Static Spirometry (SVC)
Slow Vital Capacity was arguably the first ever recorded lung volume. The full excursion of the maneuver gives a measure of the change in volume of gas in the lungs from complete inspiration to complete expiration or vice versa. The measurement begins with the subject quietly breathing in a steady-state condition followed by a maximal breath-in and a full breath-out.
The spirogram of a slow vital capacity maneuver has several key identifying components:
- Slow Vital Capacity (SVC)
- Expiratory Reserve Volume (ERV)
- Inspiratory Capacity (IC). Called a capacity because it is the sum of two lung volumes: IC = IRV+TV
Dynamic Spirometry (FVC)
Although the most widely utilized pulmonary test, it is commonly the most poorly administered and reported. Through clever use of interactive help and clinical monitoring, ComPAS provides excellence in spirometry. Flow Volume efforts can be completed in any order of breathing with full fidelity of the loop captured and stored. For reports, data is automatically selected by ATS criteria; however, the user can override both data and loop selection if desired.
The spirogram of a forced vital capacity maneuver has several key identifying components:
- Forced Vital Capacity (FVC)
- Forced Expired Volume in one second (FEV1)
- FEV1/FVC (FEV1/FVC)
Flow Volume Loops
The forced volume excursion when plotted against flow rate reveals perhaps the most recognizable shape in pulmonary function testing. There are many measurements that can be taken from this single dynamic effort:
Identifying Measurements on the Flow Volume Loop
- Peak Expiratory Flow Rate (PEFR)
- Forced Expiratory Volume after 0.5 seconds (FEV0.5)
- Forced Expiratory Volume after 1 second (FEV1)
- Forced Expiratory Volume after 3 seconds (FEV3)
- Forced Expiratory Volume after 6 seconds (FEV6)
- Forced Vital Capacity (FVC)
- Forced Expiratory Flow at 25% of FVC (FEF25)
- Forced Expiratory Flow at 50% of FVC (FEF50)
- Forced Expiratory Flow at 75% of FVC (FEF75)
- Forced Expiratory Flow 25– 75% of FVC (FEF25-75)
- Forced Expiratory Flow at 25% of FVC iso-volume (FEF25_iso)
- Forced Expiratory Flow at 50% of FVC iso-volume (FEF50_iso)
- Forced Expiratory Flow at 75% of FVC iso-volume (FEF75_iso)
- Forced Expiratory Flow 25– 75% of FVC iso-volume (FEF25-75_iso)
- Forced Inspiratory Flow at 25% of FVC (FIF25)
- Peak Inspiratory Flow Rate (PIFR)
- Forced Inspiratory Flow at 50% of FVC (FIF50)
- Forced Inspiratory Flow at 75% of FVC (FIF75)
- And many more…
Maximum Voluntary Ventilation
The volume of gas that can be breathed in 15 seconds when a person breathes as deeply and quickly as possible. The result is extrapolated from 15 seconds to show what could be achieved over one minute. At the best of times, the MVV can be a difficult test to assess in terms of patient effort and compliance. To help determine effort, each time an MVV is performed in ComPAS, the data are compared to the subject's FEV1 x 35 and FEV1 x 40.
Cough Peak Flow
In some cases of neuromuscular disease, both adults and children exhibit a weak cough; measurement of Cough Peak Flow (CPF) is useful to monitor expiratory muscle weakness and bulbar involvement. The CPF is the velocity of air being expelled from the lungs after a cough maneuver usually from maximum inspiration. This measurement can be expressed and reported in ComPAS in L/min or L/sec.
Identifying Measurements from CPF efforts:
- Cough Peak Flow (CPF)
ComPAS employs a variety of techniques for measuring the compartments of lung volume depending upon the capability of the hardware.
Nitrogen Recovery (TLC)
Total Lung Capacity (TLC) can be measured during the performance of any Single Breath Diffusion (DLCO) study. This is an excellent screening method for identifying patients requiring further lung volume study. All Medisoft instruments are equipped with the necessary oxygen sensor to enable the technique.
Identifying Measurements from DLCO efforts:
- TLC (TLC)
- Lung subdivisions using data from SVC
Working with the magnificent Body Plethysmograph, measurements of Airways Resistance (Raw) and Specific Conductance (SGaw) can be completed quickly and with ease. In routine use, a pre-test 'coaching' screen can be used to prepare the patient for testing and minimize time spent in aborted efforts. An automated routine for establishing temperature equilibrium inside the cabin ensures ideal testing conditions. When working with difficult subjects, routines that monitor each phase of the test can guide technician intervention to improve results.
Identifying Measurements from RAW efforts:
- Airways Resistance (RAW)
- Specific Conductance (SGaw)
- Specific Resistance (SRaw)
- Volume of Thoracic Gas (VTG)
- Functional Residual Capacity (FRC)
- Inspiratory Capacity (IC)
- Expiratory Reserve Volume (ERV)
- Total Lung Capacity (TLC)
- Vital Capacity (VC)
- Residual Volume (RV)
- Ratio (RV/TLC)
Single Breath Diffusion
Since the pioneering days when the test was first developed in England, testing of Single Breath Diffusion (DLCO) has been part of our heritage. Our excellence for DLCO testing and reproducibility comes from a studied application of measurement technique and hardware design guided by watchful software. Automated procedures for system preparation coupled with precision analysis make DLCO a test that is easy to perform and highly reproducible.
In many ways, DLCO is a general measure of the complete 'efficiency’ of the lungs because it is influenced by three key components: The surface area of the lung with contact to diffusing alveoli (VA – Alveolar Volume), the thickness of the alveolar-capillary membrane (Dm - Membrane Diffusion) and the volume of blood available in the capillary bed of the lung (Vc – Capillary Blood Volume).
In this test we use a special gas mixture containing 0.300% CO, 10.0% Helium, 21,0% O2 and balance N2. The CO is used to trace the diffusion in place of O2 because it is a one-way transfer across the alveolar-capillary membrane for combination with Hb. The helium in the mixture is used to obtain a measure of the alveolar volume.
The challenge of Single Breath Diffusion testing is to obtain a representative sample of gas from an area of the lungs where diffusion is taking place. In the "traditional" method for measuring DLCO the patient first breathes all the way out to residual volume and is then connected to the test gas. They breathe all the way in to TLC and are then instructed to hold their breath for approximately 10 seconds. After having held their breath for ten seconds, the first amount of gas that leaves the lips when breathing out, has been resident in the physiological dead-space (mouth, trachea and two main bronchi) and must therefore be discarded before collecting a valid gas sample.
Measurements from DLCO testing:
- Single Breath Diffusing Capacity (DLCO)
- Alveolar Volume (VA)
- Diffusion per unit area of Lung Volume (DL/VA)
Respiratory Muscle Strength
Maximum Inspiratory and Expiratory Pressures (MIP and MEP) can be measured from TLC or RV respectively or from FRC. The lung volume at which the pressures are measured is captured by the spirometry tracing simultaneous to the test maneuver.
Identifying Measurements from RMS efforts:
- Maximum Inspired Pressure (MIP)
- Maximum Expired Pressure (MEP)
- Peak Inspired pressure (PIP)
- Peak expired Pressure (PEP)
Bronchial challenge testing is highly versatile and performed with ease in ComPAS. The challenge options support methacholine, Aridol, Exercise and Cold Air. The challenge protocols can be easily designed to suit any range of procedures and from the protocol the test is calmly sequenced through each level with clear and straightforward displays. Never before has provocation testing been so beautifully designed and easy to accomplish!
Identifying Measurements from Challenge efforts:
Six Minute Walk
The Six-Minute Walk Test (6MW) is used to assess the sub-maximal level of an individual's functional capacity. The test evaluates integrated responses to moderate exercise including the pulmonary and cardiovascular systems, systemic circulation, peripheral circulation and muscle metabolism. It measures the distance an individual is able to walk over a total of six minutes on a hard, flat surface. The goal is for the individual to walk as far as possible in six minutes without jogging or running.
Test data stored on the Nonin WristOx can be directly downloaded into ComPAS via Bluetooth. The smart report can be set to provide a stand-alone 6MWT report or integrate the data into a full PFT report format.
Identifying Measurements from 6MW efforts:
- Six Minute Walk (6MW)