless of syringe check results

Explanation

Traceability means the measurement can be linked back to a known reference, which requires documenting the identity and calibration status of the calibrating device (the syringe) with each verification. Without the syringe serial number and its calibration due date, a recorded volume cannot be defended as traceable to a certified standard.

Question 48Spirometer performance, calibration verification, and quality control

A laboratory's spirometer passes the daily 3-L syringe check every morning, yet the biologic control subject's FEV1 has fallen steadily over several weeks. Which interpretation and action are most appropriate?

  1. The spirometer should be recalibrated with a larger syringe to correct the drift in FEV1
  2. The syringe check confirms only the device's volume accuracy, so the biologic trend signals a problem such as a sensor fault or a change in the control subject's health that must be investigated Correct answer.
  3. The control subject should be replaced immediately, since a downward trend always indicates deteriorating lung function
  4. The biologic control results can be disregarded because the syringe check is the definitive measure of spirometer performance

Explanation

Daily calibration verification with a syringe evaluates the device's volume and flow accuracy, whereas biologic QC detects changes over time in the entire measurement system, including sensors, software, and the subject. A sustained downward trend in the biologic control's FEV1 despite passing syringe checks requires investigating both equipment and subject factors before accepting results.

Question 49Spirometer performance, calibration verification, and quality control

A spirometer's flow sensor is a heated pneumotachograph. Which environmental condition most directly threatens the validity of its calibration verification?

  1. High ambient humidity causing condensation in the sensor Correct answer.
  2. Barometric pressure recorded in inches of mercury rather than kilopascals
  3. Ambient noise above 60 decibels in the testing room
  4. Room lighting dimmer than the manufacturer's recommendation

Explanation

Heated pneumotachographs are sensitive to condensation and moisture because water films alter the flow-resistance characteristics of the sensor and can bias measured volumes. Humidity control and proper sensor heating are therefore part of the QC plan for these devices, while noise, pressure units, and lighting do not affect the sensor's measurement physics.

Question 50Spirometer performance, calibration verification, and quality control

A technologist must decide whether a spirometer's calibration verification record is complete enough to defend the day's test results. Which combination of elements is necessary for that record to be considered adequate?

  1. Technologist initials and the number of tests performed that day
  2. Measured volume and the subject's identifying information
  3. Date only, with the measured volume written on the day's schedule sheet
  4. Date and time, technologist identity, syringe volume and serial number, measured values, and pass/fail determination Correct answer.

Explanation

A defensible calibration verification record must identify when the check occurred, who performed it, which reference device was used (including its volume and serial number), the measured results, and whether the results met the tolerance. This allows the laboratory to reconstruct the device's status for any test performed that day and to demonstrate that the equipment met accuracy standards.