A biological quality control (Bio-QC) program for pulmonary function testing (PFT) uses repeated measurements from stable, healthy staff members to monitor equipment performance and detect drift over time. Unlike mechanical calibration checks, Bio-QC captures the full system, including the device, the operator, and the environment. For ISO 15189 accreditation, auditors expect documented evidence that your lab actively monitors measurement consistency using real biological subjects. A well-structured Bio-QC program is not optional; it is one of the clearest demonstrations of a quality system in action.

TL;DR

• Bio-QC uses repeated lung function measurements from healthy staff to detect equipment and operator variability.

• ISO 15189 requires labs to demonstrate ongoing measurement quality, and Bio-QC is a primary mechanism for satisfying this requirement.

• A successful program needs defined subjects, a consistent protocol, statistical control limits, and documented responses to out-of-control results.

• Digital quality control tools, including Westgard-based tracking, make program management significantly less burdensome.

• The PFT market is growing rapidly, making robust QC infrastructure increasingly important for labs scaling their services.

What Is Biological Quality Control in the Context of PFT Labs?

Biological quality control is the practice of using a known, stable human subject (typically a healthy lab staff member) as a living reference standard. The subject performs standardized pulmonary function tests at regular intervals, and the resulting values are tracked statistically over time.

The core assumption is straightforward: if the subject is genuinely stable, any significant change in their measured values reflects a problem with the measurement system, not their lungs.

Key parameters typically tracked in a PFT Bio-QC program include:

• FVC (Forced Vital Capacity)

• FEV1 (Forced Expiratory Volume in one second)

• FEV1/FVC ratio

• PEF (Peak Expiratory Flow)

• DLCO (Diffusing Capacity, where applicable)

Bio-QC sits alongside, and does not replace, mechanical checks such as syringe calibration verification. Together, they form the two-pillar approach to PFT quality assurance described in quality system frameworks for pulmonary function laboratories.

Why Does ISO 15189 Specifically Require This Type of Program?

ISO 15189 is the international standard for medical laboratory quality and competence. It requires laboratories to implement internal quality control (IQC) procedures that detect errors before patient results are reported. According to quality system frameworks for pulmonary function laboratories, the twelve quality system essentials include quality control as a distinct and non-negotiable component of laboratory operations.

For PFT labs specifically, Bio-QC satisfies several ISO 15189 clauses simultaneously:

Auditors are not simply looking for a calibration log. They want to see a living, active system that your team engages with regularly.

How Do You Set Up a Bio-QC Program Step by Step?

Setting up a compliant Bio-QC program does not require reinventing the wheel. The following structure reflects established best practice.

Step 1: Select and Screen Your Bio-QC Subjects

• Choose two to three healthy non-smoking staff members with stable lung function.

• Confirm baseline stability with repeat measurements across at least five separate sessions before entering the program.

• Exclude subjects with recent respiratory illness, smoking history, or known lung conditions.

Step 2: Define the Testing Protocol

• Test at the same time of day (morning is preferred to minimize diurnal variation).

• Use the same device, same operator where possible, and the same room conditions.

• Perform testing according to ATS/ERS acceptability and reproducibility criteria.

• Record ambient temperature, humidity, and barometric pressure at every session.

Step 3: Establish Your Control Limits

• After collecting at least 20 baseline data points per subject, calculate the mean and standard deviation for each parameter.

• Apply Westgard rules to define warning and rejection limits (typically 2SD warning, 3SD rejection).

• Review and recalculate limits at defined intervals (e.g., every six months or after equipment servicing).

Step 4: Determine Testing Frequency

• Minimum recommendation: Bio-QC performed at least weekly for active labs.

• High-volume labs or labs with multiple devices should consider daily Bio-QC per device.

• Always perform Bio-QC after any equipment repair, software update, or consumable lot change.

Step 5: Document Everything

• Record raw values, control chart status, and any corrective actions taken.

• Link out-of-control events to a formal non-conformance process.

• Retain records in a format that is immediately retrievable during an audit.

What Are the Most Common Bio-QC Failures Auditors Flag?

Based on common audit findings in accredited PFT labs, these are the recurring gaps:

• No defined control limits: Teams track values informally without statistical thresholds. This does not satisfy ISO 15189.

• Irregular testing frequency: Bio-QC performed only when staff remember, rather than on a scheduled, documented basis.

• Missing corrective action records: An out-of-control result was identified but no investigation was documented.

• Single subject programs: Relying on one person creates vulnerability. Illness or departure collapses the program.

• Disconnected from the broader quality system: Bio-QC data lives in a spreadsheet isolated from non-conformance and action plan records.

How Is Technology Changing the Management of Bio-QC Programs?

The global pulmonary function testing system market was valued at USD 178.68 million in 2026 and is projected to grow substantially over the coming decade, according to Fortune Business Insights. Research Nester reports the broader PFT devices market was valued at USD 3.5 billion in 2025, projected to reach USD 6.5 billion by 2035. As labs scale to meet growing demand, manual Bio-QC management becomes a genuine operational risk.

Modern platforms are addressing this directly. Rezibase, for example, includes a dedicated accreditation module that manages quality control using Westgard methods, alongside non-conformance tracking, action plans, audits, and document management. This means Bio-QC data does not live in isolation; it connects directly to the quality system infrastructure auditors expect to see working as a whole.

For labs currently managing Bio-QC in spreadsheets, transitioning to a structured digital system is typically straightforward. Most data can be migrated cleanly, and the benefit of having control charts, corrective action records, and audit trails in one place is immediately visible during accreditation reviews.

Frequently Asked Questions

How many Bio-QC subjects does a lab need?
A minimum of two subjects is strongly recommended. This provides redundancy if one subject is unavailable and allows cross-checking of trends.

Can Bio-QC subjects be patients rather than staff?
No. Subjects must have stable, healthy lung function. Patients with respiratory conditions introduce biological variability that undermines the purpose of the program.

What happens when a Bio-QC result is out of control?
Testing on patient samples should be paused until the cause is identified. Investigate the device, consumables, environmental conditions, and operator technique. Document every step.

How often should control limits be recalculated?
At least every six months, or after any significant change to equipment, environment, or consumable lots.

Does Bio-QC replace syringe calibration checks?
No. Syringe calibration verification and Bio-QC serve complementary roles. Both are required.

Can one Bio-QC program cover multiple devices?
Each device should have its own Bio-QC data series. Cross-device comparisons can be informative but do not substitute for device-specific monitoring.

What format do auditors expect for Bio-QC records?
Control charts with clearly marked limits, dated entries, and linked corrective action records. Digital systems that generate these automatically are increasingly the expected standard.

About Rezibase

Rezibase is Australia's most advanced cloud-based respiratory and sleep reporting platform, built by respiratory scientists for respiratory scientists. The platform includes a comprehensive accreditation module covering ISO 15189 requirements, Westgard-based quality control, non-conformance management, and audit tools, all in one vendor-neutral system trusted by over 35 sites including NHS and NSW Health.

Explore how Rezibase can support your Bio-QC program and accreditation readiness at rezibase.com.

References

• Clinical Gate. Quality Systems in the Pulmonary Function Laboratory. https://clinicalgate.com/quality-systems-in-the-pulmonary-function-laboratory/

• Fortune Business Insights. Pulmonary Function Testing System Market Size, Trends [2034]. https://www.fortunebusinessinsights.com/industry-reports/pulmonary-function-testing-systems-market-101158

• Research Nester. Pulmonary Function Testing Devices Market Size Report 2035. https://www.researchnester.com/reports/pulmonary-function-testing-devices-market/8042