Terminating Terminology Terror Part 1 – StatisticsBy Blair Bigham Published: Sat February 20, 2010
When shall we three meet
again? In thunder, lightening or in rain? A little awkward, I thought to myself as I sat at my desk in Mr.
Bebbington's...
When shall we three meet
again? In thunder, lightening or in rain? A little awkward, I thought to myself as I sat at my desk in Mr.
Bebbington's Grade 7 English class reading Shakespeare for the first time. When
the hurlyburly's done, when the battle's lost and won. What the heck does "hurly-burly" mean? That will
be ere the set of sun. Huh? Ere?
Okay, time for Coles Notes. Well, 10 years later, I found that if there was
anything more frustrating to read and understand than a Shakespeare tragedy, it
must surely be a medical journal.
Scientists, for better or
worse, love their terminology; scientific publications are scattered with terms
foreign to most native speakers of the English language. This can make it
difficult for clinicians who browse the literature to grasp the message of any
research paper and determine if the results are applicable to the patients they
encounter. Here is Act 1, I mean, Part 1, of a series of "Coles Notes for
prehospital literature." This time, we focus on the "s" word: Statistics. Feel
free to rip this out and stick it in your protocol book.
Normal distribution: All data is distributed across a range. For example,
if we took all the response times in your area, we would find a few really fast
ones (the call was next door to the station) and a few really slow ones (there
was a snow storm and the ambulance had to drive across town). But most of the
calls will be somewhere in the middle. We call this a normal distribution.
Sometime data is not normally distributed. It is skewed away from the middle.
Consider time to backboard. Usually, we can backboard people quickly, within a
few minutes. But sometimes, the fire department will need an hour to extricate
the patient, skewing the distribution in one direction. This creates Outliers. Outliers are results that are far away from the
expected.
Average: This term can be misleading. Here is an example: 2,
4, 6, 8, 40. These are how many
pairs of shoes five people report owning. We have an outlier who owns 40 pairs
of shoes, which skews the distribution of the data. We can report this with a
mean or median, and get drastically different averages.
Mean: Add up all the responses and divide by the number
of responses. The mean of the above example is 12. This is not really
reflective of how many pairs of shoes people in our sample own; the outlier has
skewed the data, and the mean is not representative of the average. Mean is used
when the data is normally distributed. Standard Deviation measures dispersion -
how close or far responses are to the mean. One standard deviation represents
where about 70 per cent of the results fall. A low standard deviation indicates
that the data points tend to be very close to the mean, whereas a high standard
deviation indicates that the data are spread out over a large range of values.
Median: Take the middle response. In our example, the
median is 6. This measure is appropriate when data is not normally distributed.
Range measures the dispersion of
data by reporting the highest and lowest figure. Using our example, the range
is 2-40. Interquartile Range is
the range of the 25th and 75th percentile. It eliminates
high and low outliers that skew the data by showing us where the middle 50 per
cent of values lie.
Type 1 (alpha) error: This is when your conclusion is a false positive,
believing that there is a difference between two findings when in fact there is
no difference. For example, thinking drug A is better than drug B, when in fact
they are equally beneficial (or equally harmful), would be a type 1 error.
Type 2 (beta) error: This is when your conclusion is a false negative,
believing there is no difference when in fact there is. For example, you might
conclude Defibrillator A doesn't save more lives compared to Defibrillator B,
when in fact it does.
P value: the "probability value," also known as
significance, quantifies the probability that an observation is due to chance
and not an actual difference. In other words, it describes the probability of
making a type 1 error. In medicine, a P value of 0.05 is the highest allowable
P for results to be considered "statistically significant." A P of 0.05 means
there is a 95 per cent chance the results are actual and not caused by chance.
Statistically significant results must be analyzed by clinicians for clinical
significance – if fentanyl decreases pain by 30 per cent and morphine decreases
pain by 32 per cent, are we going throw out all the fentanyl? Probably not –
although these results may be statistically significant, with a p value of
<0.05, they (in my mind) don't justify throwing out the fentanyl.
Odds ratio: This value compares the odds of experiencing an
outcome between two groups. For example, the odds of death in smokers compared
to non-smokers, or the odds of survival in a control group compared to an
experimental group would be the odds ratio. An odds ratio of 1 means the two
groups experience the event of interest (death, survival, etc) equally. An odds
ratio greater than 1 means the first group experiences the event more than the
second group. An odds ratio of less than 1 means the first group experiences an
event less often than the second group.
Relative risk: This calculation compares the probability (rather
than the odds) of experiencing an outcome between two groups. A relative risk
of 1 means there is no difference in risk between the two groups. A RR of less
than 1 means the event is less likely to occur in the experimental group than
in the control group. A RR of more than 1 means the event is more likely
to occur in the experimental group than in the control group.
Confidence interval: This describes the possible variation of a value
within the margin of acceptable alpha error. For example, the odds of death for
patients treated by circus clowns (compared to paramedics) may be 2.0* with a
confidence interval of 1.8 to 2.2. This means that the odds of death are twice
that for people treated by clowns, and any value between 1.8 and 2.2 has a P
value of <0.05 and is considered statistically significant. If a confidence
interval spans 1 (ie 0.8-1.4), the p value is >0.05. *The author has no
evidence to support or refute the claim that clowns are harmful.
Odds ratio vs. relative
risk: What's the difference?
The odds ratio and the
relative risk both compare the likelihood of an event between two groups. Lets
use the Titanic survivors as an example. There were 462 female passengers:
308 survived and 154 died. There were 851 male passengers: 142 survived
and 709 died.
|
|
Alive
|
Dead
|
Total
|
|
Female
|
308
|
154
|
462
|
|
Male
|
142
|
709
|
851
|
|
Total
|
450
|
863
|
1,313 |
The odds ratio calculates
the odds of death for passengers on board the Titanic as follows. Females faced
odds of 2 to 1 against dying (154/308=0.5). The odds of death for males
was 5 to 1 (709/142=4.993). The odds ratio is 9.986 (4.993/0.5).
There is a ten-fold greater odds of death for males than for females.
The relative risk compares
the probability of death instead of the odds of death. The probability of death
for females is 33 per cent (154/462=0.3333). The probability of death for
males is 83 per cent (709/851=0.8331). The relative risk of death
is 2.5 (0.8331/0.3333), meaning males have a probability of death 2.5
times greater than females.
The choice to use an odds
ratio or a relative risk is complicated and depends on the study design and
question being asked. Think twice about any reported odds ratio or relative
risk before interpreting the findings of a study.
Whether reading The Tragedy
of MacBeth or the Annals of Emergency Medicine, its important to consider the
message of the text and, when in doubt, do a quick dictionary search on the
Internet to make sure you have interpreted the message correctly. After all,
you'd hate to get lost in the plot. Fair is foul and foul is fair: Hover
through the fog and filthy air. I'll
leave the interpretation of that line up to you.
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When a little “thank you” goes a long wayBy Brian Thomson Published: Sat February 20, 2010
Thank you. Good job. Well done. Keep up the
good work.
Those are simple words and phrases right?
So why do we crave them so much? What is in the human psyche that makes us want
to...
Thank you. Good job. Well done. Keep up the
good work.
Those are simple words and phrases right?
So why do we crave them so much? What is in the human psyche that makes us want
to hear these words? I believe that most paramedics are similar to myself in
that they don't require hearing any of these words in order to function at a
high level.
However, when someone does say something
about what a good job we did out there, or that we saved a friend or relative's
life and we could never be repaid for what we did, it becomes our motivation
for us for the coming weeks, months or maybe even years following. Why is that?
It's because a person's physical and psychological being are intertwined and
what affects one side will ultimately affect the other. For example, if you
break a leg and are off work for two months, what happens? You cannot only not
go to work, but you can't play with your children, go to the gym and work out
or even drive a vehicle for that matter. These events, at least initially will
create a path of thinking that will include denial, anger and self pity that
will ultimately lead to falling into a state of depression. In order to get out
of that state of depression the pain has to heal: the pain of the fracture; the
pain of being off work and not providing for your family; and the pain of being
the patient instead of the healer.
What paramedics do
A phrase everyone commonly hears is "the
doctor makes the worst patient." Well, this applies to paramedics as well. No
question about it. We are so used to being the ones who rescue others in need
that we sometimes fail to recognize when we are in need of rescuing. We can be
so focused on others that we lose sight of our own self and where we stand in
life. It's only natural really. How can a person look inward when they are
always looking outward? This just can't be done, at least not at the same time.
So what do paramedics do in order to
maintain a balance between a healthy physical being and a healthy psychological
being? The physical side of things is an easy one to explore. It's been well
documented how regular physical activity can create a strong body, increase
your energy level and improve job performance. The list of overall benefits of
having regular physical activity in your life is as long as the list of systems
within the body. It's longer actually, when considering the individual lists of
benefits you could put under each system. What people do to take care of their
psychological being can be just as diverse. Activities can range from positive
ones, such as meditation, reading, writing or taking a course at your local
college to the negative, such as drinking, substance abuse or anything else
that numbs the mind and senses. We survive shift after shift by using our wits,
intuition, memory recall and observation skills. Any activity that takes away from
these things can be considered a negative activity.
Can management help?
So what can management do to help? The
problem for them is this: management is not there when bad things happen on
scene. They are not the ones watching your back on scene when you're in the
middle of a domestic dispute. They might be there when there is a large MVC on
a major highway requiring an hour of extrication, but on a day-to-day basis
they have other obligations and responsibilities. So the only person who sees
how well you take care of your patients on a day-to-day basis is your partner.
What does management see? They see your paperwork. That's really all they have
to go on in making judgements about how well you are treating your patients. So
to expect much from your management team regarding recognition of a job well
done would be a stretch in my estimation. However, here are a couple of things
I've heard of certain services doing in order to recognize some of their
employees.
One thing that paramedics are is very goal
oriented. Let's get the oxygen on, get the IV started, get the backboard straps
on, let's go, let's go, let's go. How about setting up a rewards program that
sets out clear goals for paramedics to try to achieve? For example, some type
of token or gift certificate for not having to do a written response for a
problem with one of the ACRs over a certain period of time? Why not offer a
chance to do some extra training of the paramedics' own choice and have the
service pay for it? Or perhaps consider a raise in pay (thought I'd throw that
out there - I can hear the laughter from here). Anyway, you get the idea. It
doesn't have to be a big thing at all. How about once a year setting up a
one-on-one meeting with the staff and operations manager or supervisor to provide
a chance to talk about what's on their minds? This could go a long way toward
making the paramedic feel like his voice and ideas are being heard and actually
written down somewhere. These types of ideas are intended for those services
that don't currently have anything like this in place. I am certainly not privy
to what goes on in services everywhere across this country, so to those
services who do have a program that recognizes paramedic achievement I say
"good on you."
Let's work together
In many EMS services, paramedics take time
out from their personal lives to recognize each other. The local associations
have awards nights and the awards that are handed out are given to paramedics
who have been nominated for certain awards by other paramedics. Although in my
book, peer recognition may be one of the highest honours a person can receive,
it should not always be left to the workers to pat each other on the back.
Management teams everywhere could easily step up to the plate and do more than
just give credit where credit is due. It's quite easy to hand out awards for
bravery down at city hall to two paramedics who ran into a burning building and
pulled out a mother and child. How about recognizing the day-to-day,
shift-to-shift successes of all of the outstanding paramedics that are out
there in this country and indeed around the world? A little "thank you" could
go a long way.
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Muskoka redesigns ambulance exteriors with safety in mindBy Guest Writer Published: Tue December 15, 2009
In September 2008, Dr. Nadine Levick gave a presentation on ambulance vehicle safety to the Association of Municipal Emergency Medical Services of Ontario (AMEMSO) in London, Ontario. Her talk captivated Director of Emergency Services Terri Burton who worked with her municipality and ambulance service...
 In September 2008, Dr. Nadine Levick gave a presentation on ambulance vehicle safety to the Association of Municipal Emergency Medical Services of Ontario (AMEMSO) in London, Ontario. Her talk captivated Director of Emergency Services Terri Burton who worked with her municipality and ambulance service, Medavie EMS Ontario, to increase the visibility of ambulances not only for public safety, but patient and paramedic safety. The paramedic association appointed a lead paramedic, Vince Tremblay, to work with the district and the service to research materials and assist in the new design of ambulance exteriors. Paramedic Scott Trefry assisted with vendors and research. Local paramedic input played a large part in the final design. Kevin King, General Manager of Ambulance Services adds: "It is my number one mandate to ensure paramedics have the tools necessary to do the job in a safe fashion with a primary focus on patient safety, and this new design will help ensure this goal is accomplished." An innovative approach was implemented with Objective Safety's international team using a unique web-based consultation platform. Dr. Nadine Levick of Objective Safety and John Killeen, of Ambulance Visibility in Australia, collaborated with Muskoka to provide both informational resources and specific guidance to enhancing their vehicles visibility. We learned a tremendous amount about the materials during our research and had to consider the following to go ahead with selection of the vinyl:
- Ability to withstand all types of weather including extreme Canadian winters;
- Wear and tear due to road surface contaminants including salt and sand;
- Ultra-violet (UV) sun bleaching;
- The vinyl's adhesive properties and overall durability;
- Human perception and response to the colours;
- Reflective properties which include colour, day and night brightness, colour wavelength within the spectrum, total percentage of light absorbed and reflected, and the angles of reflection;
- Manufacturing process, ease of application; and finally
- Paramedic use.
Because of our harsh climate changes and environmental changes, combined with the daily shift washing of vehicles which is done year-round, all graphics have a rounded edge. There are no square edges or cuts which a brush could get caught on. Three of the major companies that manufacture reflective material in North America were evaluated: 3M, Avery and Reflexite. Each possessed the material properties we were looking for, but only one was able to comply with our projected field use. We were looking for a material that had the ability to flex and conform with curves and shapes of different types of ambulance vehicles. Our choice was not limited to one single supplier. The sheeting for the main body is primarily comprised of a high-visibility, day and night bright, and yellow-green fluorescent prismatic sheeting, which offers the highest rate of light return. This was applied to the lower portion and most visible part of the vehicle. The outline and non-major components of the lettering such as numbering and flag decal were comprised of an engineered grade retro-reflective material commonly used on road signs which are made up of microscopic glass beads; this still offers an excellent retro-reflectivity, but with a lower percentage. The key point in covering the vehicle was that the vehicle must be completely outlined so that its size and direction of travel would be noted in both bad weather and night conditions. High visibility striping went from the back to the front of the vehicle to show the size and length of the ambulance. In Ontario, we follow standards set by the Ministry of Health and Long-Term Care. Standards including wording, font type and size, and display location, but they are non-specific when it comes to the rest of the design. This ability allowed us to take this far beyond a branding exercise and truly consider all aspects of public safety and visibility. Our vinyl coverage increased from 20 per cent on the side of the vehicle to 80 per cent, and the rear increased from 30 per cent to 90 per cent high-visibility coverage. We also added roof markings (vehicle number) and additional reflective material on the inside of all opening doors. A consideration during this exercise was to address day/night vision and colour blindness of other pedestrians and drivers, the influence of colour, and depth perception. The human eye can see an unlimited distance; however, there are factors which affect what we do see. For example, we recognize certain colours. The high visibility fluorescent yellow we chose for our vehicles is not a colour found in nature or in an urban setting, therefore it draws the eye to it directly. This is similar for correct sign recognition. We recognize stop signs universally. Retro reflective and fluorescent materials have been used widely on EMS vehicles. Depending on spectral distributions of the light produced by overhead lights and head lamps, the chromaticity of markings will shift at night. Colour coding is used widely for prompt driver recognition, for highway signs, pavement markings, and other traffic markers. Human vision will not see red when the eyes have adapted to darkness, and will see red poorly when adapted to bright light. Researchers found that lateral peripheral vision for detecting yellow is 1.24 times greater than red. One quarter of 10 per cent of the male population with red-green colour deficiencies cannot see red at all. Yellow is the most easily visible colour for both normal and colour-deficient groups under all testing conditions. The spectral sensitivity curve shows the regions of maximum visual sensitivity of the eye for light wavelengths in different colours. Wavelengths or colours which stimulate the outlying peripheral photo-receptors earlier all fall within the greenish-yellow. Blue hues are detected next and the red regions are the last colours to be detected. Therefore our human vision is red-orange blind in darkness and low light conditions. Red can be perceived as black. We chose the florescence of the yellow-green material because it is very visible in daylight and during dawn and dusk. For more info, see www.ambulancevisibility.com and www.objectivesafety.net.
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Now that’s coolBy Carmen D' Angelo Published: Tue December 15, 2009
As you walk through the various 2009 trade shows featuring new EMS products and services, there are a number of questions you ask yourself. Will the product or service lead to improved patient assessment and care? Is it affordable to implement? Is there evidence or research to support the product?...
As you walk through the various 2009 trade shows featuring new EMS products and services, there are a number of questions you ask yourself. Will the product or service lead to improved patient assessment and care? Is it affordable to implement? Is there evidence or research to support the product? Are there any patient or paramedic health and safety concerns? What is required to maintain and monitor the new product? Will the paramedics utilize the equipment or leave it on the shelf in the ambulance?
You make eye contact with the sales person, and the sell is on! In Canada, there is a healthy competition amongst the ambulance vehicle manufacturers. With Crestline, Demers and Tri-Star leading the pack, the manufacturers are continuously being innovative to impress their clients. Crestline has introduced the new Driver Intention Lights that allows the paramedic to be aware of the vehicle’s motion when making decisions on patient care. And, Demers brings safety with the Obstacle Detection System, allowing the driver to be aware of obstacles when reversing the vehicle. All manufacturers are continuously improving space efficiencies in the patient compartment to maximize patient care and paramedic safety.
Do you think your service is innovative with bicycle medics? Think again. The Xtreme Green Sentinel is an electric mobility vehicle designed to replace the bicycle and foot patrol with a reliable, state-of-the-art, and efficient urban and special event patrol. With speeds approaching 45 km/hr and a range of up to 128 km per charge, the Sentinel can support paramedic services (www.xgpinc.com) in a variety of urban environments.
While the stethoscope allows you to hear what is going on inside the body, the new ACUSON P10 by SIEMENS provides the paramedic the opportunity to visualize what is going on. As the first pocket size ultrasound device, the ACUSON P10 provides the paramedic with instant images -- which are transferrable via the PDA type interface -- in confirming diagnostic assumptions in real time. In emergency medicine, the device assesses free fluid, cardiac activity, and AAA, as well as enabling critical care paramedics the ultrasound guidance for para/thora-centesis. In obstetrics, the device can provide a quick and comprehensive overview on fetal positioning, anatomy, heartbeat, fluid levels and placenta location during labour.
There are various portable suctioning units available. A new product is the Laerdal Compact Suction Unit 3 (LCSU 3) that was designed specifically for the paramedic airway bag. Its unique 300-ml canister system, LED display and variable vacuum regulator gives the power and control needed to quickly clear a blocked airway. The unit comes with an AC/DC enabled, field changeable NiMH battery pack to get the job done. As an added feature, the LCSU 3 can be easily converted to an 800 ml configuration with the purchase of the appropriate canister and bracket. The LCU 3 receives honourable mention because it signifies the growing trend in EMS to make products lighter and effective. The LCSU 3 weighs in at 1.7 kg.
Once the airway is cleared, there may be the need to intubate. However, it is a difficult airway due to poor lighting, challenging anatomy, or both. There are a number of laryngoscopes that offer white LED lighting to improve visualization of the airway. To improve the efficacy of the endotracheal intubation, the IntuBrite Laryngoscope Blade (www.intubrite.com) offers blacklight technology in order that the vocal cords will brightly phosphoresce during placement of the tube. With this improvement in larygoscopy, you can’t miss.
The system also comes with a variety of blade sizes that are disposable.
What’s next? An IV? Don’t worry about looking for that elusive vein. The AccuVein AV300 (www.accuvein.com) is a non-invasive and non-contact device that allows you the see veins on the skin’s surface. Just point and look. Regardless of skin tone or fat tissue content, the device will bounce infrared off the hemoglobin. As the veins appear, the paramedic can visualize which veins are curved and which veins are straight. All you need to do is pick the best vein to start your IV. The AccuVein AV300 comes with rechargeable batteries as weighs in at 10 ounces.
And now my favourite: The Panasonic Toughbook H1. This sealed and fanless notebook is perfect for easy sanitation via a quick alcohol swipe. No more worries about collecting germs and transferring to your co-workers. The Toughbook H1 comes with a touchscreen or digitized display thereby removing the need for physical keys. The unit has a built-in camera, integrated wireless, GPS and Bluetooth to transmit information to ambulance systems and receiving hospitals.
With long-life hot-swappable twin batteries, 80GB shock-mounted drive, and an integrated ergonomic handle, paramedics will grow to love this device that weighs in at 3.4 lbs.
Overall, there is a trend with new EMS products. The innovative products emerging in EMS are increasingly lightweight in nature, portable and accessible. The products are meeting the needs of paramedics working in uncontrolled environments. The new products are striving to improve patient outcomes in addition to protecting the health and safety of paramedics.
I can’t wait to discover what is new for 2010!
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