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Copyright © 1999, Journal of Emergency Medical Services & University Of Ottawa (Paul Morneau, BSc & J. Peter Stothart, PhD). All rights reserved. Except for use in review, the reproduction or utilization of this work in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including xerography, photocopying, and recording, and in any information storage and retrieval system, is forbidden without the written permission of the authors.
Edited and published as:
Morneau, Paul M. and J. Peter Stothart. (1999).
Abstract
Many paramedics across North America are required to sit in their ambulances for extended periods of time. The increasing use of "System Status Management" (i.e.: Stand-by's, Roaming, Balanced Emergency Coverage) has lead to increased back injuries amongst paramedics. A survey of paramedics from the Ottawa-Carleton region of Ontario, Canada was carried out to assess the effects of long periods of sitting and riding in an ambulance on the incidence of back injuries in paramedics. In addition, an evaluation was made of the characteristics of space and seats in the crew compartments of ambulances which are currently in service in Ontario. The results of the survey indicate that there is a reason for concern. Other research on the subject would suggest that paramedics should limit the duration of time sitting in a vehicle. The evaluation of seating for paramedics, in ambulance vehicles currently in service, clearly shows the seating to be inadequate. Research literature indicates that paramedics should have adjustable and supportive vehicle seats with adequate leg room in the front cab area. These results indicate that significant health and safety issues exist and should be corrected to allow paramedics to carry out their critical functions without needlessly jeopardizing their own safety.
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Emergency Medical Service (E.M.S.) providers across North America have been faced with shrinking budgets and funding which has not kept up with the increasing demand for their services. This has lead to the ever increasing use of "System Status Management." (S.S.M.). S.S.M. involves distributing emergency personnel in such a way as to maintain a balance in emergency coverage to an area when the number of available ambulances is decreased. The Ontario Ministry of Health (M.O.H.) has been deploying ambulances in the Province of Ontario, Canada in this fashion. This has historically involved placing an ambulance on "stand-by" between two areas when one areas' ambulance(s) have/has been sent on a call. In addition to this long standing practice of stand-bys, a new policy has been recently tested which involves deploying ambulances and paramedics in the Ottawa-Carleton region. This new system is referred to as "Roaming." These methods, which involve greater amounts of time spent by paramedics sitting/riding in their ambulances, are becoming a common phenomenon in North American E.M.S.
In the recent past, Ontario's ambulances would normally respond to emergency calls from various stations across their region or from a stand-by location. Paramedics would remain at their respective stations or at the designated stand-by location between calls. This was changed after a study of the "call volume" in Ottawa-Carleton was completed by the Ottawa Hospital-"Base Hospital Program" (BHP) (A.R.I.S., 1996). The BHP determined statistically dominant zones within the region of Ottawa-Carleton. These zones are numerically classified and indicate which areas contain the highest volume of most critical calls (code 4). For instance, "Zone 1" indicates the geographical area (downtown Ottawa) which has the most critical calls, most often . Zone 2 has the next highest volume of critical calls and so on. The result of the BHP study showed that many of the ambulance stations were not necessarily well positioned to respond to these zones and therefore the response times to critical calls were longer than they needed to be. Also, the BHP suggested that a mobile ambulance crew is more likely to have a quicker response time than an ambulance crew that has to leave from a station. They suggested that the time between crew notification and the crew being mobile is decreased, if not eliminated, when the crew is mobile. These assumptions have led to the addition of "Roaming" to the current daily practices of a paramedics duties.
The new system that has been implemented requires that paramedics remain mobile in their ambulances between calls for at least half of their shift (shifts are usually twelve hours long). Along with the "Roaming" policy paramedics have always had to respond to stand-by's. When an ambulance station is depleted of ambulance crews an ambulance crew from a neighboring station is positioned on "stand-by" somewhere between the two stations. The ambulance crew that is placed on "stand-by" is required to leave their station, drive to a particular intersection and wait for a call. Stand-bys are usually located at an intersection that is relatively equidistant between two stations.
Regardless of the terminology used the simple fact is that the increasing use of System Status Management has resulted in Paramedics sitting in either an idling or moving ambulance for longer periods of time resulting in a static posture with increased exposure to vehicular vibrations.
The major concern of this increasing use of System Status Management is the potentially deleterious effects on paramedics. Paramedics are sitting for longer periods of time, in idling or moving ambulances and the question is does this result in an increased incidence of back discomfort, back pain or back injuries?
Several studies in the research literature have looked at questions related to time spent riding/sitting in a vibrating environment (for example a vehicle). Pope & Wilder (1996) have shown deleterious effects of vibration and seated posture on the backs of people. Kelsey et al (1984) concluded that "the greater the number of hours spent in a motor vehicle, the higher the risk for an acute prolapsed lumbar intervertebral disc." Their study showed that men who spend more than half their workday in a car have a threefold increased risk of disk herniation
Other research on exposure to vibration in the workplace supports these results. The static seated posture and vehicular vibration lead to fatigue in those who are exposed to it. Fatigue occurs as a result of increased postural muscle use. Seat design can play a big role in how much postural musculature is recruited. Seats that lack proper design will necessitate the recruitment of the erector spinae and lateral flexor muscles among others. Continuous recruitment of these muscles is required when a vehicles seat offers little or no support (Zacharkow, 1988).
Stothart and McGill (1996) in their work on spinal shrinkage using stadiometry, have identified "static work posture" and "exposure to vibration" as known risk factors leading to back injuries. Klingenstierna and Pope (1987) completed a study that showed how disc "creep" or compression is accelerated when exposed to vibration.
In light of the broad spectrum of research indicating the connection between exposure to seated postures and vibration in vehicles in combination with an apparent large increase in paramedic exposure to vibration and long periods of time sitting in seats not designed to provide adequate support for their work conditions, the present study sought to determine the conditions experienced by paramedics in the Ottawa-Carleton region.
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The following protocol has been undertaken to determine the effects on paramedics of sitting for longer periods of time in an ambulance.
The first part of the study involved a survey of paramedics from the Ottawa-Carleton area who work regularly on ambulances (currently there are approximately 220 paramedics employed in Ottawa-Carleton). The survey was designed to determine: a) whether the amount of time spent in the ambulance by paramedics has increased since roaming has been implemented, b) whether there has been an increase in back injuries or pain/discomfort, and c) what factors might exacerbate the situation.
The survey was initially pretested with a subgroup of paramedics and E.M.S. administrators to determine whether any canges in its structure were warranted. The survey was then refined and distributed to as many paramedics in the Ottawa-Carleton region as possible.
In addition to seeking paramedic responses to the survey, an evaluation
was made of the physical characteristics of space and seats in
the crew compartments of ambulances in use in Ontario. The evaluation
was based on the characteristics of: leg room, backrest adjustment,
armrest support, lumbar support, lateral support, and vibration
damping devices.
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In order to explore the question of sitting for extended periods of time in an ambulance and exposure to vehicular vibrations a survey was distributed to Paramedics from various ambulance stations across Eastern Ontario, most from within the Regional Municipality of Ottawa-Carleton (which currently has approximately 220 paramedics employed within its boundaries). Ninety-two surveys were returned. The subjects that responded consisted of 80 males and 12 females between the ages of twenty and fifty-five (Figure 1).
The Effects of Stand-bys and Roaming:
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The average shift length worked by the paramedics was 11.7 hours. Most paramedics who were surveyed regularly work a twelve-hour shift. During their shift, paramedics estimated that they spend 56% of their day "roaming" or on stand-bys.
Seventy-one percent of respondents reported suffering from back pain or back discomfort more often now than before "roaming" was initiated (Figure 2).
Ninety-three percent of the paramedics said that they suffer from back pain or discomfort while simply sitting in the ambulances (this was not pain/discomfort due to a lifting injury). When they were asked to rate how often this pain/discomfort from just sitting occurred, 62% stated that it occurred at least once a week or more often (Figure 3).
Interestingly, 88% of paramedics within their first six years of employment complained of suffering from this back pain/discomfort at least once a week or more often. Even more revealing was the fact that 90% of all respondents thirty years of age or younger complained of this pain/discomfort at least every other shift or more often.
Ninety-five (95) percent of respondents were unhappy with the way that "roaming" and/or stand-bys have been implemented. They had several different concerns of which the most common will be discussed here. The most common complaint was that stand-bys are too long. Many subjects suggested that the application of stand-bys was very inconsistent. In some areas, stand-bys are not maintained after certain hours while in other areas they are maintained 24 hours a day. Some stand-bys are only a few kilometers from the paramedics' stations, leading them to wonder why bother placing them there for such long periods of time in the first place. Others suggested that they worked in a significantly busier area than their neighboring area. While on stand-by, they would end up responding to calls back to their own area the majority of the time. They suggested that this resulted in longer response times to more calls, more often. Others wondered why they would often be placed on stand-by so far away from their station to only end up leaving their own area without balanced emergency coverage.
Many paramedics suggested that stand-bys were used excessively as a result of a lack of sufficient numbers of ambulances staffed in the area. They said that more ambulances should be placed into service instead of continually compromising two areas with one ambulance placed on stand-by between them. They went on to discuss how the ever increasing use of stand-bys was a clear indication of a serious lack of ambulances in the area(s). They felt that stand-bys should be a rare occurrence and that if they become too prevalent then more ambulances should be staffed in those areas. Some suggested that if this could not be done then the human cost involved with maintaining too many stand-bys was too high. Others thought that it was ironic that more ambulances were not being staffed on the road when, in reality, the taxpayers ended up paying so much money in increased vehicle maintenance costs, fuel costs and "Workers Compensation" (WSIB) costs due to the prevalence of stand-bys. They said that if that money would be used towards more staffed ambulances, then there would be less need to put ambulances on stand-by in the first place and also less incidences of WSIB claims.
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Some other issues that were mentioned dealt with the lack of comfort within the current ambulance designs. Eighty-nine percent of paramedics felt that the seats in the front of the ambulances were not comfortable.
They commented about a lack of ability to get out of the vehicle and move around while on stand-by. Reasons for this were such things as: poor radio systems that have unreliable portable communications thereby forcing the crew to stay in the vehicle in order to avoid missing a call; being forced to park at remote intersections late into the night or early into the morning where walking around might be hazardous (i.e.: dark, risk of violence); severely cold or hot weather conditions forcing them to remain in the ambulance with it running the entire time while on stand-by; lack of proper facilities to stretch or exercise "If we are lucky there maybe a coffee shop open at 3 am but that is hardly a place to walk around in circles or to do stretching exercises" (survey respondent, 1998). The paramedics also complained about the constant inhalation of vehicle exhaust fumes while on stand-by.
More specifically, in regard to the vehicle design, Figure 4 shows that 80% of the paramedics were either unsatisfied or very unsatisfied with the leg room in the front cab of the ambulance. It's important to note that the average height of those "very satisfied" (3%) with the leg room in the front cab of the ambulances was 166cm (5'5") compared to the average height of those "very unsatisfied" (51%) being 179cm (5'11").
Eighty-seven percent of respondents were either unsatisfied or very unsatisfied with the ability to recline the driver's seat of the ambulances. Ninety-nine percent of respondents noticed at least some vibration while sitting in the ambulances (Figure 5).
Finally, 100% of the paramedics that returned surveys would prefer
to have armrests installed in the ambulances. All of the recent
vehicle models in Ontario ambulances have had armrests discontinued.
A few older Dodge van ambulances have armrests, but they represent
only a small percentage of the front-line fleet and are quickly
being phased out (see Figure 9)
A look at Ontario's Ambulances
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The consensus, after studying the literature on the effects of sitting in vibrating (moving or idling) vehicles, is that a strong relationship with a higher incidence of back injuries to people who work under these conditions. Paramedics work under these conditions in Ontario and in many other places across North America. They are required to "roam" or be on stand-bys for excessive periods of time in combination with all the regular lifting and driving duties that they normally perform. In a study on injuries among emergency services workers, it was determined that the most commonly injured area was the lower back. This has been found to be true in several other North American studies of ambulance personnel (Gershon, 1995). This is probably due largely to lifting injuries. However, these lifting injuries are far more likely to happen when exposure to excessive vehicular sitting and vehicular vibrations are part of the equation.
The survey of paramedics validates published research findings relative to vehicular sitting exposure and vehicular vibration exposure in that it shows that paramedics, in the population studied, demonstrate significant back problems. Lower back pain can result from several factors, however, the greatest risk is the combination of long-term exposure to vibrations and frequent lifting. (Magnusson, 1996) "Prolonged exposure to vibration when seated has been shown to lead to muscle fatigue, particularly of the erector spinae and oblique abdominal musculature" (Wilder et al., 1982) "Individuals involved in lifting activities directly after prolonged driving in a flexed sitting posture would therefore be at a very high risk for developing low back pain" (Adams & Hutton, 1988) The results of the survey agree with this conclusion.
Does the vehicle design help or hinder the problems faced by paramedics? The ambulance vehicle designs worsens the problems faced by paramedics. The two areas of vehicle design that exacerbates the problems associated with back injuries are: front cab space and seat design.
The front cab space in ambulances is very confined-so much so that many paramedics cannot recline the backrest of the seat and drive in an optimal position (figure 6). In fact, many of the Dodge ambulance conversions do not provide a backrest that will recline at all (figure 7).
As mentioned earlier, 80% of respondents to the survey felt unsatisfied
or very unsatisfied with the amount of leg room in the front cab
of the ambulances. Of those that were satisfied, their average
height was 166cm (5'5") as compared to the average height
of the "very unsatisfied" being 179cm (5'11").
So, in general, the very few "satisfied" respondents
tended to be much shorter people. These people would be able to
move the seat more forward, thereby enabling them to recline the
backrest to a more ergonomically correct position.
The quality of seats currently in Ontario ambulances vary between make, model and year. The seats that are installed in the crew compartment are not sufficient for the ambulance environment. Although the vehicle manufacturers have insisted that the seats have passed safety testing this does not mean that they are designed well ergonomically or are practical for paramedics. (Figures 8 & 9) The goal of a good vehicle seat should be to limit the amount of postural stress caused by static muscular contractions. (Zacharkow, 1988) In general, the following problems exist with the seats in Ontario's ambulances:
none of the seats have vibration dampening devices (beyond the seat cushion).
The general quality of space and seating (in providing protection against back pain/discomfort) for paramedics in Ontario ambulances is lacking. This statement is made based on the fact that paramedics are required more often to drive in this space and on these seats for extended periods of time every shift they work. These seats, along with the limited front cab space, do very little to limit the amount of postural stresses caused by sitting in them for prolonged periods. Furthermore, the trend in Ontario's ambulances is toward seat designs of even lesser quality. The Ford truck is the base model being purchased by the Ontario Ministry of Health for ambulance conversions.
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The literature is clear-exposure to a static seated position and to vehicular vibrations do result in increased back discomfort/pain/injuries. The survey of paramedics is also clear-paramedics are suffering from back discomfort/pain/injuries at an unacceptable rate. The seats that are currently installed in the crew compartment of Ontario's ambulances and many throughout North America do not provide adequate safeguards for paramedics against back pain/injury in the workplace. The seats lack lumbar support, lateral support, and minimal damping against vibration. The crew compartment space in ambulances lacks leg room and restricts reclining of seatbacks which has a serious impact on postural muscle fatigue.
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Recommendations which will help ensure the health and safety of paramedics with regard to vehicular vibration exposure and vehicular sitting exposure can be made in two general categories. The first category involves initiating administrative controls relative to policies and procedures for the use of roaming and stand-bys. The second category involves initiating engineering controls to ensure the best possible vehicular environment so as to maximally reduce the risks to the paramedics' health and safety.
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Both the literature and the survey suggest that the current policies and procedures practiced by ambulance dispatch centers (authorized by the Ontario Ministry of Health), with respect to System Status Management (stand-bys and roaming), pose a serious risk to the health and safety of paramedics. Paramedics are forced to increase their normal exposure to vehicular vibration and vehicular sitting to a significant extent by the use of System Status Management principles (stand-bys and roaming). The use of stand-bys and roaming should be limited in the following ways:
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Engineering controls to limit the amount of exposure to vibration
and to limit the effects of the static seated posture involve
changes to the crew compartment of the ambulances and primarily
to the seat design (see Table 1).
The front cabs of the ambulances are too small. In particular the length of the cab is too short. This results in inadequate room for most paramedics to correctly position their seat to be able to drive and to still be able to adjust the backrest of the seat to an ideal angle (120 degrees from the seat pan) (Andersson, 1974). This lack of adequate space forces paramedics to maintain a more hazardous static posture. Eighty percent of paramedics that responded to the survey stated that they are unsatisfied or very unsatisfied with the leg room in the ambulances. Eighty-seven percent of paramedics are either unsatisfied or very unsatisfied with the ability to recline the backrest of the seats in the ambulances. The average height of this group is 180cm (5'11") which, coincidentally is also the mean height of the males who responded to the survey. Eighty-seven percent of the population studied were males. One can make a connection then to the fact that these taller people, who make up the vast majority of the workforce, do not have the means to adjust their seats appropriately because the ambulance cab length is too short.
Actual crew compartment space was decreasing. Since 1992 changes
in (ambulance) vehicle design and chassis had taken away personal
space and increasingly pushed the seats up against the rear wall
of the cab. Further, with the introduction of the diesel turbo-charged
chassis in 1995, another 1 ½ inches of crew space was lost,
creating a tight fit for medics of any size. (Allen, 1997)
The length of the cab must be increased in such a way as to allow the back rest to recline to at least 120 degrees from the seat pan (which should be at an angle of 10-14 degrees from the horizontal) (Zacharkow, 1988) The length of the cab should preferably allow the seats backrest to recline to an even greater degree in order to accommodate a semi-fowler or an "as close to supine" position as possible for the paramedic when they are not driving but required to be on stand-by. "When the backrest inclination increased, a larger proportion of the body weight was transmitted to the backrest and thus the stresses on the spine were reduced" (Andersson, 1974). The semi-fowler position and the supine positions allow for decreased postural muscle usage and therefore less fatigue and risk of injury.
…as a direct result of fatigue (with faulty posture in regards
to sitting) an individuals ability to perform is reduced; his
output is diminished; the quality of his production is lowered;
his mental aptitude is reduced; his susceptibility to disease
is increased…; he is much more likely to commit errors, and
his likelihood to sustain personal injuries is greatly enhanced.
(Zacharkow, 1988)
These semi-fowler to supine positions also result in less effect on the compression of the Intervertebral disc while sitting.
Health Span Transportation of St. Paul, Minnesota along with their regional Braun Industries distributor-North Central Ambulance Sales devised an innovative technique to solve the problem of decreasing front cab space in their ambulances. They developed the idea of inserting a 20-inch fibre glass extender between the crew cab and the patient compartment. "The extra 20 inches was gained during a remount without significant chassis modification by using a 158 inch chassis instead of the usual 138 inch chassis" (Allen, 1997).
The seat backrest needs to be made of firm material with firm lumbar support to encourage the normal lordotic curve of the lumbar spine and thus better able to distribute the vertical forces on the spine. The backrest must also have firm lateral support in order to limit the back's lateral flexor activity (Pope, 1991). Some of the seats in current ambulances have lateral support but it is composed of a soft "foam like" material which has limited effect. Firm, adjustable lumbar support in the backrest will assist in maintaining the lordotic curve of the lumbar spine thereby decreasing intervertebral disc pressure.
Armrests are very basic features of a good chair and yet result in a dramatic increase in comfort and should be installed in the ambulances. Armrests assist in lowering intervertebral disc pressures by taking much of the weight of the arms and upper body off of the spine and thus allowing for some relief for the postural muscles of the back. Several studies have shown that both arms together make up between 9.8 to 12 percent of the total body weight (Zacharkow, 1988). Armrests act to allow the arm musculature to relieve some of the postural stresses and also help to prevent a slumped posture. They can also assist by providing some lateral support.
It is clear that administrative controls are needed to limit the amount of time that paramedics are kept roaming or on stand-bys. This, along with engineering controls, to improve seat and cab space designs, will go a long way toward safeguarding the health and safety of paramedics. Administrators must consider all the human costs involved with maintaining the current practices of roaming and stand-bys (System Status Management).
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Adams, M..A. & Hutton, W.C. (1988) Mechanics of the Intervertebral
Disc. In P. Gosh (Ed.), The Biology of the Intervertebral Disc.
(pp. 39-71). Boca Raton: CRC Press Inc.
Allen, M., (1997) Creating Crew Space. Journal
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Gershon, R. et al. (1995). Review of accidents/injuries amoung
emergency medical service workers in Baltimore, Maryland. Prehospital
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Kelsey, J. et al. (1984). Acute prolapsed lumbar intervertebral
disc: An epidemiologic study with special reference to driving
automobiles and cigarette smoking. Spine. 9 (6),
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Klingenstierna, U.& Pope, M.H. (1987). Body height changes
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risk for developing musculoskeletal disorders? Spine. 21
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Pilot Seat. WADC Technical Report 57-136, Wright Air Development
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& exercise. Springfield: Thomas Books.
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Dear Participant,
Thank you for choosing to complete this survey. By filling out
this survey you are consenting to it's use in the tabulation of
results for this study. Your identity will remain confidential.
Please do not write your name on the survey. At any time,
you may choose to withdraw or refuse to complete the survey. The
only persons who will handle the surveys will be: Dr. Pete Stothart,
a few assistants and myself. All those handling the surveys have
agreed to maintain the confidentiality in regards to the subjects
involved in the survey. All surveys will be secured in a locked
cabinet with no way to identify the individual who filled it out.
Your only requirement is to complete the survey once. There will
be no subsequent contact with you. There is no risk in completing
this survey as your name is not required.
This is a research project being carried out by Paul Morneau from
the University of Ottawa, School of Human Kinetics. Your assistance
in volunteering to fill out this survey is greatly appreciated
and will ensure that the results more accurately represent the
situation here in Eastern Ontario. The results may potentially
benefit your working environment as copies of the completed research
project will be shared with the Ontario Ministry of Health, your
employer, and your Union. You may contact myself for a copy of
the completed research project if you wish. There will be no compensation
or remuneration of any kind for participation in this research.
This is a survey being used in conjunction with research on the
effects of the seated posture and vibration on the spine.
The purpose is to determine what, if any, problems exist in the
ambulance field in regards to posture and vibration in ambulances.
If you require any more information please contact: Paul Morneau.
Thank you,
Paul Morneau
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