Accurate spirometry

Spirometry is an essential pulmonary function test that should be available at every general practitioner’s office. It provides objective information for lung health monitoring and the diagnosis of lung conditions [1], both in primary care and in pulmonology. Let us have a look at essential spirometry measurements and what they mean, the parameters that can be calculated on that basis, and the recommended reference values for interpretation.

All this constitutes a basis for accurate spirometry. Enhanced by digital technology, spirometry is entering a new era where it is becoming more time-efficient and more user-friendly not only towards the patient, but also those performing and interpreting it. The MESI mTABLET offers digital spirometry solutions for travelling health professionals (FEV6: Quick Spirometry), the GP office (Spiro: Primary Spirometry) and pulmonology specialists (Spiro+: Advanced Spirometry).

In this blog you will learn:

• Spirometry measurements and calculated parameters
• Recommended prediction models
• The role of digital technology in spirometry

Spirometry measurements and calculated parameters

Spirometry measurements range from basic to advanced, depending on the type of the spirometry measurement device and the field in which it is used (primary care, secondary care).

Basic measurement and parameters

The FEV6 basic spirometry measurement and the parameters calculated on its basis are used for a basic lung evaluation, for example at home visits by nurses. Only the expiration part of the patient’s lung function is monitored, so only the expiration and not the inspiration will be shown on the graph display(s).

In FEV6, the speed of the spirometry exam is at the forefront. This is why the maneuver of the patient (i.e. exhaling and inhaling according to the nurse’s or doctor’s instructions) also takes less time; while the full FVC maneuver can take up to 15 seconds, the FEV6 measurement can only take 6 seconds. This makes it faster and also easier for the patient. Let us see what FEV6 means and what parameters it can show.

Basic measurement

FEV6 (forced expired volume in 6 seconds): It shows the amount of forced vital capacity (FVC, i.e. the maximum amount of air expired forcefully from a fully inflated lung) expired by the 6th second of expiration. Measured in litres BTPS. In a healthy person, the FVC and FEV6 values are about the same. [1]

Parameters

• PEF (peak expiratory flow): The point of maximum expiration speed (in l/min) during a forced maneuver.
• FEV1 (forced expired volume in 1 second): The maximal volume of FVC exhaled in the first second of a forced exhalation. Measured in litres BTPS.
• FEV1/FEV6: This ratio is a simplified alternative to the Tiffeneau-Pinelli index (the FEV1/FVC ratio). Usually expressed as a percentage. [1]
• FEV6

Measurements and parameters for primary care

Again, only the expiration part of the patient’s lung function is monitored. At this level, spirometry is often used for asthma monitoring, so pre- and post-drug measurements will be carried out. Also known as bronchodilatation, this test is performed before and after the asthmatic patient has used a bronchodilator inhaler or nebuliser to open their lungs.

Primary care measurements

• FEVC (forced expiratory vital capacity): In this test, the full forced expiration will be required from the patient in contrast to the 6 seconds in FEV6. The patient will be encouraged to exhale as long as possible.
• VC (vital capacity): In contrast to FEVC, VC is the measurement of the maximum amount of air slowly expired from a fully inflated lung (the deepest inspiration).
• Pre- and post-drug measurement

Parameters

• FEV0.5: The forced expired volume at 0.5 s of forced expiration (normally used for children).
• FEV25: The forced expired volume at 25% of expiration
• FEV25-75: The forced expired volume between 25% and 75% of expiration.
• FEF50: Forced expiratory flow or mid-expiratory flow at 50 % FVC
• FEF75: Forced expiratory flow or mid-expiratory flow at 75% of FVC
• FET (forced expiratory time): The total time it takes the patient to expire FVC.
• VEXT (extrapolated volume): The extrapolated volume of the expired air that is outside the tangent on the Flow-Volume curve. According to the ATS/ERS guidelines, it serves as the hesitation criterion (if it exceeds 5%, the expiration was too slow). [1]
• FEV1/FVC: The Tiffeneau-Pinelli index, usually expressed as a percentage.
• FEVC
• VC
• FEV1/FEV6
• FEV1/VC

Measurements and parameters for pulmonologists

A specialist pulmonological examination requires more complex information, including the data on both the expiratory and inspiratory parts of the lung function (aka full-loop spirometry). This is possible due to closed-loop technology, which enables the patient to both breathe in and expire with the mouthpiece in their mouth rather than breathing in freely and then blowing into the mouthpiece. This enables a lot more measurements and parameter calculations.

Measurements in pulmonology

• FVC (forced vital capacity): The maximum volume of air that an individual can exhale with a maximally forced effort. Measured in litres BTPS.
• FIVC (forced inspiratory vital capacity): The total inspired volume after performing the expiratory FVC and reinspiring completely.
• TV (tidal volume): The amount of air moved during the inspiration and expiration while the patient rests. It indicates the subdivision of the lung.
• SVC (slow vital capacity): The volume of air expired through an unforced maneuver (slow blow). Similar to VC, but this particular measurement is more advanced.
• FEVC
• VC

Parameters

• PIF (peak expiratory flow): The point of maximum inspiration speed.
• FIVC
• SVC
• IVC (inspiratory vital capacity): The maximum amount of air that the patient can inhale after a full expiration.
• IC (inspiratory capacity): The maximum amount of air that can be inspired.
• EC (expiratory capacity): The maximum amount of air that can be expired.
• IRV (Inspiratory reserve volume): The difference between maximum inspiration and rest breathing.
• ERV (expiratory reserve volume): The difference between maximum expiration and rest breathing.
• FR (functional residual capacity): The volume of air left in the lungs at the end of passive expiration.

Recommended prediction models

No spirometry result can be read without reference to a prediction model. Prediction models are reference values that represent healthy zone for each individual according to guidelines valid in a specific country.

There are 5 different Global Lung Initiative (GLI) prediction models are becoming standard, but several others are still used as well. They are based on age, sex, height and ethnicity.

The role of digital technology in spirometry

There are many different devices for spirometry, of which there are many different types, from simple ones to large, complex devices designed for comprehensive assessment of pulmonary issues.

The advent of digital technology has brought many advantages to diagnostic measurements, including that of spirometry. The MESI mTABLET SPIRO is a digital diagnostic module for spirometry, with the following advantages for all levels of healthcare:

• Automatic calibration.
• Automated breath detection and maneuver termination.
• The diagnostic unit supports standard measurements. It is battery powered and wirelessly connected to the main diagnostic unit – the MESI mTABLET. The entire system is portable and fits into a carry-on bag or a trolley if needed.
• Our EHR management and sharing system, called MESI mRECORDS, enables automatic upload of spirometry results in the patient’s EHR, easy browsing and seamless sharing of data and spirometry results with other healthcare professionals even if they are not users of the MESI mTABLET.
• It supports a large number of prediction models, which can simply be selected from the list. Custom prediction models can be ordered.

The MESI offers three different spirometry solutions.

Quick Spirometry

Offering basic spirometry measurements, Quick Spirometry is an ideal solution for home visits. It offers enhanced visual display of the Flow-Volume curves and various parameters with automatic analysis:

• FEV6 measurement mode
• Parameters calculated: PEF, FEV1, FEV6, FEV1/FEV6 ratio
• Basic MESI mRECORDS analysis

Quick Spirometry is available as an app after purchasing the MESI mTABLET SPIRO diagnostic module, which offers Primary Spirometry – a comprehensive spirometry package for primary care.

Primary Spirometry (Spiro)

This diagnostic measurement tool covers all spirometry needs in primary healthcare:

• FEVC and VC measurement modes
• Parameters calculated: FEV0.5, FEVC, FEV25, FEF50, FEF75, FEV25-75, FET, VEXT, VC, FEV1/FEV6, FEV1/FVC, FEV1/VC
• Pre- and post-drug phase mode (bronchodilator – asthma test)
• Enhanced history graph through MESI mRECORDS

Advanced Spirometry (Spiro+)

The most versatile digital spirometer for specialists.

Advanced Spirometry is available as an app after purchasing the MESI mTABLET SPIRO diagnostic module, which offers Primary Spirometry – a comprehensive spirometry package for primary care.

• Six measurement modes (FVC, FEVC, VC; upcoming: FIVC, TV, SVC)
• Parameters calculated: PIF, FIVC, SVC, IVC, IC, EC, IRV, ERV, TV, FR
• Volume-time graph + VT6 graph
• Enhanced result view with three best curves
• Maneuver combinations (FVC and VC, or FEVC and VC)
• All parameters on one screen with live value changes
• On-screen instructions
• Criteria indicators (green checkmark if a maneuver is successful)
• Enhanced history graph through MESI mRECORDS: multiple-measurement history review
• Animated incentive mode

The MESI mTABLET SPIRO is a diverse tool that gives the primary care physician and the pulmonologist a tool for comprehensive assessment of a patient’s health beyond diagnosing possible pulmonary issues.

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