Breath Sampling Criteria - Part 2:
The logistics of obtaining a suitable sample
Counterpoint Volume 2: Issue 3 - Article 2 (October 2017)
An article for participants in the myCAMprogram
Jan Semenoff, BA, EMA
Forensic Criminalist
Disposable mouthpieces
Let’s start at the very beginning of the process – with the disposable mouthpieces themselves. They are inexpensive, cheaply constructed, and disposable. As such, we tend to ignore them, and the impact they play on a breath test. However, think of the mouthpiece as an interface between the test subject and the breath test device. They serve a number of important functions that can impact the breath test process.
Figure 1 - A generic disposable mouthpiece
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For obvious reasons of hygiene, a disposable plastic mouthpiece is attached to the external breath tube prior to collecting a breath sample from the subject. The mouthpiece is intended to provide a clean means of providing the sample, and is designed to trap saliva, liquid and other contaminants we don’t want to discuss, from getting into the breath test device’s internal components. The sample chamber must be free of contaminants, and the mouthpiece helps accomplish that goal
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The mouthpiece should be discarded after each use. I always used the remains of the sealed plastic bag as a tool for getting the mouthpiece off the external breath tube without touching the contaminated or “wet end”.
The mouthpieces offer a slightly restricted means of blowing, due to their fairly small diameter openings. In cases of inability to provide a suitable sample, where the subject appears to be blowing, it would be best to change the mouthpiece. There is a slight possibility that the mouthpiece may contain a small internal occlusion. It is also best practice for operators to seize the mouthpiece(s) as evidence in refusal cases.
Although there are different mouthpiece manufacturers, most breath test device manufacturers suggest using only their dedicated mouthpieces. Different mouthpiece designs have wider or narrower inlets (or the “straw” end) that makes providing a breath sample a little easier for the specific breath testing device design.
The mouthpieces used on most in-station evidentiary devices are fairly generic, while the mouthpieces used on the roadside testers are specific to each individual instrument. The one clear exception to this is the Intoximeter EC/IR II that uses a specific disposable mouthpiece that includes a functioning one-way valve. However, liquid can still flow through the one-way valve. More on that in a bit...
Different roadside testers use different size mouthpieces, which are not typically interchangeable. In general, they are designed to offer minimal resistance to breath flow, but do generate the small positive pressure necessary at the breath sampling port while a sample is being obtained.
The mouthpieces offer a slightly restricted means of blowing, due to their fairly small diameter openings. In cases of inability to provide a suitable sample, where the subject appears to be blowing, it would be best to change the mouthpiece. There is a slight possibility that the mouthpiece may contain a small internal occlusion. It is also best practice for operators to seize the mouthpiece(s) as evidence in refusal cases.
Although there are different mouthpiece manufacturers, most breath test device manufacturers suggest using only their dedicated mouthpieces. Different mouthpiece designs have wider or narrower inlets (or the “straw” end) that makes providing a breath sample a little easier for the specific breath testing device design.
The mouthpieces used on most in-station evidentiary devices are fairly generic, while the mouthpieces used on the roadside testers are specific to each individual instrument. The one clear exception to this is the Intoximeter EC/IR II that uses a specific disposable mouthpiece that includes a functioning one-way valve. However, liquid can still flow through the one-way valve. More on that in a bit...
Different roadside testers use different size mouthpieces, which are not typically interchangeable. In general, they are designed to offer minimal resistance to breath flow, but do generate the small positive pressure necessary at the breath sampling port while a sample is being obtained.
Figure 2 - A variety of mouthpiece designs are available on the market. The mouthpiece on the far right is designed specifically for the Intoximeter EC/IR II, and incorporates a one-way valve to prevent "suck back" by the person being tested.
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The positive pressure effect in most of the roadside testers is achieved by making the exhaust side of the mouthpiece a slightly narrower diameter than the "blowing" side. Therefore, it is essential that the donor is offered the correct side when delivering a sample.
If the donor blows through the exhaust end, no positive pressure will be developed, and the pressure transducer and timer circuitry will not be activated. The donor may appear to be blowing sufficiently but the instrument will indicate that the subject is not providing a suitable sample. This can be the cause of an inappropriate “refusal” charge. Appropriate training and operator competence should again ensure that the correct mouthpiece end is being used. |
Figure 3 - Disposable mouthpieces for the Intoxilyzer Model 400
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It is also essential that a new mouthpiece be used for each breath test. Condensation from the exhaled breath can form on the inside of the mouthpiece and cross-contaminate subsequently obtained samples. Health concerns also make it imperative that only a new sealed mouthpiece is used for each donor. If condensation is noticed during a series of repeated attempts, the mouthpiece should be changed to ensure that a false high reading is not introduced based on saliva and fresh-mouth alcohol.
Figure 4 – Opposite ends of the same mouthpiece. The subject provides there sample through the wide-lipped end (left). A positive pressure is created by the smaller diameter opening on the right.
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Often, the more expensive mouthpieces, as used with the evidentiary units, are molded from transparent plastic. Typically, the mouthpieces used by the roadside testing devices are opaque white or translucent. This makes determining if condensation is present very difficult, and again I suggest a new mouthpiece is used for each test. In cases where the subject does not appear to be providing a suitable sample, best practice is to discard the mouthpiece and utilize another new, fresh one. |
It is best practice to seize any discarded mouthpieces as evidence to prove that they were suitable in the event of a refusal case.
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The operator should then carefully remove the wrapper from the blowing end, and offer the blowing end to the subject with the appropriate explanations. Often, the wrapper is retained by the operator as a sanitary means of getting the mouthpiece off the instrument and discarded without contacting the now contaminated mouthpiece itself.
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Figure 5 - Pulling the wrapper off an inserted mouthpiece to expose the lipped end without touching the mouthpiece itself. Use the same technique in reverse to get the mouthpiece off the breath testing device without touching the saliva contaminated end.
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Limitations in mouthpiece design
Regardless of what you may have heard, most designs will NOT stop the flow of liquid, saliva or spit through the mouthpiece. The “trap” is incapable of stopping the flow of liquid. You can easily flood the inside of the tubing and sample chamber. See Figures 6-8.
I am able to easily pass water through the mouthpieces (dyed green for higher visibility).
I am able to easily pass water through the mouthpieces (dyed green for higher visibility).
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Figures 6 thru 8 - The notion that the "spit-trap" mouthpiece will prevent saliva or other liquid from passing through is false.
Substandard mouthpieces
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Sometimes the mouthpieces have extra flashing marks on the plastic castings, or mold imperfections from their casting. Again, this is a deviation from standard condition, but something to keep in mind. I have occasionally seen mouthpieces that had extraneous bits of plastic that made them very difficult, and in one case impossible, to blow through. A prudent operator will be able to identify these, and will take the appropriate precautions to ensure the overall results of the testing are not adversely affected.
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Figure 9 - Carefully unwrapping a fresh disposable mouthpiece.
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Also, very rarely, the act of opening the mouthpiece through the sealed plastic wrap can cause a bit of plastic to stretch over the outlet of the mouthpiece itself, and seal the end. Think of it as stretching plastic wrap over a bowl before putting leftovers in the fridge. The plastic can, under such circumstances, completely occlude the mouthpiece, preventing any exhaled breath from entering the device. But, this is rare. I’ve seen it only twice in about 5000 tests. However, in each case the test subject was absolutely unable to provide a sample, and it was only discovered that the plastic debris was present upon further examination.
The operator should use a fresh and sealed mouthpiece and attach it to the instrument in such a way that the operator’s fingers don’t actually touch the mouthpiece end. Case law exists in Canada concerning reasonable grounds for refusal on the basis of lack of hygiene[1].
[1] R. v. Pittendreigh (1994), 9 M.V.R. (3d) 236 (Alta. C.A.) – Concern about sanitation of an unwrapped mouthpiece is a reasonable excuse.
The operator should use a fresh and sealed mouthpiece and attach it to the instrument in such a way that the operator’s fingers don’t actually touch the mouthpiece end. Case law exists in Canada concerning reasonable grounds for refusal on the basis of lack of hygiene[1].
[1] R. v. Pittendreigh (1994), 9 M.V.R. (3d) 236 (Alta. C.A.) – Concern about sanitation of an unwrapped mouthpiece is a reasonable excuse.
The operator holds the mouthpiece with the wrapper still around the entire mouthpiece but opened at the exhaust end. The wrapped is slowly pulled back to reveal the side arm or sampling port on the mouthpiece. The side arm or sampling port of the mouthpiece is engaged onto the sampling port of the breath test device. The mouthpiece snaps into place with a positive lock.
Figure 10 - Constituent parts of a typical disposable mouthpiece.
The outlet port of the mouthpiece used by the Model 400, as shown, and the sampling ports used by other handheld testers are designed to prevent condensation from being captured and drawn into the fuel cell. This ensures that liquid or saliva does not contaminate the fuel cell itself.
Obviously, only mouthpieces designed for the specific instrument should be used.
Obviously, only mouthpieces designed for the specific instrument should be used.
Donor instructions
Once the demand for a breath sample has been made, the subject must be instructed on how to provide the sample(s). Most operators are taught to instruct the donor to fill their lungs and exhale through the mouthpiece, making a tight seal with their lips around the blowing end. Donors should be instructed to provide the sample in one continuous exhalation. Many operators find that coaching the subject through individual steps of the sampling process works better, as test subjects understand the process better with smaller instructional steps.
If you’ve ever reviewed a police video showing a test sample, you’ve heard, “Keep blowing, that’s it, keep blowing, keep blowing, keep blowing” more than once. Once the sample is captured, and the audible tone emits, I then tell them that they can stop blowing. This helps ensure that the subject does not “suck back” at the end of the sampling phase. However, if the instrument detects a loss of pressure, the tone will stop and the test will be aborted. If negative pressure is detected at any time during the test, the test sequence is again aborted.
Let’s walk through the process using a typical handheld device. I will use an older Intoxilyzer Model 400 for illustrative purposes, although the procedures are basically the same for other devices.
If you’ve ever reviewed a police video showing a test sample, you’ve heard, “Keep blowing, that’s it, keep blowing, keep blowing, keep blowing” more than once. Once the sample is captured, and the audible tone emits, I then tell them that they can stop blowing. This helps ensure that the subject does not “suck back” at the end of the sampling phase. However, if the instrument detects a loss of pressure, the tone will stop and the test will be aborted. If negative pressure is detected at any time during the test, the test sequence is again aborted.
Let’s walk through the process using a typical handheld device. I will use an older Intoxilyzer Model 400 for illustrative purposes, although the procedures are basically the same for other devices.
Figure 11 - The Intoxilyzer Model 400
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The subject should take an inhalation and then exhale through the proper end of the mouthpiece. It is not necessary to inhale to the point that the lungs are bursting, and it is not necessary to exhale hard enough to inflate a tractor tire, just a nice steady exhalation. Sometimes, subjects are over-eager to provide a sample, and blow so hard or so fast that they cannot sustain the necessary five-second time. The operator should then provide a little more instruction to, “Blow not quite as hard but a little longer”, and repeat the testing sequence. A new mouthpiece may be required. |
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The subject should not hyperventilate prior to providing the sample. This cools the mouth and upper respiratory tract and adds a variable to the sample being taken.
They should also not hold their breath, howver slightly, as this can artificially raise the reported BrAC reading. With many breath test devices, once the subject starts blowing hard enough to activate the pressure transducer, a “Flow” tone is emitted and the “Flow” light comes on. The ON-OFF switch is inhibited to prevent accidental shutdown of the instrument. The tone continues until the microprocessor has determined that a minimum time has elapsed and the pressure was maintained for a deep lung air sample to be obtained. The sampling pump is activated. |
Figure 12 - The FLOW light indicates sufficient force of the donor sample. Many units also emit an audible tone to indicate proper breath sample pressure and flow.
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This is not just a timing circuit, but a device that measures pressure and venturi (flow). This determines the volume of the actual breath sample exhaled and assists in capturing a true sample of deep-lung alveolar air. The subject’s breath sample is captured, and the tone stops. A reciprocating piston is automatically activated that draws about 1.0 - 1.2 ml of breath from the mouthpiece directly onto the fuel cell for analysis. The sample may also be manually captured by some roadside testers by pushing a button while there is sufficient flow to produce a sample.
When the device has successfully captured the breath sample, typically an audible tone is emitted, and the unit begins the analysis phase of operation. In essence, the donor must blow long and hard enough to get the instrument to emit the short tone to initiate a sample capture.
When the device has successfully captured the breath sample, typically an audible tone is emitted, and the unit begins the analysis phase of operation. In essence, the donor must blow long and hard enough to get the instrument to emit the short tone to initiate a sample capture.
Figure 13 - Analyzing the sample for alcohol. The WAIT & ANALYZING lights are displayed.
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Once the sample has been successfully captured, the instrument will begin to analyze it for ethanol content. The “Analyzing” and “Wait” lights come on, and everybody holds their breath (figuratively, not literally). The longer the sample takes to analyze, the more amperage is produced in the fuel cell, with a higher final reading often obtained. The “Analyzing” light may be on for as much as thirty seconds or more, depending upon the BrAC.
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Once the “Analyzing” light goes off, the digital display provides a reading in the appropriate unit of measure. The digital display is often lit for nighttime use.
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During the entire sampling phase, the ON-OFF switch is disabled on most devices. Should the operator wish to capture the sample prior to the five second timer, a button may be pushed during sampling. This should rarely if ever be done during operational use, because the default settings work well for most subjects.
The mouthpiece is then removed, using the wrapper for hygienic reasons, and the mouthpiece is discarded. The unit will then switch itself off automatically after a pre-set time. |
Figure 14 - The digital BrAC reading
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Breath test requirements
Breath test devices are designed to obtain a sample of deep lung air, analyze it for alcohol, and express the concentration in a given unit of measure. Most modern units operate on the principle that a person, regardless of their size, must exhale with sufficient force to activate a pressure sensor or transducer of some sort. This action in turn activates a timing circuit. The test subject must maintain an even exhalation with sufficient force to maintain the minimum pressure set for the pressure transducer. As long as this minimum pressure is maintained, the timing circuit continues, and the sample will then be received, and subsequently analyzed, at the end of expiration. Specific parameters for time, pressure and volume are required to obtain a sample that can be analyzed by the instrument.
In order to achieve the desired target goal of a deep-lung air sample, the minimum exhalation time required for most breath test instruments is set at five to six seconds duration. The minimum exhalation force required is typically set at a pressure equivalent to a 15 cm (6”) column of water. The target volume for exhalation is typically set at between 1.0 – 1.5 litres of breath.
In order to achieve the desired target goal of a deep-lung air sample, the minimum exhalation time required for most breath test instruments is set at five to six seconds duration. The minimum exhalation force required is typically set at a pressure equivalent to a 15 cm (6”) column of water. The target volume for exhalation is typically set at between 1.0 – 1.5 litres of breath.
Figure 15 - The histogram on the new Intoxilyzer 9000 shows the minimum requirements for sample provision.
It is interesting to note that the minimum requirement of pressure, time and volume have been, for the most part, the standards used for measurement of a sample to determine its suitability. An AlcoTest 7410, as an example, has similar sample provision requirements as an Intoxilyzer 5000EN, an Intoximeter EC/IR II, or an older ALERT Model J3A. This is in part due to new instruments being compared to older ones currently approved for use as approved screening devices or evidentiary instruments during the certification and review process. In short, older devices were based on these parameters. Newer devices are compared to these approved parameters to see if the new device provides equivalent readings, under similar sample provision situations. The status quo has therefore been maintained regarding sample provision for quite some time.
Figure 16 - The Breathalyzer Model 900A. Completely manually operated, it relied upon the training, experience and judgement of the operator to obtain a suitable sample.
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This is in sharp contrast with devices such as the Breathalyzer Model 900 or 900A. When I was first qualified on these instruments in the early 1990’s, it was up to the operator to determine the suitability of the sample being provided, and judge whether or not deep-lung air samples were being properly provided in order to be analyzed for the presence and quantity of alcohol they contained. Qualified Technicians are still responsible to determine that the sample is truly a deep lung air sample. As a result, persons of very large stature might be required to provide samples beyond the minimum five-second, 1.1 – 1.5 L requirement. As an example, a large, male, football-linebacker might be required to exhale 12-15 seconds AND 3.5 – 4.0 litres in order to obtain the desired sample of deep-lung air.
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Conversely, a smaller statured person would provide a true sample of deep-lung air far quicker than the above example. However, the units employing a pressure/time/volume algorithm are not capable of determining the actual lung capacity of the individual being tested. Therefore, they are designed or programmed to obtain samples given certain assumptions. The five-second, 15cm water column pressure, 1.0 – 1.5 litre minimum volume are based on persons of normal stature. Some persons will be able to exceed these requirements, while other persons may not be able to achieve the minimums mandated by instrument design.
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