Designing of stretcher for hospital patients, nurses and doctors ...

Designing of stretcher for hospital patients, nurses and doctors with ergonomics and safety approaches to reduce medical work risk and increase

the patient comfortability and safety

Utomo*, Goutama and Kurniawan

Industrial Engineering Department – University of Surabaya, Surabaya, Indonesia, 60293 ([email protected])

ABSTRACT: Stretcher is one of the medical and health equipment that is usually used in the hospital or other medical centers. The study was aimed to design a stretcher by considering the difficulties of nurse and doctor in handling and treating the patient and the safety and comfort of the patient. By modeling handling patient activities, it was known that the nurse working method was not safe, which should be improved to reduce working risks. Literature indicated that the orthodox’s lifting methods resulted more than 100 mmHg intra abdominal pressure (IAP) on the nurse and this pressure was exceed the IAP threshold limit (90 mmHg). The analysis on the existing stretcher found that nurses and doctors faced another problem correlated with the difficulties of therapy to accident victims with the leg fractural problems. Therefore a new stretcher model was designed by applying ergonomics and safety approaches. The new stretcher model applied (1) a sliding mechanism with adjustable bed’s height to avoid lifting activities, (2) safety consideration for the side guard, facilitated with infusion bar, wheel mechanism to accelerate the handling process and separated section on the patient leg (right and left leg) that could be lift one by one. By designing a digital prototyping of the new stretcher, then modeling the new working method and showing the digital prototyping to the doctors, nurses and patients it could be concluded that the new stretcher model have met their expectations and according to the computer modeling also resulted on the reduction on nurse’s working risk.

Keywords: stretcher, IAP, working risk, ergonomic, safety

1. RESEARCH BACKGROUND Stretcher is one of medical and health equipment that is usually used in the hospital or another medical

center with the main function of handling the patient. Several types of stretcher have been produced by considering various function and features. This paper will be focused on the designing hospital’s stretcher by considering the difficulties of nurse and doctor in handling and treating the patient and the safety and comfort of the patient.

In order to know the existing stretcher’s features, then a preliminary study was done to know the various types of stretcher by visiting some hospitals and browsing the stretcher models throughout internet. After the preliminary data have been collected, then the study was followed by interviewing the patients, doctors and nurses about the problems that they usually experienced. By interviewing the patients about the comfort and problem that he/she was in accordance with the usage of a stretcher, it was concluded that some problems were still happened in the usage of existing stretcher model such as: pains and complaints while the patient was being moved by nurses to another bed in the hospital, difficulty to adjust the bed/stretcher’s height by them selves, the barrier design of the stretcher that was not suitable with the patient’s needs. By interviewing the nurses it could be seen that some problems were still happened such as: difficulties of moving a patient to another bed and another room, pains and complaints on the some body segments after lifting and moving a patient, less of facility that should be added in a stretcher, such as: infusion bar, specific place of drugs, oxygen tank holder, difficulties of adjust the height of stretcher. By interviewing some doctors, it could be seen that existing stretcher has a weakness that correlated with a special therapy for a patient with fractural problem because of inflexibility of the existing bed to facilitate the physical therapy. 2. PRODUCT DESIGN STAGES

The research was begun by the problem’s identification of the end users of the stretcher. The end user refers to nurses, doctors and also the patients in the hospital. The data collection was done by interviewing and questioning the end users about the problem of usage the stretcher and measuring the dimension of an existing stretcher. The research steps continued by simulating the nurse’s working posture and analyzing them using several methods such as Rapid Upper Limb Assessment (RULA), energy consumption, and

Utomo et al./ The 9th Southeast Asian Ergonomics Society Conference ()

lifting method. To improve the existing stretcher design then for new stretcher was designed. It started by generating some ideas of improvement’s alternative concepts. By screening and scoring all of the concepts, then the best concept was found to solve the problems and concept testing was done by giving the sketch of the best concept and then showing it to the end users. After concept testing then simulated the new nurse’s working posture uses new stretcher design and continued with analyzing the working posture by RULA method, interviewed the opinions of patient, nurse and doctor about the new design in order to get the best design concept that met the users needs. The steps of the stretcher designing stages were shown in the Figure 1 below:

Existing stretcher dimension

New Stretcher Development-Identification of customer needs-Product specification-Concept generation-Concept selection-Concept testing

Modeling of initial working position

with RULA

Initial Data Collecting

Body segment analysis

Energy consumption

Strength and weakness of existing

stretcher design

Nurses complaints and new features wanted

Safe?No

Analysis of the new working position

Analysis of Energy consumption

Yes

Final concept analysis

Final Data Processing and Analysis

Initial Data Processing & Analysis

Literature study Working posture Modeling

3D Prototype Final and its specification

Problems on the usage of existing stretcher

Nurse :InterviewBody Map QuestionaireHeart pulses rateWorking position

Patient:interview

Doctor :Interview

Doctor’s complaints and new features wanted

Patient’s complaints and new features wanted

Figure 1: Product Design Stages

3. INITIAL DATA COLLECTING, PROCESSING AND ANALYSIS

By studying the literature, it was known that the existing handling method as shown in Figure 2 was an orthodox methods [1] and it resulted more than 100 mmHg intra abdominal pressure (IAP) and this pressure was exceed the IAP threshold limit of 90 mmHg.


Figure 2: Nurse’s Method of Handling the Patient

3.1 Working Posture Analysis with RULA By recording of handling patient activity, then an analysis of static working posture was done by Rapid Upper Limb Assessment (RULA) because the activity of handling the patient was involved the upper limb body segment. By modeling this activity with computer software for a static and intermitten activity as shown in the Figure 3 to 4 below, then some analysis could be done.

Figure 3: Nurse’s Posture of Lifting and Moving the Patient Assumed that a 70 kg mass of patient was handled by 2 nurses and the left and right nurse’s hand were

done the same motion, then work load of 17,5 kg was distributed equally on both of nurse’s hand. Concerning this working posture analysis, it could be shown that the RULA final score was 7 and it means that the working posture can be classified in the action level 4 which is meant the working posture was not safe and it indicates investigation and changes are required immediatelly [2].

Figure 4: Static Posture for Nurses When Lifting and Moving the Patient


Figure 4 showed that although some body segments were in the acceptable grade (green color of indicator), but the RULA final score for both of these working postures were 7. It also can be shown that the static activity had a greater effect on the nurse body segment than the intermittent activity. Finally, we must give more attention on this score because this score is the highest score in the RULA method and it telled us that this working posture was not safe and it indicates investigation and changes are required immediatelly.

3.2 Body Map Questionnaire for the Nurses

To identify the pain and complaints on the nurse’s body segment, then Body Map questionnaire was designed and distributed to the nurses. From the Body Map questionnaire, it could be concluded that the pain and complaint of the body segments were occurred in the activity of pushing the stretcher when moving the patient from one room to another room and lifting and handling the patient where to lay down them on the bed/stretcher. From the first activity (pushing the stretcher), the nurse pain and complaints was happened on the upper arm, knee, calf and ankle because there was no flexible handle bar for nurse to push the wheeling stretcher while moving the patient like to another room like shown in the Figure 5 below

Figure 5: Activity of Moving the Patient

This nurse’s working posture can’t push the stretcher maximally because the position of the stretcher’s handle bar was too low. The similar thing was happened to the second activity (lifting and handling the patient) that caused ergonomics problem especially on the low back, upper arm, shoulder, and also neck segments. The second activity caused the nurse worked in a bent position as shown in the Figure 2 and 3 respectively. This position caused a big torque moment in a low back segment that was potentially for low back pain problem [1]. Another problem that correlated with the existing stretcher design was about the position of the stretcher-control lever that often injured the nurse’s and doctor’s leg while doing a medical check. These symptoms indicate that the stretcher wasn’t designed well, so some improvement should be done to reduce more serious ergonomic problems.

3.3 Energy Consumption Analysis for the Nurses By collecting heart pulse rate data from 10 nurses, it was known that in the initial condition before they

lifted and moved a patient, the average heart pulses of 10 nurses was 79,42 pulses/min while after they lifted a patient the average heart pulses rate was increased to 102,81 pulses/min and the energy consumption would be increased from 0,599 litre/min to 1,06 litre/min [3].

3.4 Analysis of Patient’s Complaints and Uncomfortable Things

Data were also collected from the patients that used the stretcher by interviewing them about the existing stretcher and their comfort. Patient’s complaints were about the pain and other uncomfortable thing that correlated with moving activity that done by nurse, and about some difficulties of the usage of stretcher’s features such as height adjustability and safety barrier usage.

From the initial analysis on the existing stretcher, it was known that the nurses, doctors and patients also faced another problem that correlated with the difficulties of therapy, especially on the patient of accident victims that have leg-fractural problems. The existing stretcher didn’t give a special feature for fractural problem yet, so it caused some difficulties for the doctor to give a physical therapy and reduce the pain and uncomfortable feeling of patient.


4. STRETCHER DESIGNING To overcome these problems, then user’s needs were collected and identified from the patients, nurses

and doctors, then a new stretcher’s model with some special features was designed by improving the existing stretcher with ergonomics and safety approaches. The stretcher design was begin with the identification of customer needs (patients, nurses and doctors) by an interview [5]. The interview results could be summarized in the Table 1 and 2 as followed:

Table 1: Nurse’s Needs

Criteria Count Characteristic Percentage (%) Adjustable bed height 2 Can be operated by a single person 2 Easy while moving the patient 5

Easy of used 39,19%

Adjustable handle-bar height 5 Flexible wheel and can be locked 4 Comfort 39,19%

Position of the stretcher-control handle 3 Safe 13,04% There is a Infusion bag’s bar and a specific place for oxygen tank 2 Complete 8,69%

Total 23 100,00%

Table 2: Patient’s Needs

Criteria Count Characteristic Percentage (%) Functional 5 Can be operated without helps of other people 4 Easy of used 30,00%

Comfort when being moved 13 Stable when being moved 2 Comfort 50,00%

Flexible barrier for patient safety 6 Safe 20,00% Total 30 100,00%

Then product specification was done by identify the needs-metric matrix as shown in the Table 3 below:

Table 3: Need-Metric Matrix Metrik Needs

Mat

eria

l

Met

hode

and

mec

hani

sm

Bar

rier d

esig

n

Feat

ure

Emer

genc

y eq

uipm

ent

Han

dle

bar d

esig

n

Easy of used ● ● ● Comfortable ● ● ● ● Safe ● ● ● Complete Features ● ●

By external search through internet browsing [4] then some existing stretcher concepts were selected to

generate new idea’s of stretcher designing.

.

Figure 6: Existing Stretcher Models


Internal search and analysis about the existing stretcher was also done to enrich the idea of stretcher concepts. Some alternative improvement concepts were generated based on the internal and external search and also the need metric matrix that has been constructed previously. The concept generation step also considered the recommendation of safety design from US Food and Drugs Administration [6]. The improvement concepts were shown in the Figure 7 below.

Figure 7: Concepts Classification Tree for Stretcher


After some concepts of improvements were generated, then it would be selected the best one by concept screening and scoring in the Table 4 and 5 below:

Table 4: Concept Screening Concept

Criteria 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Ref. Easy of used + + + + + + + + 0 0 0 0 0 0 0 0 0

Safe + + + + + + + + + + + + + + + + 0 Comfort + + + + + + + + + + + + + + + + 0 Complete + + + + + + + + + + + + + + + + 0 Sum +'s 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 0 Sum 0's 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 4 Sum -'s 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Net Score 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 0 Rank 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Continue? Y Y Y Y Y Y Y Y N N N N N N N N N

From the Table 4 it is shown that from 16 generated concepts and one reference concept it was eleminated 9 concepts and only remaining 8 concepts. To select the most appropriate concept, it is continued by concept scoring. This step is begun with the calculation of the criteria-weight, and then every concept was given a certain score. By multiplying the weight and the score then it can be determined the weighted score of each criteria. And finally the total weighted-scored as the result of the concept scoring can be shown in the Table 5 below:

Table 5: Concept Scoring Concept

1 (ref.) 2 3 4

Criteria weight score weighted-

score Score weighted-

score score weighted-


score Easy of use 0.3396 3 1.0188 3 1.0188 3 1.0188 3 1.0188 Safe 0.1698 3 0.5094 3 0.5094 3 0.5094 3 0.5094 Comfort 0.4528 3 1.3584 4 1.8112 3 1.3584 4 1.8112 Complete 0.0377 3 0.1131 3 0.1131 3 0.1131 3 0.1131

Total Score 2.9997 3.4525 2.9997 3.4525 Rank 7 4 8 5

Continue? No No No No

Table 5 : Concept Scoring (continued) Concept

5 6 7 8

Criteria weight score weighted-

score Score weighted-



score Easy of use 0.3396 3 1.0188 3 1.0188 3 1.0188 3 1.0188 Safe 0.1698 4 0.6792 4 0.6792 5 0.8490 5 0.8490 Comfort 0.4528 3 1.3584 4 1.8112 3 1.3584 4 1.8112 Complete 0.0377 3 0.1131 3 0.1131 3 0.1131 3 0.1131

Total Score 3.1695 3.6223 3.3393 3.7921 Rank 6 2 3 1

Continue? No No No Yes

Table 5 showed that the best concept that would be developed to improved the existing stretcher model was concept 8. The features of the new stretcher’s model are: sliding mechanism with high adjustability of handling the patient especially from the bed in order to avoid lifting patient activity, safety consideration for the side guard, facilitated with infusion bar and wheel mechanism to accelerate the handling process and also could be separated in the patient leg segment (right and left leg) so it could be lift one by one. For ease purpose, than the height adjustability feature is designed using a hydraulic system in the stretcher frame. The detailed sketch of this concept could be shown in the Figure 8a and b below:


Figure 8a: Three Dimensional of Concept 8 Figure 8b: Side-view’s of Concept 8

After the most suitable concept was designed, then it would be checked by testing the new design to the users with interview and questionnaire. The summary result of concept testing could be shown in Table 6 below. The doctors agreed that with the separated right and left leg on the bed segment it would facilitate the needs of theraphy for the patients with a fractural leg problem. By showing the concept sketch to the nurses, doctors and patients then it was known that the new concept design had the average likert score more than 4 with the maximum of 5. It meaned that the new stretcher design have met the user’s expectations.

Table 6: Concept Testing Result for Nurses and Doctors

Criteria 1 2 3 4 5 Mean

Easy of moving the patient and operating, easy of adjustable bed height, can be operated by a single person

1 7 4 4,25

Comfort in the pull or push the stretcher because of the adjustability of handle-bar height, flexible wheel rotation.

2 8 2 4,00

Safe: correlated with the position of stretcher-control handle 1 8 3 4,17 Complete Features: there are some addition facility such as the place of infusion bag, oxygen tank, etc.

1 5 6 4,42

For the patients, concept testing was done by interviewing the patients directly who in hospital and they

generally agreed that the new stretcher design would be easier than the existing one, more comfortable while the patient was being moved and safer than the old one. 5. FINAL DATA PROCESSING AND ANALYSIS

After the final concept has been determined and tested to the end user, then it would be analyzed by the modeling of the new working posture using this new stretcher. Although according to the last interview in the concept testing, it could be concluded that the new stretcher model have met the doctor’s, nurse’s and patient’s expectations, but the analysis of new working posture was still needed to support the new design. By designing the nurse’s working position with the new stretcher through digital prototyping using computer software as shown in the Figure 10 below, it is known that the new working method is better than old one because on the new method, the nurses would not lift the patient but they only pull or push the stretcher to move the patient in the hospital bed if the patient need more intensive treatment.


Figure 10: RULA Output of the nurse’s new working posture

By pulling or pushing the stretcher when moving the patient, it can be reduced the nurse’s working

risk in the intitial condition using the existing stretcher. Through this computer modeling, it can be shown that the RULA score per body segment, especially in wrist, upper arm, neck and trunk become lower than the initial working condition. As the final result, this new working position has a RULA final score 4 with action level 2 and it is mean that the new working position is better than the old working position with the existing stretcher. The RULA’s result of the new working posture can be shown in the Figure 11 below:

Figure 11: RULA Output per body segment in the new working posture with new stretcher’s design

From the energy consumption analysis, the new working method needs a smaller energy consumption because of the operator need not neccessary lift the patient, but only pulled or pushed the tretcher. It can be shown the energy consumption of pulling or pushing activity is smaller than lifting of a load. [7] 6. CONCLUSION AND RECOMMENDATION

From the stretcher designing above, it was known that: 1. According to the user’s pain and complaints and also energy consumption analysis it is shown that the

initial working posture with the existing stretcher should be changed to reduce the working risk. 2. By modeling the working position of moving a patient with RULA’s method in the hospital it can be

shown that the initial nurse’s working posture with the existing stretcher resulted RULA final score 7 and it means that the initial working posture was not safe and it indicates investigation and changes are required immediatelly, while the new stretcher’s design resulted RULA final score 4 and it means that the nurse’s working posture is safer than the initial one.


3. The best stretcher’s design the one that met the user expectation was the stretcher that can move the patient altogether and it has double side guard that can be folded radially and a separated right and left of bed’s segment.

4. According to the opinion of the users (nurses, doctors and patients) it was known that the new stretcher design is easier to use, more comfortable, and safer to used than the existing stretcher. The new stretcher design also can facilitate the therapy of the patients with a fractural leg problem.

7. REFERENCES 1. K.H.E. Kroemer and E Grandjean, (1997), Fitting the Task to the Human, 5th edition, Taylor & Francis.

Great Britain 2. John R Wilson dan E Nigel Corlett (1995), Evaluation of Human Work, Taylor & Francis Ltd., Great

Britain. 3. Karl Kroemer, Henrike Kroemer Katrin Kroemer-Elbert (1994), Ergonomics How to Design for Ease and

Efficiency, Prentice-Hall Inc, New Jersey USA. 4. http://tdmachinery.en.alibaba.com/offerdetail/50799448/Sell_Ambulance_Stretcher.html

http://xxyysb.en.alibaba.com/offerdetail/57245035/Sell_Aluminum_Ally_Ambulance_Stretcher.html

http://zjgjinhua.en.alibaba.com/offerdetail/55499171/Sell_Aluminum_Alloy_Stretcher_for_Ambulance.html

5. Ulrich, Kerl T dan Eppinger, Steven D (2003), Product Design and Development, 3rd edition, McGraw Hill/Irwin, Singapore.

6. Guidance for Industry and FDA Staff, March 2006, Hospital Bed System Dimensional and Assessment Guidance to Reduced Entrapment, US Departemental of Health and Human Services Food and Drug Administration Center for Devices and Radiological Health.

7. Sanders dan Mc Cormick (1993), Human Factors in Engineering and Design, 7th edition, Mc Graw-Hill Book Co, Singapore.

Designing of stretcher for hospital patients, nurses and doctors ...

Documents

Transcript of Designing of stretcher for hospital patients, nurses and doctors ...