Pulmonary Function Technology Examination Study Guide

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A spirometer repeatedly measures a known syringe volume outside its verification limits. Check connections, syringe integrity, environmental entries and technique, then perform the manufacturer's corrective calibration process when indicated before repeating verification and testing patients.

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A 3-L syringe produces 3.01 L slowly but 3.15 L rapidly. The high-flow result exceeds the 2.91–3.09 L verification range. Investigate the flow sensor and circuit before accepting patient measurements.

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A laboratory verifies its spirometer without a filter, then attaches a different filter model for testing. Reassemble the syringe verification with the patient-testing filter configuration and investigate any resulting failure before starting the patient session.

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After a syringe is dropped, two spirometers show unexpectedly low verification volumes with it. Remove that syringe from service, inspect its integrity and compare performance using a verified reference device before recalibrating both spirometers.

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The volume trace climbs while the patient is resting with the mouthpiece nearby. Disconnect the patient as instructed, establish a genuine no-flow baseline and repeat the check before deciding that the patient's next maneuver is abnormal.

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Several patients show unexpectedly larger volumes after an incorrect room temperature is entered. Verify the actual ambient conditions and the instrument's BTPS handling, then determine which measurements require review under the laboratory's correction procedure.

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After an update, measured FEV1 stays unchanged but percent predicted rises across many reports. Review the software and reference-equation configuration, validate calculations with known cases and document the change before interpreting patient improvement.

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An analyzer's low-oxygen control fails while its other controls pass. Withhold affected patient oxygen results, investigate the failure and demonstrate acceptable control performance before returning that measurement function to routine clinical use.

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Routine controls remain stable, but an external proficiency report identifies a consistent oxygen-measurement bias. Review calibration, control targets and analyzer performance, document the investigation and verify corrective action rather than dismissing the external finding.

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A DLCO system measures syringe volume correctly but reports substantial carbon monoxide uptake from the syringe maneuver. Suspend patient DLCO testing and investigate gas analysis, leakage and signal timing before accepting clinical gas-transfer measurements.

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After sampling tubing is replaced, the gas trace shifts relative to expiratory flow and DLCO changes unexpectedly. Check the sampling configuration and signal-delay alignment using the manufacturer's validated procedure before repeating clinical measurements.

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A DLCO analyzer reads reference cylinders correctly at steady state but shows unusually rounded transitions during a maneuver. Investigate sampling restrictions and dynamic response rather than assuming that successful static calibration establishes adequate performance.

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A plethysmograph reports a known isothermal model's volume incorrectly despite apparently normal patient traces. Investigate calibration, leaks and analysis settings, then repeat model validation before interpreting the patient's unusually large thoracic gas volume.

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Box calibration passes, but the mouth-pressure channel responds incorrectly to a known pressure. Correct that channel and repeat the required checks before testing, because an accurate box signal cannot compensate for erroneous mouth-pressure measurement.

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A laboratory replaces its challenge nebulizer with a model that has higher output. Revalidate delivered-dose calculations and the protocol before testing; retaining the old concentration schedule alone would not preserve equivalent methacholine exposure.

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A fatigued patient loads a dry-powder dose correctly but inhales weakly through the device. Evaluate inspiratory performance against that inhaler's requirements and arrange an appropriate alternative delivery method when adequate powder dispersion cannot be achieved.

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A young child uses a holding chamber with a mask, but aerosol escapes around the cheeks. Correct the mask fit and observe breathing through the chamber before concluding that the medication itself has failed.

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During walking, a cold-handed patient's displayed saturation fluctuates while the pulse signal becomes erratic. Assess symptoms and safety, improve the sensor site and verify signal quality before treating every displayed fluctuation as a physiological desaturation.

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Several patients show unusually high oxygen uptake after a flow-sensor change. Review flow calibration, gas calibration and signal alignment with the current circuit before attributing the shared change to improved exercise capacity or unusual metabolism.

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A patient requires supplemental oxygen for CPET. Before collecting metabolic data, confirm that the laboratory's system and delivery arrangement are validated for those conditions, and document the oxygen configuration used throughout the exercise protocol.

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A patient scheduled for diagnostic bronchodilator testing used a rescue inhaler shortly before arrival. Record the medication and timing, review the protocol's withholding requirements and determine whether to proceed with qualified interpretation or reschedule.

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A patient develops lightheadedness and chest discomfort during repeated forced expirations. Stop testing, assess the patient and follow the laboratory's clinical response process before considering whether any further maneuvers are appropriate that day.

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A patient produces small, consistent FVC values after shallow preparatory breaths. Demonstrate a full inspiration and repeat the maneuver with clear coaching before interpreting the low volumes as evidence of restriction or progressive disease.

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For an FVC of 2.0 L, the start limit is 0.100 L. A back-extrapolated volume of 0.160 L exceeds that limit, so coach an immediate explosive start and obtain another maneuver if safe.

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A maneuver contains a clear cough at 0.4 seconds but continues to a complete expiration without leakage. Reject its FEV1 for acceptability, assess FVC separately and coach another effort to obtain a usable first-second measurement.

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An adult's largest preceding FVC is 3.00 L. A subsequent otherwise acceptable maneuver ends without a plateau after five seconds and yields 2.90 L. Its 0.10 L shortfall meets the 0.150 L comparison tolerance. A 2.80 L result would fail that pathway. If an initially provisional maneuver is followed by a substantially larger FVC, reassess the earlier maneuver against the applicable tolerance.

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An adult's two best acceptable FEV1 values differ by 0.090 L, while the best FVC values differ by 0.210 L. FEV1 meets repeatability; FVC does not, so consider further safe attempts directed at complete expiration.

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A five-year-old has acceptable FVC values of 0.90 and 0.82 L. Ten percent of 0.90 L is 0.09 L, so the larger allowance is 0.10 L; the 0.08-L difference meets repeatability.

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A patient with facial weakness shows escaping air at the mouth corner during expiration. Improve the interface and seal, then repeat the maneuver before accepting the low FVC as evidence of respiratory muscle or parenchymal disease.

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A patient with orthopnea has substantially lower vital capacity when supine despite good-quality efforts in both positions. Report the positional difference and assess it alongside respiratory pressures and clinical findings rather than labeling the cause from spirometry alone.

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During lung-volume testing, a patient takes several progressively deeper breaths before shutter closure. Reestablish stable tidal breathing and a consistent end-expiratory level before repeating the measurement and linking it to inspiratory capacity.

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True TLC is 6.0 L and the initial measured FRC is 3.0 L. Before IC measurement, the patient's end-expiratory level rises to 3.5 L. Inspiration to the same true TLC now produces an IC of 2.5 L. Combining the original FRC with this IC gives an erroneous TLC of 3.0 + 2.5 = 5.5 L. Repeat the linked sequence from a stable end-expiratory reference before accepting the apparent reduction.

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A severely obstructed patient pants rapidly and produces an unexpectedly high thoracic gas volume with poor pressure loops. Coach slower gentle panting, support the cheeks and repeat the measurement before interpreting the apparent hyperinflation.

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An obstructed patient finishes a washout while the tracer signal still indicates continued emptying. Continue or repeat according to the validated endpoint protocol and check for leaks before reporting the calculated FRC as complete.

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The largest same-session VC is 4.00 L, and the largest VA from other acceptable maneuvers is 5.00 L. An inspired volume of 3.40 L is exactly 85% of VC. Five percent of 5.00 L is 0.25 L, exceeding 0.20 L. A VA of 4.75 L therefore meets the exception at its boundary; 4.74 L does not. An inspired volume of 3.39 L fails the 85% floor regardless of how closely VA agrees.

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A patient reaches full inspiration but bears down visibly during the DLCO hold. Explain a relaxed breath-hold, allow the required recovery interval and repeat the maneuver before interpreting the unexpectedly low transfer measurement.

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Two acceptable DLCO measurements are 18.4 and 19.8 mL·min⁻¹·mmHg⁻¹. Their difference is 1.4, meeting repeatability; their mean is 19.1. Review the remaining quality requirements before reporting that mean.

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Baseline spirometry begins with hesitant efforts, but post-bronchodilator efforts are explosive and complete. Review baseline acceptability and repeatability before attributing the entire numerical improvement to bronchodilation; technique changed alongside the medication exposure.

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Pre-diluent FEV1 is 3.2 L and post-diluent FEV1 is 3.0 L. The 20% response endpoint is 2.4 L, calculated from the post-diluent value, rather than 2.56 L from the earlier measurement.

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Post-diluent FEV1 is 3.00 L and falls to 2.34 L, a 22% decrease. Stop methacholine, administer the bronchodilator and repeat spirometry after 5–10 minutes. If the recovery baseline is 3.00 L, a result of 2.55 L remains 15% below baseline and is insufficient for discharge. Continue attended management and reassessment. Recovery to 2.76 L is within 10%, but symptoms and clinical condition must also support discharge.

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A follow-up six-minute walk uses a shorter corridor with more turns and enthusiastic individualized coaching. Recognize both protocol changes as threats to comparison and repeat under the established standardized conditions when a reliable trend is required.

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A patient's first 6MWT distance is 380 m. After 30 minutes, heart rate remains above baseline, so delay the second test until heart rate and SpO2 have returned to baseline. The second standardized test yields 410 m. Record the better distance, 410 m, as the baseline result for assessing subsequent change. Keep the course, instructions, encouragement and oxygen conditions consistent so procedural differences do not obscure the comparison.

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During a six-minute walk, a patient staggers and reports chest pain despite a displayed saturation of 93%. Stop the test and assess the patient immediately; the reassuring saturation does not neutralize the symptom-based cessation criteria.

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A child's capillary gas shows a low PO2 while pulse oximetry and clinical appearance are reassuring. Do not diagnose arterial hypoxemia from capillary PO2 alone; use an appropriate oxygenation assessment and arterial sampling when clinically required.

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A patient produces low MIP values with visible mouth leakage and inconsistent effort. Correct the seal and repeat coaching at the specified starting volume before concluding that the patient has severe inspiratory muscle weakness.

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After removing a used mouthpiece, a technologist removes gloves and prepares to fit clean equipment for the next patient. Perform hand hygiene before handling the clean setup and use fresh gloves when the next task requires them.

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An older adult has FEV1/FVC of 0.68 with an applicable lower limit of 0.64 and acceptable testing. The ratio is within the reference range despite being below 0.70; interpret remaining results and symptoms separately.

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A patient has low FVC and preserved FEV1/FVC, but TLC is within its reference range and RV is elevated. Restriction is not established; consider air trapping and the complete quality and clinical information.

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A patient has an abnormally low FEV1/FVC and low FVC, but TLC is elevated. Classify the demonstrated obstruction and assess air trapping rather than calling the pattern mixed solely because both spirometric volumes are small.

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With linked FRC of 3.2 L, IC of 2.4 L and VC of 4.1 L, TLC is 5.6 L and RV is 1.5 L. Verify component quality before comparing either derived volume with reference limits.

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An obstructed patient has a larger plethysmographic FRC than helium-dilution FRC. Review panting traces and dilution equilibration first; if both are valid, poorly communicating gas offers a physiological explanation for the method difference.

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FEV1 rises from 2.00 to 2.28 L and predicted FEV1 is 3.00 L. The change is 0.28/3.00 ×100 = 9.3% of predicted, so it does not meet the greater-than-10% criterion.

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Two patients both have FVC at 80% predicted but different z-scores under their applicable equations. Use the appropriate reference limits to classify each measurement rather than assuming that the shared percentage gives them identical statistical standing.

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A patient with newly documented anemia has a lower DLCO than previously, with otherwise similar testing. Review current hemoglobin and apply the appropriate interpretive adjustment before concluding that pulmonary gas-exchange structures have deteriorated.

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Measured FEV1 remains 2.4 L, but a laboratory equation change alters its reported percent predicted and classification. Explain the reference change and compare the absolute measurements before describing the patient as physiologically improved or worsened.

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A patient's follow-up FEV1 is higher, but the first study was pre-bronchodilator and the second followed rescue medication. Identify the changed condition and obtain a comparable measurement before attributing the entire difference to long-term treatment benefit.

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A report shows a markedly low FVC with limited end-of-expiration quality, while FEV1 has better-quality support. Qualify conclusions about the low FVC and consider repeat testing rather than assigning restriction solely from the reported number.

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During exercise, VCO2 is 1.50 L/min and VO2 is 1.25 L/min, giving RER 1.20. Interpret that value with workload, symptoms and other exercise responses rather than treating it as a stand-alone diagnosis.

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A smoker has obstruction and low DLCO. Emphysema is a plausible explanation, but review hemoglobin, imaging and the broader history before presenting it as established solely by the pulmonary function pattern.

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Monthly review shows increasing unacceptable starts concentrated in one testing session pattern. Review representative curves and workflow, provide targeted coaching support and reassess subsequent start quality to determine whether the intervention actually improved measurement performance.