Contemporary Modes of Conveyance:Research HighlightsCarolyn M. Sommerich and Steven A. LavenderDepartment of Integrated Systems EngineeringThe Ohio State UniversityColumbus, OH USA

10 May 2016

1

Outline

• Statistics, background• Studies of modes of conveyance

• Stair descent devices• Cots

• Adapting to change

2

2014 Incidence rate for EMS and paramedics: 333 per 10,000 FTE, all injuries and illnesses BLS

2014 number of cases, all injuries and illnesses for EMS and paramedics: 7010 cases BLS

2014 Incidence rate for EMS and paramedics: 184 per 10,000 FTE, musculoskeletal disorders (MSDs) BLS

2014 number of cases, MSDs for EMS and paramedics: 3880 cases BLS

A total of 14,470 cases (67%) involved sprains or strains; back injury was reported in 9,290 of the cases (43%); and the patient was listed as the source of injury in 7,960 (37%) cases. Maguire & Smith, 2013

The most common events were overexertion (12,146, 56%), falls (2,169, 10%), and transportation-related (1,940, 9%). Maguire & Smith, 2013

Number of jobs, EMTs & Paramedics: 241,200Job Outlook, 2014-2024: +24% BLS

Contributing factors: stairs/steps in private residence; activity involving cot Furber et al., 1997

3

Modes of conveyance – there is a difference• Evidence of reduced physical stress:

• Less muscle activity = less force required less muscle fatigue

• Reduced ground reaction force = less weight supported by paramedic

• Reduced perceived exertion

• Other important measures include:• Time to complete task

4

Where does it seem that people who need transport are located?

5

Why can’t all homes be single story homes?

6

7

Research Study (FEMA 2009-EMW-FP-01944)

• Objectives: Evaluate different stair descent devicesfor evacuating individuals when stair descents are required.

• Types of devices: Carried, Track, Sled• Measure:

• Physical demands• Performance (evacuation speed)• Usability

• Task factors:• Staircase Width (0.91, 1.12, 1.32 m)• Urgency (Urgent, non-urgent)

88Manual Carry

Extended Handle SC Basic SC

Fabric Seat

Hand Carry Devices

9

Track-Type Devices

Long Track (Garaventa)

Rear Facing (Glider)

Narrow (AOK)2-Wheeled

(Evac+Chair)Standard (Ferno EZ-Glide)

1010

Sled-Type DevicesRoll-up (Med Sled) Corrugated

(Evacuslyde)

Wheeled (Subway Sled)

Inflatable (Hover Jack)

Hardshell (Lifeslider)

Fabric Mat (ResQmat)

11

Research methods

• Study participants: 12 experienced male firefighter-paramedics

• Patient: Rescue Randy (73 kg=160 lbs)• Measurements:

• Duration of evacuation• Electromyography: trunk, shoulder, arms• Heart Rate• Perceived exertion ratings• Spine motion• Usability information via post study interview

Findings

12

13

Stair Descent Speed: Hand-Carried Devices: 1.12 m Staircase Width

Fruin, J.J. (1971). Pedestrian Planning and Design, All age average, pg 56.

Range based on samples obtained by Peacock, Hoskins, Kuligowski (2012) Safety Science 50, 1655–1664, table 3.

Manual Carry

Basic Stair Chair

Fabric Seat

Extended Handle

Manual Carry

Basic Stair Chair

Fabric Seat

Extended Handle

Manual Carry

Basic Stair Chair

Fabric Seat

Extended Handle

Manual Carry

Basic Stair Chair

Fabric Seat

Extended Handle

Hand-Carried Devices

14

Stair Descent SpeedTrack-Type Devices: 1.12 &1.32 m staircase widths

0.0

0.2

0.4

0.6

0.8

1.0

1.2

Standard Long-Track Rear-Facing Narrow 2-Wheel

Spee

d (m

/s)

Chair Style

Fruin, J.J. (1971). Pedestrian Planning and Design, All age average, pg 56.

Range based on samples obtained by Peacock, Hoskins, Kuligowski (2012) Safety Science 50 1655–1664, table 3.

15

Stair Descent Speed:Sled Devices: 1.12 and 1.32 m Staircase Widths

p values (Width  <0.001 Device <0.001  Device x width = 0.553)

Wheeled       Hard Shell       Inflatable       Fabric Mat      Corrugated      Roll‐up

SLED TYPE

Slow, compared to track

style and extended handle

hand-carry device

16

Heart Rate – Percent MaxHand Carried Devices

54.4 47.7 47.0 35.80

10

20

30

40

50

60

70

Manual Fabric Basic Ex

% m

axim

um heart ra

te

Extended Handle

Hand-Carried Stair Descent Device

17

Heart Rate – Percent MaxTrack-type Devices

50.9 48.7 48.5 47.0 43.50

10

20

30

40

50

60

70

Glider Evac+ Garavanta AOK Ferno

% m

axim

um heart ra

te

Rear Facing 2-Wheel Long Track Narrow Standard

Device

18

Heart Rate – Percent Max Sled Type Devices

% o

f Age

adj

uste

d M

axim

um H

eart

Rat

e

41.3 40.2 39.9 37.4 36.5 35.9 35.8 35.4 34.3 32.2

0

20

40

60

80

100

Wh‐L Co‐F Co‐L Fab‐L Inf‐F

% Heart Rate

Wheeled Hard Shell Corrugated Roll-up Corrugated Roll-up Fabric Mat Inflatable Inflatable Fabric Mat(Leader) (Follower) Follower Follower Leader Leader Leader Leader Follower Follower

SLED TYPE / EVACUATOR ROLL

19

Arm and Shoulder Muscle Activity:Track Type Devices: Landing, 1.12 and 1.32m

2-W=2-Wheel / Nar = Narrow / Std = Standard/ RF = Rear-Facing / LT = Long-Track

Deltoid Biceps

Std Nar 2-W LT RF LT Std Nar RF 2-W

20

Back (Erector Spinae) Muscle Activity:Sled Type Devices:

Fabric Mat    Inflatable   Inflatable  Fabric Mat   Wheeled   Hard Shell   Roll‐up     Corrugated  Corrugated  Roll‐up          Follower       Follower      Leader         Leader       (Leader)    (Follower)   Follower     Leader         Follower     Leader

SLED TYPE / EVACUATOR ROLE

21

Fabric Mat   Corrugated  Inflatable    Roll‐up      Hard Shell     Roll‐up     Inflatable   Corrugated   Wheeled  Fabric Mat  Follower        Follower      Follower   Follower     (Follower)      Leader        Leader         Leader       (Leader)     (Leader)

SLED TYPE / EVACUATOR ROLE

Back (Latissimus Dorsi) Muscle Activity:Sled Type Devices: Landing

22

Objective Measures - Analysis Summary

Device Positives NegativesHand-Carried

Less Expensive Higher physical demands;Slower – Unless lead person can face forward

Track-type Reduced back muscle use; Faster

Latissimus use – on stairs, landings

Sled-type Low muscle demands on stairs.

Transfer in/out; High demands on landing

23

Conclusions from Stair Descent Device Studies

• Track-type devices – several advantages:• Evacuation speed• Physical demands• Ingress / Egress for occupant

• If a hand-carried device is used, device width and handles should support lead person descending facing forward

Cot study I – manual cots

• Design characteristics investigated:• Leg folding mechanism• Handle design options

• Research methods:• 15 experienced EMTs & paramedics (4 F)• Lab-based study• Tasks: load, unload, raise• Weight: 23kg for F, 45 kg for M• Measurements: muscle activity, joint stress,

subject ratings (RPE), task time

24

Cot study I

• Findings

Peak muscle activity during loading

Muscles:              arm                             shoulder                           back  25

Cot study I

• Findings, cont.

Loading: duration, perceived exertion, & preference rank

26

Cot study I

• Findings, cont.Loading: Percentage of trials where legs support weight of cot

27

Cot study I

• Unloading: Interaction of subject height and handle design

Pull-out handles Loop handle

S’s ht= 167 cm

S’s ht= 190 cm

28

Cot study II – powered cots

• Design characteristics investigated:• Leg folding mechanism

• Research methods:• 16 experienced male EMTs & paramedics• Lab-based study• Tasks: load, unload• Weight: 45, 68, 91 kg• Measurements: muscle activity, ground

reaction force, subject ratings (RPE), task time

29

Cot study II

• FindingsPeak muscle activity during loading

A B

30

Cot study II

• Findings, cont.

Vertical ground reaction forces, less participant’s body weight, represent external holding and peak vertical loads experienced

A B

31

Cot study II

• Findings, cont.Perceived exertion

A B

32

Cot study II

• Findings, cont.

• Perceived task time:“I think that the legs of this cot fold and unfold tooslowly.”Cot A – somewhat disagreeCot B – somewhat agree -agree

Measured task time

A

B

Task duration

33

Change

34

Factors that influence adoption in the early stages of implementation of safety-related changes

8 major themes in successful/unsuccessful implementation:1. Implementation leadership 2. Effective training 3. Presence of mock-up 4. Active interaction with employee 5. Trialing and flexibility 6. Employee in the loop 7. Employee's perception 8. Reflection, understanding, internalization

Radin Umar, RZ, 2015, Investigation of Factors Influencing the Adoption of Safety‐Related Changes during the Early Stages of Implementation: An Exploratory Study, unpublished dissertation, The Ohio State University 35

Study of factors affecting paramedics’ adoption of a tri-fold slide board

Weiler, M.R., Lavender, S.A., Crawford, J.M., Reichelt, P.A., Conrad, K.M., Browne, M.W., 2013. A structural equation modelling approach to predicting adoption of a patient‐handling intervention developed for EMS providers. Ergonomics 56, 1698‐1707.

36

Conclusion

• Engineering controls can reduce physical loads • Intervention adoption is a process; requires input from users, time to learn, supportive environment, must fit application and constraints, …

37

Research Collaborators

• Karen Conrad• Paul Reichelt• Glenn Hedman

• Students:• Monica Johnson (Weiler)• Radin Zaid Radin Umar• Peter Le• Jay Mehta• Pei-Ling Ko• Rafael Farfan• Mohini Dutt• SangHyun Park• Jing Li• Tom Stoughton• Xiaojing Wu • Benjamin M. Collins• Adam Kelly• Kyle Hermiller • Brittani Brown• Kailyn Cage• Nicholas Schmidt• Christina Lee

38

Bibliography: EMS research publications• Conrad, K.M., Lavender, S.A., Reichelt, P.A., Meyer, F.T., 2000. A Process for Initiating an Ergonomic Analysis in Jobs with Highly

Variable Tasks. Occupational Health Nursing 48, 423-429.

• Conrad, K.M., Reichelt, P.A., Lavender, S.A., Gacki-Smith, J., Hattle, S., 2008. Designing ergonomic interventions for EMS workers: concept generation of patient-handling devices. Appl Ergon 39, 792-802.

• Lavender, S.A., Conrad, K.M., Reichelt, P.A., Gacki-Smith, J., Kohok, A.K., 2007a. Designing ergonomic interventions for EMS workers, Part I: Transporting patients down the stairs. Appl Ergon 38, 71-81.

• Lavender, S.A., Conrad, K.M., Reichelt, P.A., Johnson, P.W., Meyer, F.T., 2000a. Biomechanical analyses of paramedics simulatingfrequently performed strenuous work tasks. Appl Ergon 31, 167-177.

• Lavender, S.A., Conrad, K.M., Reichelt, P.A., Kohok, A.K., Gacki-Smith, J., 2007b. Designing ergonomic interventions for emergency medical services workers--part III: Bed to stairchair transfers. Appl Ergon 38, 581-589.

• Lavender, S.A., Conrad, K.M., Reichelt, P.A., Kohok, A.K., Gacki-Smith, J., 2007c. Designing ergonomic interventions for EMS workers - part II: lateral transfers. Appl Ergon 38, 227-236.

• Lavender, S.A., Conrad, K.M., Reichelt, P.A., Meyer, F.T., Johnson, P.W., 2000b. Postural analysis of paramedics simulating frequently performed strenuous work tasks. Appl Ergon 31, 45-57.

• Lavender, S.A., Hedman, G.E., Mehta, J.P., Reichelt, P.A., Conrad, K.M., Park, S., 2014. Evaluating the physical demands on firefighters using hand-carried stair descent devices to evacuate mobility-limited occupants from high-rise buildings. Appl Ergon 45, 389-397.

• Sommerich, C.M., Lavender, S.A., Radin Umar, R.Z., Le, P., Mehta, J., Ko, P.L., Farfan, R., Dutt, M., Park, S., 2012. A biomechanical and subjective assessment and comparison of three ambulance cot design configurations. Ergonomics 55, 1350-1361.

• Sommerich, C.M., Lavender, S.A., Radin Umar, R.Z., Li, J., Park, S., Dutt, M., 2015 A biomechanical and subjective comparison oftwo powered ambulance cots. Ergonomics 58, 1885-1896.

• Weiler, M.R., Lavender, S.A., Crawford, J.M., Reichelt, P.A., Conrad, K.M., Browne, M.W., 2012. Identification of factors that affect the adoption of an ergonomic intervention among Emergency Medical Service workers. Ergonomics 55, 1362-1372.

• Weiler, M.R., Lavender, S.A., Crawford, J.M., Reichelt, P.A., Conrad, K.M., Browne, M.W., 2013. A structural equation modelling approach to predicting adoption of a patient-handling intervention developed for EMS providers. Ergonomics 56, 1698-1707.

39